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Old 07-01-2015, 08:50 PM
whittp whittp is offline
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Default Thrust bearing...again?

Long story short....Engine rebuilt and got 1000 miles on it and the thrust bearing went out due to pressure on the crank from the back. Took out the roller lifters and the rest of the bearings. Took the motor out, completely rebuilt with new bearings, crankshaft, and lifters. Dyno'd multiple times and no issues.

The issue was determined to be a problem with the torque converter not mating properly with the crank due to the factory spacer being installed and not needed. The converter was also not fitting into the end of the crank properly and causing some back pressure as well.

I checked the fit of the converter and had to have it machined to have a proper slip fit into the crank. I also checked the thrust bearing run-out and it measured .008. When I got the motor in I checked for the proper clearance between the converter and flex plate. It was over the spec so I added .060 washers per the instructions to bring it into range. Once installed, I remeasured the thrust bearing run out to make sure nothing was in a bind. It seemed to move freely.

Once everything was installed and it was fired up I checked transmission pressures (200-4r). Everything checked out in all the range of gears and at idle. Idle pressure was 75 psi which is the low end of acceptable. This test was recommended by the engine builder to make sure the tranny wasn't causing back pressure as well.

Fast forward 300 miles. Drove the car 30 miles to get the only 93 octane fuel available around here. One the way back, I noticed the valve train a little noisier than usual. Parked it at home and checked the oil. It was the same gray looking gunk that I saw right before the last disaster.

Drained the oil to check for metal and it does have a slight shimmer to it but I didn't see any flakes. The magnet on the oil drain plug had a ton of gray gunk stuck to it.

Just for good measure I removed my fan to get a good angle and put my dial indicator on to measure the run out again. .035 this time! I think I'm giving up on this car for a while until I can afford yet another motor rebuild but can you guys shed some light on what is happening?

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Old 07-01-2015, 08:54 PM
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Have you checked the pressure in the transmission cooling lines? I've heard plugged coolers have this effect.

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Old 07-01-2015, 09:01 PM
whittp whittp is offline
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I haven't checked that but the lines and cooler have less than 1500 miles on them along with new trans fluid. I'd hate to think that was the cause of all my bad luck.

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Old 07-01-2015, 09:52 PM
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I'm sorry to hear of your issues- my build had a similar fate after about 10 miles and the new build with a different crank this time has yet to be installed. What crankshaft in your engine?

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Old 07-01-2015, 10:55 PM
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Damn, sorry to hear this, I saw your last thread. Sometimes these cars can be frustrating. I would pull the motor and oil pan and check before it gets bad. Maybe just a bearing this time before you need a rebuild.

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Old 07-02-2015, 06:48 AM
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What crank do you have in this motor, and has its thrust surface been checked?

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Old 07-02-2015, 10:57 AM
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could be a broken converter or to much pressure at the converter forcing it against the thrust.

Was the thrust bearing cooked/smoked or just worn.

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Old 07-02-2015, 02:13 PM
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His last thread had photos of all the damage that was done with the same situation on a fresh rebuild.

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Old 07-03-2015, 08:18 AM
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Sorry to hear about your issues. I can relate to your pain.
Your engine builder is not to blame for your thrust bearing issues. I do not believe the problem is with your crankshaft thrust surface, flexplate or torque converter.
I also believe you will find that the problem will be related to your transmission.
Went thru a very similar deal a few years ago with my buddy's IA-II motor. Took out the whole bottom end on it's first outing to the track. Thousands of dollars later and the addition of a Crower billet crankshaft, the motor was rebuilt and reinstalled.
Next outing, same thing again, only this time we caught it before it destroyed the motor.
Went thru the motor again checking for any kind of run-outs or misalignment that could be causing the issue. Micro polished to crank thrust surface and added some oiling tricks to the thrust bearing. Back to the track, here we go again.
Replaced thrust bearing and this time first set engine up on a test stand and ran for at least a half hour continuously monitoring the end play. No change.
Next step, we install a different torque converter to rule out ballooning issues. Once again, he's loosing the thrust bearing. Back out with the motor for another bearing.
Next test, we pull the transmission from my car and install it in his and head back to the track. Bingo, problem solved.
The real problem was believed to be, as mentioned by others in your original thread, to be excessive hydraulic pressure into the torque converter from the upgraded ATI input shaft of the TH-400 when it was build to handle the horsepower. The stock input shaft has (2) relief holes and the ATI only had (1).
After doing some research, we found this problem has come up many times before, and others have installed an orifice at the outlet of the input shaft the limit the pressure into the torque converter.
See what upgrades were done to your transmission and you may just have your answer.
Good luck and don't give up.

