KenRudd

Not sure that is practical for me. Too much fender work.

Carl Fausett

IMO, start with -2 deg camber front and rear. Go from there depending on tire, wheels, and driver.

Many do find the neg 1.5 deg is the hot ticket in the rear - but again, that's tire width and wheel dependent. -2 neg in the front is a great place to start. I might go as high as -2.5 but not a fan of higher neg camber than that.

Negative camber above 3 deg can make the car hunt on the straights and will contribute to easy brake lock-up and flat-spotting the tires.

Also - if your wheels are the same, rotate your race tires to all 4 corners to get more life out of a set.

KenRudd

Appreciate the input, and it jibes with what is shaping up to be the common wisdom.

What are you running for Toe?

I'm running ABS, so I hadn't really worried about lock-up/ flat spotting, but will keep changes from being too extreme.

Square setup is not practical with my current front fenders and rim inventory...

harveyf

Hi Ken. Greetings from New Hill!

For dual use, you might want to consider adjustable camber plates. I made some for my 944 track car that allow adjustment in set 2* increments. Since it's a track car, I just leave them "leaned in" but it is a pretty quick job to move them in 2* for a track weekend and then bring them back out for street driving.

http://newhillgarage.com/2013/02/09/...camber-plates/

If it makes you feel any better, my track tires on the 944 are also wearing on the outside.

I also check my camber myself with a digital level and toe-in with strings. It is very straightforward to do. Drop by sometime and I'll show you my setup.

KenRudd

That is kinda cool. Never seen plates for a 928..

Edit: on reflection, are Camber Plates even possible on 928 suspension?

dr bob

No. Those are the only way to adjust camber on Macpherson or Chapman strut suspensions. The 928 ha dual wishbones, so camber is adjusted at the lower balljoint or the upper inner control arm shaft mountings. Since you are looking for more negative camber, the factory's lower balljoint adjustment is your only option with stock upper control arms.

James Bailey

NOPE.....we have double a arm suspension NOT struts

FredR

Ken,

With ET57 you should be able to get a 245 section to work. A bit more camber helps fender clearance a bit but the wheel arches need to be rolled- preferably with the proper kit and not Mark's baseball bat but to be fair, I have never tried the baseball bat approach because I had no need to.

Your front wheel external surfaces should be more or less OK given I run a 265 on a 9.5 inch rim with ET68. Tyre make influences this as well to some degree.

No idea how many folks use Carl's lower frame brace- personally I think it is excellent and eliminates the need for ever more camber. The wider the rubber the more the grip the more the need for restraint as things flex more under higher loads. The brace is intended to reduce the flexing. Before the brace I have run with 3 degrees but did not like the overall feel of the car. More than 1.5 degrees of camber on the rear and you lose grip at the traffic light Derby.

With 2 degrees up front and 1.5 degrees on the rear I find this works perfectly well on the open road without any deleterious wear patterns on the rubber and nothing has ever come past me in a bend unless I wanted it to.

Sadly I see very little time on track but the last time I was on the autodrome at Dubai at factory Porsche driver in a 911 twin turbo nearly fried his brain when he could not get me off his tail.
"Mein Gott" he exclaimed- " Vott haff you done vith zatt car? Ze 928 does not handle like that!" To which I retorted "oh really!".

Rgds

Fred

harveyf

Well, doh! on my part. I guess it's no consolation that it works nicely on a 944.

Another thought is to mount a gopro on the fender and do some local test runs, like the nice sweepers out at Sharron Harris. You might be able to see whether only the tire is falling over (most likely) versus the entire tire/wheel assembly.

Carl Fausett

Ken,

I run about 1/8" toe in the front and about 1/16" toe in the rear. Make certain that the suspension is fully settled, and always adjust toe last. After Caster, Camber, ride height, EVERYTHING

Carl Fausett

Be Proud: we were (and I think may still be) the only Porsche with double A-Arm suspension and not struts. A true racing pedigree.

Use of struts instantly increases roll center...

James Bailey

Depends on if you consider Cayennes and Panameras to be Porsches.....both feature double A-arm front suspension

dr bob

Carl--

How is toe in fractions of an inch related to toe in degrees or fraction of a degree? Or maybe "how much distance between measuring points when you measure the 1/8" of toe?"

My last serious racecar was set up with aluminum discs before the body was dropped on, so toe in fractions of an inch was very easy to calculate and keep consistent. Pretty much everything was done with a tape measure since all was accessible.

I've been playing with laser alignment at home for a while, and have it down to a casual science using a tape measure after doing all the trig in advance. I did succumb to using digital angle gauges to make caster adjustments practical, otherwise it's all hardware-store stuff.

Carl Fausett

I'm just using toe plates and tape measures... works fine.

Carl Fausett

Well then. I will go with "at the time that they were manufactured, the 928 was the only Porsche with double-a-arm suspension..."