Camber recovery. Interesting.

Do we need camber recovery on a track car?

I suspect this is more to do with a street car so we do not ware out the inside of the tires.

It would seem that the important point on a track car is the tires are at there best angle to the track and stable at the limit in a corner. Stability from getting the best possible dampening and little change in camber with compression and or front wheel angle (caster created camber gain.)

But that is just what I am guessing.

Is it just me or do these race cars look like there do not have much in the way of camber recovery? Expecially up front.

;)

Distortion from the wide-angle lens used to take the picture

Camber recovery = gain = ability of suspension to make the wheel lean less than the car does; think it is caused by compression & effects of compression via the linkage geometry

I bet Bill V. can explain it...

Interesting how many responses this thread has generated. I AX campaigned a supercharged miata that would 0-60 in 4.2 secs. The usual shocks, sways, springs, chassis stiffing mods. It was a lot of fun, but still occasionally got smoked by a well driven NA miata (and several Scoobies). I suspect it was the nut behind the wheel problem.

Our 911 feels totally superior in road feel and corner lean. The turbo and peaky torque adds a much more complicated dimension, but I would never go back. I don't race the Porsche (DE or AX) so my comments are only for the sporty touring feel. Both of my cars weighed roughly the same with fuel (2700 lbs). The 911 is much more satisfying and I can assure you that a forced induction miata is a load of fun.

Camber recovery is dependent on suspension geometry. It is how much the camber changes relative to the body due to suspension travel in bump/rebound, as one gets in roll. This therefore compensates for the roll and keeps the tire at a more optimum camber.

911st, the camber recovery IS a mechanism that keeps the tire properly oriented to the track surface, which you are so concerned about.

There's no such thing as a 50/50 Miata. The last time I had my car on the scales, the weight limit was 2350lbs for a 1.6L like mine (with 180lb. driver factored in). My weights were-

Lf-638
Rf-621
Lr-545
Rr-547

Now the minimum weight is 2275 with 180lb driver for the 1.6L. 1.8L's have to run 2400lbs., and the 99 and up cars have to run 2450lbs.

I see the pictures of the white Miata #377, and it sure looks cute. It's probably faster than my '78 911, and way faster than my Ford Ranger. But it better not pick a, autocross fight with this car:

http://forums.pelicanparts.com/uploa...1285254779.jpg


http://forums.pelicanparts.com/uploa...1285254801.jpg


http://forums.pelicanparts.com/uploa...1285254820.jpg

Racerfink,

Thx for the real info. Still I suspect the Miata still has a lot of tire per axel compaired to many 911's.

Example, your front axel is about 10% more up front and about 48% less rear axel weight than the assumed 2700 lb 911.

Assuming the Miata runs 205's the 911 would need 225 ft and about 275 to 305's rear to have about the same amount of tire where most SC body track cars run about 225/255's. Again this is a bit simplistic but my hope is it helps convey the point.


TimT,

I wondered if a wide lens was used but thought that would have bent the long straight lines in the picture and to my eye that did not seem to be the case.


All good stuff. Just trying to learn and having some fun!!!

What about toe change? The rear of a torsion bar 911 will have toe change when the suspension moves. Is this a factor?

This effect can be done in Photoshop.

RSRs usually run a lot of static camber because they have little suspension movement due to low ride height and stiff springs. This means not much motion available for camber recovery (or whatever you want to call it), even with very aggressive camber gain kinematic ratios.

A surprising factoid

from the factory
late RSRs only run -3*35' static camber in front -3*10' in back
late GT3 Cups run 4* f/r earlier versions ran as much as -4*45'/-4* 20' depending on the track, less for high speed venues like Daytona

Well, a lot compared to a street car, which most people are used to looking at. I did not mean RSRs have a lot of camber recovery, just that the way to get the camber to be optimal in a corner is to use static camber since the suspension does not move much so the roll due to tire deflection can only be compensated for with static camber, or caster if steering input is sufficiently large.

I do not think that the effect is entirely due to the wide angle lens.

We got bullied by a CSP Miata at the Packwood Tour again this year.....so did Leeds & Jodi before they broke. Anybody that doesn't think a Miata is more capable AXer than ANY Porsche production car is fooling himself....but no one else.

Given enough time & money you can make a 9eleben faster than a Miata on the track, but it probably won't "handle" better.

I agree 100%, -2 or more is pretty obvious

- what is the handling comparison between a stock Miata and a stock 911?


- 2nd question: I usually think of the advantage of progressive springing as applying to street cars. They introduce a non-linearity that the driver must compensate for (of course, humans deal with non-linear phenomena all the time), but...

what is the advantage on the track of progressive springing?

Every miata at laguna seca gets killed on the straights by the 911s. Both of the "fast straights" are up hill too. Put slicks on and do some suspension tuning and you'll have no problem taking them on. I drove my 911 at laguna and a friends miata (both had slicks) and I much prefer a 911. I feel like I should have a wig and a skirt on to drive the miata, though it was fun.

On the other hand, I went to an all miata event at Laguna and I saw some 350 hp 1.8 or 2 liter turbo/supercharged miatas that could go. I even saw an LS1-chevy V8 miata, under-tuned puting out only 350 from Flying Miata.

I can't believe this is even a serious question. It's all in the set up of the car and driver. A miata slammed with slicks and sway bars will beat a stock, street tires, "comfy" ride height 911, for sure with the same driver.

If you are running 225/205s on the 911 and the Miata is running 185s, The Porsche is going to corner way faster. If you are running 205s on the M , LE, or R Miatas I expect the Miata is going to have the edge.

Bill!

Check out the braking system on this car.

Why would one want a ballance bar and an adjustable PV?

That's probably a line lock on the central console, used in lieu of a parking brake