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Old 07-03-2015, 10:19 AM
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Yes, it seems you had all clearences right on per your post the 2nd time. I would look hard at the tranny too. Good post by Michael G

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Old 07-03-2015, 10:34 AM
pugslyx234 pugslyx234 is offline
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Damn I,m sorry to hear, so here is what I,d do pull engine, pan UG, check out, repair then run it without a trans use a manual bell to fire and run and recheck engine if all good, change trans and convert. Cause this prob is killing you.

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Old 07-03-2015, 03:29 PM
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I've been through this with a TH400. completely destroyed the original 400 block for my Formula, 4 of the main bearings spun before I realized what the problem was. Built an entirely new engine based on a 455 block with 428 crank and lost that engine too but only lost the cranks 'cause I caught the problems before anything more than crank & thrust bearings were damaged. Took me a long time to figure out the problem was with the transmission and after spending almost $10K on two engines that didn't live longer than 1500 miles each I stepped out of the hobby for quite a few years.

You have a different trans and said you measured internal pressures, so ???? I'd start by thoroughly checking the finish on the thrust surfaces of the crank. Lots of crappy crank work going on these days. If you have a crank that's properly prepped and your crank end play is within spec (you're using the term "runout" I think for this, which is a measurement of the concentricity of something, typically a crank journal and not the for-aft movement of the crank) then the problem is likely with the transmission.

In the case of the TH400 I've learned that internal pressures in these trannies when modified for high performance can cause excessive pressure on the torque converter. In short, the trans is trying to push the torque converter into the back of the engine all the time with much more pressure than was originally anticipated by the designers. The cure seems to be a restrictor in the feed to the torque converter to lower the internal pressure in the converter.

Good luck! This kind of thing is more than frustrating. Buy a tubing cutter so that you can open up your oil filters and check your filters regularly while you're working on this issue. Metal from the thrust bearing will show up in the filter first.

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Old 07-05-2015, 04:07 PM
whittp whittp is offline
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You guys have offered some very helpful advise. In the next few weeks or months when I get over my disgust with the situation, I'll get to work and let you guys know what transpires. Thanks again.

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Old 07-05-2015, 04:39 PM
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I think you should dig in asap! Pull the engine, maybe just a bearing got beat from the tranny pushing the crank. Not a total rebuild but bearings. That would make you feel better. If the crank and rod bearing sufaces look great and the thrust bearing is beat up should make you feel relief. Good luck keep us posted.

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Old 02-05-2021, 03:01 PM
whittp whittp is offline
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Default Finally ready to dig into this!

Gentlemen,

It's been a little while and I'm ready to tackle this. I decided to switch out the 200r4 with a new tremec TKX. The engine will get a tear down and hopefully just new bearings after a good cleaning. Does anyone have experience with the TKX yet? I plan on ordering a repop 4 speed console and peddle kit to keep a semi stock look. I'm going with the hydraulic clutch option on the new transmission.
What else do I need to know about the auto to 5 speed swap?

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Old 02-05-2021, 04:00 PM
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I had a SBC in my '82 k20 pick up that ate thrust bearings with a manual transmission. It even destroyed the factory forged crank shaft. It turns out that the problem was that the block was not chamfered around the thrust bearing corner. When the cap was tightened down, the sharp corner would flare the bearing out preloading it heavily. The difference here was that with a new bearing and that caps tightened I could not measure any end play. It was quite puzzling at first because checking the thrust bearing in the crank with a feeler gauge looked fine, but checking the end play with a dial indicator showed no end play. I manually chamfered the block with a die grinder and it was all good after that. Drove it many miles and never had a thrust bearing problem again.

I know this is not exactly your situation, but maybe there is something with your block or cap that is distorting the thrust bearing in a strange way. Worthing looking carefully.

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Old 02-06-2021, 07:53 AM
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When you rebuild the engine- put a .020" chamfer across the inside of the parting lines of the thrust bearing,this will direct a stream of oil to the thrust bearings faces. Next, if your thrust bearings faces DON'T have any grooves in them- then file a couple of shallow .010" -.020" grooves into them (outwards from centre to edges), this will hold a small reservoir of oil in each groove.
And yes, almost all high performance auto trans should have a converter feed restrictor in the pump, a grooved or fluted front stator bush also allows easier oil return from the converter which makes it less likely to become a hydraulic ram acting on the back of your crank. A bypass relief valve is also commonly used in the oil cooler out line-this will bypass excess pressure/oil back through a line to the pan and will reduce the possibility of thrust issues. Hope this helps.

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