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904 trans died behind 390 stroker ** UPDATE **
Posted By: tpabayflyer
904 trans died behind 390 stroker ** UPDATE ** - 10/20/08 06:03 PM
I had a fresh 904(999) lockup trans built for my 390. Lasted less than 500 miles and lost all forward gears and reverse as well. I noticed some rough full throttle 1-2 upshifts lately and have another thread on that subject.
I don't know the status of the 999 trans and I am not sure what would cause it to lose all fwd gears and reverse as well. Should I do an autopsy and take it from their or should i just plan on an upgrade to the 727??? I did install a transgo shift kit in the valve body and I was wondering if I found an A-727 lockup trans would this valve body work or should I just go with a non-lockup and re-do another valve body??
This trans did not have the low band apply as it would freewheel in 1st gear when coasting. I did do some burnouts in 1st gear so I wonder if i did some damage????
FWIW, trans looks fine with no leaks and driveshaft is intact as well as the 8 3/4 rear......... TBF
Posted By: stumpy
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 07:11 PM
You didn't answer on the other post but do you have a kickdown linkage hooked up?
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 07:24 PM
Dissect it & find out what happened. I knew of a 66 A body that was in the 10's(strip only) with a not too special 904. Stay with it, a 904 can handle it.
Posted By: dusturbd340W5
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 07:37 PM
a broken input or output shaft would cause no movement so would a stripped converter or broken pump gears so no way to know with out tearing it down.As someone thats been in the buisness over 20 years I would forget about the whole lockup deal.
Posted By: scratchnfotraction
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 07:38 PM
727 non lock up
takes more hp to turn it,but holds up better than a 904 tranny
I am in the same boat with ya right now,my 904 is going south real fast,been babying it latly since it started slipping,I tightend the kick down band and it stoped slipping but the adjuster is in all the way in with just enuff threds to hold the lock nut on
I am going with a 76 loadflight 727 with a short shaft bolt on yoke from a truck,and will build a drive shaft with a slip yoke
well thats after a rebuild cause the sprag is gone in it,took about 8 N drops to kill it after 7-8 yrs of hard driving it
best 50$ tranny I ever got from the clearwater u-pull it
gonna try and save the 904 as a spare maybe if it dont die before I gets the 727 done
good luck with it
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 07:55 PM
Thanks guys.. yes I do have the kickdown linkage installed properly... I have done some research and I wonder if the front pump has failed??? I guess the pump gears failing would have the same effect??? \
Obviously the trans will be coming out and I wonder if I should get a 727 to build??? I do like the 2.74 low gear of the 999 and I did spend over $300 for a 2,600stall lockup converter. I would also need to have the driveshaft shortened and get another converter but I would like to get a 3,000 stall to optimize my combo. I could actually use the lockup converter for my future grand cherokee 390 project so its not a big deal. I did spend a few hundred on the rebuild kit so i would like to use what I have if possible....... Is there a way I could check to see if the pump is working??? with the engine running and trans in neutral would fluid be flowing??? I have a trans cooler up front and could check that pretty easily??? I wish I could find a $50 JY tranny that would work!!! TBF
Posted By: mikepar
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 09:04 PM
Dawg
To check the front pump action note the fluid level on the dip stick WITH the engine off.
Start it up and check the level again running,
the level will be lower on the stick which means the pump is werkin
Posted By: 1BAD68
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 09:28 PM
I would stick with the 904, I have one behind my 390 and have beat the snot out of it this summer with about 3300 miles. It was stock but I added a Transgo shift kit and it made the 1st to 2nd shifts so hard I actually thought I would snap a u-joint eventually but never did.
Mine started to not downshift automatically when stopping so my plan is to have it rebuilt this winter and continue to torture it. The 904 is pretty stout and should be able to handle all that a 390 stroker can dish out.
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 11:35 PM
stick with the 904.
A bad front pump can still pump enough to raise and lower the tranny fluid level, that is not a good way to test it. If you think you want to test it first it is real simple to hook up a preasure gauge to the line preasure port and see if you have line preasure. I wouldn't bother though, it has to come out any how.
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/20/08 11:56 PM
Neck snapping shifts is usually a sign of overlap, not a good shift.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 03:22 AM
My 1-2 shift was brutal after I adjusted the front band properly...... I'll start taking this out tomorrow and report back.... TBF
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 03:24 AM
If the front pump failed would it be a relatively easy fix to get at the pump from the front of the trans or does everthing need to come out??? TBF
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 03:40 AM
Quote:
If the front pump failed would it be a relatively easy fix to get at the pump from the front of the trans YES or does everthing need to come out??? TBF NO
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 01:10 PM
Quote:
If the front pump failed would it be a relatively easy fix to get at the pump from the front of the trans or does everthing need to come out??? TBF
if the pump failed it usually breaks the tangs off the rotor and/or breaks the snout of the convertor , metal particles go everywhere ...
