Rear camber for a V8, Too slippery even with 11" out back Options

[Dr. Roger]

So here's what I'm experiencing.

Under hard acceleration, in gears 2,3,4, I can break it loose with just a twitch of the steering wheel. 5th I cannot as it is a flipped H.

I looked at the car from the rear and realized I've got probably 3 degrees of negative camber on each side. I'm thinking those 11" Pilot Sports are probably only making contact with half of the tread. The inner half.



Is their an adjustment balance of negative camber, for maximum traction, under hard acceleration and hard turning?

(IMG:style_emoticons/default/idea.gif)

[rick 918-S]

Not to mention the car probably squats a little more when you blip the throttle.

Rear anti-sway bar?

Stiffer springs?

BTW: Mine does that also with 245/50's. Throttle steering can be fun the first couple times. Then it's time to re-think things.

[byndbad914]

My experience is... not really. You need to stand 'em up straight and run a soft radial if you want to hook "better". But that said, my car *I think* makes more power (I don't recall your torque output and such, I am 438 ft-lbs at 5100rpm) and I have 12" wide GY race slicks (not DOT-R, full slick) and I have had the rears down to 1deg neg camber and I just blow them completely off thru 1st gear (my 930 box, that is blown off damn near all the way to 60 mph) then blow 'em off in 2nd if they are cold to about 80mph or so. Good and hot they will stick going into 2nd.

I am back at -3deg now for the track and they haven't a hope in hell sticking, but frankly it seems just about as bad.

edit - but for the road course, I don't blow them off once I am running. Only from stops and then hammering into 2nd until they are hot will they blow off. Once warm, I can spin from a start without issue, but that isn't an issue once on the track and rolling at all points (not stopped and hammering the gas)

At 0deg to -0.5 and a drag radial is probably the best bet for a mostly street car. Nitto or now BFG may have a stiff sidewall race radial that would work in the corners a bit too.

[wbergtho]

I've often thought about rear neg camber settings and I think you guys are correct when you mention little or no neg camber settings for the drag strip and 2-3 degrees neg camber on the track. I have always left my rear settings at 1.5 neg camber for a good all around setting. If I try to run a fast quarter this summer...I'll change to 0 and see if that helps any. Anyone else have some experience with big fat tires on a 914?

[SirAndy]

for the street, set them to -0.5, that should help a bit.

i don't know nothing about the pilot sports, what's the treadwear on those?
the softer, the better. also, what's the tire pressure you're running? if it's too high, the tires aren't going to stick well ...

how high does the rear of the car sit compared to the front? have you cornerbalanced the car?

(IMG:style_emoticons/default/idea.gif) Andy

[Dave_Darling]

First suggestion: Don't "twitch" the steering wheel! If you mean that the car tries to swap ends when you smoothly feed in some steering input, then yeah--you may have a problem. But if you mean the car gets squirrelly when you give a quick little jerk to the wheel, your problem isn't the car...

Negative camber (to a point) will help in the corners. It won't help so much on the straights. -3 is probably a bit more than you really would like to see for a street car, so try dialing it back to about -2 degrees and see if that helps.

Check the toe angle. If there's any toe-out, that will cause the tail to move around a lot. You want some toe-in, particularly at the rear!

A stiffer rear sway bar and/or stiffer rear springs will usually make the car oversteer more, which doesn't sound like what you want.

--DD

[Dr. Roger]

for the street, set them to -0.5, that should help a bit.

i don't know nothing about the pilot sports, what's the treadwear on those?

(IMG:style_emoticons/default/idea.gif) Andy

Treadwear is 220
Traction AA
Temperature A

I am going to raise the rear a little bit to get the camber going in the right direction. Then start shimming. My plan is to fabricate a wheel alignment setup similar to this one
http://wiki.seloc.org/a/Geo_Alignment_Rig_(Home_Made)

(IMG:style_emoticons/default/idea.gif)

[Joe Ricard]

As mentioned above you are probably getting lots of squat on launch so you camber is increasing even more.

Put some springs under it man!!

.5 is probably a good place to start with those hard fancy tires.

Remember to use longer bolts if you use too many shims.