Wheel alignment settings

[Viren]

Hi all, new to the forum so go easy! The zmc is due a wheel alignment however wanted to get your thoughts on whether to stick with oem or reduce rear toe and increase front and rear camber (seems to be a good way to make the car more progressive and neutral). Car is a daily driver with a couple of track days a year so would be interested in tyre wear as well. Btw awesome forum! Cheers, Viren

 

[exdos]

After experimentation my preferred settings are zero toe all round and reduced rear camber.

 

[BMWZ4MC]

After experimentation my preferred settings are zero toe all round and reduced rear camber.

And increased front camber, or did you stick with OEM front camber settings John?

 

[exdos]

After experimentation my preferred settings are zero toe all round and reduced rear camber.

And increased front camber, or did you stick with OEM front camber settings John?

I tried increasing front camber by removing the pins after I'd done all my other suspension mods, but I found that, like with the Z3MC, it makes the handling far too twitchy on public roads and therefore tiring to drive, so I reverted to OEM front camber. If I had camber/caster plates, I would increase the caster a tad, which would increase the dynamic camber but also retain/increase straight-line stability.

 

[Viren]

Cheers guys, curious to understand how the driving dynamics change by reducing rear toe and camber? Also were bmw being conservative with they rear set up (eg induce understeer however making the car less progressive)

 

[Machine monkey]

I know this is the M specific area but dose any of this apply to non M zeds? I am looking at getting all my alignment set up shortly. I have a few suspension components still to replace but do i just go factory?

 

[exdos]

Cheers guys, curious to understand how the driving dynamics change by reducing rear toe and camber? Also were bmw being conservative with they rear set up (eg induce understeer however making the car less progressive)

The Z4M's OEM geometry does a good job of preventing the car from directing itself into the scenery (unlike it's predecessor- the Z3MC). The front geometry with a fair amount of toe-in creates understeer and the rear geometry, with a fair degree of -ve camber and toe-in reduces the tendency to oversteer and fish-tailing with excessive throttle input. All in all, the car has a tendency to understeer. Reducing rear camber and zero toe all round produces a more neutrally handling car. If your car has lowering springs, the the camber and toe will change.

I know this is the M specific area but dose any of this apply to non M zeds? I am looking at getting all my alignment set up shortly. I have a few suspension components still to replace but do i just go factory?

I don't know the OEM geometry of the non-Ms but changing the settings to what I have should also make a neutral handling car. Obviously, if anyone decides to change the geometry from OEM, they do so at their own risk.

 

[Viren]

The Z4M's OEM geometry does a good job of preventing the car from directing itself into the scenery (unlike it's predecessor- the Z3MC). The front geometry with a fair amount of toe-in creates understeer and the rear geometry, with a fair degree of -ve camber and toe-in reduces the tendency to oversteer and fish-tailing with excessive throttle input. All in all, the car has a tendency to understeer. Reducing rear camber and zero toe all round produces a more neutrally handling car. If your car has lowering springs, the the camber and toe will change.

Thanks, really useful info. What camber and toe numbers are you currently running (guess toe is close to 0 given your previous comment), cheers

 

[exdos]

Thanks, really useful info. What camber and toe numbers are you currently running (guess toe is close to 0 given your previous comment), cheers

I run OEM front camber and approx -1.2 rear camber. Zero toe all round. I use this both for road and at The Ring. I must qualify to say that I also have AC Schnitzer Racing (adjustable suspension) H&R CSL ARBs, RTAB Limiter kit and 10mm wheel spacers all round, but I still think my geometry will apply with OEM suspension.

 

[BMWZ4MC]

After experimentation my preferred settings are zero toe all round and reduced rear camber.

And increased front camber, or did you stick with OEM front camber settings John?

I tried increasing front camber by removing the pins after I'd done all my other suspension mods, but I found that, like with the Z3MC, it makes the handling far too twitchy on public roads and therefore tiring to drive, so I reverted to OEM front camber. If I had camber/caster plates, I would increase the caster a tad, which would increase the dynamic camber but also retain/increase straight-line stability.