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 01:57 PM
Great.... well I'll find out later when I drop the trans..... Now back to the original question, Does anybody know what would cause the loss of all forward gears as well as reverse??? Is the front pump a likely guess? TBF
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 02:02 PM
Quote:
Great.... well I'll find out later when I drop the trans..... Now back to the original question, Does anybody know what would cause the loss of all forward gears as well as reverse??? Is the front pump a likely guess? TBF
I think what caused it was a 904 behind that motor. for you to have lost all forward motion either you have no fluid flow of a shaft broke .
Pull a line off the trans cooler , direct it int oa bucket and start it up with the car in neutral , if you get no flow then its the pump , if you get fluid you broke a shaft .
Either way I would be putting a 727 behind that , 904's to handle torquey motors need $$$ parts .
Posted By: MNobody
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 03:10 PM
Quote:
Quote:
Great.... well I'll find out later when I drop the trans..... Now back to the original question, Does anybody know what would cause the loss of all forward gears as well as reverse??? Is the front pump a likely guess? TBF
I think what caused it was a 904 behind that motor. for you to have lost all forward motion either you have no fluid flow of a shaft broke .
Pull a line off the trans cooler , direct it int oa bucket and start it up with the car in neutral , if you get no flow then its the pump , if you get fluid you broke a shaft .
Either way I would be putting a 727 behind that , 904's to handle torquey motors need $$$ parts .
That sound's like good advice to me from what i have read from several other post's.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 07:50 PM
Quick update, pump is working as a shower of trans fluid shot out the hose when I fired it up for 2 seconds...... I guess now the input shaft or the converter snout is stripped..... I am leaning towards the converter threads being stripped as it is a lockup style converter and I wonder how strong they are??? Car is jacked up now and trans should be out soon....... If I replace the converter is the same thing going to happen again???????
Maybe the 727 might be the best way to go
TBF
Posted By: Locomotion
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 09:58 PM
Whether or not the lock-up converter had anything to do with the failure, it was never intended to be used in performance applications. Valve bodies are different too and the parts don't interchange, but I don't know what the differences are. With the right parts, a lock-up trans can be converterted to a non-lock-up and, of course, the low gear sets do interchange. A regular 904 trans, built properly, will work fine. But a regular 727 is stronger and will likely last longer simply because of the bigger, stronger parts used. The key words are "regular" and "non lock-up". I have a few years on the 904 in my car built by JW but may swap it out for freshening this off-season to be safe. Nothing special or trick, just their reverse manual valve body, a low gear set and whatever HD bands and clutches they use. I also use Amsoil Supershift synthetic fluid.
I have heard that OEM bands may not hold up to hard shifts because of the material. Same reasoning if using a 5.0 lever. There are a couple different performance bands too. Between "blue" and "red", I believe the red are best. I just never got into transmissions and let JW take care of that.
I don't think a freewheeling low gear is a good idea on the street either.
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/21/08 11:32 PM
Quote:
Car is jacked up now and trans should be out soon....... If I replace the converter is the same thing going to happen again???????
TBF
Continue with the autopsy, inquiring minds want to know
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/22/08 12:03 AM
Quote:
Quote:
If the front pump failed would it be a relatively easy fix to get at the pump from the front of the trans or does everthing need to come out??? TBF
if the pump failed it usually breaks the tangs off the rotor and/or breaks the snout of the convertor , metal particles go everywhere ...
yes JohnRR is correct there would be (metal)crap throughout. I can't believe that I am actually agreeing with JohnRR 
Posted By: 1965_PLYMOUTH
Re: 904 trans died behind 390 stroker, time for 727???? - 10/22/08 12:18 AM
wow. come on guys. there's a reason MA MOPAR put 727's behind all the 340's. they needed a reliable tranny behind the horsepower. I myself have seen enough cracked torque converter hubs, and front seal leaks on 904 tranny's to just want something bigger and better. just my
Posted By: 5thAve
Re: 904 trans died behind 390 stroker, time for 727???? - 10/23/08 12:32 AM
Get a 727 it has more of a chance of lasting longer.
Posted By: Rug_Trucker
Re: 904 trans died behind 390 stroker, time for 727???? - 10/23/08 03:20 AM
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/23/08 01:23 PM
When I had the trans rebuilt I did use a heavy duty red band... The valve body is original with a transgo shift kit and the trans always would freewheel in 1st gear, even before the rebuild so that must be how it works.......
