[TR] TR4 Big End Bearings

Jerry Van Vlack jerryvv at roadrunner.com
Sat Feb 28 17:46:45 MST 2009


I can not answer your question about the bearing size but a set of mic's 
will tell real quick. Mic the crank and you'll know.

What I am writing to say is that while you're at it pull the oil pump apart 
and check the bottom plate for scoring. If it's scored I'd work those scores 
out with a piece of course emory cloth on a flat surface like a piece of 
glass. Lay the emory on the glass and oil it well then start to work out the 
scores. Using the glass insures that you remove material evenly across the 
plate. Check the rotor clearances too and replace the pump rotors if out of 
spec. Having that bottom plate tolerance in spec is very important to 
maintaining good oil pressure.

My story is similar to your's. After a 5 hour high speed run I stopped to 
pay a Turnpike Toll and my OP was maybe 5 pounds. This was in April weather 
in Ohio so it wasn't hot out and I run 20W - 50W oil. After replacing the 
rod bearings and rebuilding the oil pump I have 40+ pounds of OP at idle in 
August. Standard size crank with probably 80,000+ miles on it.

JVV


----- Original Message ----- 
From: <pbrandsema at triad.rr.com>
To: <triumphs at autox.team.net>
Sent: Saturday, February 28, 2009 7:27 PM
Subject: [TR] TR4 Big End Bearings


> Due to low oil pressure, I decided to inspect and if necessary replace the 
> connecting rod big end bearings on my TR4.  This is being done with the 
> engine in the car.  I've pulled one set of bearings, and it appears they 
> definitely need replacement.  The bearings are worn down to copper in some 
> places.  Ok, so now I need to figure out what size bearings to buy.  I was 
> hoping the bearing would have a stamping of the size.  (std., .010, .020, 
> etc)  The stamping is 117590, which according to the TR4 spares catalog, 
> this is the part number for the bearing.  However, there is no separate 
> numbers for the undersized bearing.  Since there is no undersized stamp on 
> the bearing, can I assume that it's standard size?
>
> Paul
> 61 TR4


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