Dan Wendling

In rough numbers what does adding 1 more degree of negative camber do to the front toe? My geometry tells me that the more negative toe you add the more toe out you get.

If am running with -1.4 degree camber and 0 total toe in the front on my C6 for my street setting and then for the track I take out 1 washer from each of the 4 upper control arm mounting dogs to go to about -1.8 degree camber how much would my toe would change? Seems like adding a bit of toe out for track use is a good thing anyhow.

So do I really need to reset the toe going from street to track mode?

Han Solo

I think the general consensus is tow out helps with turn in.

On my Mustang I run near zero camber on the street due to having a long straight drive into town versus a few turns made during the day. I set the toe to 1/16" in. For autox I set the camber all the way in to -3* and this drives the toe to about 1/8" out.

naschmitz

Measure the toe and decide for yourself. All it takes is two pieces of angle aluminum about 30" long to act as toe plates and two identical tape measures. Or spend $60 at Joe's Racing for the economy kit which includes the toe plates and tape measures:

http://www.joesracing.com/index.php?...product_id=385

taken19

This is just a guess, but I would bet close to 1/2" by changing camber 1 degree. About 6 months ago i moved from -0.8 to -2.1 and was almost 3/4 toe out on my first measurement. Another rule of thumb is one flat on the tie rod is about 1/32" total toe, so 1 flat on each side is just over 1/16" total toe change.

Go through some of DavidFarmer's old posts - tons of good info. For the street, slight toe IN is good (1/32-1/16"). For the track, slight toe OUT will help turn in (about 1/32").

geerookie

Why bother....... .4 degrees of camber with rubber or poly bushings is a waste of time. If you are running Hoosiers, drive fast (greater than 1.x G's in the corner) and you can get to -3 or -3.5 you will still cord the outsides with rubber (stock) bushings and if you have poly you may be OK depending on the durometer of the poly.

If you are running sphericals then .5 degree camber changes will help but even then you will need to be around -2 degrees or more.

Toe out on the front is good. Somewhere around 1/8" - 3/16" total works well if your caster is between 5 and 7 degrees.

Also the amount of toe out will depend on what your ride height is to begin with. It's all geometry. If your ride height is low to begin then you are in a different part of the camber curve than someone who starts at "normal" ride height. Bump steer will also have an affect. If your car has never had the bump steer checked or set you may get toe in when you change the camber, again depending on ride height.

The only way you will know is to do it and then check for your car. Once you do it once it will always change the same until you adjust one of the things mentioned above.

db2xpert

[QUOTE=geerookie;1581530504]Why bother....... .4 degrees of camber with rubber or poly bushings is a waste of time. If you are running Hoosiers and you can get to -3 or -3.5 you will still cord the outsides with rubber (stock) bushings and if you have poly you may be OK depending on the durometer of the poly.
QUOTE]

Too much of a generalization. I'm running -2 front camber, stock bushings, and not cording the outside of the Hoosiers.

taken19

[QUOTE=db2xpert;1581531093]Really? What toe are you running? How hard are you pushing the car?

I have 6 sessions on my R6's and it looks like the outside is wearing slightly faster than the inside with -2.5 on poly bushings. I'm curious to hear about your setup so I can compare.

taken19

Great info, can you expand on some of the things you mentioned such as geometry on a lowered car and bump steer? I understand toe and camber well but am very weak on caster and bump steer. Please focus your discussion on a lowered car if you can, but no need to discuss the effect on toe as I've already figured it out on my setup.

Thanks for the contribution.

Sean

383

[QUOTE=taken19;1581531246]I thought Hosiers liked -3 or more?

taken19

[QUOTE=383;1581531400]I thought the same, that's why I'm asking. I just bought a PFadt camber kit to get -3.0+ camber.

geerookie

I'm not an author, just some poor sap that spends too much time playing around with stuff on my car. I really need a life!
All these things are inter-related.
On a Corvette as the wheel moves from static position to compression or droop the toe, and camber change. Bump steer is how much and which way(s) the toe changes as the suspension moves up and down.
Camber also changes by design due to unequal length A-arms. Caster affects toe angles at turn in which are also affected by whether the suspension is under compression or in droop at a particular moment in time.

