Re: More 727 trans problems from dum-dum
[Re: radar]
#2638403
03/29/19 09:22 AM
03/29/19 09:22 AM
|
Joined: Jan 2003
Posts: 12,237 Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,237
Benton, IL.
|
In these cases where a shift kit has been installed and not already tested, I always recommend installing a known good unmolested valve body. That is about the easiest and cheapest test before you pull the tranny. Of course, valve bodies used to be everywhere. That is not true anymore.
And you can air check the front clutch at the same time.
Last edited by DaveRS23; 03/29/19 09:23 AM.
Master, again and still
|
|
|
Re: More 727 trans problems from dum-dum
[Re: DaveRS23]
#2638468
03/29/19 01:10 PM
03/29/19 01:10 PM
|
Joined: Dec 2005
Posts: 11,655 Fulton County, PA
CMcAllister
Mr. Helpful
|
Mr. Helpful
Joined: Dec 2005
Posts: 11,655
Fulton County, PA
|
If it stays in 2nd, it's a possible control/kickdown/governor/VB problem, i.e. the 2nd gear servo is staying on. If it goes into a false neutral and freewheels instead of going into high, then it's the front clutch not applying. But, since reverse is also not right, you are correct that the high clutch is the common element. Multiple things going on. A pressure check of different functions would help. Or as suggested, swapping in a known good VB would confirm or rule out all of the issues being valve body related. Band adjustments also need to be verified.
If the results don't match the theory, change the theory.
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2638492
03/29/19 02:25 PM
03/29/19 02:25 PM
|
Joined: Jan 2003
Posts: 25,942 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,942
Rio Linda, CA
|
I’m not sure if I ever had 3rd or not but it just never seems to go into cruising gear.
When in doubt if it's in 3rd gear, throttle back to idle and shift to 2nd...if it noses over it was in 3rd.
The INTERNET, the MISinformation superhighway
|
|
|
Re: More 727 trans problems from dum-dum
[Re: CMcAllister]
#2638497
03/29/19 02:36 PM
03/29/19 02:36 PM
|
Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
OP
top fuel
|
OP
top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
|
I am going to remove the VB and start with a front clutch air check at 150 and 40 psi to simulate R and 3rd under the assumption that if 1&2 hold so well I must have some line pressure in D and more in R. If it’s the piston seal I’m thinking I might hear engagement at high psi but disengagement will be almost instant instead of a quick sigh and at low pressure I’ll get no thud just air rushing.
If it seems to hold at both psi and not leak more than it should then I will dig in to the valve body and look for a backward piston or missing check ball. I stayed up late studying my trans books- I think I sorta have a handle on the trans circuit operations. I need to study up on valve body operation. I think the selector& throttle pressure are working and the governor vs line pressure is properly controlling the upshifts in D, at least until it needs to go to 3rd.
I never had a high stall converter before or built an auto before so I am not sure if it is sort of selecting D then slipping or what, but a lack of front clutch apply would seem to be a good candidate for my troubles. I remember doing the whole electrical tape and 15 mins in the freezer thing on the piston to try and get the seal to face down on the way in and I lubed it but did I air check it I dunno. I don’t remember it being particularly easy to install but I didn’t think I forced it…
In any case this is a new build with a handmade floor, firewall, console, etc so I was tempted to finish sealing and painting the bottom on a buddys lift but now I’m motivated to do it right- call this a successful mock up, take the body off to nicely detail and protect the underside, and have access from above to easily R&R the trans.
Thanks fellas for helping keep me moving forward in the right direction! I’ve been building this truck since May and despite some setbacks it’s really starting to come together now. The 512 is strong and the breakin oil and filter looked good, it steers, stops, and goes like a bat outta hell. Always more work to do.
Last edited by radar; 03/29/19 02:37 PM.
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2638535
03/29/19 04:13 PM
03/29/19 04:13 PM
|
Joined: Jan 2003
Posts: 4,296 Chicago, IL
TonyS451
master
|
master
Joined: Jan 2003
Posts: 4,296
Chicago, IL
|
I gotta give you credit for doing it yourself! I've heard before that 727's are fairly simple, but obviously thats all relative. I personally hate pulling transmissions on my back, so for that reason alone, I would have it built for me to (hopefully) avoid any problems . Sounds like you're getting a handle on it, and you're learning a lot as you go. Hope you get it figured out soon.
