Front camber

[Steve84N]

My current geometry is 0.02 toe front, 0.04 toe rear, 1.25 front and 1.5 rear.

I find it is lacking turn in and my H&R ARBs are the only thing making it slightly oversteer on a long radius corner, but not in a good way as the rear is too stiff and it's losing grip. I've actually gone from full hard back down to full soft after trying all sorts of permutations but with stock suspension anything harder just results in a sudden transition into slip.

My question is, for those who have pulled the front camber pins and pushed it right over what camber did you get and did it increase front end grip? I'm loathe to spend £50 (toe will need doing again too) if it's only likely to be 1.3 or something.

Thanks!

 

[RichBergh]

don't know if its the same on the z4, as it is on the e46, however, when i removed the pins and pushed the tops over on my e46), i was able to get around 2.5 degrees.

and on the rear i was able to get 3.2 ish on the rear on the standard arms.

 

[Artful-Bodger]

Disconnect one of the front anti roll bar drop links and tie it up out the way, then give the car a quick test, the result should be a much sharper front end dependant on the tyre and pressures, but, you will also get more roll, what generally happens is the roll bar dumps too much load into the outside tyre resulting in understeer which neutralises any oversteer tendencies, this is a safety issue that most manufacturers build into their cars. and the H&R bars may emulate this.

If your getting snap oversteer or understeer that's the tyre reaching it's load/slip limit, this can be caused by the spring compressing to the bump stop , often a problem on lowered cars, the tyre tucking under in roll or so much roll your unloading the inside tyre, wheelspin is often a give away to that condition.

Chassis balance is a subjective thing dependant on driver requirements, tyres, and conditions, I would suggest , disconnect both bars then testing the car, then connect the bars on full soft and you will get an idea what is actually happening, it's very important to understand what effect they have and what you need to do to adjust the balance.

Just dialling in camber is not a good idea as it then has an affect on both braking and tyre wear as your not presenting the tyre squarely to the road and it's only working at a particular roll angle/corner speed, an alternative is to use the offset front lolipops which add more castor, castor causes more camber change under lock, adds greater self centering to the steering but has the negative of causing the outer corner to lower under lock increasing the roll, so it's a balancing act, I believe the Z4M uses an offset so this is obviously a workable solution.

Chassis balance is a very complex subject, to create a balanced well handling car everything has to be working in harmony, I raced in road going classes for years and found what I wanted by MUCH trial and error (emphasis on the error) before I understood where I wanted to go, and that meant changing everything and calculating the spring rates and suspension geometry to suit the tyre.