Spitfire Spit & GT6 Rear Spring Question

[TR_Jim]

I've had a guy contact me through my web site about a Spit6 he bought. He claims it's a GT6 MKI frame. The problem he has is about 15 degree camber on the rear wheels. My question is, there are 4 springs listed in the VB calalog, is there a difference in overall length between these springs? His car is up so high that it seams to be more than just the arc of the spring. Not knowing what spring is in there, what spring would you recommend? I attached a photo. Also...non rotoflex.

Thanks,

 

[tomshobby]

Jim, isn't that a 6 bonnet?

 

[Andrew Mace]

I'll assume that the owner has unloaded the car from the trailer and let it "roll out" so that the rear suspension can settle. From the picture, it looks as if it must have bounced mightily during the trailer ride home!

There's really no appreciable difference in overall length among any of the possible springs, including Herald springs and later Spitfire or GT6 swing-springs. It would help to physically count the number of leaves, which might help determine what spring is used.

Offhand, I'd guess it is the spring that came with the GT6 frame. I'd think that would be ok, particularly if dearched, but it might be a bit too much for the convertible rear body?

 

[Alan_Myers]

Hi Jim,

This is a *good* example of why I really dislike it that a couple of the big, US LBC vendors insisted on creating their unique parts numbering systems and don't cross-reference with the original factory numbers used by most everyone else! VB & Moss' numbering systems just make it impossible to compare between vendors (which is exactly why they do what they do, I'm sure) or to be certain you are getting the correct part! Climbing down off my soapbox now... rant over. /ubbthreads/images/graemlins/wink.gif

Andy might be right, if that is a GT6 frame (I dunno if it's possible, am not that familiar with Spit/GT6 interchangeability) *and* they used the GT6 rear spring that was fitted to it, I would tend to think it's too heavy a rate for the lighter car (GT6 front coil springs would probably be okay with the heavier engine). *However* see note below about later Spit/GT6 springs at Rimmer Bros.

I have a Spitfire Mk III factory parts catalog that lists three different springs (I don't have a GT6 parts manual). OEM springs offered were: Standard 305894, Rally 307027 (heavy duty, with two people in the car), and Race 306677 (heavy duty, with driver only). It appears the only difference is the main leaf of the spring, which was originally available separately under the same numbers as above, except with an "/M" suffix.

Rimmer Bros. shows the Standard spring number listed above used on Spitfire Mk I, II and III. They don't list either of the uprated performance springs (nor does The Roadster Factory). GT6 Mk 1 and post-Rotoflex use a different spring: 307324, according to The Roadster Factory.

Interestingly, Rimmer shows Spit Mk IV and 1500 using the same spring as GT6 Mk III (non-Rotoflex): 159640, in spite of Andy and my suspicions that the heavier car would have a heavier spring!

Although not applicable here, Rotoflex GT6 (Mk II and some Mk III) appear to use a different spring altogether: 308499, according to Rimmers.

Perhaps there is a part number stamped somewhere on the spring and the above info will be useful (however, the numbers were painted on my TR4's leaf springs, and illegible after 40 years).

Other than that, is it possible the spring or any of the other rear suspension parts are installed wrong?

If necessary, a local truck shop could probably re-arc the spring, as Andy mentioned.

Don't know if this helps or not. Please keep us posted on any additional info.

p.s. Canley Classic's online catalog confirms the above factory numbers, and also lists two different springs for Herald and Herald Estate/Vitesse.

/ubbthreads/images/graemlins/cheers.gif

 

[TR_Jim]

Thanks guys for your responses.

I don't have any more info on this car, but I'll post the message I received:

Found your site on the web, sorry to bug you but thought you may have an answer Im looking for…
Just bought myself a new toy…a 68 GT6 convertible , rear body seems to be a Spitfire 72 or up to 75 model…
I did pick the car up yesterday, it does seem to be Mk1 GT6 chassis, has no wishbone …
My question is re the rear suspension, maybe re the rear leaf… wheels are sitting at almost a 15 degree ,tilting inwards at bottom…when I sit (185 lbs) w all my weight on rear bumper , nothing changes…we took off rear wheels , checked shocks ,they are fine ,almost new…
I am wondering if I have the correct leaf across there ,it has 5 Leafs in it…is this correct , or maybe from wrong car?
My thoughts are to take out one or two leafs , then check it… ? Or are there correct leafs ready for purchase?
any ideas?

I was thinking also that the GT6 spring is being used and the Spit body is much lighter. I'll post another photo, maybe someone will spot something.

 

[myspitfire]

Maybe theirs air-shocks mounted,to much air will cause this effect....Just checkin in. /ubbthreads/images/graemlins/eek.gif

 

[Andrew Mace]

[ QUOTE ]
...Interestingly, Rimmer shows Spit Mk IV and 1500 using the same spring as GT6 Mk III (non-Rotoflex): 159640, in spite of Andy and my suspicions that the heavier car would have a heavier spring!....

[/ QUOTE ]Well, I think Rimmer Bros. is just plain wrong on this one. /ubbthreads/images/graemlins/mad.gif

Canley Classics lists 159640 for "Spitfire MkIV short shaft early" cars, which would be 1971-72, and 159654 for the "long shaft" MkIV, 1500 and GT6. 159654 IS a heavier spring, which would be appropriate for a GT6 as well as for the increasingly heavier later Spitfires. I seem to recall that both are five-leaf springs; no question, however, that both are swing springs.

One thing that might help would be to determine if the car in question does, in fact, have a swing spring or an earlier fixed spring. I'd have to suspect it's an earlier spring, but not from a GT6 ("Mk1" GT6s had eight-leaf springs). For that matter, early Spitfires had a seven-leaf spring, so ????

Of course, there is another possiblity: it could be that someone did some rear end suspension work and bolted everything back together really tight with wheels still up in the air at full lower travel. Over the years, I've not usually bothered to "settle" the suspension before final tightening of bolts, but it CAN make a difference in some cases. Still, with the relatively soft swing-spring, I don't think this would account for the problem.

 

[Andrew Mace]

[ QUOTE ]
Maybe theirs air-shocks mounted,to much air will cause this effect....Just checkin in. /ubbthreads/images/graemlins/eek.gif

[/ QUOTE ]Yes, that thought occured to me as well. Might not even have to be air shocks; rather, the "new" rear shocks could simply be the wrong ones and far too long?

 

[Eleven]

I replaced my GT6 Mk1 (1968) with a 1975 Spit frame. Other than the bonnet boxes and the rear bumper extensions, there was no difference. Correction, one, the tranny rear support did not have four bolt holes, only two, Needed some welding.

 

[Andrew Mace]

What about the radiator mounting points?

 

[4aKen]

Maybe he forgot to install the rear end...or fill the trunk with cement...