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Camber gain
kango - 4/5/11 at 06:53 PM

I have built 2 "7s" so far and would like to build the next chassis to handle better.

If we assume the same suspension travel as a 7. [50mm Compression and 25 mm droop.]

What would the desired camber gain be front and back at maximum compression?

Should the front and back gain be the same?

This will be an all out racer.

I am starting to manufacture from the back and will manufacture the uprights so can create the optimal geometry.

Doctor Derek Doctors - 5/5/11 at 06:13 PM

There are many books 100's of pages long that can't even give you a definitive answer, its going to take a lot of research and working out of parameters and needs to find the optimum answer.

kb58 - 5/5/11 at 10:29 PM

You pretty much have to work backwards, deciding that "the car will lean this many degrees in a hard turn of this many Gs," then figure out how much suspension compensation is needed to keep the tires at optimum.

coyoteboy - 5/5/11 at 11:49 PM

Make adjustable arms for testing after a good guess?

Bare - 6/5/11 at 02:56 AM

Suggest copying something that works :-)
I've seen garage built Dune Buggies :-) seriously outperform distributor sponsored/prepped Porsches.. repeatedly.

NOT striving for "optimal' geometry is likest the cleverest approach :-)
Good luck.

Doctor Derek Doctors - 6/5/11 at 12:53 PM

quote:
Originally posted by coyoteboy
Make adjustable arms for testing after a good guess?


Camber gain is highly dependant on the innner pick-ups so adjustable length arms wont help.

nick205 - 6/5/11 at 01:38 PM

quote:
Originally posted by Doctor Derek Doctors
quote:
Originally posted by coyoteboy
Make adjustable arms for testing after a good guess?


Camber gain is highly dependant on the innner pick-ups so adjustable length arms wont help.



One approach would be to mount the suspension on sub-frames, this would allow you to make changes more easily by making up new subframes.

Another might be to make the inner suspension pivots on the chasis adjustable; e.g bolted on with spacers or perhaps elongated U brackets with a series of bolt holes (particularly for the upper arms).

kango - 7/5/11 at 10:51 AM

Thanks so far.

Friend gave ma all the books to read and after doing it I was non the wiser.

Then searched the forum and also nothing.

Thought I might give it an up and under here on the forum and see what I get.

Prehaps some suggestions of what is working to give me a GOOD start.

Doctor Derek Doctors - 10/5/11 at 09:30 AM

quote:
Originally posted by kango
Thanks so far.

Friend gave ma all the books to read and after doing it I was non the wiser.

Then searched the forum and also nothing.

Thought I might give it an up and under here on the forum and see what I get.

Prehaps some suggestions of what is working to give me a GOOD start.


Find a similar car that wins races and copy that. Unfortunately getting the exact data may be a problem.

So instead get all the data you can from similar cars and a 'trend' usually emerges, plonk your car somewhere in the middle of that and design in loads of adjustment. Just try to avoid copying stuff that is comprimised with donor car parts as these won't have been designed to the optimum.

As my rather wise university lecturer once advised me "Copy something that works and design in loads of adjustment"

kango - 10/5/11 at 05:37 PM

Thanks

kango - 12/5/11 at 06:01 PM

Anybody has the ATOM or Crossbow rear geometry specs?

britishtrident - 12/5/11 at 06:50 PM

It was quite common on racers in the 1950s to early 1960s (fore example on the Rudd designed BRMs) to have multiple mounting hole positions for the wishbones to enable the wishbones to enable the roll centre heights to be altered to alter the roll couple distribution to enable the oversteer-understeer balance to be altered. Problem with this approach is alters so many other variables (for example bump steer) that it isn't a trival adjustment. Then Chapman rendered it all obsolete he set the roll centres at the design stage and fine tuned the handling by adjustable ant-roll bars front and rear.