SCCA SM class rule clarification

[IsItElectric?]

For all the autocrossers out there....

From 16.1.E of the 2009 rulebook, on p. 102 of the downloadable version:

****
E. Suspension components are unrestricted as long as they use the
original attachment points. For the purposes of this rule,
“suspension” is defined as any item that is designed to move
when a wheel is deflected vertically. This includes shocks and
struts, control arms, steering knuckles, uprights, etc., but not tie
rods, steering racks, and subframes. In addition, shock absorber/
strut upper mounts are to be considered suspension
components.
****

Stock, the 325i uses an attachment point on the control arm to transmit suspension movement to the swaybar (both F&R). On an BMW E30 M3, the front swaybar uses the strut housing tube to transmit vertical force, NOT the control arm. I want to modify my strut housing to mimic the E30 M3 swaybar point.

Is the rule above specifically pointed towards attachment points of the suspension to the body of the car....or suspension points to each other (ie. swaybar to control arm / strut housing) or BOTH? If both, I believe my proposed modification would violate the rules....so before I cut & weld I want to ensure I'm not classing myself out of even SM.

Thanks,

[Hick]

From what i understand, that modification is fine. ive got mine done, and was told its even legal in DSP

[jlevie]

My reading of that rule would disallow your proposed change.

[IsItElectric?]

Great, thanks. Someone in my region replied to my local post as well, and said the same.....so I'm good to cut & weld.

Thanks,

[z31maniac]

On a somewhat related note, what class does moving pickup points place you in?

XP? Or a straight modified class?

[Hick]

xp would be my guess.

[z31maniac]

As a follow up to that, just to make sure I'm reading it correctly, we could move the rear subframe up (through shorter mounts for instance) and be legal.

The advantage being, effectively raising the pickup points for the TAs while lowering ride height and attempting to keep a more favorable rear geometry.

But since the diff mounts to the subframe, would we have to then space it back down? And would that interfere with the subframe. Hmmmmmmmm

[Hick]

or make group n rear ends.

adjustable control arms are legal too

[z31maniac]

or make group n rear ends.

adjustable control arms are legal too

Group N rear ends? Like the old E30 M3 stuff where they modified the angle? Got any links for that.

The control arms is interesting, I have been chatting with a guy from the GRM forum who has a really slick set of control arms he built. I'll post the pic he sent me when I get home.

[Hick]

i think it was group n. cant find pics. the are trailing arms with spherical rod ends to mount them to the subframe

[z31maniac]

That's what this guy did, effectively gives you adjustable wheelbase and toe. Then I suppose use an eccentric bolt in the mounting spot for camber adjustment.

[nando]

As a follow up to that, just to make sure I'm reading it correctly, we could move the rear subframe up (through shorter mounts for instance) and be legal.

The advantage being, effectively raising the pickup points for the TAs while lowering ride height and attempting to keep a more favorable rear geometry.

But since the diff mounts to the subframe, would we have to then space it back down? And would that interfere with the subframe. Hmmmmmmmm

my ix is already like this. stock ix bushings are about 1/2" taller pushing the subframe down for the 4x4 ride height, so with standard E30 AKG bushings my subframe is moved up. I spaced the diff down with some thick washers, it doesn't interfere with the diff at all, although I had it in there with no washers for 6 years without a problem.

[guibo09]

i think the SM rules do not allow you to move the subframe at all. infact, even the IE style camber/toe adjusters are illegal. which is very annoying, because in the spirit of the rule, they should be legal since they arent designed to provide geometry adjustment, only alignment.

edit: and infact, a completely tubular/adjustable trailing arm is legal even though it is countless times better than the illegal adjusters.

[z31maniac]

^I think by that rule portion up there, moving the subframe is completely legal. But if eccentric bolts are illegal, how could you get some camber adjustment back?

my ix is already like this. stock ix bushings are about 1/2" taller pushing the subframe down for the 4x4 ride height, so with standard E30 AKG bushings my subframe is moved up. I spaced the diff down with some thick washers, it doesn't interfere with the diff at all, although I had it in there with no washers for 6 years without a problem.

Ahhhh good to know. I know I'll need to take a look after I get the swap done, but do you have any idea how much you could raise the subframe without it interfering with driveshaft? The rear subframe has a "hole" that the driveshaft passes thorugh correct? I can't picture it in my head at the moment.

IE, if you were to move the subframe up you start to lower the clearance between the driveshaft and the bottom of the hole in the subframe.

[guibo09]

^I think by that rule portion up there, moving the subframe is completely legal. But if eccentric bolts are illegal, how could you get some camber adjustment back?

how are you reading it?

the way i read it is that the subframe is not a suspension component. it is therefore not free to be changed. the trailing arm to subframe connection is considered a suspension attachment point, and under sm rules, it may not be moved. the eccentric bolts move the attachment point, and are therefore illegal.

am i missing something?