Downforce at high speed causes tires to grind...

[lvjost]

hi guys. I noticed some traces of grinding on my tires...It seems, that with high speed caused downforces and on sideforces when cornering the tires grind on the inner upper side of the body/ "wheelhouses"...Anyone experienced smth. similar ? I got the KW-Suspensions, not the Intrax ones, but the same/similar ride height (120mm,160 mm)like you...

[luckyp]

When my car came back from it's safety check, I was told that some material had been taken off the inner edge of the wheel arches - the factory will know the detail.

LP

[steve_d]

Was about to say the same sort of answer. Directly above the wheel on my car the return lip of the body is no more than about 10mm wide.

Steve

[gtr-gaz]

Mine's the same as Steves'

The fibreglass around the edge is very thick, so it still does'nt flex even though a fair amount has been removed.

[luckyp]

Of course what I meant to say was, the factory...or Steve, will know the detail!!!

10mm seems spot on.

LP

[lvjost]

A big thank you to all my friends of the ultima-club
Will measure the returning lip...and grind of a bit to stop it demolishing my expensive tires

[lvjost]

hey luckyp...the safety check you´re writing about....who did it, ultimasports itself ? Or is it a company specially dedicated to prevent people to kill theirselves in self-made rockets on 4 wheels... ?

[luckyp]

Lutz,

It is something that the Factory provide as a FOC service to go over the torque settings and have a general look over your hard work.

Not sure how it works for our European or US builder friends????

Pete

[lvjost]

Measured 13mm front "lip" and 17mm rear "lip" ("lip"=GRP in the inner wheel arch...)...
Steve and luckyP...do you have 10mm left front and rear or is it just front ?
Can one remove and shorten the "lip" with grinding without damaging anything or decreasing the strength of the whole body ?

[steve_d]

Was working from memory this morning but have now measured.
From outside body surface to inside of lip.
Front 11mm Back 16mm.

To reduce the lip I would recommend using a drum sander in an electric drill. You can use an angle grinder but it is so harsh that if you slip you can go right through the body in an instant.

Steve

[lvjost]

so steve...do you think reducing front 2mm and rear just 1mm will help me ? I think I´ll jack the car up on wood on just one wheel, so this damper compresses max....and then try to measure how much I have to grind away... What do you think ?

[steve_d]

Open the clip and examine the rub mark on the lip of the body.
If the marks are on the fibreglass cut edge then the tyre is only just touching with it's sidewall. A couple of mm will probably fix it.
If the marks are on the gel coat surface under the lip then more of the tyre is contacting. How wide is the mark on the gel coat? This will give a clue as to how much is to be removed.
Report your findings if you think there would be less than 10mm remaining as this will be beginning to effect the body strength.

The damper will not compress any significant amount just by jacking. It will just lift the car in the air. If you want to check the travel jack under the chassis to take the weight off that wheel then undo the top mount for the spring and damper. You will then be able to lift the wheel up and down to watch its travel.

Steve

[usagtrman]

here is a picture of mine. It's a little hard to see since it is black but if you look close you can see the area that has been reduced. Hope this helps some.


Brad Z