Spitfire Spitfire Frame Modifications

[Dugger]

I am in the process of body - off restoration of our MKIII Spit. I was wondering what frame modifications/strengthening I should consider other than the compensator for rear wheel tuck.
This is a street car and will not be used on the track.

 

[Andrew Mace]

I'm a big fan of camber compensators, but there are those folks who prefer the swing-spring conversion. Either will improve things a good deal. I think you'll find that the camber compensator works out to be less expensive and requires no other changes, while installing a swing-spring requires changing to a larger front anti-sway bar (unless you really like terminal oversteer).

Beyond that and whatever tires and wheels you end up using, I recommend Koni shocks as a worthwhile upgrade.

 

[Dugger]

Thanks for the quick response.

Like the TR6 frame, the Spit frame has a lot of flex. I reinforced the diff mounts in 'Lil Red' which is a weak point common to all TR6's. Is there some specific frame modifications that I should consider similar to this?

I could be just paranoid, but I would find it hard to beleive that Triumph designers used any different techniques on the Spit frame than they did with the '6'.

Maybe I should rephrase my question - Where are the weak spots in the frame and what can I do to improve these areas?

 

[Andrew Mace]

[ QUOTE ]
I could be just paranoid, but I would find it hard to beleive that Triumph designers used any different techniques on the Spit frame than they did with the '6'.

Maybe I should rephrase my question - Where are the weak spots in the frame and what can I do to improve these areas?

[/ QUOTE ]Actually, the designs ARE quite different. Unlike the various frames of the TRs, the Spitfire's frame is primarily a "backbone" down the center, with some outriggers to hold up the "semi-monocoque" body tub. That's why, among other parts, the inner / intermediate / outer sill panel integrity is so important on a Spitfire, and why they begin to sag somewhat easily once serious rust hits that sill area. But the sag is nothing like that on a TR tub. I've had rusted TR tubs that virtually folded in half when removed from a chassis, while a Spitfire tub with badly rusted sills and little metal in the floor panels will still maintain its overall shape when removed from the chassis.

The earlier Spitfire chassis seems to be a fairly robust item in and of itself, and it wasn't nearly so susceptible to rust as was the later TR chassis (or some later Spitfire chassis, where the added "Federal" rear outriggers ended up being water/mud traps). /ubbthreads/images/graemlins/blush.gif

 

[billspit]

I'm not aware of any inherent weaknesses with the Spitfire chassis similar to the weakness of the TR-6. The biggest issue is rust or wreck damage, which would harm even the best designed chassis. I went to the swing spring from a MK IV because that what wsa in the parts car I bought for the OD transmission. Turns out to be great for me because the MK IV has the shorter axles, which you want for this conversion as well as the thicker sway bar. I've been pretty happy with the set up so far. I could not find a camber compensator that that time, but now know that Joe Curry sells one. Only problem I see with it is it lowers your ground clearance somewhat.

 

[Andrew Mace]

[ QUOTE ]
I could not find a camber compensator that that time, but now know that Joe Curry sells one. Only problem I see with it is it lowers your ground clearance somewhat.

[/ QUOTE ]Unfortunately, ground clearance seems to be a problem with Joe's. Some originals did not have as much of a problem, although it was there.

 

[Dugger]

Well, this seems to be good news for me. One major item is off the to-do list. Now lets see, 1 down...fifty gazillion to go.
Thanks for the quick responses, and I will keep everyone informed of the progress.

 

[GeorgiaTriumph]

I would just use a spring spacer on top of the diff. Canley has a picture on there site. Different thicknesses will render different amounts of camber and no clearance issues.