Track alignment

[Ryan13]

Researched a couple of posts concerning alignment, most of what I gathered was -3 front with around -1.8 rear. Since there was a good bit of work done around the engine area, and because previous settings when I installed Vorschlag plates was in the -2.3 front range, I dropped the car off at RRT and said give me all you can. Most people around here know them, they set up plenty of club racing cars and they run a few cars themselves.

They called and said the tower would need a little bit of dremal work, seemed logical. Had both alignment and corner balance performed. I haven't been able to test on track yet, so no feel for the changes. Previous setting with both Michelin PSS and Bridgestone RE-71 resulted in outside edges getting worn pretty badly. I checked temps a few times, biggest delta I recall was 180-155-135 (out-mid-inner) with 40psi hot...yes, we are in melting range.

Anyhow, this is what I got back...

Front
-2.7
0.12 degrees total toe (0.06 on each side)
0.00 degrees steer ahead

Rear
-2.3
0.48 degrees total toe (0.24 on each side)
-0.01 degrees thrust angle


I'm planning to run the Bridgestone this year. The sidewall is a little stiffer, the compound seems to be more sticky. I don't know if suspension matters in this question, but I have the H&R package that comes with the bilstein shocks.

Thoughts, suggestions, or wait for first track (March 11-12) and see what happens?

[The HACK]

Are you experiencing significant understeer during corner exit?

[gmd2003]

Originally Posted by Ryan13

Researched a couple of posts concerning alignment, most of what I gathered was -3 front with around -1.8 rear. Since there was a good bit of work done around the engine area, and because previous settings when I installed Vorschlag plates was in the -2.3 front range, I dropped the car off at RRT and said give me all you can. Most people around here know them, they set up plenty of club racing cars and they run a few cars themselves.

They called and said the tower would need a little bit of dremal work, seemed logical. Had both alignment and corner balance performed. I haven't been able to test on track yet, so no feel for the changes. Previous setting with both Michelin PSS and Bridgestone RE-71 resulted in outside edges getting worn pretty badly. I checked temps a few times, biggest delta I recall was 180-155-135 (out-mid-inner) with 40psi hot...yes, we are in melting range.

Anyhow, this is what I got back...

Front
-2.7
0.12 degrees total toe (0.06 on each side)
0.00 degrees steer ahead

Rear
-2.3
0.48 degrees total toe (0.24 on each side)
-0.01 degrees thrust angle


I'm planning to run the Bridgestone this year. The sidewall is a little stiffer, the compound seems to be more sticky. I don't know if suspension matters in this question, but I have the H&R package that comes with the bilstein shocks.

Thoughts, suggestions, or wait for first track (March 11-12) and see what happens?

I am running -3.4 front 0 toe , -2.4 rear .16 total toe with MCS coilovers and camber plates for track work. IMHO your rear toe is Ridiculously high , the tires will practically be dragged to death and the car will understeer a fair amount .
George

[Ryan13]

I can't speak for the new alignment yet, but for the previous settings at -2.3 front and -1.7 rear...yes, there was a good bit of understeer from mid corner to exit.

I take it that in order to get more than -3.0 in front, there needs to be a pretty good notch cut into the tower...no issue there??

[AriuSen]

Tried many different settings.
Right now I'm at -3.7 front and -2.8rear
0 tow front and 1/16 total rear

My tire wear is very good.
Was running -3.5 and -2.5 and all my tires were cording on the outside

I run Rcomp.
Every car is different so what works for me might not work for you.

[The HACK]

On the M you can install camber bolts to add MOAR camber. Up to 1.5 degrees. Don't cut the strut mount holes unless absolutely necessary.

The tire temp suggest you're spending quite a bit of time on the outer edges of the tires, but the relative even distribution of temperature variances suggest it's coming from understeer at corner exit (corner entry understeer would see much higher temps on the outer shoulder). Camber, or lowering rebound MAY help. Camber will help for sure.

The PSS is notorious for a soft sidewall (relatively speaking), which may exacerbate said problem too.

gmd2003 is right, that's a lot of toe-in for the rear at almost 1/2 degrees total. I run 1/8" total toe front and back and the car rotates at will, and that's ~0.27 degrees of toe-in. I guess drive it and see what you think, with very little toe up front it'll probably still turn in okay.

[Ryan13]

So perhaps I'm confused (very, highly likely). I'm being told that camber bolts really won't address the issue. They are saying that while static camber can be increased, dynamic camber won't change and could possibly increase (shift toward less negative camber) under load with bolts. They want to install shims to address dynamic camber. They also think I'm running too high pressure (40 hot) and feel 36-37 is a better range. I may throw some stiffer springs (H&R currently) or even sways (still on stock) at the problem.

Perhaps this is what you mean with MOAR camber, but I have no idea what that term refers to.

