Moparts
Tranny Explodes
Posted By: terzmo
Tranny Explodes - 07/02/11 09:28 PM
Just built a drag car... has a new 512 stroker motor....indy heads...727..low gear kit,manual valve body..dana..4 link suspension...33 by 17 tires.Ran a best of 10.28 so far...Car did a burnout fine...came to line..took off and spun the tires...driver let off and the tranny blew like there was 5 pounds of C4 in it...tail shaft and converter survived but the case is in a hundred parts....as everything in the case....went through the floor..broke the drivers foot in 3 places....
What would/could cause this ?
Posted By: rapom
Re: Tranny Explodes - 07/02/11 09:38 PM
Doing a burn out in 1st. gear. I'll let others explain.
Posted By: topside
Re: Tranny Explodes - 07/02/11 10:01 PM
That's the second time this week that someone's posted a trans explosion, apparently without a blanket or shield. Please run them!
Posted By: J_BODY
Re: Tranny Explodes - 07/02/11 10:14 PM
Quote:
..took off and spun the tires...driver let off and the tranny blew like there was 5 pounds of C4 in it...
Tires may have hooked and unhooked.... hard on the roller clutch. see what condition it's in when you disassemble. Stock front drum I'm assuming? Time for an aluminum or aftermarket steel drum. and as mentioned, a shield or blanket is a must. Same thing happened to a friend of mine with a low 11 Challenger. In his case the rear gear broke, shocking the rear roller allowing it to lock which spins the front drum to the point of..... well, you've been there now.
....and pop the rear cover and check the ring gear just to be safe.
Posted By: Leon441
Re: Tranny Explodes - 07/02/11 10:14 PM
Do a search on here you would have quickly found the cause.
Funny how a GM guy will listen to the warnings involved with their race parts. But, a hardheaded Mopar guy will ignore and keep going then wonder what happened when something goes wrong.
You overrun the clutch (AKA Sprag) and the front drum revs into the twilight zone. Boom it explodes. It's not the 727 as a stock one in low gear will not blow up.
It is the aftermarket parts that allow the rear drum to spin free expecting the sprag to hold it as they do not apply the rear band in low. Bolt-in sprag, still same problem.
A rear band apply valve body is the way to go. Many manual valve bodies are not. When building that 727 instead of wasting money on parts you do not need spend $500 on a billet front drum that will not explode. I know someone that blowed one but still will not buy the drum. And a no low band apply valve body.
Senseless. But, it is the 727's fault people build these trannies every day like this.
Posted By: DragDart360
Re: Tranny Explodes - 07/02/11 10:44 PM
NHRA rules require a transmission shield any quicker than 11.00
I just put a CSR shield in my Dart as I expect to run low 10's.
It's the best $300 you can spend. 904 behind a small block, bolted right up.
Posted By: Dragula
Re: Tranny Explodes - 07/02/11 10:55 PM
Car look like this one...
Posted By: Barnstorm
Re: Tranny Explodes - 07/02/11 11:11 PM
Posted By: dOc !
Re: Tranny Explodes - 07/02/11 11:30 PM
An alum drum or LBA valve body would have prevented this ...
Posted By: Steve1118
Re: Tranny Explodes - 07/02/11 11:49 PM
That's too bad, I'm glad he's OK.
I wonder if he used low gear on the burnout and overrevved it. Just wondering.
Posted By: MR_P_BODY
Re: Tranny Explodes - 07/03/11 12:38 AM
Quote:
Just built a drag car... has a new 512 stroker motor....indy heads...727..low gear kit,manual valve body..dana..4 link suspension...33 by 17 tires.Ran a best of 10.28 so far...Car did a burnout fine...came to line..took off and spun the tires...driver let off and the tranny blew like there was 5 pounds of C4 in it...tail shaft and converter survived but the case is in a hundred parts....as everything in the case....went through the floor..broke the drivers foot in 3 places....
What would/could cause this ?
