Track suspension set up

[healtoeit]

What springs/shocks work well for you guys?
Just curious!
More important to my current situation...
1) I was wondering about putting my stock 525i rear sway bar in to achieve a different feel from the back of the car.
I currently have racing dynamics front and rear.
Front full tight, and rear full loose.
2) Any tire suggestions? My tires are warn out (I have winter tires so these would be very spirited/track/autoX use only)!

Thankx for your input!

[BigKriss]

change the swaybar setup - front loose and rear tight. putting in the stock rear swaybar will produce less oversteer. i go with soft, soft on both swaybar, but they are 27 and 22mm in size. I'm not certain what size the racing dynamics bars are.

[healtoeit]

putting in the stock rear swaybar will produce less oversteer.
Really? I thought the smaller the saw bar the looser it would be... therefore inducing more of an oversteer feel...

the racing dynamics are... 27mm front (3 way adj) and 19mm rear (two way adj)

I also have a strong strut brace in the front

[Tiger]

Change your springs to Eibach or H&R... You will have to change your struts too... Sport Bilstein or Koni.

[healtoeit]

Change your springs to Eibach or H&R... You will have to change your struts too... Sport Bilstein or Koni.
H&R and billie sports are in the car!

[Tiger]

Doh! Didn't read your signature. Fiddle with your sway bar settings then. What tires are you running now?

[attack eagle]

and stagger tire pressures too.

[Jeff N.]

What do you want to adjust Healtoe? As Kris noted, your swaybar setup will produce understeer - something this car already has enough of. Loosen the front bar and tighten the rear bar for a more balanced setup. If you need more front bite/aft rotation, lower the rear TP's a bit relative to the front. If you still need more, install front fixed camber plates from Ireland Engineering.

Any good 17" summer tire will suffice. I'd get cheaper vs. more expensive as the E34 will crush the outer edge on a track due to lack of available camber.

The car will handle but you need to dial out as much of the understeer as possible and adjust your driving style to get off the brakes prior to turn in. Lift throttle oversteer is a good rotational tactic in these cars. I could drive my 535 with E36 M3s with my setup and my (better than theirs) driving style.

[healtoeit]

Fiddle with your sway bar settings then.

Any suggestions w/ the settings? I want more oversteer...



What tires are you running now?
Its also on my sig lol... however the PS2s are really warn down and I'm hunting for sticky rubber for spring!

[healtoeit]

and stagger tire pressures too.
Elaborate plz?

[healtoeit]

If you need more front bite/aft rotation, lower the rear TP's a bit relative to the front.
By TP's you mean tire pressure I assume...
how many psi difference? 1 or 2?

[Jeff N.]

Yes. Tire pressures.

Depends. You have to tune it to get it right. For a DE event, I'd 'overinflate' the fronts by +5 lbs to start and maybe have the rears -3 lbs from the front. See how you like it and adjust from there.

[Tiger]

My tire pressure is front always lower than the rear... I set 32 front and 36 rear. Give it a shot and see if you like it. With this setup, the front tires has more control of the car. People would argue it is the other way, but just try it and see for yourself.

Right now I am running the Avon Tech M500... it is goot tire... not much tread but they do seem to last okay and moderate stiff sidewall. However, it seems to be discontinued.

I also have General Exclaim UHP, but this is soft sidewall but lots of grip and I think the tread last alot longer here. I really do like General Exclaim UHP. I am not a racer though but I do push hard around corner.

Take a look...

http://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=UHP&width=235%2F&ratio=45&diameter=17&tireSearch=true&autoMake=BMW&autoYear=1994&autoModel=540i&autoModClar=&minSpeedRating=H&speed_rating=H&speed_rating=V&speed_rating=Z&speed_rating=W&speed_rating=Y&speed_rating=(Y)

[healtoeit]

front loose
I thought this would loosen the front end causing more sway in the front and therefore a more "understeer" feeling.



rear tight
I thought this would tighten the rear end causing less sway and therefore producing a more tight feeling in the rear of the can, a less "oversteer" feeling

[healtoeit]

