Re: Don't forget about the lower bushings & jo (archive)

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The only upgrade available for E28's as far as suspension in the front is to use polyurethane for the bushings. Or use the stock rubber and machined 750i upper bushings. Poly, of course, will result in a harsher everyday ride that most people don't want.

The best thing to do is replace the lower control arm, upper control arm (with 750 bushings), and tie rods and center link every couple of years. At the rate you seem to be using the car, it is not un-heard-of to replace all the front end every couple of years. Ed Walters goes through front suspension rubber like a hot knife through butter. Complete rebuild every year, at least.

You could also use aluminum lower control arms from a E34 to reduce unsprung weight. Every little bit helps.

BTW, 16x7.5 20mm offset with 225/50 is the standard size for the M5. The increased negative camber does NOT come from bending the strust tower or changing angle between the strut tower or wheel.

Ball joints fatigue over time and loose tolerance. Hence they become loose and cause excess vibration and excess movement.

Replace all the suspension rubber and ball joints BEFORE doing any other work (welding or otherwise). Make sure that your suspension is in 100% condition before any mods.

E30 M3's are overrated. If you really want to get a performance BMW do this: Take a E30 325e. Swap the head for a port and polished "i" head with bigger valves and a cam, and bore the block. Higher comp pistons will be good too (but the eta's are already in the 9:1 range). You'll end up with a 2.8 liter that'll be good for over 200 bhp. With custom chip (a necessity), headers, and lightened flywheel you should see a good 220-240 bhp. All this with torque! This set-up routinely blows away E30 M3's at the track for the simple reason that you have TORQUE and they do not - no matter what they try! AND you get the truly amazing handling of the E30 body.

Using 16x7.5 20mm offset rims with 225/50-16 Yoko AVS Sport tires. I notice these tires come extremely close to the strut housing's conical spring perch base and I wonder whether there is in fact room to increase negative camber, even if I tried slotting the bushing hole. I guess a 5mm spacer might help. When you say hard cornering takes its toll on the balljoint and they might need replacing, is that because they may fatigue and suddenly fail or because they get sloppy and result in less negative camber during cornering? I.e. is it a safety or a performance issue? Could you suggest an upgrade for the ball joint from a bigger Bimmer or aftermarket supplier, if such exists?
I already have the strut brace.

James, how do you find the M3 compares to your E28 in terms of tire scrub? A part of my mind says quit trying to make something out of the E28 that its not intended for and, if I'm going to prep for SoloI, start over with a better base in an E30 M3. You've posted usefully several times in the past on the relative merits of the two cars... I love the 535is but I feel I'm at the crossroads.

Don't forget that the lower control arm takes most of the lateral load (hence the term lateral link) from cornering. That bushing may be solid rubber, but it's still rubber. Plus, the balljoint is not a solid spherical joint like you'd see on a racecar. These two combine to reduce negative camber under cornering loads. These cars are heavy! A couple of driver school seasons really take their toll on the balljoints, so count on replacing them every two years if you do a few events a year.

You could slot the lower control arm bushing hole to increase negative camber, but then you'd need to adjust the tie-rods and upper control arms accordingly. Reinforce the metal around the holes if you decide to slot them. Some racing classes do allow this, so it's not an unheard-of procedure.

Chris is also correct when he recommends the upper strut brace. It prevents the cornering loads at the tire from pulling the upper shock mounts apart. You may not think that it's a lot of force, but think how much force it takes to accelerate the front half of your car at 0.9 g's. No, you do not need a solid-end bar, pivots are perfectly OK. There is no way in hell a 3' long bar is going to prevent upward movement of the other shock tower.

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