I did not get a chance to pull the trans yet and it will have to wait until the weekend. I wanted to take this car up to the garlits show next week but I am glad the trans broke close to home...... Keep munchin the popcorn as I will have the autopsy results soon...... TBF
Posted By: dusturbd340W5
Re: 904 trans died behind 390 stroker, time for 727???? - 10/23/08 01:53 PM
I have installed a lot of transgo shift kits tf1 and tf2s in factory VBs and never had one free wheel in 1st.Factory Vb has low band apply in manual 1st. Unless you used a tf3 that is full manual and I dont remember if they free wheel in manual 1st or not its been to long on that one.
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 12:44 AM
I always use the transgo kits and have never had one that would frere wheel. I set up the one in my 904 in my cuda with a TF1 with all the biggest shift valve holes and if you manually hit 1st at a high enough speed the rpms go way high your forehead hits the steering wheel and the back end starts sliding around, my engine makes a lot of vaccume
Posted By: dustpan man
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 03:19 AM
sounds like a vavle body problem
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 03:49 AM
I think it was the TF-1 kit but remember this is a lockup converter valve body.......It has an S-bend tube on the top..... Even before I messed with anything drove the car with the stock 318 2bbl the trans would freewheel in 1 st gear. I remember it would not provide engine breaking in 1st gear but I thin it would if i held it down in first... it would freewheel when left in drive???? TBF
Posted By: Anonymous
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 10:50 AM
Quote:
sounds like a vavle body problem
thats what I thought of too. the valves can wear out over many many miles. Or some crap got in there and is blocking something.
I put aB&M shift kit in mine many years ago and it performed great. then the car sat for several years. I just put together a motor and started driving it again and after a few hundred miles, mine started freewheeling when I downshifted to first.
I changed out the valve body for a Turbo Action Cheetah manual/automatic valve body and everything is GOOD, and I mean real GOOD, now. shifting is tight, and problems went away
Posted By: patrick
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 12:00 PM
Quote:
I think it was the TF-1 kit but remember this is a lockup converter valve body.......It has an S-bend tube on the top..... Even before I messed with anything drove the car with the stock 318 2bbl the trans would freewheel in 1 st gear. I remember it would not provide engine breaking in 1st gear but I thin it would if i held it down in first... it would freewheel when left in drive???? TBF
stock, the tranny won't downshift to first until under 5mph when coasting.
Posted By: AdamR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 12:42 PM
904 + 450+ hp =
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 03:14 PM
Quote:
I think it was the TF-1 kit but remember this is a lockup converter valve body.......It has an S-bend tube on the top..... Even before I messed with anything drove the car with the stock 318 2bbl the trans would freewheel in 1 st gear. I remember it would not provide engine breaking in 1st gear but I thin it would if i held it down in first... it would freewheel when left in drive???? TBF
Might be an issue with the over running clutch ? The lockup convertor and it's fluid path should have ZERO effect on first gear operation .
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 11:22 PM
Quote:
Quote:
I think it was the TF-1 kit but remember this is a lockup converter valve body.......It has an S-bend tube on the top..... Even before I messed with anything drove the car with the stock 318 2bbl the trans would freewheel in 1 st gear. I remember it would not provide engine breaking in 1st gear but I thin it would if i held it down in first... it would freewheel when left in drive???? TBF
Might be an issue with the over running clutch ? The lockup convertor and it's fluid path should have ZERO effect on first gear operation .
Gonna have to agree with JohnRR on this, my trans is a lock up 904 and I got no freewheeling.
I think the free wheeling is from the low reverse band not applying in manual low and it should be applying with a TF 1 2 or 3 kit in manual and auto low. If reverse is fine then the band is functional and you need to figure out why it is not applying.
BTW I really like LU in a street car especially with a high stall converter
Posted By: turbocolt2.4L
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 11:27 PM
Quote:
904 + 450+ hp =
OUCH I have 480 hp to the rear wheels with a 4cyl turbo car and run a 904 w/brake with no major problems,just took out the sprag but had over 130 pulls on the chassis dyno and 4 hard passes at the track 904's can take a beatin.........
Posted By: 469runner
Re: 904 trans died behind 390 stroker, time for 727???? - 10/24/08 11:33 PM
Yes, 904's can take beatings...those lockup torque convertors can't. Most likely that is the cause of your no-drive condition. Been there on my 88 Diplomat ofter installing a nice 360.
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 01:29 PM
Quote:
Quote:
904 + 450+ hp =
OUCH I have 480 hp to the rear wheels with a 4cyl turbo car and run a 904 w/brake with no major problems,just took out the sprag but had over 130 pulls on the chassis dyno and 4 hard passes at the track 904's can take a beatin.........
and that colt weighs HOW MUCH ??? 904 will live just fine bolted to a ROLLER SKATE ... 
