Suspension set up

[Bobnic]

Just plumbed in the final bits of the brakes and clutch, driver's floor in this morning (I hate sikaflex!!), next big job is the suspension and steering set up. How did you guys do yours, and what are the sort of numbers do I want for camber, castor, toe in/out etc?? Also should the front lower wishbones be parallel with the floor when it's on it's wheels? Wheels are being refurbed at the mo, so will have them back in a week or so (hopefully!!). Bear in mind it's a heavier M3 S50 1994 engine, that fills the engine bay and then some!! Then it's the interior, tidy up the electrics and start fitting bodywork.........

Thanks in advance for your pearls

Rob

[NigelB]

Hi Rob,

Camber is -1 degree. Toe in I don't know but I guess there's a bit of trial and error there. I asked Marlin Mark about castor and he was most indignant that I should suggest that it may need adjusting from that built into the chassis. But he did say that I could move the washers around on the upper wishbone pivot pin if "I thought I could do any better than him". "You'll probably find it won't need adjusting" was all the answer I needed...............!!

I originally set my front lower wishbones parallel to the ground but that gave me less than 3 inches clearance under the sump. So I lowered the outer ends by an inch (5 degrees) to give me 4 inches under the sump and none of the regular contributors on this forum believe that will be an issue.

So when's the first outing........................??

[Bobnic]

Originally Posted by NigelB

Hi Rob,

Camber is -1 degree. Toe in I don't know but I guess there's a bit of trial and error there. I asked Marlin Mark about castor and he was most indignant that I should suggest that it may need adjusting from that built into the chassis. But he did say that I could move the washers around on the upper wishbone pivot pin if "I thought I could do any better than him". "You'll probably find it won't need adjusting" was all the answer I needed...............!!

I originally set my front lower wishbones parallel to the ground but that gave me less than 3 inches clearance under the sump. So I lowered the outer ends by an inch (5 degrees) to give me 4 inches under the sump and none of the regular contributors on this forum believe that will be an issue.

So when's the first outing........................??

Hi Nigel, Not sure when the first outing will be, hopefully late Feb/ early March sometime (which year though, I reserve the right to divulge later!!)

Thanks for the info, hopefully our castor is bob on factory set too!!
Have a sinking feeling our sump clearance will be low too, but will need to wait until it's on the deck before I get too stressed about it!!

Cheers

Rob

[MartinClan]

Whatever suspension setting you finally use don't forget you need to demonstrate self centering steering for the IVA test. On most builds I have followed, and mine, this has meant changing the suspension settings from the theoretical perfect. As I remember I had to change both the camber (make it a little positive) and toe in for it to work well.

Also you will probably find you have to raise the front suspension a tad so that the headlights pass the height test.

Cheers

Robin

[Bobnic]

Originally Posted by MartinClan

Whatever suspension setting you finally use don't forget you need to demonstrate self centering steering for the IVA test. On most builds I have followed, and mine, this has meant changing the suspension settings from the theoretical perfect. As I remember I had to change both the camber (make it a little positive) and toe in for it to work well.

Also you will probably find you have to raise the front suspension a tad so that the headlights pass the height test.

Cheers

Robin

Thanks Robin, I am now familiar with final/non-final set ups/jobs sadly!! Will see what we get when it's on its boots, and get the ruler out to check light heights etc, thanks for the heads up on that one.

Rob

[Bobnic]

Just had this through for Marlin, seems to answer most, if not all the questions I think I needed answers for!!

1) Front ride height should be set with the bottom susp arms all but parallel to
the ground (very slightly down hill from the chassis mounting to the ball
joint mounting of the lower susp arms).
2) As a second check the steering arms should also run or but parallel to
the ground.
3) The front wheels you can run them where suits you best ie. Total 3mm toe
in parallel or 3mm toe out.
One of these 3 settings may offer you your most comfortable setting.
4) Camber front wheels should be in the neg range (ie the top of the wheel
leaning in towards the middle of the car). Practical useable range would
start at 1/2 deg neg to as much as 2 deg neg each wheel.
5) Camber rear wheels similar to the front in that your useable range is
going to be between 1/2 deg neg to 2 deg neg each wheel.
6) Tracking rear. The rear wheels should be toe'd in by minimum of 3mm total
& possibly up to 5mm total. They must never be set either parallel or
toe'ing out.
7) Tyre pressures. Tyres can be run at any pressure between 10 & 20psi when
cold but as a general start setting Mark would suggest 16psi for single
occupancy or 18psi for two people would be good.