Suspension geometry

Does anybody have the original suspension geometry of the GT40?
I have been playing with suspension for years, and wonder how they coped with a doubling of tread width, and vastly more grip, through their racing career.
I would kill to know the pivot poiints etc
regards, Robert Lawrence

Robert, I can tell you the settings that we use on the GTD cars used on track in UK, including camber, caster, tracking alignment and ackerman if that will help. Frank

Those figures would be great thanks!
Did the GTD cars use the original geometry?

Robert Lawrence

Robert, I am in the process of building a GTD40. It does not share the suspension geometry of the original GT40.

Frank, I am very interested in what suspension settings you are using on the GTD40s set up for track use. Please mail as much info as possible!

Robert, Most all replica gt-40's have revised the geometry of the suspension. The advances in technology over the years has proven there are better ways to design the suspension over what was used originally. The current crop of replicas drive and handle far superior than the originals ever dreamed.

Hi Robert
try these setings
Front Alignment
Caster +6 degrees +/- 1/2deg
Camber 0 degrees +/- 1/4 deg
Toe-in 1/8" +/- 1/32"
King pin inclination 7 1/4 deg. +/- 1/2deg

Rear Alignment
Inclination of the rear hub carrier towards the rear 7 1/2deg
Camber -1 deg +/- 1/8 deg
Toe-in 3/32" +/- 1/32"

Tire pressures (cold) 22psi front, 25 psi rear, depending on tire brand and size, these pressures will be a resonable compromise between ride and responsiveness

Chris Melia

Bob,

As far as I can tell the basic geometry - arm lengths and roll centers - were not changed at all during the entire MK1 and MK2 runs. I think that the MK4 used the same hub carriers, but the geometry was changed at that time.

On the ERA, we lowered the roll centers a bit and lengthened the theoretical swing axle radii to make the geometry closer to the MK4, figuring that most customers would use pretty wide wheels.

As I recall, the Alan Mann cars had different front suspension geometry. I think it involved the front upper arm pivot points and length of the arm to change dive/lift parameters. The Mann MK IIs were built from Abbey Panels tubs and were not assembled by FAV but rather by Mann and thus had several differences to my knowledge.

Rick

to BOB PUTMAN
Many thanks Bob, I would be very interested to know what the Mk1/11 and Mk4 specs were: Is any of this public knowledge?
I fully realise that the design of the mid '60s on cross plys has little relevence to today, however I am facsinated none the less!

Robert Lawrence

Don't knock cross plies! I use them today and find they give a very controllable drive even in competitive situations. The ones I use are Dunlops from the Post Historic series, front 10 by 4.75 by 15 and rears 12 by 6 by 15. These tyres were used on the original 40 in the sixties for racing. They are very sensitive to tyre pressure changes but do allow adjustments on handling/balance by changing the pressures. I compete on them against other 40's on modern slicks, 15 and 17 inch road tyres and hold my own comfortably. The only downside is wet weather. They are no where near as good as a modern tyre in displacing water. They do look fantatstic on the car and fill the arches beautifully. Oh and they are cheap (ish)

Malcolm M

Please don't assume that I am knocking cross- plies: it is just that very few people use them in a competitive environment, nor on the public roads.
One such exception is where the worlds best drivers often come from: Karting!
I have raced a few myself..
Rob