I cracked my 31TH trans case

[johnl]

Shot peen, for starters, to stress relieve, but aluminum pros will know about heat treating - first to relieve stresses and then a different way to build strength.

Find a Mil Spec inspection facility and pick their brain, I've found that they love to take in something unusual/new and will give me great deals, just because they get to do something different.

[zin]

Hey John, you posting from a tablet too? When I post from my Nook, it "doubles down".

Good advice too, heat treating would be the way to go, just not too extreme as it could affect the tolerances...

I'm thinking Cryo-treatment might be the way to go, not too much heat used there (they do typically heat the piece to be treated, just in case that sounded a bit dense!)

Mike

[A.J.]

Find a Mil Spec inspection facility and pick their brain, I've found that they love to take in something unusual/new and will give me great deals, just because they get to do something different.

I have no idea where to even start looking for a place like that so that's probably not going to happen.

[zin]

Might try these guys: http://www.phoenix-heat-treating.com/

Mike

[Reaper1]

I'm not sure it would work all that well with welds, but with casting lines you grind them down, them hit the area with a hammer...basically peening the part. I don't think that would be exactly easy in this case, though.

[Force Fed Mopar]

Time to put a 41te in

[boots]

2 step on an auto is a smart idea because you can build boost without the rpms going up (putting even more load on the transmission) and as said, the retarded ignition timing kills power. In this situation you are building boost thanks to poor combustion instead of full WOT combustion. I think I would also not let boost get too high for the actual moment of launch. I know some guys with auto transmissions (powerglides etc on RWD small engine turbo cars) hit the spray right before launching to flash their converters up but I would not want to do that with the problems that are being reported.

Red Sled has made a lot of passes that are much slower then it has gone in the past and I feel that regarding what Vigo says, this is part of a very careful boost/launch control setup that is intended to protect the transmission while still launching well. I think there have been a lot of difficulties getting things right. I think the best time for that car is still on spray and a tired old motor, meaning making HP is not the problem.

The sled has been breaking it's 60ft records this year and going consistent 1.44-1.45 foot braking with no issues. We are not holding anything back, we keep adding boost/speeding up the ramps and improving each time out. We just got the car back into the 5.9x's, the car needed relearned after the fuel change. In the four years I've been doing this, I haven't seen a single broken case. It's been planetary problems, the pinion bearing cup spinning the snap ring.

[Ondonti]

The sled has been breaking it's 60ft records this year and going consistent 1.44-1.45 foot braking with no issues. We are not holding anything back, we keep adding boost/speeding up the ramps and improving each time out. We just got the car back into the 5.9x's, the car needed relearned after the fuel change. In the four years I've been doing this, I haven't seen a single broken case. It's been planetary problems, the pinion bearing cup spinning the snap ring.

I bought a 1996 and 1994 31te transmission for 3.0's to have as backup for my wife's car and the cases are significantly different. The giant rear motor mount setup that changes how the differential is braced on top and the bellhousing has end to end trusses and a bit more meat. The 2.2/2.5 guys do not have this case option but I figure with the transfer gear retainers etc I would always use a 96+ case if I did an auto build.

To me, I still figure you are holding back on how much load the transmission sees while foot braking. Guys here on this site don't have the capabilities to ramp things up over time or mph so they either start things off too hot or bog or get it perfect. To them, perfect also means going fast, not avoiding failures.
There is a difference between holding back on performance and holding back on wild transmission abuse that still cannot match the performance of a very careful setup.
If you are still adding to your launch then you were holding back. Its not an insult. As I said, guys here often sit on the brake until the boost stops climbing or they start to pull through the brakes. Some of those people find ways for the brakes to hold more and tweak out the transmisison even more sitting at the line. Case failures are common for a reason. Most of the cars have been running near stock electronics, sometimes with basic fuel and spark map changes.

[turbovanman²]

Seems like brake boosting causes most of the failures of the "Hard parts" of these transmissions. I cannot imagine the stress on the case and even the input shaft and transfer shaft. I'm sure the LSD ( which is much better than the open diff) does not help out the situation because your hooking up better and all of the stress has to go somewhere. Wonder if anyone has ever tried to do a trans brake on these?

There was one being built before but he disappeared. I was trying to get the rights but can't get ahold of him,

So is it a general consensus that it's the brake boosting that's the problem? I've researched this transmission and didn't see any case failures. On the SRT-4 forums they have failures with the $9000 DCR transmission but the owners don't do their own work on the transmissions and DCR doesn't announce what their failures are. I might have to consider going the nitrous route just for the track when I launch.

I've split my case in 2 around the diff and had a small crack under the pump. That case lasted 6 years of serious abuse. I think its just par for the course, like cracked 6.2/6.5 diesels, its simply random.

[Mr overkill]

Bring this from the dead what about using a 2 step controller to say limit boost to say 7 psi then after launch it engages full boost. That save on stress

[A.J.]

That's a possibility. Mega Squirt has it, I just haven't messed around with it yet.

[Ondonti]

I'm not sure it would work all that well with welds, but with casting lines you grind them down, them hit the area with a hammer...basically peening the part. I don't think that would be exactly easy in this case, though.

What about rotopeen mr engineer? You get a lowercase for suggesting a hammer :P I want to pick up some of these supplies.

[Reaper1]

Hmmm...now THAT is interesting! I'll have to look that up! Thanks!

[Ondonti]

Hmmm...now THAT is interesting! I'll have to look that up! Thanks!

Hmmmmmmmmm no wonder you got moved

[Reaper1]

Lol...from planning to emergent support/R&D...I think it was a great move! I hated moving operation codes around and copy/paste work instructions. BLECH! (

[contraption22]

Just an update to this. My brother disassembled my A413 to use some of the components in my 3ITH. The case of the 413 was cracked. Almost in the same place as before, but the reinforcing that we added only moved the crack over an inch. No external leakage of the trans. Car drove fine before taken off the road.

[mopar-tech]

How many people have cracked their cases? I never remember hearing much about cracked cases till recently. Most of the ones in the past were caused by a failure of something else.

The Reliant? Never and it comes out of the hole at 27 psi.

Torque converters? Oh yes it eats them like popcorn but never a case failure.

[contraption22]

Another update, the 31th I was going to use, which had been welded in the same manner, is also cracked in the same manner as the A413. It was never run in a car since being welded. I am not sure when or how the crack occurred, but I would have to deduce from this that our welding process is causing more harm than good. I have an unwelded bare case to use.

[A.J.]

Another update, the 31th I was going to use, which had been welded in the same manner, is also cracked in the same manner as the A413. It was never run in a car since being welded. I am not sure when or how the crack occurred, but I would have to deduce from this that our welding process is causing more harm than good. I have an unwelded bare case to use.

Wow, that's something to think about.

[Reaper1]

Are there any pictures?