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 01:45 PM
I am fixing to find out as I am putting a 904(& a /6 one at that)behind a 451 going into a 65 dart) with a JW ultrabell. I am not going to romp on it too much
Posted By: babarracuda
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 02:35 PM
I have had 904's since 93 with everything from a 275HP 318 to a 500 HP race 360. A lock up converter is weak. I am so sick of 727 gurus hailing them when they have no practical experience with 904's. I sold my engine and trans to a guy in 2002 and he is still running the trans. Talk to John Cope at CRT. I think the biggest problem is the lockup trans, not being a 904.
Tune in for my next sermon " too big a cam will make a good street motor a dog"
Posted By: fasteddie
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 07:18 PM
My tow vehicle is a '89 3/4 ton van with the 999 with lock up (hd 904). I've had it for 11 years and towed locally and made a few trips towing out of town. It was still towing fine but started leaking bad out the front seal and it stopped locking up. Had it rebuilt while it was out for the front seal fix and put in a new converter.
Last week we towed to Elk Creek Dragway, about 70 miles one way and up and down a couple of steep mountains. No problems. It towed like a champ.
Race car and open trailer weighs about 4900 lbs.
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 08:56 PM
Being a lock up does not make it a bad tranny. The only thing different is the converter has a clutch to lock up at cruising speed. If you want to run a lock up behind a high-po mill just drill the releif passages in the VB out so it locks up faster (buy the Trans-go TF 12 or 3 kit of your choice for details) drill the holes to max diameter or even one size bigger to really firm it up so it don't slip and burn. Also install the stiff spring to delay engagement untill a higher speed. I have built several for my various cars and a couple were race cars, all were strong street cars at the least and the only one that I ever had fail was one where my cooler line blew on the way to the track and I kept driving it, it wouldn't hardly move when I got there, I raced that night after fixing it at the track. And the next day the forward clutches gave out, I rebuilt it and used the same converter and never had another problem racing that trans till I sold the car. If you build the trans right the 904 is not a problem and LU is not a problem.
PS ask Andy Mayes about the LU 904 in his roofing truck I built with a TF3 kit. He still cusses at me for building a manual shift trans for a work truck, I just did it to see if I liked it and then he bought the truck from me and is still driving it years later, says hes going to put a 727 in if he can ever kill it
Posted By: MoparDonny
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 09:29 PM
Drain the converter and look way inside at the splines that the input shaft engages into. Just replaced a converter in a customers car yesterday for that reason, sheared splines. Have seen alot of 904's with busted hubs too. Ya, a 904 or a C4 (ford) can be made to take abuse, but they are no 727 or C6. Anyone I've ever known with a hard driven 904 got it refreshed on a regular basis.
Don.
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 10:01 PM
Quote:
I am fixing to find out as I am putting a 904(& a /6 one at that)behind a 451 going into a 65 dart) with a JW ultrabell. I am not going to romp on it too much
If you haven't upgraded the guts you're gonna be sorely disappointed. Slant 904's only have 3 pinion planetaries and 3 disc clutches.
Posted By: turbocolt2.4L
Re: 904 trans died behind 390 stroker, time for 727???? - 10/25/08 11:09 PM
Quote:
Quote:
Quote:
904 + 450+ hp =
OUCH I have 480 hp to the rear wheels with a 4cyl turbo car and run a 904 w/brake with no major problems,just took out the sprag but had over 130 pulls on the chassis dyno and 4 hard passes at the track 904's can take a beatin.........
and that colt weighs HOW MUCH ??? 904 will live just fine bolted to a ROLLER SKATE ...
2495 with me. BTW i leave with 29psi of boost on the brake at 7500rpm so we'll see if the 8.75 holds........... :
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 02:27 AM
Quote:
Quote:
I am fixing to find out as I am putting a 904(& a /6 one at that)behind a 451 going into a 65 dart) with a JW ultrabell. I am not going to romp on it too much
If you haven't upgraded the guts you're gonna be sorely disappointed. Slant 904's only have 3 pinion planetaries and 3 disc clutches.
yes that does sound pretty skimpy. I have this one already milled down to the front pump so I would be well advised(thank you slantzilla) to tweak it ahead of time.
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 03:01 AM
Quote:
If you haven't upgraded the guts you're gonna be sorely disappointed. Slant 904's only have 3 pinion planetaries and 3 disc clutches.
yes that does sound pretty skimpy. I have this one already milled down to the front pump so I would be well advised(thank you slantzilla) to tweak it ahead of time.
Bright side is that all the V-8 guts will fit right in the Slant case. I have the 4 disc clutches and 4 pinion planetaries in mine and have never hurt it running low 12's on the hose.
IIRC, there are also 5 disc drums in some truck trans' that will drop in too. 
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 03:28 AM
what truck apps had the 5 clutch drums? & I do have a 904 from a 318 laying around. If I end up really beefing this thing I'm going to have to romp on it just to check out my handiwork.