As soon as he let off in first gear at high RPMs is
when it killed the sprag/over running clutch and
then it spins the drum 2.2 times faster than the
engine RPMs... centrifugal force did the rest...
all you have to know on those trannies is not to
let off in first gear at high RPMs... SHIFT to second
then let off(over running clutch isnt in play then)
Posted By: cudadoug
Re: Tranny Explodes - 07/03/11 12:57 AM
Just what Mr. P body says.
GET A BLANKET OR A SHIELD!!!!!
Wait a second. How does a 4-link car with a funny car tire SPIN...??
Posted By: MR_P_BODY
Re: Tranny Explodes - 07/03/11 01:15 AM
Quote:
Just what Mr. P body says.
GET A BLANKET OR A SHIELD!!!!!
Wait a second. How does a 4-link car with a funny car tire SPIN...??
Simple... pump them up like a basket ball
Posted By: terzmo
Re: Tranny Explodes - 07/03/11 01:23 AM
Quote:
An alum drum or LBA valve body would have prevented this ...
Can You explain LBA valve body....thanks in advance
Posted By: hemigod426
Re: Tranny Explodes - 07/03/11 02:21 AM
did he not have a bolt in sprag? first gear burn out? slipped out of gear?
Posted By: MR_P_BODY
Re: Tranny Explodes - 07/03/11 02:48 AM
Quote:
did he not have a bolt in sprag? first gear burn out? slipped out of gear?
Bolt in sprags will break also... they are for a loose
race in the housing... unless its a super sprag with
lots of rollers
Posted By: dartman366
Re: Tranny Explodes - 07/03/11 02:49 AM
Quote:
did he not have a bolt in sprag? first gear burn out? slipped out of gear?
bolt in sprag will not remotely help in preventing an explosion, it is simply a fix for a damaged case, they do have some out that have improved holding ability but still they are not the end all be all of preventing a explosion,,LBA valve body and proper use during burnouts (second gear start) and driving charicteristics is the way to make them live. 
Posted By: DJVCuda
Re: Tranny Explodes - 07/03/11 02:53 AM
Quote:
Quote:
did he not have a bolt in sprag? first gear burn out? slipped out of gear?
bolt in sprag will not remotely help in preventing an explosion, it is simply a fix for a damaged case, they do have some out that have improved holding ability but still they are not the end all be all of preventing a explosion,,LBA valve body and proper use during burnouts (second gear start) and driving charicteristics is the way to make them live.
That combined with an aluminum / billet steel drum to prevent the hand grenade from going off.
To answer the OP - The drum exploded, you had the stock cast iron drum in there and you need to call John Cope and get a billet or aluminum drum in your next tranny.
The super sprag or at least a bolt in unit will prevent things from going bad as well, but the drum is what exploded.
Posted By: Dragula
Re: Tranny Explodes - 07/03/11 03:03 AM
Quote:
Quote:
Quote:
did he not have a bolt in sprag? first gear burn out? slipped out of gear?
bolt in sprag will not remotely help in preventing an explosion, it is simply a fix for a damaged case, they do have some out that have improved holding ability but still they are not the end all be all of preventing a explosion,,LBA valve body and proper use during burnouts (second gear start) and driving charicteristics is the way to make them live.
That combined with an aluminum / billet steel drum to prevent the hand grenade from going off.
To answer the OP - The drum exploded, you had the stock cast iron drum in there and you need to call John Cope and get a billet or aluminum drum in your next tranny.
The super sprag or at least a bolt in unit will prevent things from going bad as well, but the drum is what exploded.
We found parts of the sprag and the drum in the car. Litterally, one of the sprag bearings went thru the floor like a bullet, left a hole just like one. Other parts were larger and it could have been really bad. I talked with Paul today, and even though he doesn't feel lucky, I told him some of the stuff we found in the car.
The trans is toast, but all the parts to put a new one are in. It will have a sheild & a super sprag. The floor boards on the other hand are a real mess. Its going to take some sheet metal work to fix.
It spun off the line due to a bad burn out procedure which seems to be because the line lock button was moved and its not comfortable were it ended up. It is being moved before I climb in...
