Alignment Settings for Z4MC OEM Suspension

[bakes100]

Hello Chaps,

I am looking to get my alignment checked / revised in the near future to try to get the car slightly more neutral and less inclined to under-steer. The car is used as a daily driver / fast road car (no track work) so I don't want anything too extreme that will shred the inside edge of the tyres in no time. I am running Goodyear Eagle F1 Asymmetric 2's all-round.

I have done a small comparison of a few cars setups:



This shows that the Z4MC set up is pretty conservative compared to the CSL and in some ways even the Z4MR. Also shows the MC & MR have the biggest front to rear toe difference (0˚ 18').

What I was thinking of doing was the following:

Front
Total Toe 0˚ 04' - this is the lower end of the MC tolerance/matches the MR.
Camber -1˚ 30' - as far as you can go with the strut pins out??

Rear
Total Toe UNSURE - I am not sure how far to go with the toe at the rear. The CSL is running 0˚ 04' to match the front but may this cause the Z4MC to be unpredictable with its shorter wheelbase?
Camber -1˚ 50' - OEM

I am hoping this setup would remove the slight outside edge wear I am experiencing on the fronts and also increase the front end grip slightly. With the rear I am hoping that decreasing the toe in will help balance the car out further while also reducing the inside half tyre wear experienced with these cars.

What setup do you lot use and what differences have you found by tinkering with the alignment?

Any thoughts welcome

 

[XMetal]

I find that my MC is already a bit twitchy with the OE settings. Decreasing Toe and increasing Camber may exacerbate that. I'm also contemplate on this same thing as I'm also experiencing more outside edge wear, but not sure if I want to do the "stability" trade off :x

Assuming that you're still within specs on the rear Toe, decreasing Toe will INCREASE inside edge tyre wear.

 

[mad4slalom]

was told the other day by a serious track day afficionado that a good improvement on the m is to remove the two bolts that hold the bottom of the front strut to the hub thingymajig replace them with slightly longer ones and space the strut out with 2 washers, says it gives more neg camber than removing the pins at the strut top mounts, that mod, track day tyres and h and r springs make it handle a lot better. I know washers sounds a bit heath robinson but when you look at the strut, a plate wouldnt really fit as it is shaped where the bolts protrude. ps when i say serious track day afficianado I mean serious so am sure he knows his stuff. any thoughts on the results of this, sharper turn in but any negatives ? :?

 

[mmm-five]

was told the other day by a serious track day afficionado that a good improvement on the m is to remove the two bolts that hold the bottom of the front strut to the hub thingymajig replace them with slightly longer ones and space the strut out with 2 washers, says it gives more neg camber than removing the pins at the strut top mounts, that mod, track day tyres and h and r springs make it handle a lot better. I know washers sounds a bit heath robinson but when you look at the strut, a plate wouldnt really fit as it is shaped where the bolts protrude. ps when i say serious track day afficianado I mean serious so am sure he knows his stuff. any thoughts on the results of this, sharper turn in but any negatives ? :?

Depends whether you're worried about wearing out the inside edge of your front tyres in about 4000 miles and having a car that follows every rut, crease, join on the road.

 

[mad4slalom]

mmm think i would be, leave well alone then!

 

[exdos]

I run zero toe all round with reduced rear camber albeit with AC Schnitzer Racing suspension. This gives more neutral steering. Increasing front camber will make the steering "bump steer" on bad roads. Running zero toe reduces "scrubbing" and will reduce tyre wear.

 

[bakes100]

My table is actually wrong, a CSL is apparently 1˚ 45' ± 20' camber on the front.

Exdos, do you think the relatively small amount of extra camber from removing the pins could cause unwanted bump steer? as it is only around 1˚ 30' tops I think (less than the M3 CSL).

Also would you recommend running zero toe all-round on an OEM setup with its stiffly sprung rear compared to the front? It might become a bit too lively!

 

[exdos]

Exdos, do you think the relatively small amount of extra camber from removing the pins could cause unwanted bump steer? as it is only around 1˚ 30' tops I think (less than the M3 CSL).

Also would you recommend running zero toe all-round on an OEM setup with its stiffly sprung rear compared to the front? It might become a bit too lively!

I've done a LOT of experimenting with suspension set-ups for the Z3MC and the Z4MC and I've found that increased static -ve camber makes these cars far more ready turn than when with less -ve camber. I know that we're only talking about increasing -ve camber by only 0˚ 20' by pulling the locating pins, but it does make a very noticeable difference. The problem is that if you set the toe with increased -ve camber, and you don't like it and then return camber to OEM, you need to reset the toe angles. Getting the front toe angle right makes a lot of difference to the car's willingness to turn, a tad of toe-out makes the car like "The Wild Mouse", but zero toe, gives great straight line stability but with a willingness to turn with driver input, rather than with road input. As most Z4M owners know, the OEM toe-in gives a tendency to understeer.

You've already got quite a bit of -ve camber at the rear with toe-in, so reducing toe in at the rear won't make your car too lively. In any event, when adjusting geometry you are doing it to make the car easier/safe to drive. When getting used to different geometry settings, you should approach corners with the "slow-in, fast out" approach and then you can acclimatise yourself to any new behaviour that might occur from changes, therefore the car becoming "too lively" should not occur. It's your right foot which can be the problem not bad geometry.

 

[Vanne]

Also, not sure if someone has mentioned it, but when you get the alignment done, it's supposed to have drivers weight in the drivers seat...

 

[BMWZ4MC]

I've pulled my camber pins and there is a noticable reduction in understeer with sharper turn in. However, this combined with Eibachs, 19" wheels / low profile tyres and a strut brace has rendered the car extremely hard to drive on rough road surfaces as it tramlines like mad. I haven't had any problems with the rear becoming unduly lively through the adjustments I've made.
I'll report back in a few months when I've fitted KW Clubsports / camber plates, front and rear ARBs, RTAB limiters, rear top mounts, and perhaps a rear strut brace.

 

[FR08MEE]

I've had mine done recently and ill post up what i went for when i get in later... i would say the allignment makes a big difference and the amount of negative camber you can get without the front pins varies car to car and depends if your car has been lowered.

 

[dannyg_m3]

So Exdos,

My h&r lowering springs have just arrived! I'm a club level racing driver, and therefore want the Z to handle properly.

Would you suggest, pulling the camber pins and removing all toe in as a fast road / light track use setup up?

Cheers,
Dan

 

[gwatson]

I recently lowered my Z4M on Eibach's and had the suspension setup to CSL spec. Big improvement in the way the car turns in. To get -1.5 degrees of camber since lowered they only had to pull the pin out on one side and it's only been shifted ever so slightly to get the -1.5, could almost get the pin back in.

 

[exdos]

So Exdos,

Would you suggest, pulling the camber pins and removing all toe in as a fast road / light track use setup up?
Cheers,
Dan

Definitely have zero toe all round. But if you do a lot of driving on bad A&B roads, you'll find increasing negative camber can make the car a bit twitchy from bump steer and then it can become tiring to drive. But until you've tried any change in geometry you'll never find out for yourself what works best for you.

 

[gwatson]

^ Yeap. I should of expanded that my CSL spec setup was referencing camber only, not toe.

I had 0 toe at the front front and just 0.05 toe in at the rear.

 

[dannyg_m3]

Excellent stuff! Thanks...