General Exclaim UHP
http://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=UHP&width=235%2F&ratio=45&diameter=17&tireSearch=true&autoMake=BMW&autoYear=1994&autoModel=540i&autoModClar=&minSpeedRating=H&speed_rating=H&speed_rating=V&speed_rating=Z&speed_rating=W&speed_rating=Y&speed_rating=(Y)

looks like a good tire, but I was looking for something w/ more grip. I race and Autocross my car and have a dedicated set of wheels/tires for it. I need new tires on those wheels though. I want them to be DOT legal so I can get to and from the event on those tires.
Was looking at

Bridgestone RE-01R
and
Nitto NT-01 (currently my top choice)
and
Michelin Pilot Sport PS2 (currently on the wheels but need to be replaced)

[Tiger]

Talk to Tirerack... You are gonna have to shave and 'burn in' tires no matter which one you get unless they are competition tires. You are autocrossing but you are not racing for money...

You can buy the best tire in the world for $$$$ but it won't help you unless you master your skill and car. I would buy in the midrange or cheap so I can replace every year or other year.

Again, I don't autocross but I do know tires... It is exciting to change new tires all the time because you don't know how much better it than your old one. You also learn to tune in to the capabilities of the new tires.

[Johntee540]

You are running the same suspension Set-up I am running in my 5. Bilstein Sport Shocks / HR Racing (Sport) Springs / Racing Dynamics Sways F-R (Set to Neutral) / Racing Dynamics Strut Brace. The tires I run every day and also on the track when I use my 5 for DE are the Toyo T1-r 17/245. They handle really well and also wear really well.

As far as Handling improvements go - The biggest upgrade I have done to the car lately is to replace the Rear Sub-Frame Bushings (Mounts) and that has tightened up the car very dramatically. The difference is night and day - even over all the other things I have done to the car. So if you car has greater than 100k miles and these have not been done - I would do this first. - JT

[Tiger]

Good point! I would say the greatest improvment I have done for stability is the sway bar links... on all 4 corners... the reaction is like night and day.... loosy to solidly planted.

[healtoeit]

You can buy the best tire in the world for $$$$ but it won't help you unless you master your skill and car.

I'm not saying I'm a master, but mult. people at my last even commented that better tires then my current ones would help me out. I was going around a corner and my instructor commented that if I had better tires I could go faster through it.

[healtoeit]

Good point! I would say the greatest improvment I have done for stability is the sway bar links... on all 4 corners... the reaction is like night and day.... loosy to solidly planted.

I have sway bar link and rear subframe mounts sitting in the garage... :(
Damn school! ;)

[Tiger]

Now that you mentioned the sway bar links is waiting... that's your problem... Really... You will find out once you changed them out. It is not the tires... tires does affect things but not as much as the rest of the car. You got good Michelin tires already. I personally hates Michelin... nothing good about them.

[Tiger]

School almost over for break... Do sway bar links first and go for a drive before thinking of subframe bushings.

[healtoeit]

School almost over for break... Do sway bar links first and go for a drive before thinking of subframe bushings.

The links are ok, the sub frame bushings I dono...
I have powerflex bushings for the subframe so those should help, however I was wondering what other pieces should be replaced, Ive done dogbones and rear links, they are fine once the sub frame bushing is in what else should I look at (everything else I can see looks good)?

[Tiger]

It is not that simple as if the link is okay... whether you got new link or original link makes a huge difference.

[healtoeit]

It is not that simple as if the link is okay... whether you got new link or original link makes a huge difference.

well, in the rear I have the RD links, and in the front they have about 50% life I would say,

What would you suggest if all the links and bushings are ok?

[Tiger]

If everything is okay, then tire pressure is a big deal then it is the tires you have. If you buy the same tires you have now, you will have same issue. Then I'd set your sway's as other has suggested to see if it further helps your situation.


Another aspect to racing is how your brake performs... seems like you took care of that there... EBC as far as I heard is not the best thing so you need to try different pads.

[healtoeit]

Another aspect to racing is how your brake performs... seems like you took care of that there... EBC as far as I heard is not the best thing so you need to try different pads.
Worked fine for me! BUT I have been wondering how Hawk pads would work...
A more important factor on the track (in terms of safety) is the brake fluid (I run ATE DOt-4).

