Best E30 Rally Suspension Setup

[iamsam]

It's true, positive camber is bad, and lifting the car will cause some positive camber. How much, I don't know.

Also, it is true the rate difference won't be all that noticeable, probably not noticeable at all.

HOWEVER, Ross told me that E36 springs are a good 1.5" taller than E30 springs, and there lies the benefit, is in the added travel.

[MasterOfPuppets]

Just a thought, but unless e36 springs are muuuuch taller, you wont notice any benefit. The change in rates is on the order of 10% front 5% rear (eyeballed percents), which isnt all that different in terms of keeping oil pan off ground stiffness needs. Youll notice a tiny difference, but im not sure it is any better than running oem springs. Remember, raising car means gaining positive rear camber, which is bad.

The small difference in rates likely wont do much of anything, the height would.

Agreed. On the positive camber point, I'm trying to think of a clever way to slightly decrease camber by way of offset bushings or some other easy trickery. The only thing I can think of would be to actually mount the subframe lower on the body with some kind of spacers, but that defeats much of the point of increasing ride height (much, not all) and lowers the overall strength of the attachment. Anyone more familiar with E30 suspension have an idea?

[iamsam]

Mike, best way to correct camber is by moving the top of the strut around in the strut tower. The ghetto way is to re-drill holes and weld over the old holes, a better way is solid camber plates that move the struts over a fixed amount in the towers, or adjustable camber plates where you can move the struts around to your heart's content.

try www.bmw2002.com, they have some solid (non adjustable) camber plates iirc.

[MasterOfPuppets]

What about the rear?

[KennyT]

I would try to increase spring rate while mantaining OEM 325i ride height. Shoot for 250/200(Wheel rate) ish spring rates for gravel, and a set of iS springs with spacers for snow. You don't need to be any higher than stock for clearance, but stock height with a little more camber (1* rear static camber).

[iamsam]

What about the rear?

rear camber doesn't change much w/ height change. The camber angle of the wheel is fixed to the trailing arm, as it is all one piece (no rear ball joints) and the pivot axis runs transversely to the car, sort of co-linear to the axles.

[MasterOfPuppets]

I would try to increase spring rate while mantaining OEM 325i ride height. Shoot for 250/200(Wheel rate) ish spring rates for gravel, and a set of iS springs with spacers for snow. You don't need to be any higher than stock for clearance, but stock height with a little more camber (1* rear static camber).

When you say more camber, you mean "more" as in an increase in negative camber? Or is the idea to run a bit of positive under the assumption that the suspension will be in jounce most of the time and correct for it?

rear camber doesn't change much w/ height change. The camber angle of the wheel is fixed to the trailing arm, as it is all one piece (no rear ball joints) and the pivot axis runs transversely to the car, sort of co-linear to the axles.

I guess it's not as bad as a swing axle or something, but still similar. I guess it be best to measure the camber change per inch of trailing arm travel and figure out what makes sense.

[iamsam]

Negative camber is always good for racing applications. I'd suggest these.



They are from Ireland Engineering, and they are fixed plates that add 1.25 degrees of negative camber, which may nicely negate the positive camber gain from the lift, and then some.

Of course, at $135/pair, I think we can make some for alot less money, with the help of Duane and his machine shop of course! ;)

[iamsam]

Something to get the excitement brewing...

I have some random pics of the rally car that I took yesterday.

Here it is parked behind my car.



And if anyone so desires, feel free to photoshop an awesome rally color scheme of your choice on this Pic, Mike has already been through a few schemes.



BBS's on the left are for sale. 16x7.5, 4x100, crap tires. More info in a later FS thread that I will eventually make.



My packed garage. Yes there is a bed on the wall and two lawn mowers. Anyone want one?




First step was removing the ST swaybars.



...And that is all I got to. That and the seats. But no seat pics, sorry!

[MasterOfPuppets]

Here was my take:



Ended up a bit over the top because I just kept going and going with the edits, but the color scheme I think is pretty solid. May end up being a brighter blue depending on the availability of dark blue rustoleum.

[iamsam]

I'm gonna go ahead and suggest this scheme:



(yes, its an E34. Found it here: http://houston.craigslist.org/cto/2314971503.html)

[KennyT]

You want somewhere around -1.5 degrees of camber at ride height.

[cjm]

Should ask DynoTechJerry69 what he did to build this: http://www.r3vlimited.com/board/showthread.php?t=204484

[iamsam]

I did.

[SlapDash]

Forgot to post this before, but here's the difference betwixt 'regular E30 tire' and 'gravel E30 rally tire'...