[Fot] A type O.D.

[Randall]

---- Larry Young <cartravel at 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