Camber suggestions for track only E36 sedan?

[JeremyGl]

Bought a track only e36 sedan. It has all the suspension mods including sway bars, poly bushings, and h&r/ Bilstein all around.

Just got new 200 wear rating tires. 245/40.

How much camber front and rear?
Tire Rack website says "as much negative camber as you can get out of the car" but it has aftermarket camber adjusters, so I'm pretty sure I could overdo it if I go to limit...

[aeronaut]

Which tires? which h/r springs? There are some very sticky 200 tires out there. That said, you'll probably want to start in the range of -2.5 to -3deg camber in the front, then watch your tire temperatures across the tire, and/or your tire wear, and/or how the car handles (braking, turning, etc.)

It also depends on what camber you can run in the rear. The starting guideline is to have about 1 to 1.5 deg difference between front and rear (eg if front at -3, rear at -2). ISH. That is, these are all starting points.

That's the basics.

It took me a year (3 different alignments) to get my camber #'s "perfect" for my car, tires, and tire wear.

[NeilM]

I'm pretty sure I could overdo it if I go to limit...

Bet you couldn't!

The E36 front is happy at least up into the low -4.x degree range, although most adjustable camber plates will max out at a degree or so less than that. The stiffest front swaybars also can live with less camber, so that plays a part too. Rear should typically be about 1.5-2 degrees less than whatever the front is, which may call for aftermarket lower control arms.

Neil

[aeronaut]

I agree -4 isn't too much. Unless it's too much. I wouldn't recommend -4 to a novice driver on (true) 200w tires, for example.

[NeilM]

I agree -4 isn't too much. Unless it's too much. I wouldn't recommend -4 to a novice driver on (true) 200w tires, for example.

And that's a good point.

Neil

[JeremyGl]

Thanks guys. I'm just looking for a starting point, as I'm new to BMW and RWD. Not new to road course or autocross.

Tires are 245/40ZR-17 HANKOOK VENTUS R-S4 SL

I am not sure of front spring or shock specs, as they are marked "custom" with a sticker on top of the model number.
Rear h&r are 400lb, 160mm with Bilatein b8 sp.

I have it at shop right now. We're going to see how much camber we can get in rear and try to get around 2.5° to 3° back there, and front 1.5° more than that, 4° it's the goal.

Will see! It will be a starting point and I can always adjust from there.

[badmonkey]

Smidge toe out front, smidge and half toe in rear.

[emoore924]

Running -3.5 in the front, -2.4 in the rear. Big sways with coilovers (can't recall the spring rates). Essentially the same results with several different tires - NT01, Toyo RA1, RE71-R, etc. Still pushes a little bit in slow and mid-speed corners when the tires overheat. Most of the tire wear is on the outside half of the tire so it could probably live with a little more camber and/or less spring in the front next time.

[JeremyGl]

Update, so it turns out the previous owner already had it pretty well set up.

My guy at tire rack told me as much caster in front as possible, and there was already 6.5° of caster.

It also turns out there's no camber plates or etc. So we were stuck with factory adjusters.

All the caster made the front camber go to -3.1° and 0.5° toe.

On the rear, we were able to easily get -1° and 0.25° toe.

We basically just straightened things up in the back.

A 2° difference front to back, so I'm thinking we will be ok.

[aeronaut]

Update, so it turns out the previous owner already had it pretty well set up.

My guy at tire rack told me as much caster in front as possible, and there was already 6.5° of caster.

It also turns out there's no camber plates or etc. So we were stuck with factory adjusters.

All the caster made the front camber go to -3.1° and 0.5° toe.

On the rear, we were able to easily get -1° and 0.25° toe.

We basically just straightened things up in the back.

A 2° difference front to back, so I'm thinking we will be ok.

That's a good start. I would have pushed for more rear camber if available. And, if it's truly a 90% track car, I would go 0 toe in front, or as stated above, a smidgen toe out. Although, toe-out, in the rain on the road, can be interesting.

And if you're getting -3 camber in front w/o camber plates, something else has been done to get there. That's not stock.

[MINIz guy]

Since there's a lot of caster to, I'm guessing flipped 96+ M3 top mounts up front.

I think you're gonna roast the outer shoulder of the rear tires with only -1 degree back there. Definitely try for more.

[NeilM]

Since there's a lot of caster to, I'm guessing flipped 96+ M3 top mounts up front.

My bet also.

I think you're gonna roast the outer shoulder of the rear tires with only -1 degree back there. Definitely try for more.

