383 Crankshaft thrust bearing question

[volarebb]

I bought a 383 4 speed car with a rebuilt engine for the engine. I took it apart today. When I went to pull the transmission it would not come out. It turned out the input shaft on the transmission was mushroomed. Apparently the crank is not machined for the input shaft and it mushroomed when it was tightened. The engine has about 10 miles on it and an hour of run time. The engine ran fine and the transmission shifted good while I had it. Is this enough to have damaged the thrust bearing or surface of the crank. I am going to pull the pan and see what I can see, but I am not too sure what to look for.

 

[Aspen500]

It is possible the thrust got damaged. You can pry the balancer forward and backward and see how much play there is. Should move just a hair (like .006"-.008" IIRC). If that's the case, it's probably OK. If the engine is out, like it sounds, still a good idea to pull the pan and check visually anyways.

 

[SRTMirada]

The input shaft can be shortened and a bushing which locates on the torque converter register can be used.

 

[Aspen500]

I double checked the specs to be sure I wasn't giving false information earlier and the end play spec is .002"-.009" with .010" being the max limit.

 

[volarebb]

It is at .013 I am going to pull the pan and the cap and look at it. The guy who does our engine work at work said to check the connecting rod side clearance. If it is over .013 I should be okay leaving it alone. He also told me how to tighten in up a little. It is a mild build going behind an automatic so hopefully it will be okay. Sometimes it feels like for every step forward I take 2 back.

 

[volarebb]

The input shaft can be shortened and a bushing which locates on the torque converter register can be used.

I used a bearing style like that on one of the Oldsmobile's I changed to a 4 speed in the past. This car had the bearing in it, but they didn't shorten the input shaft enough or at all. I would think you would have to know the transmission wasn't going in right with it like that or that would make noise, move with the clutch pedal depressed, or something that would raise a red flag. When I got it it sounded good. In case anybody is wondering getting a A833 out with a mushroomed input shaft is a nightmare.

 

[Aspen500]

Too much end play can mess with the flexplate and torque converter, and cause belt misalignment. Not that .013 would cause any of that though. Could make a knock noise however.

 

[volarebb]

Here is another thing I was wondering about. Does the crank tend to push forward or backward while the engine is running or does it just float within that thrust spec? Would it benefit me to slide the bearing backwards when the cap if off and have less clearance toward the rear and more toward the front considering the damage is on the back side?

 

[Aspen500]

The bearings don't move, they're indexed in one spot only with a tab, and the thrust bearing fits tight around each side of the main bore. I don't think the thrust is really one way more than the other, although I may be wrong. Just have never run into a worn thrust bearing or thrust surface on a crank that was worn on one side only.

If you have it apart, and the bearing is worn (crank OK), you may want to just replace the thrust bearing and be done with it. Unsure if you can buy the thrust bearing individually however.

 

[volarebb]

I pulled the #3 bearing cap today. There is clear wear on the rear side of the thrust bearing. The crankshaft looks good still thank the Lord. Since I have the original bearing part number and the engine has such low run time I am going to get another set and roll in a new #3 bearing. Hopefully all the clearances will be okay and it will be good to go.

 

[Aspen500]

Have a feeling everything will be good to go with the new thrust bearing.

 

[volarebb]

I put the new thrust bearing in and the thrust clearance is now .004. I also had to adjust the oil pick up tube. They had it for too high at about 7/8 of an inch. That probably kept some of the thrust bearing material from being sucked into the engine. It should be all good now.

 

[Aspen500]