[Jeff N.]

To fix something you need to define a problem. You haven't outlined anything. For example, my car understeers when I attempt to move the apex. Or, I'm having excessive outer edge tire wear. Or, my car over rotates during trailing throttle.

I think you need to find a problem first. Otherwise you're just farting around.

Jeff < -- CCA instructor and more track time in an E34 than you have. ;)

[healtoeit]

Jeff < -- CCA instructor and more track time in an E34 than you have. ;)
If I wasnt farting around I wouldnt get anything done!

This was to see what other people's set ups were, a way to compare and discuss what others have found to work.

1) My car understeers after I hit the apex, early turn in hit apex and throttle, only problem is the rear doesnt come around and I end up pushing the car (understeering), I want the rear to come around.
2) I have excess outer edge tire wear in the front. I am planning on camber plates to help this

On the track I tightened my front sway bar and the car would hold tighter through turns at higher speeds but I was pushing (understeering) around almost every corner. I want the rear to "sway" before the front (by sway I mean I want to feel the rear move out before the front) , this complements my driving style better. When you see a well set up car go around a corner the rear looks like it is sticking and the rear of the the body is rolling out, I want the car to handle like this! Jeff, you know what I'm talking about, your an instructor, I know you do I just cant describe it well.



Jeff < -- CCA instructor and more track time in an E34 than you have. ;)

Now your just being mean! :p

[healtoeit]

What springs/shocks work well for you guys?


Has anyone been to the track w/ the ground control kit?

[Tiger]

What tire pressure were you using front and back?

[healtoeit]

What tire pressure were you using front and back?

Street: 35psi front and back
Track: 32 psi (cold) warms up to about 38-40 psi when hot font and back
AutoX: 38 psi front and back

Trying to set up my suspension and keep tire pressures constant at the moment

[Tiger]

That is the problem. With front and back equal, they are all fighting with each other around a corner and would definitely be understeer. Lower your front to 32 PSI and rear to 36 PSI and drive the car. You will notice the front will have tremendous traction and steering response and the rear will follow.

You don't even have to be on the track to feel this setup. It is so simple and cost you nothing.

[sal_park]

Street: 35psi front and back
Track: 32 psi (cold) warms up to about 38-40 psi when hot font and back
AutoX: 38 psi front and back

Trying to set up my suspension and keep tire pressures constant at the moment

I'm curious - why are you running the same pressure front and back ? From memory rears should be higher pressure (although this could be the other way around) - something like 2bar front, 2.3 bar back.

[healtoeit]

I'm curious - why are you running the same pressure front and back ? From memory rears should be higher pressure (although this could be the other way around) - something like 2bar front, 2.3 bar back.
I've just always ran them that way.
Same pressure means the car is more equal imo. I already have 50/50 weight distribution and I wanted to tune my suspension.

[healtoeit]

That is the problem. With front and back equal, they are all fighting with each other around a corner and would definitely be understeer. Lower your front to 32 PSI and rear to 36 PSI and drive the car. You will notice the front will have tremendous traction and steering response and the rear will follow.


Will adjust tonight!

[Tiger]

It has nothing to do with weight distribution... Take a look at what BMW recommends on the door pillar. You will see even they do that.

[healtoeit]

It has nothing to do with weight distribution...
I know. But the more weight you have front or back the higher the pressure has to be to account for the greater % of weight over that axle.

[healtoeit]

Lower your front to 32 PSI and rear to 36 PSI and drive the car. You will notice the front will have tremendous traction and steering response and the rear will follow.

Well, had a good test on a nice spirited run through VA back country roads tonight! All is well and I like the set up!
Thankx for the help Tiger

[Jeff N.]

Tiger. Git yer facts straight buddy. More front pressure to rear pressure = less understeer.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=58

[Tiger]

Glad you experienced the dramatic change just by the tire pressure... If you want more consistent performance on the autocross, you should consider having your tire air replaced with 100% nitrogen... this way, the tire pressure doesn't change as much so the tire performance doesn't change along the racing... Onlythe termperature of the tire changed but not the tire pressure

[Bruno]

Has anyone been to the track w/ the ground control kit?

