She's a bit FAT! + New Alignment Specs

[yandy]

Installed the Dinan fixed camber plates and I'm surprised and happy I was able to get -2.5 out of them on each side. Also weigh her in, cause I was curious.

[jphughan]

Fyi I'd consider reducing rear camber. I just went through my second set of rear PSSes that wore significantly faster on the inside than the outside, and that was only running -1.8. Due to the uneven wear, each set of rears only lasted about 9K miles, which included 6 track days on each set, but there was significant tread depth remaining in the middle and outer grooves at that time. So I just had an alignment shop drop that to -1.6 after doing some research here that confirmed that tracked M3s often need less rear camber. I also specified 1/16" total toe-in on the rear rather than your 1/8", but that's not as big a deal.

My front setup (with Vorshlag camber plates) is exactly the same as yours though.

[yandy]

Originally Posted by jphughan

Fyi I'd consider reducing rear camber. I just went through my second set of rear PSSes that wore significantly more on the inside than the outside, and that was only running -1.8. Due to the uneven wear, each set of rears only lasted about 9K miles, which included 6 track days on each set, but there was significant tread depth remaining in the middle and outer grooves at that time. So I just had an alignment shop drop that to -1.6 after doing some research here that confirmed that tracked M3s often need less rear camber. I also specified 1/16" total toe-in on the rear rather than your 1/8", but that's not as big a deal.

My front setup (with Vorshlag camber plates) is exactly the same as yours though.

Less camber even for track in the rear? I'll keep an eye out next weekend and see how that goes. I was at -1.8 before, didn't much outside wear, but also no negative inner wear either. I'll keep an eye out though, thanks for the heads up. I did -2.0 in the rear just to try and keep some front-to-back balance.

[jphughan]

Originally Posted by yandy

Less camber even for track in the rear? I'll keep an eye out next weekend and see how that goes. I was at -1.8 before, didn't much outside wear, but also no negative inner wear either. I'll keep an eye out though, thanks for the heads up. I did -2.0 in the rear just to try and keep some front-to-back balance.

Yep, even for the track. In fact, especially for the track, because all of that rear weight transfer that occurs when powering out of corners increases negative camber during that time (similar to how lowering a car does), hence the increased inside wear. I read quite a few threads on this and several others found that the high end of the stock range was too much for cars tracked even somewhat regularly (I do 6-8 days per year). Of course there are several factors that determine wear patterns, so your mileage may vary.

Yes, I'm almost certainly giving up some absolute grip in the rear by dialing camber back a bit there, but considering that this car understeers pretty significantly (even with camber plates), if anything this change should get me closer to neutral handling. I also installed 255/35 tires on the front, which helped a lot, but even with those two factors my car still understeered a bit even with -1.8 in the rear, so -2.0 in the rear paired with stock front tire sizes would make that even more noticeable. But like I said, the rear camber reduction came mostly because I was annoyed at having to throw out two sets of rear PSSes way earlier than would have been necessary based on the rest of the tread grooves, not as much for handling considerations. In any case, you definitely didn't need to increase rear camber just because of the front camber you added; your car still would have understeered even if you'd left rear camber alone, and now while you'll probably have a bit more grip in the rear, that means you'll also have more of a tendency to understeer.

Just something to keep an eye on. Have fun out there!

[yandy]

Originally Posted by jphughan

Yep, even for the track. In fact, especially for the track, because all of that rear weight transfer that occurs when powering out of corners increases negative camber during that time (similar to how lowering a car does), hence the increased inside wear. I read quite a few threads on this and several others found that the high end of the stock range was too much for cars tracked even somewhat regularly (I do 6-8 days per year). Of course there are several factors that determine wear patterns, so your mileage may vary.

Yes, I'm almost certainly giving up some absolute grip in the rear by dialing camber back a bit there, but considering that this car understeers pretty significantly (even with camber plates), if anything this change should get me closer to neutral handling. I also installed 255/35 tires on the front, which helped a lot, but even with those two factors my car still understeered a bit even with -1.8 in the rear, so -2.0 in the rear paired with stock front tire sizes would make that even more noticeable. But like I said, the rear camber reduction came mostly because I was annoyed at having to throw out two sets of rear PSSes way earlier than would have been necessary based on the rest of the tread grooves, not as much for handling considerations. In any case, you definitely didn't need to increase rear camber just because of the front camber you added; your car still would have understeered even if you'd left rear camber alone, and now while you'll probably have a bit more grip in the rear, that means you'll also have more of a tendency to understeer.

Just something to keep an eye on. Have fun out there!

makes sense, about the squatting under power. For the track I do run 275/35/18 square, and on the street is 275/255 19 PSS. I'll report back soon on how it all is.

