finally found out the relationship between ride height and camber/toe

10742 Views 16 Replies 5 Participants Last post by Sean, May 2, 2002

bmw325

Discussion Starter · May 1, 2002

Is as following:
As the car is lowered, camber becomes more negative and the wheels toe-out (tend to face away from each other or toe negative). This makes sense to me, but i finally found a good web page that describes it on some Ford muscle car site of all places.

This means that if a BMW is not aligned in BMW's normally loaded position (with 150 punds each from seat, 150 in the rear, and 50 in the trunk with full fuel tank) which obviously affects ride height, and they try to bring it into BMW's alignment specs, they'd end up making the camber too negative with not enough toe-in-- I guess that would actually be desirable in a track car but would lead to nervous highway handling and greater tire wear.

CHeck the last paragraph:

Alignment

1 - 17 of 17 Posts

The HACK

· #2 · May 1, 2002

robg said:
Is as following:
As the car is lowered, camber becomes more negative and the wheels toe-out (tend to face away from each other or toe negative). This makes sense to me, but i finally found a good web page that describes it on some Ford muscle car site of all places.

This means that if a BMW is not aligned in BMW's normally loaded position (with 150 punds each from seat, 150 in the rear, and 50 in the trunk with full fuel tank) which obviously affects ride height, and they try to bring it into BMW's alignment specs, they'd end up making the camber too negative with not enough toe-in-- I guess that would actually be desirable in a track car but would lead to nervous highway handling and greater tire wear.

CHeck the last paragraph:

Alignment

Toe in-Toe Out: Toe in means your wheels, when viewed from above, points towards each other on the front. Toe out is the opposite.

Camber: Camber is affected when you lower your car. The lower the suspension travel, the more the wheel will tend to bow out on the bottom and point in on the top. That's Negative Camber. When you put your car up on a jack, or when the car is lifted off the ground and the suspension is free to travel, the bottom of the wheel tend to point in and the top of the wheel tend to point out, that's positive camber.

Learned all this from playing Grand Turismo 3.

Kaz

· #3 · May 1, 2002

Re: Re: finally found out the relationship between ride height and camber/toe

The HACK said:
Camber: Camber is affected when you lower your car. The lower the suspension travel, the more the wheel will tend to bow out on the bottom and point in on the top. That's Negative Camber. When you put your car up on a jack, or when the car is lifted off the ground and the suspension is free to travel, the bottom of the wheel tend to point in and the top of the wheel tend to point out, that's positive camber.

This is generally the case, but not always. The design of the suspension will dictate what happens under load with regard to changes in toe and/or camber. Most cars these days will tend to develop negative camber as the wheels move up, but cars with solid rear axles (pickups, Camaros, etc.) for example, will not since there is no way for camber to change at all. This obviously implies that the degree to which these change also varies from design to design. A VW Bug with swing-arm rear suspension will have far more camber change per suspension travel than a Nissan with a multilink-beam setup.

The HACK

· #4 · May 1, 2002

Good job Kaz. Also, if you look at the design of the rear suspension you'll notice there's two control arms, an upper and lower. This design also limits the amount of camber travel when car is lowered/raised. In practice, when you use lowering springs on all 4 corners of the car, you will need to adjust the camber settings up front but not for the rear. Hence on E46es you SHOULD get a camber plate for the front...At least that's the way I understand it.

Kaz

· #5 · May 1, 2002

There is an adjustable E35/46 rear lower control arm (BMP sells it) that is for the exact purpose of making this adjustable in the back. Nifty.

The HACK

· #6 · May 1, 2002

E35?

Nick325xiT 5spd

· #7 · May 1, 2002

WHich brings us back to the question of "What settings are actually best?"

Kaz

· #8 · May 1, 2002

The HACK said:
E35?

Typo. You know what I mean.

The HACK

· #9 · May 1, 2002

Kaz said:
Typo. You know what I mean.

Hehe...Just busting your chops bud.

By the way, I'm fairly certain you mean E36, right?

Do keep in mind, the E36/7 chasis (Z3) uses the older suspension which DOES require camber adjustments when you lower your car. Same as the E36 Compact.