The problem with going coil over (I have the full ground control with Advance design dual adjustable shocks on the race car) is that you need to know what spring rate you want.

Coil over is the ultimate setup, allows you to chang the spring rate and to corner balance your car. (I have yet to do that).
And you can also adjust the ride height.

But it isn't cheap...

[healtoeit]

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=58

I completely forgot aobut those tech articles! TYTYTY

[healtoeit]

The problem with going coil over (I have the full ground control with Advance design dual adjustable shocks on the race car) is that you need to know what spring rate you want.

Coil over is the ultimate setup, allows you to chang the spring rate and to corner balance your car. (I have yet to do that).
And you can also adjust the ride height.

But it isn't cheap...

Is the spring rate adjustable on the GC kit for the e34?
http://www.ground-control-store.com/products/description.php/II=744/CA=68
It says that "A broad selection of street spring rates are available" is that what they mean by selecting the "ride feel?"

[Tiger]

Okay... let's talk about tire pressure...

Depends. You have to tune it to get it right. For a DE event, I'd 'overinflate' the fronts by +5 lbs to start and maybe have the rears -3 lbs from the front. See how you like it and adjust from there.
Jeff < -- CCA instructor and more track time in an E34 than you have.

So... from standard 4 tire equal... 32PSI... You would want Front to be 37 PSI and rear 29 PSI. And getting the fact from Tirerack... Front tire decrease understeer and rear is also decrease understeer....

It doesn't make sense to me... rear tire hs more traction due to lower pressure and The front has less traction due to less tread contact. Thus will force the front of the car to understeer. Tell what is wrong with this picture... Tirerack info stated same tire pressure for FWD and RWD car... this is wrong.

Understeer by definition ie best explained here:

http://www.drivingfast.net/car_control/understeer.htm

http://www.drivingfast.net/car_control/oversteer.htm

If you look all the way to bottom... it suggest on tire pressure... It is complete opposite of TireRack info. I strongly believe the TireRack info is for FWD cars.

[Washburn]

Depends on the car, spring rates, roll resistence, tire brand/construction,... there is no one hard and fast rule regarding tires pressures and their affect on handling. Most "rules" printed about thids assume an already sorted and setup car that is neutral, the they list the theorictical changes that might result.

Personally, unless your running R-compound tires like A6's, V710's, ... those pressures seem too low. You will see pretty good rollover at those low pressures without a competition tire. (That, along with lack of nagative camber, may explain your outer edge wear.) Most autocrossers will run "street" tires at 42 to 50 PSI. Higher pressures will create a stiffer sidewall, resulting in a better dynamic contact patch. So....less pressure does not necessarily equal more grip. You can go over the line too...I know people who run the rears up over 60 to 65 PSI to help a FWD car rotate. I know some that run them at 28 PSI to get the same affect. Like was said....you need to test and experiment, it's not all in a book.

Typical setup to help reduce understeer is a soft front bar, and a stiff rear bar. (Again...without knowing your spring rates and such, this is a generality.) Rates will affect the sway bar rule too...I used to run a Stock classes Neon with a huge front bar. Most people would tell you that this will create understeer. Quite the opposite...by reducing body roll on the softly sprung car, and thus dynamic camber gain, we picked up a lot front end grip by keeping a better contact patch. All depends.

[Jeff N.]

Pat's correct.

Tiger - to your question. What i'm referring to has nothing to do with the BMW recommended TP. Those are designed for load capacity, comfort and factory intended handling characteristics. "Factory intended handling characteristics" 99.9% of the time translates into understeer. The natural driver correction when the car is doing something unexpected - throttle lift - is the generally correct correction to recover from understeer. Therefore, for safety's sake, almost all cars are setup to understeer. If you don't believe me, just talk to a driver of an early model 911 and ask them what it's like to learn on a track how to drive with a car the prefers to oversteer.

