Shock Replacement???

[FSETH]

Originally Posted by vinuneuro

I've seen many shock dyno's at not once has has aftermarket damper's valving matched the oem. There's no reason to go with any aftermarket damper in this situation since BMW developed the oem shocks, and Sach's (ZF Sach's) manufacture's them.

If you're really obsessed with Bilstein you can buy one new front and rear oem damper, have it dyno'd, and then have Bilstein revalve the bilstein shocks to oem specs.

Just curious, but could the fact that the car appears to sit higher with new shocks have anyhting to do with the fact that most people who change their shocks have significant mileage on the springs? In other words, could the springs be sagging a little by typical shock replacement milage, 60-150K? That would make the car appear a little lower and then when you slap some stiffer Bilsteins on there it raises up? Could that also be part of the issue?

Sorry kjack, I would have never in a million years guessed that shocks could make a car ride higher. I know the Bilsteins are stiff, but figured the weight of the car would have been to much to make a difference.

[vinuneuro]

Originally Posted by FSETH

Just curious, but could the fact that the car appears to sit higher with new shocks have anyhting to do with the fact that most people who change their shocks have significant mileage on the springs? In other words, could the springs be sagging a little by typical shock replacement milage, 60-150K? That would make the car appear a little lower and then when you slap some stiffer Bilsteins on there it raises up? Could that also be part of the issue?

Sorry kjack, I would have never in a million years guessed that shocks could make a car ride higher. I know the Bilsteins are stiff, but figured the weight of the car would have been to much to make a difference.

Bilstein monotube's are notorious for a slight ride height increase. The spring is not a consumable, but you do have a point. I'm sure a worn shock would allow the car to sit lower. That coupled with a Bilstein replacement is probably the difference he saw. Monotube's in general are high-pressure shocks, but that pressure affects the shocks stiffness/softness little. It's the rate at which the oil passes through the shims and piston that affect the ride/handling.

All this being said, on basically any vehicle other than a BMW, I'd go with a Bilstein damper for a replacement (I think Euro Porsche's and VW's come with Bilstein from the factory, for NA they use super-crappy Monroe shocks).


If you'd like to learn about dampers, read through the Penske manual. Some of it just regarding their shocks but they also discuss damper tuning. Quickly before you look at it: bump is the compression stroke, rebound is the opposite. For basic purposes, bump controls the unsprung mass (suspension components), rebound controls the sprung mass (body). Low-speed (shock piston movement) movements are things like rolling in a turn, mid-speed is situations like more gradual undulations, high-speed is curbs, potholes, etc. Notice that on any shock dyno graph, the force produced by a shock is a function of (piston) velocity.

http://www.penskeshocks.co.uk/downlo...TechManual.pdf

From the Bilstein site, this is basically what the inside of a monotube damper looks like:

[fangbosun]

My 2003 3.0D has Bilstein as OEM (the stickers are still on them). My Alfa Romeo 147 has aftermarket Bilsteins as the OEM shocks are crap. They did lift the car a little bit, the rears actually came with nylon strapping to stop the shafts from pushing past the ends of the packaging.

Vinuneuro, i agree with most of your comments but surely different drivers want different ride/handling characteristics and that BMW (indeed any other car maker) tries to give the best compromise to the widest possible market. Why would BMW offer a sport suspension option if they got it right the first time? I'm sure the folks at Bilstein might put a bit more of an effort than you allude to. When the OEM shocks need replacing, I'd definitely consider upgrading to 'aftermarket' Bilsteins.

[ewoods12003]

Hello all! Having a problem and wondering if anyone can tell me the issue and how to resolve. Every two days that I dont drive my X5 4.4i 2002 , the rear passenger side part of the car is down like a low rider. But when I start the car it rises back to original position. Air leak or what?

[FSETH]

Originally Posted by ewoods12003

Hello all! Having a problem and wondering if anyone can tell me the issue and how to resolve. Every two days that I dont drive my X5 4.4i 2002 , the rear passenger side part of the car is down like a low rider. But when I start the car it rises back to original position. Air leak or what?

Sounds like the typical air bag leak. You can do a quick search and probably get tons of info on this topic here.

[amacman]

you can buy a leak detector spray from plumbers or mix weak solution detergent and water then spray onto component where bubbles will form if there is a leak .

[ewoods12003]

Is there some kind of quick fix or are we talking total replacement? if a replacement is needed, where can I find a good price? Thanks everyone.

[Kewl X5]

I would like to correct misconceptions re: Bilstein and OEM shocks. My 2001 X5 3.0i with sports package and rear self-leveling air springs and the OEM rear shocks are made by Bilsteins. The OEM Front Struts on my X5 is made by Delphi.

With the help with Hayaku, OEM struts and shocks were replaced with Rogue Engineering camber plates added...
http://www.xoutpost.com/bmw-sav-foru...rugged-up.html

[X5 in AK]

According to Bilstein's website, and to the guy at Bilstein in California I talked to, and to other vendors that sell them, Bilstein does not make a rear shock for the X5 with self-leveling suspension.

What is up with that? I thought nearly all X5s sold in US had the self-leveling option.

Are OEM shocks the only option?