Andy,
Actually it was Feb 73 when that change ocurred (serial number 50,000
accordin g to Thomason). I meant to type "Mid MkIV" production instead of
Mid 71. And I totally agree that the longer axles were the main
contributing factor in the spring sag issue. My thoughts (as I have
previously opined) are that the swing spring didn't work particularly well
on the shorter axles so Triumph lengthened them to induce more negative
camber. That also puts more stress on the spring and therefore the reason
why you haven't seen the short axle MkIV's sagging.
----- Original Message -----
From: <zoboherald@aol.com>
To: <spitlist@cox.net>; <jimmuller@rcn.com>; <spitfires@autox.team.net>
Sent: Tuesday, October 31, 2006 8:05 AM
Subject: Re: sagging rear/advice
> Jim Muller wrote:
>
> Another possible factor is the longer axles which started in mid-
> 1979, if I remember right. It wouldn't apply to DR's '77, or course.
>
> and Joe Curry replied:
>
> The longer axles started in mid 71, so they definitely DO apply here.
> In
> fact they are a major contributing factor in the sag problem.
>
> Perhaps we could compromise and say that the longer axles began with
> the 1973 model year (lst 1500s in the US), which is when it happened.
> ;-)
>
> Again, it's only my own experience and observation over the years, but
> I've seen almost no "short-axle" MkIV Spitfires with any rear end sag
> (one OR both sides). Same with the early 1500s. The '73 (again I'm
> talking "Federal" cars here) as a whole was essentially unchanged
> except for the bigger displacement engine and wider rear track. '74s
> added the rear chassis outriggers to support the big "triangular"
> rubber bumper overriders in the rear, so a bit of weight was added. In
> '75, different rear rubber bumper overriders were added, along with the
> heavier, reinforced rear bumper (center section). It is on cars from
> '75 on that I've noticed the dreaded sag over the years.
>
> It's certainly plausible that the wider track could help make the
> problem worse, but I still think that an increasingly heavier car with
> no correspondingly heavier (or even better quality) rear spring has a
> lot to do with it as well. Check out the specified curb weights of
> "Federal" Spitfires from the mid-1970s to the end; they put on a bit of
> flab. ;-)
>
>
> --Andy Mace
>
> *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.
> -- Cut-price Airlines Sketch, Monty Python's Flying Circus (22)
>
> Check out the North American Triumph Sports 6 (Vitesse 6) and Triumph
> Herald Database at its new URL: <http://triumph-herald.us>
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