Ah...thanks for clearing THAT up ....NOT!....Just when I thouhgt I knew all I
needed to know, BPSL has thrown me another curve...FK29131 is what is stamped
on my diff, car manufacturing date January 1972...Can you tell me , oh wiser
than I, what the hell my gearing is?...Oh yes, one more thing! Got the
flywheel for the 7.25" clutch so I can adapt the O/D trans with the 20 spline
input shaft...Now I see the bolts are of a different dia. What should I do
here...shim the originals to fit the larger bore holes in the flywheel...Or
rethread new bolts with .375" die up to shoulder heighth?...This has certainly
been a Project with a capital P
Chris "give me a freakin smoke" Prugh
----------
From: Andrew Mace[SMTP:amace@unix2.nysed.gov]
Sent: Monday, June 24, 1996 2:21 AM
To: Chris and Karen Prugh
Cc: 'CWNicholls@aol.com'; 'Triumph List'
Subject: RE: Overdirve Diff in a Mk3 Spit??
On Sun, 23 Jun 1996, Chris and Karen Prugh wrote:
> Clark,
>
> Being in the middle of my trans swap project, I can assure you, the only
> differences possible (in North American models) are that the rear ends
> in MKI, II, III, and IV all have 4.11:1 gearing and the 1500's have
> 3.89:1...
To be my usually PAINFULLY correct ;-) about this, the 1971 Mk.IV Spit
had a 3.89:1, as did U.S.-spec. 1973-on 1500s. The 1972 Spit went back to
a 4.11:1 to cope with the very low compression 1296. BTW, same gearing,
but NOT the same diff. as the "round-tail" Spitfires.
> Now, should you take the O/D trans from a late model 1500 and put it
into an early Mark IV....well this seems to be my situation...so figure it
> out and let me know...How will this affect my speed shown on speedo vs.
> actual (or what the CHP says he clocked me at) ???
As implied above, it depends on which year early Mk.IV you're dealing
with: 1971 -- 3.89:1; 1972 -- 4.11:1. So, if your Mk.IV is a '71 with
original diff., not to worry, as you really haven't changed anything.
--Andy
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* Andrew Mace e-mail: amace@unix2.nysed.gov *
* *
* Mrs Irrelevant: Oh, is it a jet? *
* Man: Well, no... It's not so much of a jet, it's more your, er, *
* Triumph Herald engine with wings. *
* -- The Cut-price Airline Sketch, Monty Python's Flying Circus *
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