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 04:02 AM
Not real sure, but I would guess 4wd trucks.
Posted By: turbocolt2.4L
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 10:54 AM
I thought the cordoba's had the 5 clutch direct drums but you need to machine the pump to fit the drum(non l/u)
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 12:42 PM
Quote:
I thought the cordoba's had the 5 clutch direct drums but you need to machine the pump to fit the drum(non l/u)
That is entirely possible.
BTW, your car is incredible! 
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 05:34 PM
the late 70s 360 4bbl motors and mabey even the 2bbl motors in cars had 5 clutch front drums with non LU trannys. They were called A-999s. They were a heavy duty 904 non-lu. Later LU 904s from trucks in the early 80s and later had 5 clutch front drums and low 1st and 2nd gears. The low ratio gears are the toughest stock gear sets also, 4 pinions and steel cages. I know there is some way to put these drums in a non-lu 904 but I don't remember exactly what needs to be done.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/26/08 09:52 PM
Thanks for all the reply's fellas... If the converter snout is fubarred like the previous picture than what is the best course of action??? 727?????? non lockup converter????? I have even been kicking around the idea of putting in a new 451, hyd roller cam, E-head motor that I have been sitting on for a few years now.... I even have an extra B-727 trans in the garage I could build..... I figure I could sell the new 390 and get the parts needed to convert the Cordoba over to Big Block power................
I won't have a chance to get the trans out until tuesday now I will have an update then.... TBF
Posted By: CJK440
Re: 904 trans died behind 390 stroker, time for 727???? - 10/27/08 01:23 PM
A&A sells a special thin disk with grooves to install in a 4 clutch drum so you end up with 5 disks. The grooves evacuate the fluid fast when applied since its a shifting clutch.
The parts needed out of the A-999 are the front pump, Front drum (deeper) and rear drum (has a wider hub to engage all 5 disks).
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 06:52 PM
Well.. I don't who the lucky winner is but it looks like the input shaft snapped in half...... The remaining threads show some evidence of twisting before failing.....
Now, If I put a new input shaft in can I expect the same problem to happen again?? I would think so... Is this problem associated with the lockup converter system?? Does a non-lockup have a solid style input shaft that is thicker and stronger??? If so can I install a non-lockup input shaft in this trans and just get a different converter????
Or should I just dump this whole mess and build a nice 727????? TIA TBF
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 06:54 PM
input shaft end
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 06:55 PM
threads are twisted a bit... kinda blurry.. TBF
Posted By: scratchnfotraction
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 07:07 PM
way to go!!!
a 390 with 3.73 gears done killed flight 904
wonder if anything else was damaged?
full of shavings? pan still clean?
in the long run..I would go 727 IMO
dont guess your gonna get to drive up to big daddys this weekend
do you have a 727 core yet?
may find one quick at the clearwater u-pull it,holler if ya need a hand with it,may take friday off and be over there looking for one myself
turkey day weekend sale is a comin also
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 07:36 PM
Thanks anyway but I am heading out of town until sat morning.. trans looks good except for a clean break in the input shaft... no debris at all.. TBF
Posted By: scratchnfotraction
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 07:41 PM
replace shaft in it and hammer it again,
I let you know what I see there as far as 727s
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/29/08 07:50 PM
Quote:
trans looks good except for a clean break in the input shaft... no debris at all.. TBF
replace it & continue on. Sometimes parts do fail.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 12:20 AM
Well.. if I replace it will I be back here next month with the same problem ???? I have maybe 500 miles on the engine and trans and I don't want to go through this exercise again...... Is there a heavy duty input shaft that I can get????? Is there anything I can do to minimize the chances of a repeat???? FWIW, when the trans failed I was at the dragstrip with my drag radials on for the first time and it let go at the 1-2 shift........ At this point, I would rather spend the time and money and go 727. I don't want to just replace the input shaft and hope for the best as I think a new one will just end up snapping again. I do like having the 2.74 low gearset and I spent alot of money on a fresh rebuild with good parts but if I can't be somewhat assured that I won't break a new shaft I don't think it is smart money to "hope" I won't have another failure.... I want to have fun with this car and take it to the strip often. TBF
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 12:40 AM
I think it will be fine. Mabey have the new one magnafluxed shot peened or something. I have ran them in similar apps and have been running in daily use with no problems. The LU shaft is a bigger diameter than the non LU shaft but it does have as hole in it. It should work out to them being about the same and mabey even a touch stronger on the non LU but I am sure there could be a huge debate about that. Many guys are running stock input shafts on strong motors and it is just not a typical weak link
Posted By: Anonymous
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 02:36 AM
Quote:
Well.. if I replace it will I be back here next month with the same problem ???? I have maybe 500 miles on the engine and trans and I don't want to go through this exercise again...... Is there a heavy duty input shaft that I can get????? Is there anything I can do to minimize the chances of a repeat???? FWIW, when the trans failed I was at the dragstrip with my drag radials on for the first time and it let go at the 1-2 shift........ At this point, I would rather spend the time and money and go 727. I don't want to just replace the input shaft and hope for the best as I think a new one will just end up snapping again. I do like having the 2.74 low gearset and I spent alot of money on a fresh rebuild with good parts but if I can't be somewhat assured that I won't break a new shaft I don't think it is smart money to "hope" I won't have another failure.... I want to have fun with this car and take it to the strip often. TBF
whats the build specs on the motor. unless youre running SERIOUS HP, you shouldnt worry about breaking shafts like that. most likely had a defect
Posted By: MoparDonny
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 03:37 AM
If it makes you feel better, I've been working in a transmission shop for 7 years and never seen a broken input shaft. As I stated before, only ever seen the splines gone out of the converter. I think you should be fine. Get another input shaft and put it back together. Then as a good upgrade later on, do up a 727. May as well get some life outta that 904.
