Rear wheel spacers... only.. made a big difference in cornering.

[TurnAround]

Everything I researched on the E36 Coupe board suggested that adding track width to only the rear would noticeably add understeer. My primary goal was looks, but I also wanted to avoid replacing the wheel bolts (with 5mm - 20mm H&R spacers you're looking at replacement bolts that are silver.. and won't hold black paint well. 25mm DRA spacers allow you to bolt the spacer to the hub, and then bolt the wheel to the spacer with the factory bolts).

My plan was to put 25mm DRA spacers on the rear of the Coupe and the X5, and then evaluate whether I had to put them on the front for looks... or to counter act the increased understeer.

I have to say, and am pleased to report, that both cars handle waaaaaay better with just the rear spacers installed. A full 2" of track added (1" per side). I'm not detecting ANY additional understeer. Now.. to qualify that, I'm not tracking either car, and I'm not cornering the car on country roads at 117mph. I'm definitely taking these cars to 8/10ths, and so far, I see only benefit.

So there it is. Something actually worked out for once... where you get good looks, safe simple easy install, and the car's performance actually noticeably improved.

I would highly recommend getting rear spacers on yer X5. Cheap easy mod that makes your BMW look fat and cool.

[dkl]

T/A, good to hear that everything worked out well for you. But you forgot to mentioned that you added spacers to your non-staggered setup. So most of us with the staggered setup is already on par with you without using spacers, which cost $0...a cheaper mod

BTW...do you have a picture of your setup?

[TurnAround]

Originally Posted by dkl

T/A, good to hear that everything worked out well for you. But you forgot to mentioned that you added spacers to your non-staggered setup. So most of us with the staggered setup is already on par with you without using spacers, which cost $0...a cheaper mod

BTW...do you have a picture of your setup?

hmm.. that doesn't make sense. According to the ET offset numbers nearly all of the extra width of staggered rears goes... to the inside. Not the outside. All BMW's work that way. Based on Et's, a few milimeters go to the outside. Like.. 3 or 4. All the rest, goes to the inside of the car.

But I'm open to learning if I've got that wrong.

[dkl]

You're right. I stand corrected. The type 132 staggered setup have an ET48 for the front 19x9 and ET45 for the rear 19x10. Having an ET45 on the rear means that it will extend only 3mm out toward the fender compared to an ET48. This suggests that the staggered setup gained only a measily 6mm in track width in the rear.

[jvit27]

Adding anything more than 8-10mm will affect the alignment geometry. It also adds more stress on suspension components and changes the scrub radius of the tire.

Something about putting an extra INCH has always made me wary..

[RichiRich]

This is great news and THX for the Input.....I just bought 30mm H&R from another member here. I was just going for looks also, but I will not mind better performance either. Can't wait to install.

RR

[TurnAround]

Originally Posted by avanti27

Adding anything more than 8-10mm will affect the alignment geometry. It also adds more stress on suspension components and changes the scrub radius of the tire.

Something about putting an extra INCH has always made me wary..

I'm not seeing how it would alter the rear wheel camber or toe. It seem like there could still be an effect though. Even though the toe wouldn't change I can see how adding track would "amplify" the toe that the car did have... your scrub radius note. That makes sense. As good as differentials have gotten, they would still be too blunt of an instrument to compensate for the slight changes in scrub. Net result.. the tires could wear a little bit faster. My guess would be that this is why BMW places the majority of the extra width with wider rims to the inside.

Four wheel overall alignment wise.. yeah, there's no way that this won't increase under steer. Its one of the items on the long standing handling equation list. The one that goes, "change (factor here) and you increase (result here). But my results are teaching me that the amount must be very, very small, and can only be detected when taking the car to 9.7/10ths.

Its been very educational putting racing suspension on the Z3 Coupe. I've learned... even though these kits are designed specifically for a given model of BMW, you are still significantly messing with the BMW engineer's equations. One has to be willing to accept certain down sides, like slightly faster tire wear. The guys that are really into it drop the car's subframes and weld in permanent precision adjusting frame mods that allow them to fine tune the four wheel alignment.