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Spitfire autocross/track day car questions ...

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jaywelchy Avatar
jaywelchy Jay Welch
Salem, Oregon, USA   USA
Good a place as any ...

Ive got a few questions here, hopefully the guys racing their cars will find this ...

First, Ive got xtra leaf springs .. could I use a main leaf stripped down, mounted under the diff as a camber compensator?? Fabrication is easy .. and I havent seen the aftermarket CC in person to visualize one. Anyone have a close up pic of their CC?? Ends, center mount, etc.?

Second .. Im going AVO or Carrera adjustable shocks ... were to find heavy front springs?? (475# or so)

Next .. wheel studs. Hate to spend 10 bucks a pop for extended studs .. heard landrover freelander studs work, about 2.75 inches long .. Yes?

After lots of research, I am keeping the factory swing spring .. one of my cars had a stiffer than stock unit, and for the swing axle I think its the best set-up. Quick ratio rack up front, and I made adjustable track bars out back for simple toe changes.

I will be getting 4 heim joints to take place of the leaf spring mounting holes on the uprights, for ride height adjust-ability.

Plan is 1" front sway bar ... though may get a selection from stock up to 1".

My biggest "build" plans are adjust-ability. I am trying to get as much into the car as possible, using fabrication, factory parts and pieces. Engine will be mild, trans and rear end stock .. but plan is to have a few ratios. I have 3 rear ends in the shop. Would like to have all 3 usable, with different ratios in each.

Cage work will be simple hoop behind seats, another under the dash, tied together along the rocker panel line inside. May draw two bars through to tie the under dash bar to the spring buckets. Rear hoop will also tie into body mounts that set under factory tank location. Fuel cell will be used, in trunk. Car will be used to blast down to the oregon coast on occasion, WITH the wife sometimes ... need easy access using factory doors. So no permanent side bars at this point. If I keep her a part of my plans, then hours spent on projects are no sweat winking smiley

If anyone has any good ideas, or any good advice, love to hear it.

Jason
jaywelchy@gmail.com

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OFRacer Avatar
OFRacer Mike H
Poughkeepsie, NY, USA   USA
Hi Jason, here's a link to a page about my 63 Spitfire purely race car. 63 Spit.

I run a 1" front bar, no camber comp, Spax adjustable shocks set about 7/ 10 towards firm. The rear axle is key, the factory one is OK for the street but when you put sticky tires on, they break where it's machined to hold the bearing at the upright. I'm running a 1500 spit length axle with the standard 63 locked in place mount. Adjustable rear brackets for toe in, multiple settings available on the rear uprights but I like it at the stock height position so I don't get tire rub. I have 3 diffs, all welded, 4:11, 3:89 and a 3:27. I did have a 4:55 which gave me great acceleration but killed my lap times, no top end.

The front bushings are all machined Aluminum parts with grade 8 hardware. Short GT6 springs, 325 Lbs. The car came with a very short pair of 550 Lb fronts but they only fit the Koni adjustable shocks. When the Koni bodies started showing stress cracks I didn't replace them, out of production now and not worth the $1200 per corner price they quoted me for a special app replacement.

The car is locked down fairly tight, I spent a few seasons trying different spring, sway bar, tire pressure and shock combos and I'm very happy with the way it handles now. There's no roll, it takes a set very quickly in a corner, both left and right. I came from a go kart and mid engined formula car background so I prefer a stiff car that will do power on over steering. So folks prefer under steer and it can be dialed in with a thinner front bar and a softer rear shock setting but to me it's not as much fun.

Experiment, it's half the fun.

mike

jaywelchy Avatar
jaywelchy Jay Welch
Salem, Oregon, USA   USA
Thx Mike ...

Good info.

And I did hear about the rear axle weakness ... need to address that. Heard Summers bros. has a fairly priced set of axles for the Spit.

But sounds like I am on the right track!

I did order a 1" rear leaf spacer .. and plan to drill holes in the uprights, about 3/4" down also. Just for fun smiling smiley Wont use the spacer AND the lower holes .. would be on the ground.

No CC on rear .. cool, Ill try it without first.

Thx again,

Jason

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turner4366 Avatar
turner4366 Tom T
Danville, California, USA   USA
I would not recommend using stock axles or early stub axles. Axles have a tendency to break at the outer end just behind the rear hub. The weak point is the step for the retainer. Look at Mark Williams competition axles. They are good for about 10 years of hard racing with fat sticky tires. The early rear ends had small stub axles. The later year rears had fatter stubs inside the differential. Find one of those before you snap one off. Breaking a stub axle causes the axle to slam around under the car. I had mine rip through the trunk floor right where the stock tank would be - luckily I had a fuel cell. For axles breaking, think about going into a high speed corner - the wheel suddenly leaves the car and, if it clears the bodywork, you are doing 3 wheel donuts. If it jams under the bodywork or the car you will be flying without a licence and hoping you come down dirty side down - but don't bet on it. Axles are not cheap but cheaper than rebuilding the car. Later rear ends may be found in junk yard.

1964Spitfire Avatar
1964Spitfire Tim P
Santa Clara, CA, USA   USA
Very bad things can happen when an axle breaks at speed.



Chequered Flag Racing also makes a nice heavy duty axle kit.

http://www.chequeredflagracing.net/

turner4366 Avatar
turner4366 Tom T
Danville, California, USA   USA
Yes! I've seen that before and it is a good reminder that axles can't be over looked and that as they get old, they too can break.

Tom

hymodyne Avatar
hymodyne james king
salisbury, MD, USA   USA
1972 Triumph GT6 MkIII "Baby Blue"
+1 on the stub axles being weak. had one snap on my GT6 at highway speed years ago...

James

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CASpitfireGuy Avatar
CASpitfireGuy Cody Crowley
Los Angeles, California, USA   USA
I don't mean to hijack this thread, but I have a lot of the same questions for autocross...I'm beginning to regularly run my car in CSCC Solo events.

I have a stock 1969 Spitfire Mk3, but I have heard about the diff output shafts being easy to snap, as well as the axle hubs/axles. What would be the recommend set-up?

In regards to the Chequered Flag race axles, I'll be seeing Joseph Siam next month...he rebuilt my engine and recommended welding some baffles in my oil pan to combat oil sloshing during hard cornering...guess I'll ask about the axles, too...can't afford it right now lol.

turner4366 Avatar
turner4366 Tom T
Danville, California, USA   USA
I use Mark Williams axles with Chevy yokes to the pumpkin. Also, make sure you have the large stub axles as are found in the later model Spits. Over 20 years of racing I've had both break at different times - it is heart stopping.

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