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Front Wishbone geometry

amalyos - 4/5/06 at 09:57 PM

Does the geometry look right for my wishbones. I thought the wishbones should be level top and bottom.

What do other RT+s look like?

Steve
Rescued attachment Front Wishbones.JPG

graememk - 4/5/06 at 10:06 PM

i wasnt very good at geometry at school, is it somewhere near france ?

Avoneer - 4/5/06 at 10:29 PM

Looks spot on to me.

Top should be angles slightly to keep the wheel vertical when going up and down.

Pat...

G.Man - 5/5/06 at 03:45 AM

Looks perfect to me also

britishtrident - 5/5/06 at 07:04 AM

quote:
Originally posted by amalyos
Does the geometry look right for my wishbones. I thought the wishbones should be level top and bottom.

What do other RT+s look like?

Steve

Me thinks perhaps you have been looking at F1 cars -- they are a special case as the suspension is rock solid because of the tons of of downforce from the aerodynamics.

Take a look at F1 cars from the mid 1960s such as the Lotus 33 and 49 or Brabhams and that will give you a better idea of standard practice.

Syd Bridge - 5/5/06 at 08:45 AM

[quote
Take a look at F1 cars from the mid 1960s such as the Lotus 33 and 49 or Brabhams and that will give you a better idea of standard practice.

The above may have been 'standard practice' with narrow cross-ply tyres, but...

A much better guide would be the suspension geometry of 80's F1 cars, and even some up to current LeMans cars.

Geometry thinking changed markedly with the introduction of wide flat tyres, and modern tyre constructions.

Have a really good look at the rear geometry on most current F1 and Sports cars, then have a good hard think about what is going on, and moreso, WHY? , with regard to the wide flat tyres and how they operate best.

Cheers,
Syd.

Bryce - 5/5/06 at 08:59 AM

The set-up you have is called “ Unequal length converging wishbones “. The wishbones converge at a point outside the vehicle. Since the wishbone mounts are already fixed the important part is the position and length or your steering rack, this controls bump steer. First of all you need to get the camber right, with the correct amount of camber check the castor. Then adjust your track rod arms to get the correct amount of toe-in. Put the suspension through bump and then droop whilst mapping the toe-in and toe-out of the wheel. If the front wheel moves from toeing-in to toeing-out or the opposite then you have bump steer, usually on the locost its because the rack is positioned to high.
Rescued attachment DSC00048.JPG

G.Man - 5/5/06 at 09:59 AM

Its all about camber change...

The lower inner top mounting point will cause more negative camber to be applied as the car rolls to the left (right hand corner) maintaining a flat contact between the tyre and the road..

Dont worry about the theory, get Marc to set your car up once its completed and SVA'd

amalyos - 5/5/06 at 10:15 AM

Thanks for the comments, it's put my mind at rest.
Now I just need to worry whether the engines a going to run!!!

This project was meant to help releave the stress of work!!!! but I know what I'd rather be doing

Steve

marc n - 10/5/06 at 07:20 AM

lloks good to me steve , starting to get miffed now everyones car is further ahead than mine, been trying to find time to finish one of mine for the road for two years now