The biggest problem on stock Corvettes run on the track with sticky tires is the bushings used to locate the control arms.
As you go into a corner the bushings collapse and allow the control arm to move, effectively making it shorter which allows the bottom of the tire to come in closer to the frame and eliminates needed negative camber. This is why you need so much static negative camber in order to not cord the outer edge of sticky tires. You are trying to compensate for all the camber you will lose when the bushing collapses. I run spherical bearings in all the pivot points of the Corvette suspension so when I go into a corner nothing moves unless it is supposed to. Therefore I can get by with much less static camber.

Here's a link to a book that covers all kinds of suspensions and how the geometry works in each.
http://www.scribd.com/doc/49139753/Suspension-Geometry

geerookie

[QUOTE=taken19;1581533091]There is a difference between what they "need" in a particular car and suspension and what they are designed to run with. Due to the soft bushings (rubber or poly) typically used in track Corvettes they require a lot of camber to keep from cording the outside edge prematurely.
-3 to -4 degrees is what's needed to compensate for the collapsing of the control arm bushings. If you get rid of that the Corvette suspension works well with Hoosiers with around -2 degrees of camber.

ALSO, the Pfadt camber kit is to replace the eccentrics which tend to move under high g-force loads produced by sticky tires. It doesn't give you any more camber The only way to gain camber is to either move the mounting points of the upper or lower control arms or lower the overall ride height of the car therefore effectively moving the mounting points.

383

Are spherical bearings something you can take from car to car?
I plan on trading up to a Z some day and if I drop 2Gs on spherical bearings Id like to have them for a while.

taken19

Good insight. I will look into that book.

autoxer6

FWIW, I have used 10 sets of Hoosier A6's on my C5Z. All with 2.1 deg of front camber and rubber bushings installed in at the factory in 2004. I flip the tires once on the wheels and I will wear the front tires down past the wear bars before I cord the outside corner.

geerookie

Autocross or Road Course?

If road course racing or DE?

Flipping the tires adds significant life for sure

fatbillybob

I'm a T1 racer and same results as GeeRookie. Guy not getting outside wear might be using HooHoo recommended tire pressures. I never did the testing just coppied my T1 breathren. Tire pressures that yield fastest times are lower then HooHoo says. Perhaps due to less sidewall support we T1'ers are also seeing the outter wear.

Bill Dearborn

[QUOTE=geerookie;1581535870]I just installed the Pfadt kit on my car. I had the cams set at their max and the washers behind the upper A arms pulled. Camber was about .5 degrees greater before I put the camber plates in than after.

Bill

taken19

[QUOTE=Bill Dearborn;1581545741]Just installed mine yesterday. Gained an additional -1.3 on the left side (eccentric was not maxed out) amd -0.8 on the right (eccentric was maxed out on this side). I would say that you can pick an additional 0.5-1.0 degree of negative camber with the Pfadt kit.

davidfarmer

I'd say 0.4deg camber change will give you about 0.4deg of toe change, or about 1/4". It doesn't matter though, as you absolutely HAVE to measure and readjust based on actual numbers, not trying to expect to be able to reproduce and accurate alignment based on math.

While Hoosier likes high Camber for maximum grip, recent tire failures, feedback from Hoosier reps, and even commentary on the Grand Am races (rebranded Hoosiers), you should limit the camber to 2deg at high load tracks (rovals, other tracks with cambered turns). There is some speculation on my part here, but I've seen a lot of failures lately, combined with actual feedback from Hoosier, and to me it seems they've lost focus on durability in search of grip!

And finally, both GM, Hardbar and Pfadt Camber plates WILL give you more camber, assuming you use the maximum offset . The slot in the subframe is slightly larger than the OEM concentrics will allow, so using the camber plates will give you a bit more travel. I've only seen about 0.2deg addition, but your mileage may vary.