Posted By: MR_P_BODY
Re: Tranny Explodes - 07/03/11 03:05 AM
To answer the OP - The drum exploded, you had the stock cast iron drum in there and you need to call John Cope and get a billet or aluminum drum in your next tranny.
The super sprag or at least a bolt in unit will prevent things from going bad as well, but the drum is what exploded.
I still run a stock drum... its what you do and dont do
that keeps it from blowing... and a bolt in sprag
wont save anything... if you want a good sprag you
better be looking at a super sprag or the like
Posted By: DJVCuda
Re: Tranny Explodes - 07/03/11 03:22 AM
Quote:
To answer the OP - The drum exploded, you had the stock cast iron drum in there and you need to call John Cope and get a billet or aluminum drum in your next tranny.
The super sprag or at least a bolt in unit will prevent things from going bad as well, but the drum is what exploded.
I still run a stock drum... its what you do and dont do
that keeps it from blowing... and a bolt in sprag
wont save anything... if you want a good sprag you
better be looking at a super sprag or the like
Dont get me wrong - some people - make that alot of people do it - does it make it right? if doing something unsafe and getting away with it makes it right? nope!
The bottom line is there is a bomb in every single stock drum 727 out there. the part that explodes is the drum, you can dance with the devil your whole life and win, or tomorrow might be your time -
WHY RISK IT?
It could go through your body and kill you... is that really worth it?
just to say you can do it?
Posted By: MR_P_BODY
Re: Tranny Explodes - 07/03/11 03:29 AM
Dont get me wrong - some people - make that alot of people do it - does it make it right? if doing something unsafe and getting away with it makes it right? nope!
The bottom line is there is a bomb in every single stock drum 727 out there. the part that explodes is the drum, you can dance with the devil your whole life and win, or tomorrow might be your time -
WHY RISK IT?
It could go through your body and kill you... is that really worth it?
just to say you can do it?
Dont do STUPID SH***T... and 1 is letting off the
pedal in low gear at high RPM... I believe its 13.5K
for that stock drum to over rev and blow
EDIT
and when you let off at high evs it blows the sprag
and then it turns 2.2 times the engine
Posted By: Steve1118
Re: Tranny Explodes - 07/03/11 03:44 AM
"Dont do STUPID SH***T... and 1 is letting off the
pedal in low gear at high RPM... I believe its 13.5K
for that stock drum to over rev and blow
EDIT
and when you let off at high evs it blows the sprag
and then it turns 2.2 times the engine"
That pretty much sums it up.
If a drum blows, it is because on either that run, or shortly before, someone did something dumb or made a mistake and never checked it. The sprag doesn't turn by itself. DJV, To insunuate that us old timers who have been using pretty much stock Torqueflites since Moby Dick was a minnow are either too stupid to know better or are spitting in the eye of the reaper is insulting. We just take issue with your statement. I'm pretty sure that I speak for all of us when I tell you that if we were convinced that it was an overly unnecessary risk, no one would take it. But, to my mind, it is low on the list of things that could happen, if one is careful and pays attention to what they are doing. Do I use a blanket? Of course, that is the smart thing to do. My belts are also up to date, and my suit and helmet meet specs. My brakes also work.
I've been doing this since 1964, and have only seen one explode, and it was preventable. This, of course, is not including the neutral start craze of 67-68, which is another story altogether. That was before the advent of high stall converters, and Chrysler itself was involved with that. Dave Wren "invented" it at the Chrysler proving ground, and everyone was doing it. The famous pic, earlier in this post, was of Dick Oldfield's Iron Butterfly 64 Hemi at Indy while the neutral start deal was in vogue. Ron Mancini had a big one at Bristol earlier that year, and NHRA stopped it after Dick's deal. Whoever posted that pic should have been more specific....that is famous pic that has appeared about everywhere. One needs to tell the whole story, providing they know it. Otherwise, hysterical threads like this have every eighteen year old kid who races a 318 Duster out buying $700 drums that they really can't afford because "every 727 has a bomb in it". Gimme a break.....big time overstatement.
Posted By: quick77rt
Re: Tranny Explodes - 07/03/11 04:59 AM
I've been doing this since 1964, and have only seen one explode, and it was preventable.