2 kids and a dog
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2640975
04/04/19 03:10 AM
04/04/19 03:10 AM
|
Joined: Mar 2011
Posts: 3,089 Michigan
A727Tflite
master
|
master
Joined: Mar 2011
Posts: 3,089
Michigan
|
Those two rings are for the front clutch drum - looks like you found your problem. Check the mating bore in the front clutch for damage. The reaction shaft support looks a little worn below the seal, I would polish that up with 400 paper. Make sure the new metal sealing ring turns easily within that groove - I would carefully take a fine file and make sure no burrs or edges exist in the groove and follow that with more paper polishing.
Make sure you have the ends locked after installation of the seal in the support.
Not sure what reference material you are using but the built front and rear clutches when placed on the pump can be pressure tested on the bench by using a rubber tipped blow gun and approx. 30 psi.
Just hit each round hole (not the pump attaching holes) around the pump - one is for the front, rear clutch, the others are converter in and out so ignore those.
Using high presssure hides issues liked nipped rubber seals and damaged seal rings.
Last edited by Transman; 04/04/19 03:22 AM.
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2640980
04/04/19 05:59 AM
04/04/19 05:59 AM
|
Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
|
master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
|
Absolutely found the problem, yes. The rings seal the drum feed. The thing is, there should be no way that any portion of the ring was found in the pan, unless the drum is now all ground to heck. The ring parts would need to be pretty small to fit between the support and drum. Could this have happened on installation?
"use it 'till it breaks, replace as needed"
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2641065
04/04/19 09:25 AM
04/04/19 09:25 AM
|
Joined: Nov 2015
Posts: 882 Missouri
jwb123
super stock
|
super stock
Joined: Nov 2015
Posts: 882
Missouri
|
Ok I got her out and apart.
The air checks were all good except the front clutch which just blew air- no clutch apply sound.
I found a couple parts of a sealing ring in the pan- turns out they were off the snout behind the pump. My front clutch piston outer seal actually looked fine. It is flipped down, and not ripped or folded and needed a little pressure to go back home which I did twice inspecting between.
The kolene steels and red fibers saw some heat. The fibers are a little black around the edges and the frontmost steel (not the thick pressure plate) is noticably warped. I think I had some spares left over from the rebuild.
Could that steel sealing ring on the back of the pump be my culprit? The front clutch gets pressure from the reaction shaft right?
Thanks for the help fellas
Radar Yes you found your problem. If you did not do it cut off some 5/16 threaded rod and screw two short lengths in the case to help you align the pump as you install. Buy some regular trans assembly lube, very thick, coat the rings after you install, it helps keep them from hanging and breaking. Lot of guy now use the teflon type rings, they wear the drum less and seal better at high RPM's Make sure the grooves the rings go into on the pump are not damaged, 727's are prone to wear those grooves, and make sure the bushing in the drum is good. If the bushing is loose the drum will wobble at high rpm's and take out the rings. https://www.ebay.com/itm/DR-TRANNY-...SSION-ASSEMBLY-LUBE-M465TG-/192450963604http://coperacingtranscom.ipage.com/?product=727-teflon-sealing-ring-kit
|
|
|
Re: More 727 trans problems from dum-dum
[Re: radar]
#2641116
04/04/19 11:37 AM
04/04/19 11:37 AM
|
Joined: Mar 2006
Posts: 9,869 MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,869
MI, usa
|
What thickness snap ring are you using? There are multiple thickness available. I believe .104" is the thickest. Drum ring surface looks OK. It the ring surface that the input shaft rings ride on inside the reaction shaft support. As I said check for ring groove tape with the ring in the groove. If its tapered it'll kill the ring in short order. Doug
Last edited by dvw; 04/04/19 11:40 AM.
|
|
|
Re: More 727 trans problems from dum-dum
[Re: dvw]
#2641286
04/04/19 07:35 PM
04/04/19 07:35 PM
|
Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
OP
top fuel
|
OP
top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
|
What thickness snap ring are you using? There are multiple thickness available. I believe .104" is the thickest. Drum ring surface looks OK. It the ring surface that the input shaft rings ride on inside the reaction shaft support. As I said check for ring groove tape with the ring in the groove. If its tapered it'll kill the ring in short order. Doug It’s a wave washer and it’s fifty thou thick. I have four steels & fibers in there and with some oil on everything there is basically no free play. My book says measure the clearance under the high section of the wave- I can probably fit a few more thou but .045” feeler guage slides in with no force. The fibers can move fairly freely but I think I want more clearance for the front clutch than the forward/rear right? A little room for the un-applied pack to spin freely but not so much that the seals could pop out? My book says with the wave washer I want .082”-.151”. Would milling .045” or .050” off the pressure plate be the easiest fix here so I don’t burn up my fibers when not in 3rd or R? Thanks for the tip on ring groove squareness I’ll check that tonite!
Last edited by radar; 04/04/19 07:57 PM.
|
|
|
|
|