Another thrust bearing failure

[jim44]

Hello all, first time poster here long time lurker, im on my second bad thrust bearing and ive narrowed it down to hydraulic pressure in the torque converter, my question is how do i eliminate high pressure on the converter ? Im seeing pressure coming out of the cooler outlet at the trans going above 90 psi not even leaving the garage... this is a 200r4 thats been built up quite a bit and a non lock up pro torque converter, any help or advise would be greatly appreciated, anything you need to know just ask away
Thanks
jim

 

[S10xGN]

Should prolly post this in the trans section...

 

[Lil Truck]

I take it you have already checked all the converter to crank clearances? I had to cut 0.100 off my PTC converter mounting pads when I changed from a stock engine to a forged crank and after market flex plate. They were touching and would have taken out my thrust bearing if I did not check the clearance when I assembled them.

 

[bison]

I take it you have already checked all the converter to crank clearances? I had to cut 0.100 off my PTC converter mounting pads when I changed from a stock engine to a forged crank and after market flex plate. They were touching and would have taken out my thrust bearing if I did not check the clearance when I assembled them.

Can you explain this further? Where was the interference? Cutting the pads moves the converter closer to the flex plate.


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[bison]

Hello all, first time poster here long time lurker, im on my second bad thrust bearing and ive narrowed it down to hydraulic pressure in the torque converter, my question is how do i eliminate high pressure on the converter ? Im seeing pressure coming out of the cooler outlet at the trans going above 90 psi not even leaving the garage... this is a 200r4 thats been built up quite a bit and a non lock up pro torque converter, any help or advise would be greatly appreciated, anything you need to know just ask away
Thanks
jim

Remove the pressure regulator assembly from the pump and post pics


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[jim44]

The converter is about .200 away from the flexplate. Just figured id post in the engine section since the engine is what gets damaged, must be over a hundred threads of people with damaged engines mainly caused by the transmission but i should put a thread in the trans section if no one lends a hand here...
Only thing that was changed in the front pump was the non lock up valve and a different converter, does the lock up valve have something to do with the converter feed ? also the 2nd land on the pr valve was ground down a little more aggressively than im used to seeing but it worked fine with the locking converter setup and never hurt the the thrust....

 

[jim44]

hope this works

 

[Lil Truck]

Can you explain this further? Where was the interference? Cutting the pads moves the converter closer to the flex plate.


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The flex plat clearance was 0.00 with the converter fully seated and trans bolted to the block. There was plenty of clearance from the converter hub to the crank surfaces.

I checked a rechecked the the SFI flex plate to crank mounting and measurements. Debured the flex plate to make sure it was not hanging up on the crank.

After all this I compared measurements and mounted the trans on my stock motor and found the clearance was good.

With this info I had 0.300 + clearance between the converter hub and the crank to work with, I had the pads cut 0.100 leaving 0.200 + clearance at the crank and around 0.090 clearance between the flex plate and converter pads.

 

[bison]

hope this worksView attachment 261654

Does the valve have a hole in it? Maybe the current converter isn't vented as much as the old one. I'd replace the valve with one with an unaltered land


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[jim44]

yes it does have a hole out the very end and on the side, luckily i have a valve with out the lands cut

 

[BobbyBuick]

here is a mod when I make when i rebuild one for an engine that gets some abuse don't really know if it helps I learned it from an old timer engine shop.i just modify the bearing to relieve oil to the thrust side .You need to check line pressure and converter clearance also to find what is causing it .You do know you can buy oversized thrust surfaces on bearings

 

[TurboTdr3.8]

The flex plat clearance was 0.00 with the converter fully seated and trans bolted to the block. There was plenty of clearance from the converter hub to the crank surfaces.

I checked a rechecked the the SFI flex plate to crank mounting and measurements. Debured the flex plate to make sure it was not hanging up on the crank.

After all this I compared measurements and mounted the trans on my stock motor and found the clearance was good.

With this info I had 0.300 + clearance between the converter hub and the crank to work with, I had the pads cut 0.100 leaving 0.200 + clearance at the crank and around 0.090 clearance between the flex plate and converter pads.

I had a converter like that one time , called the Converter people and they said it was built too tall , they sent me another converter and problem solved

 

[jim44]

here is a mod when I make when i rebuild one for an engine that gets some abuse don't really know if it helps I learned it from an old timer engine shop.i just modify the bearing to relieve oil to the thrust side .You need to check line pressure and converter clearance also to find what is causing it .You do know you can buy oversized thrust surfaces on bearings

View attachment 261655

I actually did that mod as well as some other mods the second time, the old timer who welded my thrust surface up after the first failure said he worked at gm and machined the original buick crankshafts for the gn's as well as the normal 3.8's, he said he normally see's this type of damage on big blocks with turbo 400's.

