racerxrick

I just replaced my front tires after a local "high performance" shop's poor alignment ruined the insides of BOTH front tires.

I have the car here at work (a dealership) and have a guy I trust that will put it on the alignment rack. I suspect it will be obvious what was "off" that ruined the front tires. We have the Porsche specs.

Question: what (if any) adjustment should we make for a "performance" alignment?

Thanks!

racerxrick

actually this is a perfect example where I should have used search.

My apologies.

I just read enough to confirm I really don't know..now? What?

Haha, seriously kinda leaning toward stock specs to preserve the tires. Maybe a little extra front caster for the larger 18's?

My car has only seen two track days in 20k miles of ownership.

racerxrick

and...in defense of the shop who did my alignment. I did ask for a "perfromance alignment". I'm thinking it was too aggressive. It will be interesting to see on the rack later today.

btw, I run 18's with 285/30 and 245/35's.

Tedro951

Rick, for what its worth, we run the exact same tire sizes. My recent alignment was done to the specs listed on Omnis thread on alignment. 1500 miles later I see no wear and am very happy with it. I'm runnin late right now, but if you search for it, it'll pop up with his image of the alignment.

Thanks Jim!

Tedro951

Here you go....found a little time...

https://rennlist.com/forums/showthre...ferrerid=50950

racerxrick

oh cool...Omni AutoX his quite a bit.

Thanks Ted!

schip43

Interesting link. So 2.1 deg neg camber in the rear is within factory spec? Cool! Only thing I can add is that on my 89 951, I had them max out the caster. Great for 120+, the car is rock steady...but I have found that at normal speeds, the car is slow to move from off center, that doesn't work for me so, I'll be dialing back the caster.

User 52121

Cool to see one of my earlier posts was actually helpful!

I've had the car re-aligned a few times since posting that. The one posted in that thread was no doubt the easiest on the tires and worked totally fine for autocross. I started running more DE's in 2011 and as such started to add negative camber back in (I was chewing up the outside edge of the tires in longer sweeping turns otherwise). I'm now at -2.5 in the front (max I can get out of it before I add camber plates) so will most likely be back to chewing up the insides again But I had to pick a compromise and as I started getting better/faster with autocross, and started chasing down some friends at DE's (and found myself frustrated that the nose just wouldn't stick in long sweeping turns), I opted for a more track-focused alignment.

When I get back home tonight I'll try to remember to post my most recent alignment sheet. IIRC it's not really any different from that old one, other than -2.5 camber in the front.

Tedro951

Yep, they didn't appear all that aggressive, but when I priced 285/30-18s, it was a no brainer to go with a stock oriented set-up. The thought of making it stick any better falls off my curve of $$.

racerxrick

It will be interesting to see the before and after, our alignment machine will allow that as well. It was likely VERY aggressive. The tires were at 50% up front and the insides ate up in maybe 1500 miles!

racerxrick

so here are the current specs...I snapped a shot. He is not real comfortable with aligning this car (unfamiliar) therefore I just wanted to know where it was at...and why it's eating the inside tire out.

Looks like a lot of toe.

Caster looks good.

Camber I seem to be findinjg different stock specs. Our machine stated -.6 to -.1 and yet Omni's spec sheet showed -1.8 to -1.3?

As you can see one side had -2.2 and the other -1.6

Pics of the tires attached too, don't know the exact miles but around 1500 maybe? The tires still had 50% tread at the time, in fact the center still has about the same amount.

User 52121

Interesting on the difference in official specs. I have no idea. I can only speculate that since Fischer does a LOT of 944 work, it's possible that the "spec" listed on his machine are HIS specs for a standard-issue street driven 944?

Those fronts are WASTED. WOW. In 1500 miles? I ran all last year at -1.9 on the front, 5 autocrosses (x2 drivers, my wife and I) plus several DE's (x2 drivers in some cases, 20+ sessions) and just pulled them off this morning. They had about 9,000 miles on them, and aside from the outer edge on the driver's front being worn (not corded like yours, but worn past the wear bars) they had plenty of meat left on them to be used as a street tire.

I think something else is wrong.

racerxrick

hmm...the tires were not new. Somewhere around 50% tread left. As you can see in the middle of the tire there is still plenty of life left even now. I'm only guessing 1500 since the alignment. Let's put it this way, the rears were brand new when I had the alignment down...and still look brand new!

Oddjob

WAY TOO much toe-in. Should be something like 0.01 to 0.05 deg per side, max. That may be the wear problem, moreso than the neg camber.

racerxrick

yeah, if my limited understanding serves me at all I'm thinking the two combined equals exactly what happened.