Who can explain this one? (im at a loss for words)

[Guest 71turboTEK]

Hey guys,

 

This SBC and Th350 combo came out of my 64 chevy truck (not the Z, i know, sorry, just thought you guys would like to see this). Everything seemed fine until i was doing some timing and had the motor spinning at 2500 rpm. I heard a loud clack and the motor shifted, at first i thought i had snapped a rod, but after poking around for a few hours I found this!

 

Note: the partial half of the convertor housing still attched to motor.

 

 

Any ideas on what may have caused this? The truck ran like a champ up until this craziness. Motor and trans mounts seem fine, no excessive "bouncing" of the motor, im dumbfounded.

[awd92gsx]

It...hmm...damn.

 

Does your tranny's input shaft still spin freely? Maybe it somehow locked up on you???

 

You'd figure something else would give before the tranny case, though...

[80LS1T]

Probably just a stress crack that finally gave out. Get a "new" case and put it back together. While its a part though make sure to look for internal damage.

 

Guy

[Jolane]

Do you have the stock type mounts in place? I know that some of the 4x4 guys break their tranny cases similar to yours when they build different tranny crossmembers and mounts. The reason is that the tranny mount needs to be able to rotate axially (roll axis). The engine mounts should stop that motion, and if the tranny is mounted more rigidly, the engine torque is working to twist the tranny case instead. Does this make sense?

Are the engine mounts okay? Maybe one is bad and the engine tried to twist in yaw?

Joshua

[A. G. Olphart]

Looking at the twists in that stator support and input shaft, it'll take more than a case. The torque converter may have successfully isolated the engine from the damage, but on the other hand, its' failure may have caused the problem...

 

Is the metal at the case fracture all shiny and new, or is it greasy part of the way around form having been cracked for a while?

[waynekarnes]

i have seen that before, when transmission was drawn into the engine with the bolts and input shaft wasn't properly aligned with the torque convertor. convertor got damaged, came apart inside, ruptured and went through the tranny case ...

 

that was a powerglide trans ...

 

not saying this is what happened here, but it is a thought.

 

more likely, a broken or loose mount, case was cracked, removing it from the truck allowed the crack to grow ( it was held in place by what ever mounting and friction was there ). engine trans pulled out ... no support under the trans, especially if engine and trans were pulled as a unit ... additional stress on housing, of weight of trans hanging from the bolts, crack expanded ...

 

trans bolted to new mount in car ... gets twisted, tugged, stressed in directions it wasn't subjected to in the truck. metal, fatigued, crack expands and piece breaks off, smacks convertor, gets stuck between housing and convertor .. acts like a small hammer, running around inside the housing, busting the case into pieces.

 

or could have been a loose bolt, that got thrown out and trapped between housing and convertor ... rips the housing apart.

 

number of variables here and reasons that it may have happened.

 

sorry to see that ...

 

good thing is, no one hurt or disfigured ...

 

lost money, time and disappointment ... but no one harmed ... we live to tell the story and rebuild ...

 

good luck with the project

[dot]

I know I would be checking the back of that engine for damage. All that stress had to be carried some where else. I split a 427 block down the valley by dropping a valve at idle!

[Guest 71turboTEK]

hey guys,

 

well, looks like the trans just needs re-cased and a new torque converter. I think that the motor mounts were a little to forgiving, although they were working just fine, it was too much "roll" for the trans to deal with under acceleration. Oh well, live and learn. Im going to weld up the stock mounts and take the 3/4" of rubber out of the equation. Hopefully i can finally stop wrenching on this truck.... the 5 year ground-up resto was finished last year but things just keep creeping up. Just gotta get it hammered out.

 

Thanks!

[TOMAHAWKZ]

Ive seen this a few times, usually when the trans mount is upgraded to a polyurathane type due to it being worn out from a leaking rear transmission seal and the motor mounts go unchanged or are replaced with the stock type. The engine with then deflect more than the trans and wala broken bellhousing. Makes a real neat sound until you figure out what just happened.

[Sparks280zt]

This exact same thing happened to my moms 1996 Plymouth Voyager van. We were just going down the road one day and "BLAM" it scared the crap outta her and we were left stranded But like the others guys are saying we just bought a new tranny case and put that baby on and it was good as new.

[Jolane]

Sparks,

Their may have been another problem with that Plymouth Grand Voyager. My brother was (decided to go back to school) a heavy line mechanic at a Chrysler dealership here and had a similar van come in with a broken flex plate. He replaced it, all was good, until about a month later, when it came back with another broken flex plate. Other mechanics also had similar problems with returning problems related to trannies. Ends up, Chrysler did NOT put the two alignment dowels in the block! Not an obvious problem, but once the dowels were put in, no returns. I guess a bunch of vans were like this. Whether it was a manufacturing mistake or design flaw, I don't know. I do know though that the dowels are very important!

Maybe this is what happened to the van you are referring to?

Joshua