Don.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 03:41 AM
O.K.... thanks for the input fellas.... well, I guess I will try and find a new shaft and give it one more shot!!!!
Are these input shafts from a forging??? I would think so and I did look closely at the shaft and there may have been some porosity issues at the break point. You can't see it too well from my picture because my flash overpowered the shot but it looks like something is there right at the break..... when I get back home I will try and take a better pic.... also fwiw my trans mount was pretty much shot which was allowing some movement and I wonder if that may have been a factor here??? TBF
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 03:53 AM
Another question is the sprag.... The overrunning clutch issue with the 727's is a big deal whenever you have a driveline issue such as a rear end failure. I wonder if I should check it out??? When this thing snapped it did not seem to put a load on, or shock the driveline at all. I just hit 2nd gear and pretty much coasted to the turnoff....... This engine is not a real powerhouse, maybe 430-440HP at the crank..... 1970 318 block .030 over, ported magnum heads 2.02 intakes, 4" crank forged pistons 9.7-1 C/R, Comp HE-275HL cam 231/237,1.6 roller rockers .565lift, hooker headers 1 3/4tube 3"collector and Torker 2 intake..... I think I may have gotten unlucky with a bad input shaft.....Now who has one for a 999 Lockup trans or do I have to scrounge around at the junky??? TBF
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 12:39 PM
Quote:
Another question is the sprag.... The overrunning clutch issue with the 727's is a big deal whenever you have a driveline issue such as a rear end failure. I wonder if I should check it out??? When this thing snapped it did not seem to put a load on, or shock the driveline at all. I just hit 2nd gear and pretty much coasted to the turnoff....... This engine is not a real powerhouse, maybe 430-440HP at the crank..... 1970 318 block .030 over, ported magnum heads 2.02 intakes, 4" crank forged pistons 9.7-1 C/R, Comp HE-275HL cam 231/237,1.6 roller rockers .565lift, hooker headers 1 3/4tube 3"collector and Torker 2 intake..... I think I may have gotten unlucky with a bad input shaft.....Now who has one for a 999 Lockup trans or do I have to scrounge around at the junky??? TBF
The trans should be completely disassembled and checked out .
It's not HP that breaks stuff it's the TORQUE .
If it were me I wouldn't waste another penny on that trans .
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 08:52 PM
If you were having trouble with the 1-2 shift you probably were having overlap, not a firm shift. That will break lots of parts too.
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 10/30/08 11:07 PM
I got a couple layin around PM me and I will take a good look at them and see if I got a nice one for ya cheap.
Posted By: MoparDonny
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 01:00 AM
Quote:
Another question is the sprag....
You wouldn't have damaged the sprag from breaking the input shaft. It's when something lets go behind the trans that you worry about the sprag.
Don
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 01:13 AM
Quote:
Quote:
Another question is the sprag....
You wouldn't have damaged the sprag from breaking the input shaft. It's when something lets go behind the trans that you worry about the sprag.
Don
but he says he has a problem with no engine braking in first gear
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 01:24 AM
Posted By: MoparDonny
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 01:41 AM
Quote:
Quote:
Quote:
Another question is the sprag....
You wouldn't have damaged the sprag from breaking the input shaft. It's when something lets go behind the trans that you worry about the sprag.
Don
but he says he has a problem with no engine braking in first gear
...... Forgot about that John. 
my bad.
Don.
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 01:47 AM
normally I am a believer in listening to your gut but not this time. fix that part & give that 904 another chance
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 03:57 AM
I found this chart in an article from carcraft.......
Mopar Automatic Transmission Guide
This list is not conclusive or absolute, but provides general guidelines with respect to power ratings.
