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Re: More on them nasty thrust washers....

To: tigerpb@ids.net
Subject: Re: More on them nasty thrust washers....
From: Bob Lang <LANG@ISIS.MIT.EDU>
Date: Fri, 11 Apr 1997 14:55:14 -0500 (EST)
Cc: triumphs@Autox.Team.Net
Hi,

I am not an auto machinist.

I have had problems with thrust washers. Specifically, I installed a set 
backwards on my TR6.

In my case, I merely ground some of the crank away due to the crank 
riding on the non-babbitted surface of the thrust washer.

I did not measure the amount of wear to the crank, but I presume it was 
about .010 or so. My point of reference is that I installed a .015 over 
thrust washer to get back to acceptable crank end-play.

In short, if you are going to only put limited miles on the engine and 
your "spare" is almost ready, I'd say get a variety of thrust washers, 
stock, .005, .010, .015 over and try to install and then measure.

I would not replace a main bearing cap, as the correct way to do that is 
to align bore the crank journals to insure straightness. It _might_ work 
and if might not. If it does not, you'll break a crank and then you'll be 
bummed and have a lot of parts you cannot use.

Note: the .020 groove in your rear main cap could be welded up, but I'd 
be real careful about doing that because you need to maintain the correct 
geometry and clearances that you currenly have. In other words I wouldn't 
do that either unless I was going to align bore for the crank.

If you do throw in new thrust washers, and that is all, then you should 
just make it a habit of checking the end float every time you drive the car.

A positive spin on your problem would be this: when you take this current 
motor out, have the rear main cap machined to accept upper and lower 
thrust washers (and get them "pinned") when you go to rebuild that motor. 
Part of the machine work has already been done for you! ;-)

I'm not so sure what the long term ramification of the wear on the crank 
is. I presume that the crank should be welded. It is pretty "thin" in the 
area of the thrust surface shoulder, and I wonder about how deep the 
hardening is in that area. The source of my concern is that my current 
crank is like that and I hope it does not break! So far so good. I've 
driven at least 2000 miles since I played with all that stuff. So far, so 
good!

That's my $.02 worth.
rml
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