DIY Camber Adjustments?

[grover]

I'd like aggressive negative camber for racing my 2004 Boxster S, but this car is also my DD and I worry about premature tire wear. I have the repair manual and it looks pretty straightforward to adjust camber by moving the position of the upper shock mount, but how easy is it in practice? Is this something I could reasonably adjust myself to max negative camber before a race, and then back into a more neutral position (with reasonable tolerance) afterward?

Edited January 19, 2009 by grover

[RFM]

The problem is, if you change the camber, the rest of the alignment changes too, they are related.

[grover]

The problem is, if you change the camber, the rest of the alignment changes too, they are related.

How so? It's a Macpherson strut, and it's nearly vertical (castor is fixed at 7.7°). It may add a small amount of toe-out when camber is moved negative as the strut tilts slightly towards the back of the car, but gaining toe-out for a race is desirable, too. What else would be impacted?

I've never attempted to change my alignment, and never watched anyone do it. I know a lot of things look easy, but are anything but in practice. Hypothetical: I get a street alignment, and mark the position with a sharpie. Before a race, I loosen the 3 bolts... and just push the top of the shock mount in along the adjustment slots? How does that work, are there any special tools or do I just put pressure on the socket/tire to slide it? Afterwards, do I have a reasonable chance of returning the bolts to the marked street alignment position? Even a half-assed attempt at returning the camber to 0° should be better for my tires than driving around all year with the alignment 1° off whack.

Edited January 20, 2009 by grover

[Sboxin]

The problem is, if you change the camber, the rest of the alignment changes too, they are related.

How so? It's a Macpherson strut, and it's nearly vertical (castor is fixed at 7.7°). It may add a small amount of toe-out when camber is moved negative as the strut tilts slightly towards the back of the car, but gaining toe-out for a race is desirable, too. What else would be impacted?

I've never attempted to change my alignment, and never watched anyone do it. I know a lot of things look easy, but are anything but in practice. Hypothetical: I get a street alignment, and mark the position with a sharpie. Before a race, I loosen the 3 bolts... and just push the top of the shock mount in along the adjustment slots? How does that work, are there any special tools or do I just put pressure on the socket/tire to slide it? Afterwards, do I have a reasonable chance of returning the bolts to the marked street alignment position? Even a half-assed attempt at returning the camber to 0° should be better for my tires than driving around all year with the alignment 1° off whack.

We have done this front camber adjustment just fine - no problems.

You need to lift the wheel off the ground and use a large screw driver to move the top of the shock - put it in the hole and push shock toward the inside for increased camber. Yes, mark with a sharpie the original position of the bolts. Its a 5 minute job at the track.

Take care :cheers:

Ed

[grover]

Thanks! The repair guide wasn't clear- do I need to loosen the center bolt, or just the 3 outlier bolts?

[Brad Roberts]

Just the three outer.. BUT.. this causes TOE_IN which you DO not want for track use. Most of us tracking Boxster's either run zero toe or 2mm's total toe out :) On *some* of our 997 GT3CUP IMSA Challenge cars we run 4mm TOE IN, but we are compensating for the amount of movement the suspension has under braking (we want ZERO Toe under braking, makes for a more stable car)

Honestly.. max out the camber and reset the toe. With stock lower control arms you will only get *maybe* -1.2 or so out of it. This is fine for the street. What 99% of the people out there don't understand: camber does not wear tires. TOE wears tires. If you do not set the toe.. it will literally SCRUB away the inside of the tires.

If you'd like, I can describe how to adjust toe at home with 4 jackstands and some string or fishing line :)

B

Edited February 11, 2009 by Brad Roberts

[grover]

I saw that how-to online already, actually :) I'm a bit confused as to why you say adding negative camber would cause toe-in; with the strut canted several degrees towards the rear of the car, it seems it would cause a very slight toe-out when negative camber is added. (Roughly 2.4mm net toe-out if my guestimates on the angles are close.) Toe is right about dead even at 0.01° right now, so I'll have to watch that.

My plan right now is to wait until my new tires come in, and DIY the alignment (slide the front camber to the stops). The local big chain tire store has been offering a free alignment check, which will conveniently tell me exactly how I did and what the toe and all looks like, so I can choose then whether I want to pay them to realign it, leave it alone, do it myself with string and chewing gum, or take it down to the local race shop.

Of course, the local chain tire store used the wrong wheel weights when they patched my flat last month, and did a lousy job of balancing it, too.

Edited February 13, 2009 by grover

[Brad Roberts]

I'm a bit confused as to why you say adding negative camber would cause toe-in;

I'm on crack.. You are correct, it would cause toe out. I mis-stated that the toe links are behind axle centerline (I had the rears on my mind) The fronts are indeed ahead of axle centerline and it would cause toe out!!

B

[grover]

Thanks, had me worried! What difference would 2mm or so of toe-out make in handling and tire wear? Would I notice a change in either?

[Brad Roberts]

2mm total? or 2mm's PER SIDE for 4mm total? :)

B

[grover]

2mm total, but I think I messed up my math so that's probably N/A.

I just got back from a corner weighting session with the local autocross club, which was far more theory than DIY, extremely interesting, and got into a lot of the alignment stuff. Turns out a lot of the other guys in the club do their own alignments like this, too, and tweak it constantly as they drive & adjust.

Anyhow, I gave checking it a shot today :) I have 0 front toe (less than 1/32" at least), which matches the alignment done 8k miles ago (0.01°LF and 0.02°RF, both toe-in). My DIY camber measurements different, though; I measured -0.8°LF and -0.3°RF which differ considerably from the alignment record (-.2° and 0.0° respectively). I did just top off my gas tank today, though, so this is likely reflecting slightly higher loading than normal for a static alignment on raceday when I try very hard to consistently start with 1/4 tank. Or they may have shifted since alignment, hard to say.

