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Re: [Fot] A type O.D.

Subject: Re: [Fot] A type O.D.
From: Randall <tr3driver@ca.rr.com>
Date: Fri, 2 Aug 2013 22:57:13 +0000
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---- Larry Young <cartravel@pobox.com> wrote: 
> I checked 
> several manuals (but not the TR4 workshop manual) when we wrote the 
> articles. There were often discrepancies between different sources.

I agree.  But I believe that part of those discrepancies are that the OD 
operating pressure was customized for every car/engine (and of course for IRS). 
 Some people seem to feel that it should be the same for all cars, but the 
factory didn't see it that way.  For example, the original A-type service 
manual (from Triumph, PN 502274) specifically gives different values for the 
TR2 and the Vanguard/Renown.  Service bulletin T-64-3 quotes a range of from 
360 psi to 520 psi for the A-type (presumably large accumulator since I don't 
think any Triumphs had IRS in 1963).  And the TR6 workshop calls for 410-430; 
while the Stag workshop calls for 480-500 (both small accumulator A-type).  

> Since the inner 
> spring doesn't do much, I may have used a small accumulator spring as 
> the inner spring

That's an interesting thought.  I didn't think it would fit, but I may not have 
checked it.

> or used a plug to shim the inner spring more than the 
> outer spring. 

That's what I did (after taking out one of the shims on the main spring), but 
it still didn't do much.  ISTR a 3/4" plug only raised the pressure about 30 
psi.  I assume the main function of the inner spring is to reduce resonance 
effects.

Randall
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