I just had no basis to know what pressure is too much, line pressure in the trans at the drivers side tap gets to a max of about 250 psi in reverse and manual low and the cooler line pressure at the outlet ive seen it approach 90 psi, i replaced the trans lines with new ones and bypassed the coolers and there was not much difference in pressure still high.

If i bottom the converter into the pump i have about just shy of a 1/4" clearance between the mounting pads and the jw flexplate, the flange of the crankshaft where the flexplate bolts up to the crank is perfectly flush, the dial indicator did not even flinch on the as machined gn1 stroker crank.

 

[jim44]

I also ran the trans coolers in parelel instead of in series, the main bearing clearance is .0015 and the rods are a .002, engine oil pressure was 65 psi cold with a low of 22 psi hot with the smallest regulator spring and hv pump.
The engine block was stamped weber racing and was advertised as ready to go but when i put the dial bore gauge to it the front and rear mains were about .001 + out of spec so it had to be align bored to bring it back to spec, the guy who sold it to me must have completely destroyed his crank in there as it would have had less than .0005 clearance

 

[turbobitt]

Hello all, first time poster here long time lurker, im on my second bad thrust bearing and ive narrowed it down to hydraulic pressure in the torque converter, my question is how do i eliminate high pressure on the converter ? Im seeing pressure coming out of the cooler outlet at the trans going above 90 psi not even leaving the garage... this is a 200r4 thats been built up quite a bit and a non lock up pro torque converter, any help or advise would be greatly appreciated, anything you need to know just ask away
Thanks
jim

Need more info on the charge pressure. What is it at max TV pressure?
AG


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[jim44]

Need more info on the charge pressure. What is it at max TV pressure?
AG


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max tv in park at idle was around 70 psi

 

[Nick Micale]

I actually did that mod as well as some other mods the second time, the old timer who welded my thrust surface up after the first failure said he worked at gm and machined the original buick crankshafts for the gn's as well as the normal 3.8's, he said he normally see's this type of damage on big blocks with turbo 400's..................................

Lots of opinions here, and will give you mine as well.

The problem I see is you should have trashed the original crank instead of welding it.

Common sense tells me since the thrust is trashed a second time, is not a converter issue.

In over 20 years we have built 600+ turbo Buick V-6 engines from stock to over 1000 HP and only 2 had thrust issues. Both engine ran the same type and brand multi-disk converter that caused the thrust to be destroyed.

We installed a new crank and different converter for both owners, and never an issue again.

The racers with TH-400 transmissions can have an issue unless an oiling mod is done to relieve pressure forcing the converter forward.

My race car has over 1000 runs on a TH-400 and never trashed a thrust bearing.

 

[Chuck Leeper]

If i bottom the converter into the pump i have about just shy of a 1/4" clearance between the mounting pads and the jw flexplate

1/8" to a max of 3/16" is what PTC recommends. 1/4" is giving up too much pump mesh, unless you are adding washers to take up the excess.
My 400 had that hi psi, too. The mod dropped it to 40.. I did the mod, per Donnnie Wang, so No thrust failures.
Not sure how the 200 is modified.

 

[jim44]

Lots of opinions here, and will give you mine as well.

The problem I see is you should have trashed the original crank instead of welding it.

Common sense tells me since the thrust is trashed a second time, is not a converter issue.

In over 20 years we have built 600+ turbo Buick V-6 engines from stock to over 1000 HP and only 2 had thrust issues. Both engine ran the same type and brand multi-disk converter that caused the thrust to be destroyed.

We installed a new crank and different converter for both owners, and never an issue again.

The racers with TH-400 transmissions can have an issue unless an oiling mod is done to relieve pressure forcing the converter forward.

My race car has over 1000 runs on a TH-400 and never trashed a thrust bearing.[/QUOT

Thanks for the reply, Looks like im going to be in the market for another forged steel crankshaft just hoped i could save it and the work looked really good, having a hard time not finding a definate reason why the thrust is being trashed in such a quick manner not even beating on the car at all, the thrust bearing was set exactly the way i was instructed on this site and ive been building engines for 27 years, seating the thrust was really no different on a buick than any other engine and i was really meticulous about checking everything multiple times, this is just really upsetting after you pour your haeart and soul into something and it keeps punching you in the mouth lol...

 

[jim44]

1/8" to a max of 3/16" is what PTC recommends. 1/4" is giving up too much pump mesh, unless you are adding washers to take up the excess.
My 400 had that hi psi, too. The mod dropped it to 40.. I did the mod, per Donnnie Wang, so No thrust failures.
Not sure how the 200 is modified.

so 3/16 to decimal is about .1875 wich would put me about .0125 too far off the pump gear, I/ll have to find some presice washers to get the converter deeper into the pump drive closer to .125.
it would seem that no one knows how to lower the charge pressure on the 200