Re: 535is springs and sway bars... (archive)

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The main question here is, what condition is your current suspension in? Does it need new shocks? Does it need new tie rods? Are your upper and lower control arm bushings worn? Are your rear subframe and rear pitman arm bushings worn? These are the questions you need to ask yourself before thinking about suspension modifications.

A stock E28 suspension is surprisingly well handling when in good condition. If your suspension is worn out (for whatever reason), I recommend putting in all new bushings in the front are rear, and getting either Boge or Bilstein HD shocks to replace the ones you have in there now. (Bushings in front: upper strut bearings, lower control arm bushing and ball joint, upper control arm bushing and ball joint, tie rods, pitman arm bushing, idler arm bushing, and a new upgraded (from E34) steering arm bolt); Bushings in rear: rear diff mount, rear pitman arms, rear shock mounts, trailing arm bushings, subframe bushings (yes, these are the PITA ones everyone keeps talking about))

Now, on your car, Boges came standard. If you want to return to a comfortable, yet firm when necessary ride, I recommend Boges. Bilstein HDs will stiffen the damping and make the suspension seem more firm.

Now, 535iS springs were not any lower or stiffer than 535i springs. In fact, the front ones were the exact same spring, you can see by the part number. Even the USA M5 used the exact same spring as the 535i/535is. ALSO, some later 528e's used the 535i/535is/M5 spring. All the springs used by the the big six engined (533i, 535i, 535iS, M5) E28's had roughly the same spring rate (160-165lb in). The 528e had slightly less spring rate than the 535i (about 155-165lb in, depending on year and transmission), because the 528e was slightly lighter, and needed to have a set ride height because of bumper height regulations. The only reason why the 528e may seem softer is because it came with Boges originally, and most people who owned that car stuck in the same, whereas the 535iS came with Bilsteins (with stiffer damping) and most people put in aftermarket Bilsteins on 535i and 535is's to make the car feel more firm.

Now, if after you redo the suspension (or it is in acceptable condition to be considered not worn), then you can think about suspension modifications. You generally have 3 options for aftermarket shocks, 4 options for aftermarket springs, and then 4 options for "tuners" systems. The 3 options for shocks are Boges, Bilsteins, and Konis. The springs are BavAuto, H&R, Eibach, and Racing Dynanamics. (You can try to mix and match these combos, but there are usually 2 combinations I recommend out of the bunch). The 4 "tuner" systems are Alpina, Hartge, Dinan, and M-Tech. Alpina, Hartge, and M-Tech use their own springs with specially valved Bilsteins. Dinan uses its own springs as well with a choice between Koni or Bilstein. Scroll down below (to about 1 week ago) and see my posts on these suspension systems. Or email me if you have any more questions.

I have a '88 528e That needs some improvement in the handling department as it feels like I'm driving an old mattress. Are 535is springs shorter and stiffer than my 528e springs? Are the sway bars bigger and if so, what size are they? If the items in question are bigger and better, does anyone have any for sale? Thanks...

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