Cracked overdrive housing #3

[JBallou]

Helping a friend with his new to him truck. An 03 quad cab short bed 4x4, automatic trans that has been built, tripple disk convertor. Has 290k miles on it. It has had the housing replaced at least once. The PO had a transfer case mount put on. It supports the t-case, yet looking at it, put a torsional load on the case. More specifically the overdrive housing.

Well it's cracked at the mating flange to the transfer case. Again. So something must be wrong still for it to break again.

The front and rear deive shafts have spicer greasable joints in them, no noted play, or vibration while driving. We visited a local 4x4 shop. Jantz engineering. He seems very confident that the end of the t-case and the end of the transmission need to be supported equally. The band-aid mount from pact puts a torsion on the case.

He thinks we would be best served with the mount just under the output shaft on the t-case, and a small cross member. Using a chevy trans mount like the pact one.

What does everyone else think? The root of the problem needs to be solved

 

[NIsaacs]

Any idea why it was modified from the original? If the motor mounts are bad it could put too much torque on the trans/transfer case, especially in 4x4. Does he sled pull?

Nick

 

[JBallou]

It was modified from the origanil because it kept breaking the housing, the PO was very concerned that I have been running my truck without the extra mount. He sounded like it was the cure all. The truck in question use to haul a 5er, but was mainly long distance hiway. Now it is used by a family man with 2 kids, firewood, lumber, dirt, etc. But he really could get by with a gasser 1/2 ton. No sled pulling, no power adders ever have been on the truck.

I have seen a couple threads on various forums before this truck came along about OD housings breaking. But now the same truck has broke 3 of them? Not a coincidence. Something is wrong.

 

[jgillott]

By chance, does he know if that truck was ever in a front end collision?

 

[JBallou]

Unknown about a front end collision, however, I have given it a twice over and haven't found anything to make me think it has. No thickness variations in paint, all of the sheet metal under the hood is OEM, has the appropriate stickers, etc.

It does have boxed aftermarket red control arms, like the synergy arms. Has a leveling kit, consisting of spacers and the arms.

 

[jgillott]

A buddy of mine owns a auto body shop and works primarily on rebuilding trucks to resale. Almost every one that has been hit in the front, especially the drivers side where that left front control arm is driven back, has a busted trans housing when they come in. He is absolutely anal about getting that front end square before they go back together. That's the reason I asked. It almost sounds like it was hit, never brought back to perfectly strait, and has that trans housing under enough stress to crack on the next big stress.

 

[jelag]

I've owned several 4x4's all towing heavy trailers... all the trailers were in the 15K-18K lb range... we kept a truck for 400K miles... in all those trucks and must be a couple of million miles we lost 2 transfer cases... both from being low on oil and the lube center not catching a very slow leak and not checking the box... their thought, no leaks no reason to waste the time... in both cases we overhauled them and returned them to service....

All were stock trucks.... I've been on the this forum for a lot of years and don't remember a problem with cracked cases on transfer cases.... I can only assume a miss alignment, or the HP been turned up above its ability to handle the torque and HP...

But to me it has to be a miss alignment... and since it continues from one transfer case to another I can only assume its in the way it bolts to the transmission.. I guess i'd build a fixture... install a dial indicator and sweep the output shaft of the transmission and do the same with the input of the transfer case.... I can't imagine a rear bearing on the transmission being loose enough for that to damage the transfer case....

And of course you wonder if the previous owner had lots of problems with this.. .threw his hands up and sold it....

 

[JBallou]

Jelag, it is the OD housing that has cracked, yet the tcase has been a carry over. You do bring up a good point on the run out of the output shaft. That will be checked. The fuel hasn't been turned up. But I do think that the owner did throw up his arms in frustration and sell it.

 

[jelag]

Sorry I missed that... All my 4WD trucks have been sticks... I think I'd find an alignment shop with the ability to check the truck with a wheel alignment where a fixture is attached to all 4 wheels and they can look for setbacks, skewed axles, and those kind of issues....

I have been involved with 3 HD trucks where the clutch wouldn't release, and the bell housing would crack.... and in each case it was from the engine transmission skewed in the truck from an accident and the repair shop had missed the slight angle that caused the problem... on a truck its a simple thing to leave the clutch out.. and sweep the input shaft with a dial indicator and find the problem... good luck

 

[DonFitzwater]

Find another truck of the same vintage/model and crawl under and take a bunch of measurements. Compare the two, should show something up?

 

[Tweak]

I know this post is almost as old as dirt but..for anyone else with mystery vibration...
check the rear differential for movement...mine had a vibration and did not find it until it smashed the OD unit. The diff was not bolted tight enough and was "climbing" when stepping on it. was very obvious with the shiny metal around the u bolts and spacers blocks...after the fact of course.
another possibility is pinion angle if truck had been lifted. it was not the cheapest lesson and even a tad scary at 60mph...the speed the vibration usually went away. I now look past the ujoints when looking for a vibration in drivetrain.