Ok 1964 was a long time ago, so vs any of the older crowd getting bent lets just flip it around and blame these two recent exp. 727s on the ignorance of the youth of today.
With that the fact remains just this week there has been two blow and one guy hurt, I myself have never had an oem 727 come apart, however even in my street beater spray car I run a crt pro race as well with the blanket because I do value my feet and my passenger.
So really at the end of the day does it matter how old one is in this whole big picture, 727-s blowup.
What im really surprised about is the moral police on moparts should be all over this one but I guess as long as its not there foot busted up its ok.
Do I really care if one gets there foot blown off, young or old, not really its just silly to see it happen, when things can be done to prevent it or reduce the chance of driver harm.
Ive noticed that many who have not replied to this are the people running the right drums and shields or blankets as required by tech, and now dam, what am I to do with a guy like John Cope selling me a perfect working trans that I have zero worries with except say THANKS!
Posted By: J_BODY
Re: Tranny Explodes - 07/03/11 05:01 AM
Ran the stock/lightened one on the right for 15 years or so. Early Tranz Act NON reverse band apply t-brake (still in the car). I started having some psi issues and had the trans freshened and went with a billet front drum. I asked about upgrading the rear roller assy and the builder said mine was fine and that he wouldn't spend the money unless the race was worn or loose.
Posted By: J_BODY
Re: Tranny Explodes - 07/03/11 05:03 AM
...and been running this since....well a long time!
Posted By: 440Jim
Re: Tranny Explodes - 07/03/11 05:08 AM
Sorry to hear about that disaster.
An aluminum front drum would have prevented the major damage.
But the cause is letting off the throttle in 1st gear with no low band (rear band) apply in 1st gear. Some valve bodies have it, some don't. The best thing to do in a TF trans is shift to 2nd when that happens, not just lift.
Posted By: J_BODY
Re: Tranny Explodes - 07/03/11 05:08 AM
This one had the engine set back about 10 inches. Rear gear broke on the launch, folded the springs in the roller with the shock, and the rest made a mess.....and he walked away!!! Pieces of trans stuck in his door panel, dent in the roof, and a chunk of drum wiped out the gauges if I recall. This was long before Al Gore invented the interwebs so we hadn't ever seen/heard anything like it. But we learned!
Posted By: FastmOp
Re: Tranny Explodes - 07/03/11 05:10 AM
I have one on the floor that's ready to blow up right now. It whines and rattles and starts humming like it is just waiting to blow.
It was in the valiant when the rear end let go lol So now im building a new tranny with an alum drum and a pro tree break.
Can't wait to be able to trans break it every pass.
Posted By: dOc !
Re: Tranny Explodes - 07/03/11 05:28 AM
You can put a CAST IRON shield around it... with two blankets. THAT might prevent the floor from being damaged ... but how about the converter, the case, valve body and everything else ? ...
Could be JUNK if all that happened.
A billet steel drum is good ... but a steel-jacketed alum drum is the ticket. The 727 can NEVER "blow-up".
Posted By: Anonymous
Re: Tranny Explodes - 07/03/11 05:38 AM
So if I'm running the 17156 manual valvebody (no low band apply) that Turbo Action sells, I shouldn't let off the gas in first gear crusing down the street?
I'm aware of the no first gear burnout deal.
Posted By: Thumperdart
Re: Tranny Explodes - 07/03/11 05:41 AM
I think that`s the one I have and I never get on and off the gas in first ANYWHERE. Sometimes on the street I even take off in second and cruise parking lots in second also.
Posted By: Hutch
Re: Tranny Explodes - 07/03/11 05:57 AM
Quote:
But the cause is letting off the throttle in 1st gear with no low band (rear band) apply in 1st gear.
So your saying the direct(front) drum is being spun to burst speed when you lift throttle in first gear and the roller clutch freewheels?
I really think you are misinforming people with this statement.
Hutch
I have had 2 different sprag failures on my 904 without blowing the front drum(stock), both times I caught it early on launch as it acted just like the tires were spinning and never got the Engine Rpm up high enough to cause burst damage. I think many people mistake wheel spin for sprag failure to begin with.
