Do I need new struts?

[vince0210]

I know very little about suspension. How do I know if I need new struts or springs? My ride is not smooth. Car has 220k miles on it. No idea if they have ever been replaced, is there anyway I can tell?

[Deanx2009]

first.not smooth as in,

car bounces repeatedly after hitting speed bumps etc.

you can feel every bump in the road

Its easy to push down on your car and move if signifigantly?

[LouieD]

I just bounce the front or rear and see how long it takes to settle back. It should just bounce once and settle back. Look for any wetness around the top of the struts for visible leaks. Also look for cupping of the tires, as worn shock will allow the tire to bounce as you drive. When driving worn shocks will allow the car to continue bouncing after a substantial road irregularity and give a real floaty feeling.

[vince0210]

I'll try the bounce thing. What I notice is especially in the rear of the car when I hit bumps it feels and sounds like I have a bunch of metal in the truck bouncing all of the place.

[LouieD]

broken upper mounts?

[4500 RPM]

The bounce isn't a good test, this isn't an old American car. You can get some indication but not much. I could fully compress my old shocks and it would pass most "bounce tests".

If you have to ask, then they're toast. But they should have a Cadillac ride, not a harsh ride.

[LouieD]

The bounce isn't a good test, this isn't an old American car. You can get some indication but not much. I could fully compress my old shocks and it would pass most "bounce tests".

If you have to ask, then they're toast. But they should have a Cadillac ride, not a harsh ride.
I thought these weren't old American cars? Are the physics different for a BMW vs. a Buick? An object in motion wants to stay in motion and the job of a shock absorber is to suppress and control that motion. So if said strut is worn it will exhibit the same characteristics as say mono tube hydraulic shock absorber from the 60's. The technologies are different but the intended job is the same. So why wouldn't a "bounce test" work? Probably because we, as a collective, don't let the struts reach that point before we replace them, usually in the name of "upgraded performance" so we don't hear much in the terms of "my car is bouncing down the road", but a bad shock regardless of make will eventually lead to bounce. Your shocks, and mine btw, probably allowed compression because the internals were worn on the compression side but did not bounce because the rebound was still beign controlled.

[trinity03]

first.not smooth as in,

car bounces repeatedly after hitting speed bumps etc.

you can feel every bump in the road

Its easy to push down on your car and move if signifigantly?

i agree...

[Binjammin]

I thought these weren't old American cars? Are the physics different for a BMW vs. a Buick? An object in motion wants to stay in motion and the job of a shock absorber is to suppress and control that motion. So if said strut is worn it will exhibit the same characteristics as say mono tube hydraulic shock absorber from the 60's. The technologies are different but the intended job is the same. So why wouldn't a "bounce test" work? Probably because we, as a collective, don't let the struts reach that point before we replace them, usually in the name of "upgraded performance" so we don't hear much in the terms of "my car is bouncing down the road", but a bad shock regardless of make will eventually lead to bounce. Your shocks, and mine btw, probably allowed compression because the internals were worn on the compression side but did not bounce because the rebound was still beign controlled.




The reason a bounce test is tougher on an e34 than an old domestic is because they have much shorter, stiffer springs. You should see the springs in my 65 Cadillac, they're almost 3 feet long decompressed. It allows for MUCH more float, and a bounce test is a dead giveaway. On an e34 a decompressed spring is about 18 inches and a lot stiffer. Much harder to bounce against.

[4500 RPM]

I thought these weren't old American cars? Are the physics different for a BMW vs. a Buick? An object in motion wants to stay in motion and the job of a shock absorber is to suppress and control that motion. So if said strut is worn it will exhibit the same characteristics as say mono tube hydraulic shock absorber from the 60's. The technologies are different but the intended job is the same. So why wouldn't a "bounce test" work? Probably because we, as a collective, don't let the struts reach that point before we replace them, usually in the name of "upgraded performance" so we don't hear much in the terms of "my car is bouncing down the road", but a bad shock regardless of make will eventually lead to bounce. Your shocks, and mine btw, probably allowed compression because the internals were worn on the compression side but did not bounce because the rebound was still beign controlled.

See Binjammin's post. You're forgetting the spring characteristics and suspension design.

I've had two sets of totally blown struts...I didn't even know they were blown until I removed them.

http://img.photobucket.com/albums/v244/Georgia4Runner/Bimmer/IMG_0625.jpg

[CaryNC]

I'm glad you asked the "Struts Needed" question. Saves me from asking. My '95 525i has 135k miles on it and handles quite well, but the ride is stiff. Just seems like replacing the struts at/or above 100k would be a given?

Anyone have an idea about how much this should cost including labor, or is it a fairly straight forward DIY project?

Thanks All !

[4500 RPM]

The ones in the pic were OE with 60k on them. Totally blown.