May not be possible, or at least not by much. Those eccentric adjusters don't have much range, hence my earlier comment about adjustable rear control arms.

Just for clarity to the OP: Neither front camber nor caster are adjustable in any way as stock. You can only make changes either by selective assembly using other stock parts (e.g. 96+ top mounts swapped left/right), by shimming the strut mount bracket at the steering knuckle for camber, or by use of aftermarket camber plates (fixed or adjustable).

Neil

[Haifisch M3]

I'm running -3 to -3.5 up front and -2.5 rear. Occurred to me that camber settings negatively impact straight line braking by reducing contact patch. Since following the main straight in most tracks there is heavy straight line braking...just wondering if anybody has tested info on this.

Basically camber favors performance in turns while giving up straight acceleration and braking. Need to design a variable camber system ...or does it already exist?

[NeilM]

Occurred to me that camber settings negatively impact straight line braking by reducing contact patch.

Check out the amount of front negative camber F1 cars have. Good thing tires are flexible!

Basically camber favors performance in turns while giving up straight acceleration and braking. Need to design a variable camber system ...or does it already exist?

Yes, but it's usually preceded by contact with the Armco.

Neil

[JeremyGl]

Thanks everyone... yeah so the rear has eccentric bolts and it's set as much camber as possible using what's in there.

The front, honestly I don't know but I could maybe take some photos. There was no adjustment available for camber, but IIRC he found a way to adjust toe. He showed me where the strut mounts and there was no adjustment where there would normally be, and even if there was, then there were 2 other bolts that would have stopped it from adjusting.

Maybe next upgrade is some sort of camber adjustment for rear, to get a bit more than 1 degree....

[NeilM]

There was no adjustment available for camber, but IIRC he found a way to adjust toe. He showed me where the strut mounts and there was no adjustment where there would normally be, and even if there was, then there were 2 other bolts that would have stopped it from adjusting.

Here's how that works.

Toe is adjustment is provided by the tie rods, which link the steering rack to the steering knuckle. The tie rods have threaded sections which, once unlocked, allow their length to be varied by turning them. Getting an alignment consists of setting each wheel to the identical — well, unless you're an oval track racer! — and specified steering angle.

The struts mount to the kingpin by three bolts, see diagram here: http://www.realoem.com/bmw/enUS/show...diagId=31_0420
The upper bolt (#5) is oriented along the long axis of the car and acts as sort of a pivot during assembly. The lower bolts (#3) clamp the bottom of the strut to the kingpin. By sandwiching suitable washers ("camber shims") on the bolts between the strut mounting bracket and the kingpin it's possible to increase negative camber. (Slightly longer bolts will be needed.) There's also an available factory eccentric version ("crash bolt") of the #5 bolt that works like the rear eccentric bolts to make small changes in front camber.

There are some limitations to the camber shim approach. There's a practical limit to the shim thickness that can be installed, plus the shimming process tilts the top of the tire closer to the strut, potentially leading to clearance issues at the lower spring perch with wide tires. On the other hand camber shims are easy to use and dirt cheap.

Neil

[Haifisch M3]

Check out the amount of front negative camber F1 cars have. Good thing tires are flexible!



Neil

Tires are flexible, F1 just like track cars spend majority of time pulling lateral G's. In that scenario the negative camber can be set to such angle as to give even tire wear on average and maximize grip in cornering

However, once track car is on the street tire-wear occurs on the inside even with 0 toe.
That clearly indicates that in mostly straight line application the tire's road contact surface is not loaded evenly which only makes sense .
This also proves that in straight line (on road or on track) camber hurts (even if only minimally) performance both acceleration and braking

[jakermac]

However, once track car is on the street tire-wear occurs on the inside even with 0 toe.

But the rate of wear will be minimal (IMHO) with the toe set correctly. I got about 15,000 miles out of my street tires (Dunlop Direzza 1st gen, 200tw I think) before needing to flip and about the same out of my next set of street tires (BFG Rivals). That's with 4 degrees neg camber in the front with about 1/8" toe out.

That clearly indicates that in mostly straight line application the tire's road contact surface is not loaded evenly which only makes sense .
This also proves that in straight line (on road or on track) camber hurts (even if only minimally) performance both acceleration and braking

The return on investment for track and autocross use for "enough" negative camber for cornering far far outweighs the loss in longitudinal acceleration (both positive and negative)..

[NeilM]

The return on investment for track and autocross use for "enough" negative camber for cornering far far outweighs the loss in longitudinal acceleration (both positive and negative).

^^^^
This

Neil