Glad your buddy hobbled away from this one. Hope he feels better soon.
Posted By: J_BODY
Re: Tranny Explodes - 07/03/11 06:57 AM
904 drum has less mass than a 727. When I was talking to Dave Smith on this subject he said he'd never seen a 904 drum come apart.
Posted By: 1_WILD_RT
Re: Tranny Explodes - 07/03/11 07:53 AM
Quote:
Quote:
But the cause is letting off the throttle in 1st gear with no low band (rear band) apply in 1st gear.
So your saying the direct(front) drum is being spun to burst speed when you lift throttle in first gear and the roller clutch freewheels?
I really think you are misinforming people with this statement.
Hutch
No! That is not what he is saying... The explosion occurs when you launch after having let off the throttle at high RPM with the shifter in first gear with no low band apply.... This can allow the sprag to lay over... Once the sprag lays over the pin has been pulled.. If you miss the signs an explosion is eminent... A bolt in sprag does nothing to stop the problem because all a bolt in sprag does is secure the outer portion of the sprag to the trans case with bolts rather than splines & a set screw... A low band apply valve body prevents the issue by holding the low/reverse drum so the sprag doesn't see the load that could cause it to fail... An aluminum or billet drum doesn't prevent the sprag failure but the drum is of higher quality & if the sprag does fail the drum doesn't fail so theres no explosion.. What is being pointed out is if your aware of the problem, know the cause & drive with the proper procedure than there is no problem... Either start the burnout in second or shift to second before getting out of the gas..... Also be out of first before the tires hit dry pavement.. The shock of the tires grabbing coming out of the burnout box can shock the sprag causing it to lay over.... Be aware...... Or don't pay attention & just buy a low band apply valve body so your protected....
Posted By: Scamp408
Re: Tranny Explodes - 07/03/11 11:51 AM
Could loosing traction at the line roll the sprag?
Is there any signs that the sprag is shot before you start running the car?
Posted By: cudadon
Re: Tranny Explodes - 07/03/11 04:36 PM
Quote:
This one had the engine set back about 10 inches. Rear gear broke on the launch, folded the springs in the roller with the shock, and the rest made a mess.....and he walked away!!! Pieces of trans stuck in his door panel, dent in the roof, and a chunk of drum wiped out the gauges if I recall. This was long before Al Gore invented the interwebs so we hadn't ever seen/heard anything like it. But we learned!
What was the gauge/thickness of that modified trans tunnel?
Whoever drove that car was VERY lucky that day!! 
A lot of racers complain about safety rules...They are trying to make our sport safer.
If your foot or hand gets broken/mangled and you can't work, now what?
I ran with a stock drum for a long time.
When it was being freshened we would look for cracks, and replace.
I ALWAYS start my burnout in 2nd gear.
I also had a trans shield and flexplate shield per NHRA rules. Just to be safe.
Never tested the shields, thank GOD.
Don
Posted By: hemigod426
Re: Tranny Explodes - 07/03/11 08:08 PM
Quote:
To answer the OP - The drum exploded, you had the stock cast iron drum in there and you need to call John Cope and get a billet or aluminum drum in your next tranny.
The super sprag or at least a bolt in unit will prevent things from going bad as well, but the drum is what exploded.
I still run a stock drum... its what you do and dont do
that keeps it from blowing... and a bolt in sprag
wont save anything... if you want a good sprag you
better be looking at a super sprag or the like
727 6-Bolt Ultimate Sprag (1966-1989) - A&A Transmissions good bolt in spaq is 200 bucks here from a+a i dont build mine with out it. they dont blow up 
they'll often fill the car with fire as an added bonus. super sprag, billet drum, blanket or shield, and a low band apply valve body, and he'd still be racing. my street car has all of the above and more. i like spending money on things that make my car more reliable at high performance levels. i hate fire and shrapnel in the car. it takes the joy right out of it.
Posted By: moparacer
Re: Tranny Explodes - 07/04/11 01:21 AM
If you are making ANY amount of serious power JUST PUT A GLIDE IN IT....