As Pat pointed out, tire pressures for track and auto-x are always higher then factory pressures unless you're running an R compound tire with a very very stiff sidewall. To help an understeering car rotate, one tactic you have is to lower the rear TPs relative to the front. This works to keep the front contact patch larger than the rear patch leading to a larger front friction circle than the rear. This, combined with correct driver inputs will help the car rotate. Rotation will get the car pointed in the correct direction quickly so the driver can open the turn radius sooner and get back in the throttle sooner than otherwise. Doing this makes you faster than someone who isn't.

My experience with summer type tires for track sessions is that you need to set E34 cold TPs about at about 38 to 40 lbs in the front, 35 to 36 lbs in the rear. During a track session, you'll see about about a 7lb gain due to heat typically with a little more gain in the front than the rear. This gives you hot TPs around 45 to 47lbs front, 41 to 42 in the rear. This differential seems to work well to give decent traction and mitigate understeer.

But - it's all relative. Start with general rules and work to specifics. Your advice to lower front TPs relative to rear TPs to mitigate understeer is contrary to how most every car will behave and my specific experience with the E34.

Sorry, not trying to be an ass but I do think it's important to get the basic facts correct.

[Tiger]

I know cars are inherently udersteer by design for safety reason. I agree with high pressure for racing and to reduce the overheating of tires at such extreme condition. I know tire pressure increases with hard driving... perhaps this is why racing cars use Nitrogen gas instead of air... however, Nitrogen gas is hard to get and costly unless someone already figured out a way to reduce the pressure fron Nitrogen bottle.

I don't race but I do drive hard around corners... I always love to see how smoothly I can go through it without tapping on brake. With all 4 wheels equal pressure... pretty bad understeer and must slow down. With rear tire higher, easy and fast cornering.

For the benefit of doubt, I am gonna try your suggestion and reverse the air pressure and see what I feel.

[healtoeit]

With rear tire higher, easy and fast cornering.

Tiger, I got to test your set up in an abandoned parking lot w/ very few obstructions (it was big: I could get to 65mph in it and have enough room to slow down safely)

All the car wanted to do was understeer (if you do not believe me I can try and post a video, but I am not that tech savy). I was going HARD and I could not get the rear end to come around.

Then I took my car to some twisties on the roads, and the car handled fine.

In conclusion I do not think think that this set up (32 front, 36 rear) reduces understeer.

[Tiger]

Try the reverse like Jeff said... 40 front and 33 rear.

It is interesting that you said on normal driving the car handled fine... maybe you do like it better with front lower for normal driving compared to all equal pressure.

I am going to try reversing my pressure to see how it responds on normal driving... it is kinda cold here that I can't do exuberant driving... but I can tell regardless.

[attack eagle]

I run lower pressure in the front also.

I set the fronts by contact patch though, not pressure, and the higher rear pressure reduces that slightly.

Also helps that I have a touring and am used to AWD understeer/power oversteer (or neutral under power) and still drive slow & tight ins with fast drifting out.

I don't run on a track or auto-x anymore but as I recall Jeff's stagger was more common on just about everything modern except some really fast FWD (the tire picker uppers in particular), classic british, and AWD where the harder rear was easier to break free controllably.


I might just go back and try inverting my tire pressure stagger one of these days

[Jeff N.]

Keep in mind setup is only an enabler. You also need to correctly manage driver inputs.

If the car is understeering, to mitigate you need to also need to assist with any of the following inputs:

- avoid trail braking - trail braking is braking while turning. It essentially means that you reducing your available turn in traction because you are making the tire work to brake, not turn. Get all your braking done prior to turn in and get the car balanced at turn in.

- avoid heavy throttle application prior to apex. If you are trying to make the apex and the car is understeering, you are going to fast for the turn radius. You need to slow your entry and avoid throttle application until you are past the apex and starting to unwind to the trackout. This also assumes you are not trail braking. Without exception, just about every single novice (no advanced training) driver will enter the turn too fast. Remember the racers adage - slow in, fast out.

An advanced technique to initiate rotation and mitigate understeer is called lift throttle oversteer.

