HardRider

I was playing around with my 911 and decided to check rear camber. I found it at -3.2 degrees with the front at -1.5 degrees ($14.00 camber gauge off amazon, other cars I have were around - 1.2 degrees in rear). My new rear tires are starting to wear on inner edge. Amazing what you can learn with a $2.95 tread depth gauge. Any recommendations for alignment shops around Houston? I know Porsche can handle but curious of an aftermarket recommendations. I want to go as neutral as possible. For a base 991.2 two wheel drive does anyone have the alignment specifications? . Thanks!!

HardRider

Found best alignment shop, ME. I converted Porsche alignment specification from degrees to mm. Set up a perfect parallel box with string and pvc pipe (key is to cut pipes identical for string slots). In end rear toe was zero (this all but confirmed my string set up was dead-on as I got identical measurements from side to side. Front toe is a little out of spec. Rear camber at max spec and front camber at max spec. Soooo in end an alignment is not urgent. Total front toe was 2mm with spec at 1mm. When doing camber critical to be on level ground or account for it. I may adjust rear camber to get closer to bottom spec which is 1.25 degrees or 11mm. I at 19mm. By the way 991.2 must be the easiest car on planet to adjust, only minute challenge is front tie rod access in front... But again easily doablele.

HardRider

So I adjusted rear camber today. Went from -2.8 degrees (well out of spec) to -1.3 degrees. I was shocked that rear toe did not change with rear camber adjustment. Triple checked my toe measurements with my string, Again adjusting rear camber did not change toe. When measuring camber best way is with a piece of metal or aluminum that spans rim edges. Obviously use tape to protect your wheel. Then get the Tremec app for angle finder on your iPhone. Again test set up (phone on metal) on perfectly vertical wall. I was getting .3 to .5 degree error from zero. Turns out it was the on and off button on phone preventing phone from sitting flat on metal, lol. couldn't figure out while phone kept turning off. Crap camber gauge from amazon just that. Oh my front is "toe" is well within spec, my steering wheel was minutely off center, once I centered toe reading perfect. Great learning experience and $12 worth of PVC kept me entertained for 8 hours, lol. At this point I see zero benefit to get an alignment. I checked but never adjusted anything on front and everything in spec. Rear toe was perfect before and after camber adjustment. Amazing my 911 doesn't look like a fast and furious Honda with the tires kicked out in rear.... I can tell zero difference in the way it drives that being said I do not track car, I do not race car.

HardRider

Ok, I can't leave well enough alone. If you have a 4 post life and the same wheels and tires as I then the key measurement is 14mm. That is how far the center of the front rim is further out vs back center of rim. This is huge if you have a 4 post lift as now you can just run your line on your lift and make adjustments in real time since you know exactly how far the line needs to be from the front rim and back rim to be parrallel to center line of car. Let get to the important part. My goal is minimize tire wear and maintain handling and control. My rear camber started at -2.2 degrees, spec is -1.3 to -1.8 degrees. I used a digital inclinometer. I set at -.8 degrees (Same as BMW sedans) that about all the adjustment there was. This removed 15mm of inward tilt from bottom of rim to top of rim!!! My rear toe and front total and individual tire toe are zero. Front spec (-.4mm to 1mm) my rear is out of spec (1.6mm to 4.4mm). I have raced the car as hard as I could on public roads, had above 150 mph on freeway and cannot perceive any difference in handling or stability. Tracks 1/2 mile straight without touching the steering wheel. The rear of car doesn't look like fast and furious anymore and I have no doubt this will drastically reduce tire wear.

Adjusting rear camber only affected rear toe by 1/2mm. It makes it go negative or toe out. Usually you want a little toe out on the drive wheels since they pull together when you accelerate but Porsche wants total toe 1.6 to 4.4mm. 4.4 mm is insane and will rapidly wear your tires quicker than -1.8 degrees camber!!!!!. No wonder tires don't last 10K miles. Front camber adjustment DO affect TOE to a greater percent and if adjusted toe must be checked. Toe plates are useless and should not be used. The line method is what guarantees you are parallel to center of car.

To minimize tire wear:
No more than -1.0 degrees camber on any wheel, (my Lexus, 4 runner, have zero camber!, BMW X5 has -.5 degrees). Even -1.0 is aggressive.
Front total toe 0
Rear total toe 0 to 1mm.

I mixed degrees and mm since I knew how to convert degrees to mm for a 20" wheel. I have a base 911 which sits in traffic and if I get up real early Sunday morning I can't race it around. If you track the car, have 550hp, may want to stay with factor specs, if you use your car and don't want to dump $1200 in tires every 10K miles consider what I have done or better yet make your alignment guy align to my values. I do not recommend doing you own alignment unless you have tons of free time with nothing better to do....

ram_g

Interesting "thread" (pun intended!). Thanks for posting!

BTW I'm in Houston too - want to align my car also?

HardRider

Once I have my line parallel I clamp magnetic post to lift with c-clamps with my fishing line as tight as guitar string, perfectly centered in wheel. Truth be told my measurement now were with 1/4mm of my jack stand set up. My new method is extremely repeatable I can hit my line all day and nothing changes as far as readings. I played around making the line a little high, a little low to see how accuracy was affected and truth be told the 90% of time my values for "toe" stayed the same. A slack line will screw you. I played with setting the offset between 13 and 15mm and again within 1/4- 1/2mm. You want to get that right. I went back and added .8mm toe to rear wheels so 1.6 mm total toe. I did some research and the reason you want positive toe in rear is in a high speed stop the rear could get unpredictable. Obviously I tried to verify this with no success car was steady as rock and I took hands off steering wheel. But for grins I put some negative toe in just in case.

The other cars I have do not have any adjustment on rear. So an alignment on those consist of just setting toe on front, camber was perfect at 0 degrees. So I checked my 4runner and Tundra. My readings were dead on with Toyota specs. I wonder what I do with the $99 for each alignment I saved but more importantly the $15.00 shop fee they charge for their paper towels.....

As far as the 911, I have no desire to sale but if I do I will take it to a reputable shop (actually found one in Houston) and have them set to factory specs that way nobody has to deal with my specs. Without a lift I would never attempt, its so nice to make adjustments and verify measurements vs setting up the string every time.

Strange thing happened. I checked total toe with tape measure for grins. Perfect it matched my string measurements. Took car for drive, checked total toe and all though my total toe stayed the same the dimensions across the back and front of tires changed 3/16". Now my kid and I have measured this 100 times? so we were in the same tread on each tire. My only explanation is tread squirm. I adjusted toe on lift, even though I used a garbage bag under wheel to help it move but when drove it settled down. This again confirms toe plates are garbage. Adjusting toe with those you may just be deflecting the tire....