I'm not trying to get into a challenge one way or the other, just trying to understand. I drive 9/10 to 10/10 every lap, seriously. I know I'm pushing the car hard. I don't care, I'm not trying to save tires, brakes, or anything else. I get called in all the time for hanging the rear two off the pavement. When TrackDaze opens their 2-hour open track window, I'm out there the entire time. But contact patch is only outside edge...inside edge of the last set MPSS after 10 track sessions looks practically untouched. The RE71R have 4 sessions, same results.

What is MOAR camber or is that a play on words?

They agreed on the rear toe, so will adjust. But at the rate I'm wearing the rear outside edges (not terrible in the rear, compared to front) dragging the tire will not be the culprit for replacement.

Presume everyone is running upgraded sways and poly bushings everywhere?

[dc_wright]

Originally Posted by Ryan13

So perhaps I'm confused (very, highly likely). I'm being told that camber bolts really won't address the issue. They are saying that while static camber can be increased, dynamic camber won't change and could possibly increase (shift toward less negative camber) under load with bolts. They want to install shims to address dynamic camber. They also think I'm running too high pressure (40 hot) and feel 36-37 is a better range. I may throw some stiffer springs (H&R currently) or even sways (still on stock) at the problem.

Perhaps this is what you mean with MOAR camber, but I have no idea what that term refers to.

I'm not trying to get into a challenge one way or the other, just trying to understand. I drive 9/10 to 10/10 every lap, seriously. I know I'm pushing the car hard. I don't care, I'm not trying to save tires, brakes, or anything else. I get called in all the time for hanging the rear two off the pavement. When TrackDaze opens their 2-hour open track window, I'm out there the entire time. But contact patch is only outside edge...inside edge of the last set MPSS after 10 track sessions looks practically untouched. The RE71R have 4 sessions, same results.

What is MOAR camber or is that a play on words?

They agreed on the rear toe, so will adjust. But at the rate I'm wearing the rear outside edges (not terrible in the rear, compared to front) dragging the tire will not be the culprit for replacement.

Presume everyone is running upgraded sways and poly bushings everywhere?

MOAR is just a forum spelling for MORE. The Z4M front suspension design is taken from the E36 front suspension design which can also use the camber bolts to adjust camber. I had them on my E36 and did dozens of autocross events and several track days and I periodically checked and they NEVER moved. (torqued them to 85 ft. lbs) They're essentially no different than any of the other alignment adjustments on the car that use slots or other types of clearanced bolt adjustment like rear toe, etc. and those don't move when properly tightened. WRT to your pressures, 40 psi hot is really high for a street tire, particularly for the RE71s which have a really stiff sidewall. If 40 psi is your end of session temp, what's your start of session pressure?

[Ryan13]

Had the car aligned again and we are at -3.5 front and -2.4 rear.

I'm also using RE-71 tires and will lower the pressures to 36 hot. Or is there a better hot pressure? I know that's a terribly loaded question, for a lot of reasons.

[gmd2003]

Originally Posted by Ryan13

Had the car aligned again and we are at -3.5 front and -2.4 rear.

I'm also using RE-71 tires and will lower the pressures to 36 hot. Or is there a better hot pressure? I know that's a terribly loaded question, for a lot of reasons.

It's different for every tire , I find 34 hot works well for most street tires . You are running the sane settings as me now so that should work well for you . Have fun !

[Ryan13]

Did the test and tune with the Audi club at VIR earlier this week. Ran pressures between 34-36 all around. Did not experiment with different pressure front-rear. Stayed round 2:14-2:15 on the full course. I got a few low 2:13 time with the pressure at 34. I'm leaving a few seconds out there, but it was my first time on full course. Entry to roller coaster with a double shift, while trail braking, and going downhill into a turn gave me some trouble from time to time. It was really fun when the shift knob came off in my hand and I had to get it back on while coming down the shoot. Put in a little over 100 laps in the two days. The tires looked great, no weirdness on the track, felt really planted. The Porsche cup cars were blowing my doors off however...they had to be running sub-2 minutes times.

I hate to start a new thread for a off topic quest, but the shift knob. I'm still using the basic. I see Jaffster, Little Nicky, ZHP, BMW performance, and the M5. I've not installed a SSK yet...maybe in a few months when I put the 4.10 diff in the rear. Got a preference?

[CTMP4me]

Originally Posted by Ryan13

I hate to start a new thread for a off topic quest, but the shift knob. I'm still using the basic. I see Jaffster, Little Nicky, ZHP, BMW performance, and the M5. I've not installed a SSK yet...maybe in a few months when I put the 4.10 diff in the rear. Got a preference?

F10 M5 - some DIY cutting and gluing required around Z4 plastic boot base since the F10 boot is part of the shift knob, but this way the light up function of the original is retained. For me, this mod plus the clutch delay valve are a cost effective way to improve shifting without going with a UUC solution / race shifters.