track mods help needed?? - The Unofficial BMW M5 Messageboard (m5board.com)

2002m5BGM · 29th June 2004, 23:15

I was told by an instructor that if I put a larger rear sway bar on the car, it will reduce the lean of the car in corners and help reduce understeer. If I have the stock suspension, it this a reasonable mod to make the car lean less and help to reduce understeer?

The choices seem slim - Dinan offers a rear sway bar that is 1mm larger in diameter. Comments please.

The other suggestion mod was to put the KMAC adjustable camber plates up front since the stock set up allows for no adjustments with front camber or caster. Bavauto offers these. But I hear it will raise up the front of the car. Has anyone done this?

I am looking to make small low cost, incremental changes to help with the understeer. I was told the camber plates will help even out the wear on the front tires. Right now the outside edges are taking all the wear and stress.

Thanks for your help.

mottati · 30th June 2004, 00:34

The dinan rear bar will help reduce understeer. It is only 1mm larger, but is adjustable, so you can increase it effectivness by moving the mounting location inward. I'd try it on the middle hole and see how you like it. Another low dollar mod is to get a spare pair of rear wheels, tires and 3mm spacers (you can get those and 3mm longer lug bolts from tire rack). The extra rubber at the front really improves grip at the front, the car will turn in much better.
Mike

Redshift · 30th June 2004, 01:21

For track use, I would make the very first modification camber plates of some sort. You will eat through tires VERY quickly without them, because the front camber setting of -0.5 degrees is NOT adjustable.

I tore through a brand new set of tires in only a few events because the lack of camber wears the outside edge of your tires down fiercely. I posted a thread showing what happens with the stock setup under hard cornering at the track - NOT GOOD.

Second I would go for brakes. Factory brakes are marginally acceptable for aggressive street driving, but unacceptable for the track at anything more than a novice or intermediate level I would imagine. I went with StopTech and could not be more happy, but other brands are available.

IMO, you are wasting your time with fatter front wheels and tires if you do not fix the camber. What good is the extra 30mm of tire width if only 10-15mm of that is touching the ground under hard cornering?

I do have a Dinan rear bar adjusted to the middle setting and the car, with my coilovers, camber plates, and 275mm front tires feels very neutral on track. I also have BeastPower rear swaybar mounts which are also a must have item (pricey, but very nice, and will save you time and hassle having to fix broken BMW parts all the time).

Let us know if you have more questions, and I hope to see you at the track some time!

Nolift911 · 30th June 2004, 01:32

Hello all,

I will toss in my .02 since I am a new M5 owner but have spent some time on the track, albeit in my 911 and yes two totally different track beasts.

I am not sure of the mods mentioned above as they apply to the M5, but I would like to suggest the use of a tire pyrometer and a good tire gauge that has half pound increments. If you already have these and use them regularly read no further.

I found a huge difference in playing with tire pressures and using the pyrometer to "read" the tires and the setup of the car. I am not sure how this stuff translates for an M5 but for the 911 there are tons of articles on setups and pressures and it makes a huge - huge difference. Keep a log at the track and note pressures after each run. The pyrometer is helpful with which parts of the tire are getting really hot and which parts have little to no contact. Take your readings to a good alignment guy to work with you on.

Again, I know this stuff is not groundbreaking but I found it very useful for my 911 track time. I have since went full mods on the 911 after getting all I could out of the basics.

Anyway...hope this helps.

-Jeff
nolift911@hotmail.com

capup · 30th June 2004, 01:53

Tire pressure may help with a 3000# Porsche but is not effective in the 4100# M5. I tried and felt no improvement. I tried the 275's up front with a very slight improvement. I went for the Dinan stg 3 suspension. It made a neutral car out of it. I would guess the adjustable rear sway would be the least expensive and most immediately effective one step upgrade. I agree with the camber plates. The cost can be offset by the uniform tire wear. You'll enjoy better handling plus more track time per tire. Have fun.

