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MG TD TF 1500 - Main Bearings Tight


I am having way too much trouble fitting Moss County main bearings. Everything is clean. The clearance measured and with Plastigage is fine but there are several places on the bearings that are showing contact with the crank (Shinny spots)when the crank is turned during assembly. They are mostly on the front and rear bearings. Since the crank is uniformly round, I'm sure its due to uneven bearing surfaces in spots. When torqued, the crank will turn, but there is some minor drag, again, I believe caused by the shinny places on the bearings. I ground the side clearance(end float) of the center bearing on a piece of 220 paper on glass and it is in spec.

Bottom line, I don't want to use these bearings------ Does anyone have a set of .030" Vandervell, Repco, AE, Federal Mogal or any of the good old school main bearings they could sell me?

Richard Cameron

Here's a picture of the rear one.

Richard Cameron

What were the actual clearances from the plastigage check? Was the block line bored? Has the crank been reground and checked for true?
I've never come across a split bearing with uneven thickness as you suspect. Bad bore alignment or an untrue crank are common.
Let's see what the gurus suggest.
T W Moore

TW, I believe you are correct. The crank mains were turned and there may be an alignment problem (may not be concentric), but its funny how the contact spots are sporadic and not full width of the bearings. I just installed another crank (.020") in the block and it doesn't have any problems. So that tells me the block saddles are not the problem. I also tried using a set of used but good .030" Vandervell bearings with the problem crank, and they also have tight spots. Narrows it down to the crank which is not a nice thing to realize because I now will be in the market for a good crank. I don't believe I will try to get it right by turning the mains to .040".
Thanks for your sound advice. I still am not that impressed with the Moss County bearings, they just aren't finished to the same degree as the old name brand bearings.
Richard Cameron

Please disregard my previous request for main bearings. I'm now convinced my problem is related to the crankshaft. Thanks for those interested in my problem.
Richard Cameron

Richard, if you decide not to use the suspect crank then send me an email. I have a good crank (0.010, 0.010) that has been crack tested but will need a grind to the next size.
Cheers, Hugh
H.D. Pite

I would still measure the bearing "housing" (block/torqued main caps) with an internal dial indicator to make sure they are really round. Also double check no burs or grit under the bearing shells. Also, put the crank in v blocks and spin it and make sure it is true and not wobbly- I bought a NOS late 80s Moss crank that had been stored laying down and it was about 10thou "bent". George
George Butz

Mr Pite's suggestion sounds like a good course of action. My crank was cracked and I shelled out $2500 for a Phoenix forged lo-alloy steel one from B&G in the UK. (No one in NA had one in stock).
G Butz is right: your m/shop should be able to tabulate bore sizes and c/s runout if you don't have the equipment. Better to have a best possible dimensional understanding before taking action!
I suspect you're right about bearing quality: I returned a rod bearing set for my Lotus Elan which had some sort of gritty particles on the surface.
Let us know what you find out.
T W Moore

This thread was discussed between 15/11/2014 and 18/11/2014

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