If I have 0 toe on the street with 1/16-1/8" (?? what's the sweet spot?) for racing, I'll be thrilled. But from what you and others are saying, I might as well just set my car with camber to the max (-1° or thereabouts), neutral toe, and just leave it alone after that as camber in this range isn't terribly abusive to tires. I'm shifting to slightly larger tires in the front (225 vs 205) so that may impact the most desirable alignment, too.

Edited February 14, 2009 by grover

[Brad Roberts]

You'll find out after a couple of events that the camber you get with stock control arms will wear the outside of your tires as you get faster in the car. This is why all of us switch to the GT3 control arms and can adjust in upwards of -5 -6 or -7 degrees of camber. Each tire used has a different requirement as well as different drivers require different settings. I *hear* the new Hoosier AutoX tire does not need as much negative camber for AutoX and works well in the -2 range.

Max out the negative and adjust toe. It will be fine.

B

[Brad Roberts]

(?? what's the sweet spot?)

Something I try to get across to people: align the car FOR YOU. You can take advice and try others suggestions, but ultimately it is YOU who has to drive that car.

The very first GT3Cup car I touched came off the boat in early 2000 with -5.5. We sent the driver out and he was SLOW.. took tire temps and figured out very quickly.. he is not PRO and cannot use all of the tire with that much negative in it. The cars were setup for Formula 1 glass smooth tracks and PRO drivers. We backed off the camber to -3.5 front and -3.0 rear and he dropped 4 seconds off his times on the second lap out in the next session. He was more comfortable in the car (at CAL Speedway)

My point: take in as much information as possible BUT throw out all the information from people who are SLOWER than you. I use a sports analogy with people I coach/instruct: I used to play AAA two man sand volleyball, it did my partner and I NO good to play people who were worse than us. You will learn nothing from people worse than you :) Now, that being said, listen carefully to those faster than you, but understand you will need seat time to get to their level :)

B

[grover]

Finally bit the bullet and adjusted my front camber. Will see at the autocross tomorrow if it makes a difference!

This is the right-front, which was WAY bad to start (slightly positive). The left wasn't so bad to start, and not quite so drastic an adjustment.

Edited May 2, 2009 by grover

[996noob]

Finally bit the bullet and adjusted my front camber. Will see at the autocross tomorrow if it makes a difference!

This is the right-front, which was WAY bad to start (slightly positive). The left wasn't so bad to start, and not quite so drastic an adjustment.

After loosening the nuts, how did you lever the shock to move?

Did you have to raise the car? One wheel off the ground, or both? Or none?

[mmontfort]

Finally bit the bullet and adjusted my front camber. Will see at the autocross tomorrow if it makes a difference!

This is the right-front, which was WAY bad to start (slightly positive). The left wasn't so bad to start, and not quite so drastic an adjustment.

After loosening the nuts, how did you lever the shock to move?

Did you have to raise the car? One wheel off the ground, or both? Or none?

This is a simple adjustment and is camber only to the greatest extent. I just loosen the bolts use a rubber tipped pry bar to move the top of the shock and tighten the bolts. No lifting necessary because the toe movement is minimal.

[flyingpenguin]

Here's a good write-up on a DIY alignment check / adjustment.

http://www.planetporsche.net/reviews/showp...=232&cat=10

and

http://www.planetporsche.net/reviews/showp...=230&cat=10

I messed with this on my 2000 996 after I got a bunch of parts from Brad (thanks for the quick shipping and excellent prices BTW).

Not cheap but once you get to the Hoosiers, you really need -2.5 / -3.0. Obviously the car is not really streetable anymore. I have to agree with Brad though that it's not so much camber but toe that wears the tires. I have -3.0 in the front with neutral toe and tires (both track and street) wear very little. The rear is at -2.6 with about 0.15 degrees of toe in on each side (for a total of 0.3 degrees) and they wear quite fast.

Interestingly enough this setup wore out the Hoosier rears (275/35/18s) in only 15 sessions. I upsized to 285/30/18s now and my initial impression is that the wear is now much more even (inside vs. out). Maybe this has to do with my improved driving resulting in actually using all of the tire's capabilities.

JP

[agip]

Did you notice a big different after you add more negative camber on the front? What is the alignment specs after the adjustment?

Does anyone know what's the stock alignment specs on Boxster?

Finally bit the bullet and adjusted my front camber. Will see at the autocross tomorrow if it makes a difference!

[Loren]

Did you notice a big different after you add more negative camber on the front? What is the alignment specs after the adjustment?

Does anyone know what's the stock alignment specs on Boxster?

Finally bit the bullet and adjusted my front camber. Will see at the autocross tomorrow if it makes a difference!

Please do a search - its already posted here.

[grover]

I didn't notice much difference at the autocross, but something this subtle is going to be hard to notice at my skill level (just my 2nd year- managed to win street tire class at both local clubs though which I'm super happy about :D) Thanks to my overly aggressive style, I wore the tires out in about 8000 miles instead of the 15,000 I expected. I did see uneven wear on the inside corner of the tire, probably a 1/16" difference. I had neutral/slight inside toe before the camber change. I had not attempted to measure it since.

After loosening the nuts, how did you lever the shock to move?

Did you have to raise the car? One wheel off the ground, or both? Or none?

You only have to raise the front, but my jack is too tall and only fits under the rear jack-point, so I just lift the whole side.

I put a big socket and some extensions on the top of the shock and brute-forced it while the springs were as unloaded as possible. If I start moving it back and forth for every race, I'm sure I'd find a good technique pretty quickly.

Edited January 23, 2010 by grover