[Colin70TA]

Hinton/west carleton said they did but like I said, D&D were good in the past. Nobody is always 100% perfect and mistakes do happen. Not sure if I should get the crank checked for dimensions at Hinton this week or not. I don't want to pull the motor again but also there is a track day at Calabogie I am supposed to run with the car on Sunday. Ill see what I find out monday from D&D. I won't have new bearings in my hands till Wednesday.

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[Colin70TA]

Tearing down further tonight...the main bearings, what would cause this?

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[hurryinhoosier62]

Trash in the block from not being cleaned thoroughly.

[steve25]

Or in the Cranks oil passages if it was ground and or polished.

[gtofreek]

Or bearing not sitting flat in cap/saddle due to debris behind it or high spots on the back of the bearing, which is why I always tune-up the bearings before I install them.

[mgarblik]

I don't think it has been mentioned in this thread yet, so I will. This is an auto trans car? If it is it looks to me like the thrust bearing is getting the crap pressed on it through the torque converter. Make sure your converter has plenty of clearance to the flex plate and that the converter has a stiff anti-ballooning plate in it. That's the #1 most common cause of thrust bearing failure in auto trans cars.

[Colin70TA]

Thanks guys,
Bottom end of the motor is all apart now, crank out etc. We have a friend that's a retired GM tech that has a lathe that he has polished thrust surfaces numerous times on. He is also going to help with the install to make sure it goes right this time. New bearings just came in today and I will take a jewelers file to the back to make sure they are smooth as suggested Paul.
Once I start putting it back together what's the ideal end play number? between 5 and 7?
If there are any tips you can give please share, I don't want to do this again!!

[Colin70TA]

It is an auto trans car and I spoke with the machine shop that did the work and that's what they think went wrong. How much clearance should there be? To note, when I first put the motor together I still had my 13" Continental behind it but about 200 miles in I changed it to the 10" PTC that I bought for the set up. It's definitely possible that the Continental was ballooning. The wear on the thrust bearing is on the side closest to the rear main, which would mean that the pressure could have been coming from the converter correct?

[mgarblik]

Once the thrust surface has been polished very smooth by the gentleman you mentioned, turn your attention to the new bearings. It looks from the pics the old bearings were FM 113M? If the new bearings are the same brand, you may need to detail them a little. When FM switched their production to Mexico, the main bearings became a little less consistent. I dress the thrust bearing sides on a surface plate with 1200-1500 grit paper oiled. That is to make them flat across the surface to start with. I use a little layout dye and gently sand the rearward facing flange until smooth and flat. Then I install them and measure the clearance with a dial indicator. Generally, with just this done, the clearance will fall within .005-.007". So you are done at this point.

However, sometimes the whole process can be a real PIA. Aftermarket crankshafts and OE ones that have been ground poorly can give you all kinds of weird readings. Sometimes you need to install only the block half of the bearing and measure the clearance. Then install the cap half separately. This is to verify the cap is sitting straight on the block. The thrust clearance should not change more than .001" with each half installed. It you have for example .006" ..with just the lower half in place and .002" with the cap half in place the cap is cocked on the pin and register on the block. This will require a proper line hone to correct. It all seems simple and it is until a bunch of mismatched parts are involved. Then it gets complicated fast. Looking at your bearing, it looks like a torque converter has caused the flange wear. However, some others posted some weird spot wear on the other bearings.

If this were my engine, here is what I would do to be sure of everything. Assuming everything is clean, assemble the caps to the block with the fasteners, lube and torque you plan to run. Measure the housing bores to make sure all 5 are at the middle of the spec. +- .0002". With that done, install the bearings and torque. Re-measure the housing bores with the bearings installed. Do all this with a dial bore gauge. Measure the crankshaft with a .0001" resolution micrometer. Subtract the crankshaft measurements from the housing bore with bearing measurements and now you have the actual oil clearance. Dress the thrust bearing as mentioned above and see where you are.
Sorry for the long post, but this is the way you assure everything is absolutely right. It takes me about 3 hours to properly fit a crankshaft in a block. It's not a ten minute job. Best of luck to you.

[dataway]

Couldn't a person zero the bore gauge with the outside mic used to measure the crank, then just insert the bore gauge into the bearing bore to get the clearance? That should reduce gauge error to practically zero.