- lift throttle oversteer is where you are past the turn-in and moving to the apex. You want the car to turn sharper. To do this, you slightly lift off the throttle pre-apex. This initiates a forward weight transfer that does two things. Increases the weight on the front tires causing more turn in bite (increases their friction circle), decreases the weight on the rear tires generally causing them to begin to slide (decreases their friction circle). (Lower rear TPs assist here because the lower pressure helps the rear tire loose traction before the front tire) The net is that with the front gaining traction combined with the rear loosing traction the car starts a controlled slide in the back (oversteer) that moves the nose of the car to the apex (rotation). As the nose moves to the apex, you stop the rotation by carefully re-applying the thottle to move the weight aft again thus sticking the rear tires back down and stopping the rear slide.

It's subtle and if you want to practice this, go to a track first. If you fubar this technique on a wet on-ramp, you'll likely stuff your car to into the inside barrier wall.

Net is this - no matter what you do with TP's, they will never overcome bad driver input. A good setup enables good driver input.

[Jeff N.]

Order this (http://www.amazon.com/Secrets-Solo-Racing-Techniques-Autocrossing/dp/0962057312/ref=sr_1_1?ie=UTF8&s=books&qid=1227376754&sr=8-1) book by Henry Watts.

I've looked a bunch of driving technique books but I think Hank's book is the best, most direct, easy to follow book there is. Highly recommended.

[Washburn]

Excellent post Jeff, and a point I was going to make until I read your's. We're ignoring drive inputs to a large degree when talking about all this stuff. Slow in, fast out = golden rule. Your parking lot romp may have caused you to over drive your entrances, not having any other points of reference or limiting factors like cones or ditches. That might explain the handling difference on the road...ditches. :) There's an old saying I use when I'm instructing autocross drivers (going on 20 years now) "Cars do not understeer, driver do." While not always 100 percent true, it steers your thinking in the right direction.

I will typically set a car up to oversteer. (Front, rear, of AWD) Under autocross conditions, this allows throttle application much earlier than what Jeff suggests, often well before the apex. (The STU prepped Evo I drove tha last two years, that resulted in awesome 4 wheels drifts off the apexs as it tried to put down the 330 or so WHP on street tires.) Not a great idea on the track, but works in AX situations. Fun too!!

[Jeff N.]

Pat - you auto-x's are nuts. Every time I ride with a talented auto-x driver I wonder what just happened. Pitches, dives, brake and thottle assisted rotations in machine gun order. Helluva a talent. I'm a marginal auto-xer at best.

I've got the need for speed. For me there's nothing like a perfectly managed high speed corner where I've got the car balanced on the edge of traction in a precise 4 wheel drift, throttle steering the car to an inch of the apex and working every last millimeter of pavement on the track out. And then doing that again and again lap after lap.

Here's favorite pic of the ol' 535 (now track retired) working turn 5b at Pacific Raceways.

http://home.comcast.net/~jsnord/pics/pr_535.jpg

[Bruno]

Is the spring rate adjustable on the GC kit for the e34?
http://www.ground-control-store.com/products/description.php/II=744/CA=68
It says that "A broad selection of street spring rates are available" is that what they mean by selecting the "ride feel?"


The ride height is adjustable, the spring rate is set by the spring, you need to change it to change the spring rate.

With different spring rate, the car can be soft or stiff, depends what you need.

[Washburn]

I've got the need for speed. For me there's nothing like a perfectly managed high speed corner where I've got the car balanced on the edge of traction in a precise 4 wheel drift, throttle steering the car to an inch of the apex and working every last millimeter of pavement on the track out. And then doing that again and again lap after lap.

Here's favorite pic of the ol' 535 (now track retired) working turn 5b at Pacific Raceways.



Nice! I can almost see the slip angle your carrying...fun! I've done some track days, but never really had a good weapon. Porsche 914...great in the corners if you can stay awake long enough in the straights. A2 V Dub - same thing. Hell of a lot of fun, but I got tired after awhile trying to find tenths in an underpowered car that was maxed out. Ran a Formula Ford for a few years...never bothered to un-do the AX setup for some track time. AX setup = suicide on a track! :) I like the speed too, and what your doing is an art with the right car, but I also like the challenge of AX. (And can afford it more. I'm too old, got too many kids, and not enough insurance for road racing!) Nice to hear someone who tracks their car appreciate AX too...not a lot of road racers do.