Nuff said....
I might be a mopar guy at heart but I do happen to value walking around with both feet properly attached thank you.
Posted By: dOc !
Re: Tranny Explodes - 07/04/11 02:18 AM
Quote:
I might be a mopar guy
at heart but I do happen to value walking around with both feet properly attached thank you.
But NO ... you are not ..... you are deep-down a GovernmentMotors 
..... 
... 
Yes ...feet are important part of the body ...and YES ... 727's BLOW UP .....
But if you have the proper parts IN THE TRANS .. they are as "safe" as any 727 in a daily-driver.
Posted By: Hutch
Re: Tranny Explodes - 07/04/11 02:43 AM
Quote:
Quote:
Quote:
But the cause is letting off the throttle in 1st gear with no low band (rear band) apply in 1st gear.
So your saying the direct(front) drum is being spun to burst speed when you lift throttle in first gear and the roller clutch freewheels?
I really think you are misinforming people with this statement.
Hutch
No! That is not what he is saying... The explosion occurs when you launch after having let off the throttle at high RPM with the shifter in first gear with no low band apply.... This can allow the sprag to lay over... Once the sprag lays over the pin has been pulled.. If you miss the signs an explosion is eminent... A bolt in sprag does nothing to stop the problem because all a bolt in sprag does is secure the outer portion of the sprag to the trans case with bolts rather than splines & a set screw... A low band apply valve body prevents the issue by holding the low/reverse drum so the sprag doesn't see the load that could cause it to fail... An aluminum or billet drum doesn't prevent the sprag failure but the drum is of higher quality & if the sprag does fail the drum doesn't fail so theres no explosion.. What is being pointed out is if your aware of the problem, know the cause & drive with the proper procedure than there is no problem... Either start the burnout in second or shift to second before getting out of the gas..... Also be out of first before the tires hit dry pavement.. The shock of the tires grabbing coming out of the burnout box can shock the sprag causing it to lay over.... Be aware...... Or don't pay attention & just buy a low band apply valve body so your protected....
I am very aware of WHY they blow up that is why I made a comment about the statement I quoted prior to yours which states the "cause" which is inaccurate and misinformative IMO. Im not looking to get into it , just to offer proper accurate info. Lifting off the throttle w/o low band apply does nothing to the roller clutch. Improper burnout procedure , jackstand transbrake tests , improper assembly of roller clutch (roller diameter or spring direction/condition) inner race preparation and the list goes on is the cause of the problem. Low band apply helps stabilize the clutch but is not the cure.
Hutch
Posted By: Mr.Yuck
Re: Tranny Explodes - 07/04/11 03:48 AM
Sorry to hear about that. mine let go at the other end (116mph). U-joint puked a cap and the vibration trashed the trans. Parts were everywhere.
Good luck bro.
Posted By: 6pakdakota
Re: Tranny Explodes - 07/04/11 05:45 AM
i have a used manual valve body 727 that i am getting ready to put in my truck. how can i tell if it is a low band apply valve body or if it is already damaged or not?
Posted By: Otherlane
Re: Tranny Explodes - 07/04/11 12:49 PM
Are the tranzact transbrake LBA or is it different with a transbrake?
Posted By: 440Jim
Re: Tranny Explodes - 07/04/11 12:54 PM
Quote:
Quote:
But the cause is letting off the throttle in 1st gear with no low band (rear band) apply in 1st gear.
So your saying the direct(front) drum is being spun to burst speed when you lift throttle in first gear and the roller clutch freewheels?
I really think you are misinforming people with this statement.
Hutch
I am not trying to misinform people, you don't understand. You are the one that posted the burst speed statement, not me. I was commenting on driving technique.
It is the unloading and reloading the sprag that can damage it. It all started (in this case) with lifting in 1st gear with no low band apply. That in itself may not roll the sprag, but if the driver shifts to 2nd before lifting, the reloading of the sprag will never happen and therefore avoid damage.
Only after the sprag is rolled, and the trans is in 1st gear with no low band apply and power is applied; then the front drum spins at 2.2 engine speed. This could happen on the next launch, when the damage was done in the previous launch.