[mgarblik]

Originally Posted by dataway

Couldn't a person zero the bore gauge with the outside mic used to measure the crank, then just insert the bore gauge into the bearing bore to get the clearance? That should reduce gauge error to practically zero.

Sure, or use a setting fixture if available. That will get you +-.0001". I just wasn't getting the warm and fuzzy look from any of those main bearings. That's why I suggested the full, more lengthy procedure. That way you know the line hone is good, the bearing crush will be correct and hopefully the oil clearance, if the crankshaft was machined and polished properly.

[Colin70TA]

Thanks for all the awesome info.
Here is what I got done today. Did as you instructed for the thrust bearing, cleaned up the surface and checked with each half. Ended up with 0.0065 for thrust which I am happy with.
My main bearing measurements seems okay, maybe a bit tight but my figures from last time were about the same. Mains measured between 0.018 and 0.021.
Not sure if I should stick with that or try to get more clearance? I see butler has extra clearance mains but I am in Canada so not that easy to get.
Thanks again for taking the time to help.
I still need to check the torque converter and make sure that didn’t cause this either.

[taff2]

If you have a TH400 auto-especially a street/strip type- there can sometimes be a problem with the converter pushing on the crank hard enough to cause a thrust bearing problem. There is a mod routinely done in the trans to stop this. (a restrictor in the converter charge feed hole)
I also mod every thrust bearing to increase oil flow to the surface, just use a small file to put a .020" chamfer on the inside edge of the bearing parting line.

[steve25]

Your mains are ok. But if you like on the hair tighter Bearings you can take some 1000 grit paper and soap & water and sand off the Gray breakin coating.

[mgarblik]

Originally Posted by taff2

If you have a TH400 auto-especially a street/strip type- there can sometimes be a problem with the converter pushing on the crank hard enough to cause a thrust bearing problem. There is a mod routinely done in the trans to stop this. (a restrictor in the converter charge feed hole)
I also mod every thrust bearing to increase oil flow to the surface, just use a small file to put a .020" chamfer on the inside edge of the bearing parting line.

I don't think the bearing itself could have caused that much wear. So do as suggested above and make sure the torque converter and trans are OK. If you are using FM 113M bearings again, they do not have the flash tin coating Steve 25 was referring to, so I would not work on the bearing surface itself.

[lust4speed]

Originally Posted by taff2

If you have a TH400 auto-especially a street/strip type- there can sometimes be a problem with the converter pushing on the crank hard enough to cause a thrust bearing problem. There is a mod routinely done in the trans to stop this. (a restrictor in the converter charge feed hole)...

This needs to be repeated. I've only had one torque converter balloon but we have had two occurrences in our car club where excess pressure inside the trans pushed the converter forward hard enough to wipe out the thrust bearing.

So one failure is the converter expanding and the other is like a hydraulic jack behind the converter pushing it forward. Either one will destroy the thrust surface.

[Colin70TA]

Thanks guys,
The motor is all back together and in the car running without issue motor wise. I will get the tranny out next week and go through it and make sure it wasn't causing the issue. The more I think about it I do beleive that's what caused it. Since having this new motor in this year it's been a bit all over the place shifting. Example 1st gear 20mph roll car does not accelerate hard at all...aka doesn't even brake the tires loose. But at a 40-45mph roll in 3rd it will spin the tires/go sideways a bit before pulling hard. At first I thought it was carb and fuel system related but more and more it seems like a tranny issue. Trans was built 18 years ago and was not far off from a stock build. Worked great when I was running 12.70's with the original engine but this motor is throwing a whole lot more at it.

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[Formulas]

Here is a pic of the TH400 pump restriction mod it helps keep the converter from pushing on the crank

You can use a jeweler's file to create a more direct pressure feed to the back of the thrust bearing at the parting line but that's before assy

.

[Colin70TA]

Thanks! I am pulling the trans next week and will address that mod and also go through the whole thing. I was at the race track this past weekend and a racer friend brought up another point to look at, driveline angles. With a lowered car and a bunch of other modifications he said the problem could be cause from the rear end back. Anyways, he said he lost a few transmissions and thrust bearings to this as well on a few of his race cars. Worth checking out regardless!