gsfent · 30th June 2004, 03:22

If you are serious about tracking the car, I would suggest an extra set of wheels and use dedicated race tires. Toyos and Kumhos are good and good value. Hoosier probably the best, but an extra couple of tenths per lap for a DE is meaningless, and you will go through a set per weekend!!! You will get better wear out of both sets when used for their intended purpose.
Regards,
Jerry

stever · 30th June 2004, 06:13

i agree with Redshift that camber plates are a must for track. the cost and effort of installing camber plates makes one think seriously about springs and shocks -- the Ground Control coilovers with camber plates are a huge bang for the buck -- if they'd been available and i knew i'd be tracking the car as much as i have, i'd have chosen them over the Dinan 3 -- similar shocks and spring rates with the advantage of the excellent GC camber plates and significantly less $$ -- and both the Dinan 3 and GC will make you much happier with the car as a daily driver as well

unless you're running at tracks that are easy on brakes, just putting in Superblue and performance street pads in front like Axxis Ultimates will only work if you are willing to manage the brakes (not a lot of fun and acutally quite difficult when you're learning to drive on track, concentrate on the line, etc.) -- you can get by with track pads like PF97s in front but changing pads in and out and re-bedding is a nuisance -- if you don't drive many miles or use brakes much on the street, or worry about some squeal, the PF 97s can be used on the street -- they work just fine when cold (they're only cold for one wheel revolution on an M5). i did not have good luck with Pagid Oranges which many Audi and Porsche drivers use on the street -- they are just not up to the weight of the M5 on the track, deposit on the rotors - mess

so my recommendation is

1) invest in a complete suspension package, it will save $$ in the long (no, medium) run

2) high temp brake fluid is a must, and you'll have to make a decision about track demands, your time, $$, re pads and rotors. i'll have to say that Stoptechs on the front are a lot of bang for the buck and running them with PF97s and braking with the Porsches is a satisfying experience

3) there was a post about a seat belt clip -- a good low $ alternative to the Schroth harness -- much easier to concentrate on care control when you're not using the steering wheel to help stay in the seat

4) rear wheels and tires on the front are definitely good once the camber issue is taken care of

stever · 30th June 2004, 06:20

i think a set of track tires and wheels is only justified if you run upwards of 500 track miles a year

at this point i would only recommend Toyo RA41s - Kumhos will just not last on an M5, Hoosiers certainly not, and my personal experience with Michelin Sport Cups is disappointing with mixed results from other drivers

the main advantage of track tires is that they will not get "greasy" after a few good laps, particularly in hot weather -- and if you have them on a set of track wheels the chips from the inevitable "off" won't stare at you every day

gsfent · 30th June 2004, 15:39

Quote:

Originally Posted by stever

i think a set of track tires and wheels is only justified if you run upwards of 500 track miles a year

at this point i would only recommend Toyo RA41s - Kumhos will just not last on an M5, Hoosiers certainly not, and my personal experience with Michelin Sport Cups is disappointing with mixed results from other drivers

the main advantage of track tires is that they will not get "greasy" after a few good laps, particularly in hot weather -- and if you have them on a set of track wheels the chips from the inevitable "off" won't stare at you every day

Stever
I guess we can agree to disagree on this one. If you are going to the trouble to get camber plates and/or coilovers, and thinking of BB kit, it is to set up the car for the track. If you do 2-3 events per year, you will want the upgrade, although I do agree to do the suspension first. The M5 does everything well enough in stock form for sane (or even slightly insane) street driving. Like suspension and BB kit, there is a one time investment, primarily in the wheels. You can pick up a stock set used for under a grand, a little more is you want 4 rears. Tires are consumables. If you take full or nearly full tread street tires out, you will eat them up quickly. Chunking is a problem. If you have worn tires, say 5/32, they are good track tires but getting marginal for the street. As we know, the M5 is not svelte for a track car. If you have coilovers and a BB kit, you are going to be working the car, and the tires, especially the outside front will show that in short order. If you don't work the car that hard, then you can get away with good street tires, but I think you can also get away without other upgrades too and just work on your driving skills.
My experience with other heavy cars on the track is that Toyo is the best (given bang for bucK, we agree there) and Kumhos slightly behind, because they are very sensitive to small pressure adjustments. I run the RA1's on my heavy street car and my much lighter track car and find they last a long time and performance is constant. When I use a street car for a DE, I find it easy to swap the wheels at the same time I swap out the pads for the track(wheels are off anyway!), not a big deal. I will do that a few days before the event and bed the pads. I change back a day or two after the event. Of course, as we know, YMMV!

Regards,
Jerry

fgbaloh · 30th June 2004, 19:56

Ok, help me with the camber plates and coils. I am now ordering my third set of front ps2's after 5 days on the track. I expect to "kill" the front left tire in two track days but I would prefer to keep the tire longer and improve handling if possible. Are the camber plates and coils dinan? My dealer does dinan and I would prefer to stay through them as I don't plan to do any of the work myself. What kind of money are we talking? I plan on replacing the car in the next 2 years and it may be more cost effective to simply keep buying new tires ( or at least left front) after every two days. Thanks for the info.

frank