I'm looking forward to experimenting with mine once I've fitted everything. I'll likely be running as much negative camber as possible on the track but I do agree it makes for a very twitchy ride on poorly maintained roads. Fortunately, I have camber/caster plates :wink:

 

[Vanne]

Hi exodus,

Getting my h&r lowering springs with my new blistein hd's installed tomorrow, what settings would you recommend for this setup? I realize the new springs will need to bed in for about 500kms. Any insights to the setting if I use a 10mill spacer for the fronts and 3mill for the rear?

 

[exdos]

Hi exodus,

Getting my h&r lowering springs with my new blistein hd's installed tomorrow, what settings would you recommend for this setup? I realize the new springs will need to bed in for about 500kms. Any insights to the setting if I use a 10mill spacer for the fronts and 3mill for the rear?

Vanne,

If you are using lowering springs, this automatically increases -ve camber, and at the same time it changes the toe angles. Personally, I would get the toe angles set at zero (or very slight toe-in) and reduce the rear camber to about -1.2 degs.

The whole concept of setting static geometry is to optimise the car's handling and tyre contact patch in the dynamic situation. The geometry settings always will be a compromise which attempts to account for the changes in damper length (ride height), pitch, squat and lateral bodyroll, all of which change the car's handling and tyre contact patch dependent on the attitude of the car in the dynamic situation. You'll find the front toe angle has the biggest effect on the perceived handling of your car.

I know that lots of negative camber on the front wheels looks cool, but unless you get the same degree of bodyroll as the angle of -ve camber when hard cornering, then you aren't actually using the full width of the tyre in the contact patch, consequently the inners of the tyres tend to wear excessively, especially with some toe-in. If you can reduce bodyroll with better suspension then IMO, there's less need for increasing -ve camber. I hope this makes sense to you.

 

[FR08MEE]

Hi exodus,

Getting my h&r lowering springs with my new blistein hd's installed tomorrow, what settings would you recommend for this setup? I realize the new springs will need to bed in for about 500kms. Any insights to the setting if I use a 10mill spacer for the fronts and 3mill for the rear?

Vanne,

If you are using lowering springs, this automatically increases -ve camber, and at the same time it changes the toe angles. Personally, I would get the toe angles set at zero (or very slight toe-in) and reduce the rear camber to about -1.2 degs.

The whole concept of setting static geometry is to optimise the car's handling and tyre contact patch in the dynamic situation. The geometry settings always will be a compromise which attempts to account for the changes in damper length (ride height), pitch, squat and lateral bodyroll, all of which change the car's handling and tyre contact patch dependent on the attitude of the car in the dynamic situation. You'll find the front toe angle has the biggest effect on the perceived handling of your car.

I know that lots of negative camber on the front wheels looks cool, but unless you get the same degree of bodyroll as the angle of -ve camber when hard cornering, then you aren't actually using the full width of the tyre in the contact patch, consequently the inners of the tyres tend to wear excessively, especially with some toe-in. If you can reduce bodyroll with better suspension then IMO, there's less need for increasing -ve camber. I hope this makes sense to you.

Regarding the tyre wear i have set my front -ve camber to maximum negative camber with the pins pulled (approx 1.2-1.3 degrees i believe... possibly more with 0 toe) and the tyre wear across the front tyres is now even where it wasn't before.

Although my allignment was pretty far out i believe that adding negative camber on the front of an M (within reason) actually improves the tyre wear on the inside of the front tyres (same applies to an E46 M3) although this may also be down to changing the toe to 0/ a combination of both.

The wheel allignment i had certainly had a big impact on my car and would highly recommend getting it done regularly especially considering its a relatively small outlay. I should also mention my car is completely standard in terms of suspension.

 

[exdos]

Although my allignment was pretty far out i believe that adding negative camber on the front of an M (within reason) actually improves the tyre wear on the inside of the front tyres (same applies to an E46 M3) although this may also be down to changing the toe to 0/ a combination of both.

It's toe that scrubs the tyres far more than camber, because the wheels are not rotating in the direction of movement of the car unless toe is at zero.

 

[Viren]

So here's what I'm thinking:

Front camber: 1.0
Front toe: close to zero or slight toe in (0.04)

Rear camber: 1.4
Rear toe: 0.06 toe in

Given the car is used daily, mostly road use, couple track days a year seems an okay compromise. Any thoughts?