The point I was trying to make, without the long and confusing explaination, is to shift to 2nd when something goes wrong. If you need to lift the throttle for other safety reasons, still shift to 2nd!
Posted By: terzmo
Re: Tranny Explodes - 07/04/11 03:58 PM
Quote:
Doing a burn out in 1st. gear. I'll let others explain.
This was on launch..not burnout
Posted By: terzmo
Re: Tranny Explodes - 07/04/11 03:59 PM
Quote:
Quote:
Just what Mr. P body says.
GET A BLANKET OR A SHIELD!!!!!
Wait a second. How does a 4-link car with a funny car tire SPIN...??
Simple... pump them up like a basket ball
tire pressure was no over inflated
Posted By: VernMotor
Re: Tranny Explodes - 07/04/11 04:44 PM
Quote:
Quote:
Doing a burn out in 1st. gear. I'll let others explain.
This was on launch..not burnout
But did he do the burn out in 1st gear ?
Posted By: dOc !
Re: Tranny Explodes - 07/04/11 05:34 PM
Quote:
Quote:
Doing a burn out in 1st. gear. I'll let others explain.
This was on launch..not burnout
From what I have heard(never seen this happen) ... is that you can damage the sprag on a burnout(when coming out of the water by hooking then spinning then hooking again).....THEN on the launch the sprag comes apart and the insides spin 2.5 times engine speed.
WITH an alum drum(or billet steel) ... no V8 Mopsar engine is capable of reving HIGH ENOUGH to explode the front-drum.
Posted By: terzmo
Re: Tranny Explodes - 07/04/11 07:18 PM
Quote:
Quote:
Quote:
Doing a burn out in 1st. gear. I'll let others explain.
This was on launch..not burnout
But did he do the burn out in 1st gear ?
no..2nd
Posted By: Dragula
Re: Tranny Explodes - 07/04/11 08:09 PM
You guys are making way too much out of an improper burn out and the reflex to lift when it spun at the hit.
Turns out we could not get a LBA VB as too many don't like the drag they produce, so it will be the standard one....
Posted By: Hutch
Re: Tranny Explodes - 07/05/11 12:38 AM
Hutch
I am not trying to misinform people, you don't understand. You are the one that posted the burst speed statement, not me. I was commenting on driving technique.
It is the unloading and reloading the sprag that can damage it. It all started (in this case) with lifting in 1st gear with no low band apply. That in itself may not roll the sprag, but if the driver shifts to 2nd before lifting, the reloading of the sprag will never happen and therefore avoid damage.
Only after the sprag is rolled, and the trans is in 1st gear with no low band apply and power is applied; then the front drum spins at 2.2 engine speed. This could happen on the next launch, when the damage was done in the previous launch.
The point I was trying to make, without the long and confusing explaination, is to shift to 2nd when something goes wrong. If you need to lift the throttle for other safety reasons, still shift to 2nd!
Once again , your confusing people. You stated ,when you get into trouble on the track we should now shift to 2nd and that will prevent future roller clutch failures? HELL NO!!
If we lift throttle in low gear and do not shift to 2nd we will kill the roller clutch? HELL NO!!!
Pedalling the car in low gear can damage a roller clutch. HELL YES!!
Just wanting to clarify this with you.
Hutch
Posted By: joshking440
Re: Tranny Explodes - 07/05/11 02:33 AM
I have had 2 bad breaks with my 727 in my car. Both in 1st gear, both under serious power (25-30lbs of boost)
One pass I broke an axle, motor went to the moon, next year broke something inside the trans, motor went to the moon (9500rpm)
What I can say is that I run a low band apply vb with billet steel drup and a super sprag and never had a serious issue like the op did.
I will say though for me all I could do was call hutch and get some info in where to get a bullet proof turbo 400 and he did just that (proformance in chicago) as I am sick of breaking parts
![Attached picture 6710729-102_2607[640x480].JPG](https://board.moparts.org/ubbthreads/upload2/6710729-102_2607[640x480].JPG "6710729-102_2607[640x480].JPG")