Kaz

· #10 · May 2, 2002

The HACK said:
Do keep in mind, the E36/7 chasis (Z3) uses the older suspension which DOES require camber adjustments when you lower your car. Same as the E36 Compact.

This I'm aware of. In fact, I've been thinking that a E36/5 with a M drivetrain conversion (M3ti) might be a nice toy to get.

The HACK

· #11 · May 2, 2002

Kaz said:
This I'm aware of. In fact, I've been thinking that a E36/5 with a M drivetrain conversion (M3ti) might be a nice toy to get.

About 1.5 years ago Roundel had an article of a guy who did the E36 compact to ///M conversion...Pretty interesting car, lighter than the lightweight, slightly more rigid (hatchback design) and infinately more tossible than the E36 M3.

Of course, if we all live in Germany you can just get AC Schnitzer or Hartge or, god forbid, Alpina to "produce" you an E36/5 ///M3 Kompact.

Kaz

· #12 · May 2, 2002

I'm not really serious about this (money) but I'm thinking this might be the sort of thing to be able to get cheap used (Yes, even more checking than usual used car buying) since I figure mods like this aren't exactly resale-friendly. Also, there's a shop in the Valley (RMS) that pioneered this conversion who also did my friend's 318i->M3 conversion, and I'm sure other major shops (XP, Bullet) have also done it.

Sean

· #13 · May 2, 2002

What are BMWs recommendations for acquiring the proper alignment? By this, I mean what weights? Is it as you mentioned above?

bmw325

Discussion Starter · #14 · May 2, 2002 (Edited)

Sean-

For all cars other than the M models-- BMW requires that the car be in the "normal loaded position" They specify doing the following to achieve this:
-Full fuel tank
-front seats in middle of tracks
-68kg (about 150 pounds) on each front seat
-68 kg in the middle of the rear seat
-21kg in the center of the trunk

You're then supposed to measure the ride height and compare it w/ the ride height for that model/suspension-- for example I believe that an E46 sedan w/ sport suspension is supposed to have a ride height of 586 mm as measured from the bottom of the wheel rim to the lip of the wheel arch. I think the tolerance is +/- 10mm but it actually could be as little as 1 mm (i forget)!
BMW states that their alignment specs are only valid if all of this is done-- of course you also have to make sure that there are no worn bushings, etc. And that the steering wheel is straight (not just by sight-- you're supposed to check that the 2 hatch marks on the steering column and steering rack line up), and that brake pedal is held down w/ depressor.

Now who wants to guess how many BMW dealers bother with doing all of this? :tsk:

INteresting points on the effects of ride height for different suspension types-- it makes sense-- the Z axle in the E46/36 is designed to maintain a certain geometry under a variety of loads and in turns-- the older trailing arms in the compact/Z3 experience greater deflections under load. But I still think that the general rules (lowering is more negative camber and more toe out) apply to all suspension types-- just to greater or lesser tendencies. Since the front of our cars are Mac struts, I'd bet that they are more sensitive to lowering than a double wishbone type of suspension.

Also regarding camber adjustments on the front-- it is possible on the E46 to adjust camber using a BMW special tool by +/- 18 minutes (not very much only about 1/3 degree). I assume that when most people lower their cars they lower it to a point that changes the camber beyond 18 degrees and they need to get camber plates to compensate. I wonder how many people do this? I guess even if you don't it some people might like the effect- more negative camber would allow for greater tire contact in turns and better stability at speed.

See less See more

Sean

· #15 · May 2, 2002 (Edited)

).

Now who wants to guess how many BMW dealers bother with doing all of this

Not many. :thumbdwn:

My 2nd retrofit steering rack was installed today. The gas tank was only half full and afterwards I noticed something was put in the passengers seat, but it does not look like anything was put in the drivers seat, unless the tech that aligned it was sitting in it and had the remote (doubtful).

bmw325

Discussion Starter · #16 · May 2, 2002

How can you tell that something was in the passenger seat? How does the new retrofit rack feel?

Sean

· #17 · May 2, 2002

Because my spotless interior was no longer spotless. Something very dirty and shaped in a square was but there.

1 - 17 of 17 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.