Most likely causes - my 300CE is really bouncy over bumps
 

This problem has been most noticeable of late - right after getting 4 new tires. Best description of symptoms - when I go over bumps on the highway, at highway speeds my front end "bounces" and "vibrates"...steering wheel shakes some and it feels like the tires are 'bouncing' quickly on the pavement...

I replaced the steering damper, which made little to no difference. Car has 80,000 miles on it...

I have eyeballed the tie rod ends, drag link, ball joints, shocks...my first thought is bad shocks - any ideas?

I am just trying to avoid replacing parts...I took it back to the tire shop after they replaced the 4 tires and they suggested steering damper/drag link, but nothing definitive...


ryan

Hi, Ryan. Just a thought, but have you checked your tire pressures, cold, with your own gauge? I've seen some tire jockeys overinflate tires for one reason or another (bad gauge, ignorance, used the "max" on the sidewall, etc.) and overinflated tires will do exactly what you are describing.

Another thought is to carefully inspect your tires to be sure they are installed properly. Some tires have unidirectional tread (meaning they always have to turn the same direction) and some have a graded tread pattern that requires the "outside" to always be mounted to the outside (regardless of rotational direction). When I last bought tires mine were the latter, and when I looked at the tires on the right side of the vehicle, there in the tire mold were the words, "MOUNT THIS SIDE IN". DOH!!! I was looking because the car kind of had a nervous feeling at certain speeds, but I took it back, they re-mounted the right side tires and rebalanced them, and problem solved.

Anyway, since it started just after getting new tires, those are some things that are worth checking. Might as well recheck the torque, too, if that's not even odd things can result as well.

Good luck.

fwiw, I'd put shocks near the bottom of the list. If 80k is true mileage, they should have life left, unless the car has been ridden hard. My 300ce has 132k and the dealer just told me the original shocks were near the end of their life.

Some possible suspects:
Loose (or worn) bearings, worn tie rods, ( how do the boots look.), front end alignment, and maybe the tire(s), new or not.
2 months ago, I had pretty bad shimmy at 60 to 65 that led me have the dealer inspect the front end and tell me that I should replace or repack the bearings ( one was loose) replace a tie rod (worn with a ripped boot) and the shocks were worn.
Had the tires replaced by an indy first along with the tie rod, then an alighment after he tightened up the right bearing. Rock solid now. Shocks were 750+ I was told! I'll get around to that come spring. There's always something!:o

My 260E had bad shocks at 85k miles. I would bottom out in the road constantly and that was before I lowered the car. Other than that it would ride okay, so that's my experience with bad shocks on these models.

Front shocks are ~$120/each and can be done with some basic tools. As long as you put something to support the lower control arm so the spring doesn't force the arm down, its perfectly safe to tackle.

I know they changed your tires, but did they balance them? That sounds like the obvious problem as I'm sure anyone that has driven with unbalanced tires can tell you.

how does the car feel on smooth pavement at speed? what size wheels and tires? it could be that you have light wheels, and thin sidewall tires, resulting in lower unsprung weight than the shocks are set up for...
oh, and I thought the 91 used struts...

it could also be bad tower bearings... they rattle and can make the car feel unstable on bumps, and rattle the steering wheel...

Well, I checked the tires to make sure they were installed properly, and they are. Also, they are the same tires that I had previously installed (Falken's - not a great tire, but decent enough). On the highway, smooth rode the car just glides along - runs great. It's only when I hit the bumps - and I'm not talking pothole bumps...

So, I checked the air pressure and they all had around 38 psi (Max pressure stamped on the tire is 51 psi). My gas flap says Max front at 28 psi, rear at 33 psi...so I removed some air - fronts are down to 30 psi and rear's are right at 32 psi. Car does run better, I need to take it out on the highway, but the bouncing has definitely been reduced. Still there some and it really 'feels' like shocks to me...

My question - can 6-8 psi make this much difference? Do you guys generally ignore Mercedes recommended psi's after the original tires are gone? Big difference between 51 Max psi on these tires and 27-33 psi on the gas tank door...

ryan

Ryan, I would attribute the bouncy condition to worn 21 year old struts. Although it is odd that the condition started after the new tires were installed. Perhaps you were more focused on the car's ride after the new tires were installed. Michelin is the only brand tire I run on our MB automobiles.

FWIW on our 124 cars I inflate all 4 tires to 34 psi.

Finally got around to replacing the front struts this weekend - got delayed by having to order the rubber bump stops as mine were half gone!

Wow! The difference is remarkable - ride is much better, no more bouncy feeling. Now I have to change out the motor mounts.

ryan

tower bearings? Are those the rubber shock mounts?

Silly German Engineers
 

'Waste all that time and effort,providing the BEST tire pressure for our Mercedes
AND YOU IGNORE IT!

I can tell 1 PSI difference in the ride quality on the 124.128...
(With Michelin MXV4 s and Koni s)

What is your reasoning for having your tires at 38 psi? And what does this have to do with the max pressure on the tire?