E36 Lower Control Arms modified for camber gain

[cpt97M3]

Anyone have any experience with these:

http://www.roadracetech.com/products...6_e30_arms.pdf

They are Lemforder lower control arms with heavy duty bearings, and optionally they will lower the arm relative to the ball joint to maintain the camber curve on lowered cars. Sounds like a good solution if it works out OK.

Chris

[M3corey]

yeah if u can afford them .. lol i think i called there and they said around 350 a piece .. ouch

[B.Watts]

I'll let you know. We should have them mounted up (with an added surprise) to the E36 CMod car along with our new Euro motor for the Race of Champions at TWS in March.

I'll know even more after we go back to VIR for the club race in April and can compare some data to past trips there.

[frayed]

Chris, I'm not completely convinced that the marketed improvement in steering response is due to the bearing replacement or the spacer to modify suspension geometry. Knowing that the stock ball joints are tough as nails, I'm thinking it's the ability to run spacers and correct geometry for lowered cars (aren't we all lowered to some extent?)

Bryan, which weekend is the deal at TWS? I didn't see it on the schedule. If for real, I'll carve out the time to come up and give you a hand in the pits (if you need it) and bust Mel's balls to come out that weekend.

Edit, just looked up the weekend on the club racing site to be the 19th - 21st. I have a particular aversion to the assclowns that run the PCA down here. . . . may come up anyway.

Sorry for the OT.

[B.Watts]

Originally posted by frayed
I'm thinking it's the ability to run spacers and correct geometry for lowered cars (aren't we all lowered to some extent?)

Amen...our LCA's are nearly past parellel to the ground at this point. These arms are going to be a HUGE help for us. We should be able to go even lower on the front and still maintain a solid camber curve (which means less static camber and hopefully better braking).

Now we just need a replacement for the rear upper control arms that would both save us some weight and add some additional adjustability to the rear geometry. Ever since we went to a rear coilover I've been wanting to get rid of the stock UCA with it's large spring seat.

Edit, just looked up the weekend on the club racing site to be the 19th - 21st. Very cool. Does anyone know if they are mixing a DE into the race weekend?

My first assumption is that there won't be a DE since it's also a PCA race weekend. But, I wouldn't be the one to ask.

[TeamZ4]

I would ask for a camber vs bump steer curve chart before making a decision

[cpt97M3]

Originally posted by TeamZ4
I would ask for a camber vs bump steer curve chart before making a decision

Good Point. Does seem like you would need to move the tie-rod down also if you move the control arm to minimize any additional bump steer. Anyone know if the stock E36 M3's have a lot of bump steer? I have heard that the 96-99's are worse, but I am not sure why that should be or by how much.

Chris

[Def]

I think I remember reading that James from RRT was developing a new tierod that will solve bumpsteer problems with relocating the control arm's attachment point to the spindle.

I've wanted to adjust the front suspension geometry along with lowering my car for the longest time, since I feel that BMW made too many compromises in this area to keep costs down and use existing control arms, but the price looks like a bit too much for anyone that doesn't NEED that last tenth of a second around the track.

Wouldn't it be possible(note possible != easy) to make a spacer for the stock bushing control arms to offset them and get a more favorable camber curve and still use the factory rubber bushing? Hard rubber is, IMO, by far the best material to use in suspension bushings for a street driven car, since a spherical bearing WILL wear out when exposed to the elements one encounters in the daily grind - the only question is how long will they last until you get the nice "clunk-clunk" of a worn race.

[1BADM3]

Originally posted by Def

Wouldn't it be possible(note possible != easy) to make a spacer for the stock bushing control arms to offset them and get a more favorable camber curve and still use the factory rubber bushing?

I don't think the bushing would change anything but caster. The problem with both roll center and camber is corrected by lowering the whole control arm/ball joint.

Bob

[Def]

The ball joint is replaced by RRT in their upgraded control arms, this mounts the arm to the spindle, which is not the offset/centered bushing that mounts the arm to the chassis. The chassis mounted bushing is the one commonly changed to affect caster.

Putting a spacer between the control arm and the spindle will drop the arm down, effectively moving the roll center closer to the center of gravity. It also gets you in a more favorable part of the camber curve for our strut suspension. As soon as the arm goes perpendicular to the spindle, anymore suspension travel only nets positive camber gain.

I'm thinking the budget street solution would just be '95 M3 arms and centered bushing, along with a small spacer to move the roll center up(assuming this small part doesn't require a ridiculous amount of machining, and is actually feasible given the stock bushing). You'd affect bumpsteer a bit, but a small spacer would probably give more positives than negatives.