 

[exdos]

So here's what I'm thinking:

Front camber: 1.0
Front toe: close to zero or slight toe in (0.04)

Rear camber: 1.4
Rear toe: 0.06 toe in

Given the car is used daily, mostly road use, couple track days a year seems an okay compromise. Any thoughts?

Provided that the pins are still in your front top mounts, I'd leave them at that, which is around -1.2 degs camber. I'd reduce the rear camber to nearer to -1 deg.

 

[Viren]

So here's what I'm thinking:

Front camber: 1.0
Front toe: close to zero or slight toe in (0.04)

Rear camber: 1.4
Rear toe: 0.06 toe in

Given the car is used daily, mostly road use, couple track days a year seems an okay compromise. Any thoughts?

Provided that the pins are still in your front top mounts, I'd leave them at that, which is around -1.2 degs camber. I'd reduce the rear camber to nearer to -1 deg.

Thanks for your help exdos, once done will let you know how it feels. One question, why would BMW dial in to much negative as standard? I would have thought by reducing rear camber the tyre contact patch on high speed bends would reduce therefore cause the back to slide and outer edge tyre wear (maybe my lack of technical knowledge! 8) ), cheers

 

[exdos]

Thanks for your help exdos, once done will let you know how it feels. One question, why would BMW dial in to much negative as standard? I would have thought by reducing rear camber the tyre contact patch on high speed bends would reduce therefore cause the back to slide and outer edge tyre wear (maybe my lack of technical knowledge! 8) ), cheers

Manufacturers use negative camber and toe-in on the rear axle to resist any tendency to oversteer, even in FWD cars. Take a look at the Smart car and many other small low powered cars: many of them have such a configuration.

During high speed corners the rear camber angle (in relation to the road surface) does reduce, and if the static camber angle is correct for the amount of bodyroll (i.e. static camber of say -1.6degs and 1.6 degrees of bodyroll) then the contact patch will be across the full width of the tyre when the bodyroll produces a vertical attitude of the tyre, and this will wear the tyre evenly. Having said this, when the car corners, the outside suspension gets an increase in load, which compresses the outer suspension, which in turn increases relative static camber, say to -2.2degs. Therefore, if bodyroll is 1.6 degrees, this means that with that much bodyroll, there is still -0.6degs of camber on the outer rear wheel in my example, so the contact patch is still not evenly across the full width of the tyre at peak cornering load. I think this is the case with the Z4M rear geometry, hence I think that -1 degree of camber works better.

At the front, the negative camber on the outer wheel increases during turning of the wheel due to the effect of caster (watch any modern Mercedes doing a parking manoeuvre for a demonstration of caster/camber change with steering input).

 

[Vanne]

okay, i am understanding the camber, but why would you want to toe in? (or out for that matter) zero toe will be the best for the tire right? i wanna get this right as i need to get 2 new rears anyways and want to do that after ive done about 500 miles on the new setup so its betted in a bit. might as well hit 2 fly's with one rock.

so rear camber about -1.2 around zero toe in/out and what about the front camber?

Viren, why did you go for 0.06 toe in at the rear?

(hmmm, i should stop hi-jacking this tread)

 

[exdos]

okay, i am understanding the camber, but why would you want to toe in? (or out for that matter) zero toe will be the best for the tire right?

In the dynamic situation, when the suspension is either compressed or decompressed through its range, the camber angles will change and since toe angle is related to camber angle with MacPherson strut front suspension (Z4M), the toe angles change with camber change. Setting static geometry is therefore based upon establishing a compromise of finding the correct range of toe angles for the range of camber angles (and vice versa) in the dynamic situation through the range of suspension movement.

Personally, I find that the toe angles have the greatest influence on the handling of a car, where toe-in creates understeer and toe-out creates oversteer. Since understeer is considered to be a much safer characteristic for most drivers, manufacturers invariably use OEM geometry settings, which tend towards the safer handling of their cars (but not the case with the BMW Z3MC)

so rear camber about -1.2 around zero toe in/out and what about the front camber?

I'd stick with the -ve camber that the OEM top mounts give with the pins located, which will increase the -ve camber somewhat with lowering, but then correct the front toe, to give zero toe.