500E Yaw problem.... - PeachParts Mercedes-Benz Forum

Bryan Harter · #1 04-29-2003, 09:09 AM

I seem to notice a Yaw to the left whenever I get on the go pedal lately....not sure but I think it is the rear suspension twisting, maybe worn bushings? I have had the rear auto leveling system rebuilt. Possibly the right side is not compensating for squat under load.

I also hear a groaning (like a wheel bearing) as I was making a gentle left thru the parking lot at the airport the other day...haven't heard it since. Car has 115K, it might be time for bearings...

Michael · #2 04-29-2003, 09:48 AM

How old are your rear links? They were updated in later cars ('93 methinks) and might account for the sway. Or, could it be the front? Check your front sway bar attachment "links" - they are cheap metal and snap occasionally (but it assuredly feels like the front washing out, so likely ain't your prob but I thought it worth mentioning)

Bryan Harter · #3 04-29-2003, 10:38 AM

Thanks Micheal,

I will recheck the front end, I installed a RennTech front bar 2 years ago and replaced the mounts / links then. I have had extensive work done to the front end. Idler arms/ drag links etc...
I think my tech would have noticed anything loose as he is pretty familiar with my car.

yhliem · #4 05-03-2003, 04:27 AM

most likely rear bushing - thrust arms in particular, but you might as well replace them all if your car has 100k miles or more. Just replaced the thrust arms on my 16v and the bushings were GONE. resulted in considerable caster and toe-in changes under acceleration and deceleration. MASSIVE amounts of rear-end steering and a handful to drive in the wet.

whenever you have one end of some thing fixed, the free end will move in an arc. This is counter productive to the goal of allowing suspension articulation while not affecting caster, camber or toe because allowing lateral movement of the wheel as the suspension compresses and rebounds would induce rear-end steering. one way to fix the problem would be to allow the component which connects the fixed point and the free end to tlelscop, thereby eliminating the arc. since this is usually an axleshaft, telescoping is out of the question. mercedes-benz decided to go another route and designed the 5-link suspension.

in very basic terms, the mercedes-benz 5-link suspension uses a modified double wishbone design: 2 a-arms are located - one on top and the other below. these a-arms are then cut apart to provide 2 links each. the arms are all of different lengths and control the caster, camber, and toe.

the 5th link is the thrust arm which eliminates the lateral movement of the wheel to about 1/16th or 1/32 of an inch. the issue of lateral movement which occurs is dealt with by using the rubber bushings.

the bushings in the 5-link suspension are what allows the required play to occur in the system while keeping the track (the distance from the centerline of one tire to the other) the same.

This is why the car is so predictable in handling and why the bushings wear out quickly. this is also why the bushings are sold as a unit with the control arm AND this is why the heim-jointed control arms aren't the greatest idea on a street bound MB. all the stresses generated are no longer absorbed by the bushings and wind up being transferred to the subframe and chassis.

you can expect to find metal fatigue on cars with the aftermarket suspension links in a few years.

Bryan Harter · #5 05-03-2003, 11:15 AM

Thanks yhliem !
When I had the H&R springs installed I believe a couple bushings may have been done, one small control arm was also bent (tow truck tied it down on the flatbed (Previous Owner)) - caused some pretty nasty tire wear.
I suspect that it is the rear links as it seems to almost feel that the car is steering from the rear.

need2speed · #6 05-03-2003, 08:14 PM

yen-hsen: thats the most "articulate" description of the rear 5-link suspension I've yet read....thanks for convincing me to go K-Mac!!

yhliem · #7 05-05-2003, 01:28 PM

Dean: I'm here as the voice of reason, logic, experience, and knowledge