Thanks again

[Richbot]

This car doesn't need much negative in back. Typically standing up a tire helps with longitudinal grip which is exactly what you need on Accel. More lateral grip won't help you if you are overwhelming the tire as soon as you get near the throttle

The fact that it also helps steady state balance to stand it up a little is a win win. Only downside is more snappy behavior in quick transitions

As a side note, this trade off is one of the reasons a staggered setup is more flexible in terms of chassis tuning. If you have a taller tire in back you can trade some forward bite for lateral grip by adding some rear camber and still have the same forward traction you would with the smaller rear tire. But that's expensive, time consuming to get right, and annoying logistically so I get why most don't bother

[Malek@MRF]

Toe looks good (if you are at stock or near stock height), rear camber is too negative. I would try and stay between -1.6* - 1.8* for the rear.

Front, you will never need more than -2.5*, it will wear the insides of the tires more rapidly, but very ideal for track work. For track work the front toe is a good combination for street and track.

[TheKosherStogie]

Nice!


I noticed a big difference when I went from 2.5 to 3.0 and ran 2.0 in the rear. Car performed beautifully. Very balanced. No understeer.

[PrimeBMW]

Do you want to go fast on the track? Well then you probably don't care about tire wear on the street. Go with the camber that provides the best performance. Run your street tires up to 40 psi hot to save the insides.

[yandy]

Originally Posted by Richbot

This car doesn't need much negative in back. Typically standing up a tire helps with longitudinal grip which is exactly what you need on Accel. More lateral grip won't help you if you are overwhelming the tire as soon as you get near the throttle

The fact that it also helps steady state balance to stand it up a little is a win win. Only downside is more snappy behavior in quick transitions

As a side note, this trade off is one of the reasons a staggered setup is more flexible in terms of chassis tuning. If you have a taller tire in back you can trade some forward bite for lateral grip by adding some rear camber and still have the same forward traction you would with the smaller rear tire. But that's expensive, time consuming to get right, and annoying logistically so I get why most don't bother

Thanks! Seems surprising that even 2.0, which is not all that much more than 1.8 would be make such a big difference in this car. I will def keep it in mind though and keep an eye out, for now it's a bit late for my next track day.

Originally Posted by Malek@MRF

Toe looks good (if you are at stock or near stock height), rear camber is too negative. I would try and stay between -1.6* - 1.8* for the rear.

Front, you will never need more than -2.5*, it will wear the insides of the tires more rapidly, but very ideal for track work. For track work the front toe is a good combination for street and track.

I wanted a bit of toe-out in the front with some compromise, glad that's what was achieved. Again, may just need to keep an eye out for the fronts.

Originally Posted by TheKosherStogie

Nice!


I noticed a big difference when I went from 2.5 to 3.0 and ran 2.0 in the rear. Car performed beautifully. Very balanced. No understeer.

Can't really do 3.0 in the front this way, only got camber plates because I'm doing as "I get faster" upgrade cycle in the car. When I go full coilovers, then I'll start playing a bit more with the camber. The Dinan plates are fixed, so not much more to do there.

Happy to hear you liked the 2.0 in the rear.

Originally Posted by PrimeBMW

Do you want to go fast on the track? Well then you probably don't care about tire wear on the street. Go with the camber that provides the best performance. Run your street tires up to 40 psi hot to save the insides.

Gotta pay to play, though some compromise is good, I like to have a bit of fun.

[jphughan]

^ Hmm, I missed that you're running toe-out up front. I'm running 1/16" total toe-in on both axles and I'm already noticing that the car is more darty on the road. But like we've all said, it's always a compromise unless you want to adjust your alignment before every track event or have a dedicated track car.

[Sleeper519]

Originally Posted by jphughan

^ Hmm, I missed that you're running toe-out up front. I'm running 1/16" total toe-in on both axles and I'm already noticing that the car is more darty on the road. But like we've all said, it's always a compromise unless you want to adjust your alignment before every track event or have a dedicated track car.

One easy adjustment that i've been doing at the track is changing front toe.

I am running 1/16" toe IN on both front and rear for Street, and do a simple tie rod adjustment on front axle to give 1/16" toe OUT for track. I get my alignment guy to mark the tie rod with 2 hash marks for both measurements while car is on the rack. Then when I'm changing to my track tires that morning I do about a 3/4 revolution of left front tie rod and, voila.. better turn in response! Simple to change back after event so no abnormal tire wear on street.

FWIW, my camber is Fr -2.6* and R -2.0*. I was told to keep the front and rear close to ~.5* difference on E9X setup (not sure why). But I have been running this static camber setup for 2 years now with no abnormal wear at all on my PSS street tires. Having said that, I will probably dial back to -1.8* rear just because of Malek's input above.

[TheKosherStogie]

Just rechecked and I ran 2.3 rear 1/16 toe out and 3.0 camber front 0 toe

[kitw]

The E9x gains a good amount of camber under roll at the rear, so you really don't need a whole lot of static camber at the rear - more just hurts you putting power down coming out of a corner. I liked -1.6 with -2.4 from the Dinan suspension and camber plates on my first E90, and I continued to run -1.8 with -3.0 from KW Clubsports on my E92. (much lower ride height... couldn't get the rear any LESS negative than that) Crappy strut suspensions, even the nice one on the M3 with the dual links, can't gain much camber so you have to run a lot of static camber up front.