bear with me cuz here's my problem. I installed a TH400 in my car a few years back when i had a 355 LT1 (about an 7K dollar motor). Motor saw about 2500 miles maybe.... come to find out after those miles and just a few track passes in the low 10's my thrust bearing is shelled.... motor is fubar, completely needed a rebuild.....

rebuild turns into "let's go all out and build 8 second setup and go for world record"..... fast forward about two years to now and i'm getting ready to pick up my 15,000 dollar 383 stroker motor with top dollar EVERYTHING.....

here's my problem.... same old TH400 and same converter is sitting on the floor waiting to go in behind the new motor.... converter is ATI fuel/blown converter with anti balloon plate (I never ballooned the converter with my old setup)..... I paid a grip for the ATI TH400 with brake and all the bells and whistles but i feel like if I put this ************ behind my new motor who's to say that it isn't going to take out my brand new engine in 2000 miles..... and i've done research on thrust bearing failures and even big companies don't really know for sure what causes it......

I talked to someone at Continental converters who says he can modify my converter and drill holes inside it that alleviate the pressure buildup inside the converter which typically causes thrust bearing failures but i'm not sure if it's just some "pixie dust" fix that i'm wasting money on..... cuz it seems i'm one of the rare few that have TB problems...... someone help me decide.....

also one other question i have is the clearance between converters and the flexplate.... if the converter is BOLTED to the flexplate how is this adjustable???? My converter (ATI) has tabs on it that bolt to the flexplate and they are at the bottom and pretty thick... when the converter is bolted up to the flexplate there is at least 1/2" between the converter and the flexplate itself.... how can it be any less when bolted up?????

 

Have you talked to Ati about this? They make some of the best converters and transmissions on the market. I would trust their opinion before any others. What makes you concerned about the distance between the converter and the flexplate when bolted together? The only concern you should have there, is the backspacing of the converter when its unbolted and pushed into the trans. And what makes you think that the previous problem lies in the converter/trans? If you are uncertain, I would send them both back to ati, and have them inspect both pieces for a potential problem.

 

GM addressed this back in 1970 in the Pontiac Ram Air IV TH400's. You will need to remove 2 splines on the input shaft with a dremel 180 degrees apart, this was what GM did back then. You could restrict the torque converter feed also. Someone here might have a photo of this restriction in the pump. This is the solution to this.

 

Well from everyone i have asked says that the only way you destroy a thrust bearing is by something EXTERNAL acting on the motor since front/back movement is not something a crank does on it's own. the engine builder could have set it up wrong but he was very reputable so i don't think that possibility holds alot of water.

I just found my documentation that came with my tranny and i re-read it for my personal knowledge....

Basically what it said is make sure you have at least 1/8" but preferably 3/16" freeplay with the converter NOT bolted to the flexplate.... so you can move the converter towards the flexplate.....

and you need to make two measurements... measurement of the surface of the flexplate to the back of the block as '1', and the measurement of the tranny mounting surface to the tabs on the converter that bolt to the flexplate as '2'...... the measurement of '1' must always be less than that of '2' or you will be binding up the converter.... i completely understood that. I'm going to call ATI tommorrow and ask the question. Everyone i ask about ATI says they are the **** when it comes to trannies and converters so i will ask them if there is a fix for it.....

PBA-That isn't the first time i've heard about that fix.. chris at continental converters said something along the same lines... he also says that he has a mod, (along with John Kilgore on here) where he drills holes in between stators inside the converter to relieve the pressure inside the tc..... supposedly that will also do the trick.... do you have any more info about it or possibly pics of what it looks like? Cuz I have a dremel and if it looks within my ability to do it i'll definitely try it.... i just don't want to possibly **** up my input shaft....