Trans Year Small-Block Big-Block Stock Modified
904/998/999 '60 X -- D B
727 '62 X X A A
500 '88 X -- C C
518/618 '90 X -- A A
Note: In place of a vacuum modulator, Chrysler automatic transmissions use a rod or a cable to control throttle pressure and kickdown.
*Ratings: A = High torque, heavy car; B = High torque, light car; C = Low torque, heavy car; D = Low torque, light car
I have a somewhat heavy car with a somewhat high torque engine and I think I am on the edge with this trans holding up....... I think I need some pepto bismol to quiet my gut down
TBF
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 04:01 AM
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 04:08 AM
Quote:
I think I need some pepto bismol to quiet my gut down TBF
Dont give up now you are so close & when it holds up the 2nd time you'll appreciate the fact that the lower weight(overall & rotating) is giving YOU a performance edge. You were ready to go for it until Johnrr chimed in & got you to thinking again 
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 06:45 AM
Posted By: scratchnfotraction
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 12:07 PM
IMO..727 all the way
add motor for the drag loss of a bigger tranny
might not be the input shaft that lets go next time out
then it becomes wasted $$$
and you will need the core 727 just to start over
let ya know what I see at the the u-pull it
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 12:50 PM
Quote:
Quote:
I think I need some pepto bismol to quiet my gut down TBF
Dont give up now you are so close & when it holds up the 2nd time you'll appreciate the fact that the lower weight(overall & rotating) is giving YOU a performance edge. You were ready to go for it until Johnrr chimed in & got you to thinking again
Sure, I'll stop pointing out the OBVIOUS 
Posted By: patrick
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 12:50 PM
looking at pics of the failure, it's kinda hard to tell because of the out of focusness, but I'd guess there was probably a defect on the face of the shaft (a small nick or something) that was a stress concentrator, where a crack propagated from....I'd get a new shaft, inspect it, and if there are any nicks, etc, smooth them out, and run with it.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 03:07 PM
When I get home tomorrow I will try and take some better pictures of the fractured shaft..... As far as wanting to go with the 727, John did not change my mind but he did re-inforce my belief that what you see is what you get......
I broke the shaft once and that is not a good sign. It looks like it is an unusual failure and quite rare so hopefully it was a defect in the shaft that caused the failure. I will try and give this trans one more shot and see what happens..... If it lets go again I am going to install my edelbrock head, hyd roller cam 451 in with a b-727 I have sitting around. This 318 stroker (390) is quite a torquey engine and is in fact larger than a 383 that the factory never put a 904 behind. I have better heads, exhaust, and more cam than any stock 383 so I think I am on the edge with this tranny
...
But I'll give it one more shot. I almost hope it breaks
again as I want to go big block and weld in a roll cage! TBF
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 03:16 PM
Quote:
It looks like it is an unusual failure and quite rare so hopefully it was a defect in the shaft that caused the failure. I will give this trans one more shot TBF
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 04:30 PM
You need to find out what the 1-2 banging is , thats what BROKE the shaft .
Posted By: 5thAve
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 06:09 PM
Go with your gut and get a 727. You know you want to
Posted By: slantzilla
Re: 904 trans died behind 390 stroker, time for 727???? - 10/31/08 08:51 PM
Quote:
You need to find out what the 1-2 banging is , thats what BROKE the shaft .
Yep.
PM board member 727specialists . He does my 904's and they are pretty tough. He will help you make a Torqflite hold up w/o all that high dollar crap people lead to believe you need.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 01:29 AM
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 12:48 PM
the weight is for harmonics , most people ditch it , if you havea vibration afterwards return it or check the driveshaft balance .
the mount didn't break the shaft .
I have a cryo'd output shaft in my ram 47RE , haven't broken it yet , but I also haven't TRIED to break it after the last time
Posted By: MoparJoe
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 01:54 PM
Thats the first time I've seen a 904 break an input shaft, usually they break the case before any internal parts let go.
Maybe I missed it but who built it?
Posted By: RapidRobert
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 02:28 PM
Quote:
On a side note, has anybody ever done the "cryogenic freezing" of parts?? I heard it may make some parts stronger by "aligning' the molecules somehow??? I have no knowledge of this space age PFM type stuff so I wonder if I should look into dipping my new input shaft in the deep freeze TBF
I hear it works but is extremely $$$ as you are dealing with frozen nitrogen rather than your kitchen freezer. If anyone on here is having their body cryo'd after death maybe they could do you a favor & let you dip a part.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 10:18 PM
Thanks John.. great minds think alike!!!!! I had no idea that somebody had actually had that done..... I remember reading something about this cryo treatment but I can't and won't spend alot of money to have it done. How much did you spend???? Enquiring minds want to know
I will try and post a better pic of the snapped shaft after I mow the lawn... TBF
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 11/01/08 11:13 PM
better photo of snapped shaft... TBF
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 11/02/08 06:50 PM
Quote:
Thanks John.. great minds think alike!!!!! I had no idea that somebody had actually had that done..... I remember reading something about this cryo treatment but I can't and won't spend alot of money to have it done. How much did you spend???? Enquiring minds want to know
I will try and post a better pic of the snapped shaft after I mow the lawn... TBF
i actually got it done for free , the trans shop I was dealing with gave it to me after I broke the one in my truck to test it out for them , but they told me later that guys have still broken them , it was my daily drive so I was to scared to do what I did before , rev the engine against the torque convertor to build boost , and get stranded again . they now have a BILLET piece , but it's 800 bucks.
