Ride height measurement

[Geoff Deakin]

I'm slowly getting there!

I've reached the stage where I'm about to buy new springs and dampers.

I'm trying to determine the ride height - I'm thinking 5" front and 5 1/2" rear.

However, I've got a dropped floor. Should the rear ride height be taken from the dropped floor or from the chassis, at the rear of the tanks. I'm measuring the front ride height from a point beneath the bottom wishbone rear mount.

The car is a KVA Type C - What about spring rates and damper lengths?

Any ideas gratefully received.

Cheers,

Geoff.

[Mike Pass]

Ride height measurements should be from the chassis. The ride height should be set by setting the suspension to the correct static point. You need to look at the angle of the suspension. By this I mean that you should look at the location of the points where the swivels are at the chassis end and at the upright end. Ignore the actual metal of the wishbone tubes. The actual "wishbone" is a straight line drawn between the attachment points. The lower wishbone should be angled slightly downwards and the top one angled upwards at a steeper angle. This should give the static ride height position. The idea is that as the suspension is compressed the top wishbone end moves inwards and the bottom one moves out thus increasing the amount of negative camber. This is to compensate for the car rolling as it corners and helps to keep the tyre flat to the road.
Usually a GT40 would be set up to have an amount of rake with the rear about 1/2" higher than the front. Most run about 4" front but set the wishbones at the correct height to give the best geometry. The dropped floor is irrelevant apart from danger to your nether regions over speed bumps!
Cheers
Mike

[Chuck]

As an aside, we made four blocks at the desired ride height. Lot easier than a ruler.

Three sections of 2x4 gave us 4 1/2 inches for the front. Added 1/2 inch scrap to the rear blocks to give us five inches in the rear. Just slide the blocks under the chassis at the front of the A arm.

For a street car I would be reluctant to go any lower than 4 1/2 on the front.

[Cliff Beer]

Ditto what Mike said as a rough guideline to getting the basic setup in the right range. 1/2 inch higher at the rear is a good general rule of thumb. You should be able to visually notice a very slight rake up of the sponsons towards the rear.

If you have dropped floors I would make sure that whatever height you set the front and rear at, you have at least 4 or 4.5 inches clearance under the floors, preferably 4.5+ inches. Just a suggestion.