there was a place local to me that does cryo but I haven't talked to them in years and don't know if they are still around , I was going to have some other parts done , the yonly wanted a 100bucks or so for as many parts as they could fit in at one time .
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 11/04/08 04:28 AM
Quote:
looking at pics of the failure, it's kinda hard to tell because of the out of focusness, but I'd guess there was probably a defect on the face of the shaft (a small nick or something) that was a stress concentrator, where a crack propagated from....I'd get a new shaft, inspect it, and if there are any nicks, etc, smooth them out, and run with it.
Patrick, you must be a regular McGuyver.... Upon a real close inspection, It looks like someone gripped the input shaft right behind the splines and it left 2 sets of marks in the metal. Guess where the shaft snapped??? Exactly at the marks on the :shock........
I still have not been able to find a lockup input shaft but I was wondering if a regular non-lockup shaft is hollow like the lockup design???? If so, could I simply get a non lockup style converter and use the non lockup input shaft??? Would the lockup valvebody still work??? I did install the transgo TF-2 and it works pretty good.
If the lockup shafts are hollow and the regular style is not than they have to be alot stronger right???? TBF
Posted By: patrick
Re: 904 trans died behind 390 stroker, time for 727???? - 11/04/08 01:30 PM
no, not Mcguyver, just a Mechanical Engineer who does some fatigue analysis, so I know a little about crack propagation, stress concentrators, notch factors, etc.
and in this type of loading, the primary load on the input shaft will be torsion, not shear or bending. the material in the center will have very little impact on torsional strength of a shaft, so I would not expect a solid input shaft to be significantly stronger than a hollow one.
I had the 904 out of my 5th ave that I sold to a guy north of detroit, he was just going to cannibalize the gearsets to put them into a non lockup 904, so he probably has in input shaft. unfortunately I don't think I still have his contact info...
I'd suggest putting a wanted ad up in the classifieds here, or over at the dippy.org forum, lots of F/M/J dudes there that could probably help you out...or just pick up a whole spare tranny out of a 5th ave in a JY....
Posted By: JohnRR
Re: 904 trans died behind 390 stroker, time for 727???? - 11/04/08 02:15 PM
Quote:
Quote:
looking at pics of the failure, it's kinda hard to tell because of the out of focusness, but I'd guess there was probably a defect on the face of the shaft (a small nick or something) that was a stress concentrator, where a crack propagated from....I'd get a new shaft, inspect it, and if there are any nicks, etc, smooth them out, and run with it.
Patrick, you must be a regular McGuyver.... Upon a real close inspection, It looks like someone gripped the input shaft right behind the splines and it left 2 sets of marks in the metal. Guess where the shaft snapped??? Exactly at the marks on the :shock........
I still have not been able to find a lockup input shaft but I was wondering if a regular non-lockup shaft is hollow like the lockup design???? If so, could I simply get a non lockup style converter and use the non lockup input shaft??? Would the lockup valvebody still work??? I did install the transgo TF-2 and it works pretty good.
If the lockup shafts are hollow and the regular style is not than they have to be alot stronger right???? TBF
TBF , I have a trans from a 78 lebaron , it's parts for an earlier trans I would like to update a little , you are welcome to the input shaft for the cost of shipping it .
Posted By: HotRodDave
Re: 904 trans died behind 390 stroker, time for 727???? - 11/04/08 04:08 PM
The LU shaft is bigger diameter than the non LU shaft so that will probably give it more strength than what it lost from having a small hole drilled through it, Patrick could probably have an interesting comment on this.
Posted By: patrick
Re: 904 trans died behind 390 stroker, time for 727???? - 11/04/08 07:16 PM
that's probably about right. I don't know the specific diameter differences, so I couldn't give you specific numbers on each section's relative stiffness, but generally, for maximum effectiveness, you want the material as far away from the neutral axis (center line of a shaft). a hollow tube has material removed where it's least effective. a larger diameter section has more material where it's most effective.
Posted By: tpabayflyer
Re: 904 trans died behind 390 stroker, time for 727???? - 11/05/08 01:23 PM
Thanks dave. PM sent
TBf
