Wobbly ride

Question for those of you with the R129 SL -- does your car feel wobbly when you drive without the hardtop on? In other words, do you notice any difference in ride quality with or without the hardtop? Whenever I drive with my hardtop off, my car loses its composure if I go over minor dips or bumps in the road. Not sure if I'm experiencing the infamous "cowl shake", but the wobbly feel has really asserted itself these past few months and is driving me nuts. I'm wondering if something needs to be tightened like a sway bar or suspension component.

On a separate note, do changes in the weather increase the likelihood of squeaks and rattle sounds? Now that the weather has warmed up a bit, my 95 SL320 is beginning to make all sorts of noises that I've never heard before.

Thanks.

[bobterry99]

The hard top of my 300SL is never on the car. With the top down my experience driving over rough pavement and small bumps is similar to yours. Cowl shake is quite noticeable. This is in marked contrast to my experience driving W107 and W113 SLs.

I suspect there is nothing wrong with your car or mine. I looked at a recent issue of the English magazine Car and the brief comments on the R129 SL500: effusive praise, but they were critical of excessive cowl shake.

[bobterry99]

I just sold an SL to a buyer that noticed the car was not as solid as her 1980-something 300SD, and I was reminded of this old thread. My experiences with owning several 129s over the three years since confirm for me what I wrote then. This chassis is particularly sensitive to imperfections in wheels, tires, and road surfaces. With the top down, any of these will produce a considerable amount of cowl shake which is greatly lessened with the hard top on the car.

[bobterry99]

The Ken Rockwell article that was cited here has a link to a road test which makes the following comment:

But here's the biggest complaint across the board from the test drivers: The platform...isn't as rigid or stiff as modern designs, which you can feel when going over bumps, and we yearned for a more solid ride...The bumps (even trivial ones) also revealed a very squeaky and creaky interior.

[bobterry99]

I found a bulletin from MBNA dated 5/94 that addresses customer complaints of "hard uncomfortable ride quality or vibration at approximately 30-55 MPH". It states this is because "the sporty design of the model 129 chassis requires a hard damping rate."

The solution offered is to install softer damper struts. The part numbers are 129-320-14-30 for the front and 129-320-01-31 for the rear. They are available from Phil.

[Mike Miller]

Just chiming in. I have basically replaced my entire suspension (struts, front and rear and upper and lower radius arms in the rear). The ride is 100% improved. However, cowl shake, hard top off versus hard top on is still noticable and I am sure will always be there. Your R129 should feel very solid on the road and handle like it was on rails!!! If you get a little cowl shake, what the heck! It is the best and sexiest darn convertable on the road!!

[Strife]

I think the 107's design, pre-computer, probably, solved the cowl shake problem with metal, and lots of it (the weight of the car is incredible considering its size). I've been in a lot of convertibles, and no convertible I've ever been in except possibly an MGB (which hardly weighs anything) can even come close to the 107. But the 129 doesn't weigh much less...

[bobterry99]

I believe cowl shake among the SL lineup is only a feature of the R129. The earlier models don't suffer because their suspension setups are considerably softer and more compliant. The R230 has no cowl shake -- and it handles well --probably as a consequence of its active ABC suspension. If so, then an R129 with ADS may have no cowl shake as well.

I found a bulletin from M-B that shows in early '96 the suspensions of all 6- and 8-cylinder SLs were modified to give them a more comfortable ride. The softer struts that were offered on special request beginning in '94 became standard, and the previous strut was no longer available. On the SL320 the torsion bar on the rear axle was eliminated.

One other note. I can't find a bulletin that describes this, but the Electronic Parts Catalog shows that for MY99 and later there was an alternate strut available for the SL500. There is a note by it that simply says "Freeway Hop". I would guess that this is a firmer strut that M-B made available for those wanting more controlled, sporty handling.

[Broxin]

I too have been quite unsatisfied with the ride of my 94 SL500. My tires are quite old, so that may be part of it. I did improve the ride by replacing front cracked strut mounts.

Bobterry99, I see that the first part number refers to a "Strut Assembly Heavy Duty" and the other is "unavailable." How do I know if I am getting a softer strut when ordering from Phil or Bilstein directly?

Has anyone here replaced their shocks with 'softer' shocks and experienced improvement?

[cbdo]

Actually, the 107 weighs at least 500 pounds or so less than the 129. Test drove a 97 SL320 yesterday, having thought that it might be fun to upgrade from my 560SL, but it felt too plasticky and didn't have that same all-carved-from-one-ingot-of-steel feeling which has always been what I like best about Mercedes. (But then the signs of hydraulic leak down onto the front doors from the latch cylinders in the windshield header were also a bit of a negative!) The ride seemed more harsh as well; having read the above, now I understand that yes, it's real, and here are the reasons.

Even in my 107, there's definitely a difference with the hardtop on-even more rigid than with it off. And yes, the squeaks vary with the temperature. My 107 has more if it's cold, but my Saab when it's hot.

[Carlos Serrano]

My 99 SL500 with the heavier engine drives like a Panzer tank, then again it was built in the same factory, on the interstate stiff and noisy without the hard top, stiff and much quiet with it on.This is with Michelin Pilot Sport A/S tires,I buy the same tires the car came with, the ones recomended by MB. It shows some amazing differences when the hard top is removed, there is this curve close to the house that I've taken at high speed several times with the hard top on and always make me smile as I zoom thru it, I even kick down and pass other cars on this curve without hesitating, but a week ago I drove thru it with the top down after getting around a Lexus and a CLK and I felt lower intestinal muscles tighten when going thru, I've never since I bought this car experience this, the car actually leaned, the road curves towards the right and I felt like I could touch the road with my hand, there wasn't that much difference in the speed I drove that day with the top down than when I drove with the hard top on, maybe is time for a new suspension at 60,000 miles, won't be doing that again any time soon untill I have my high blood pressure prescription refilled

[bobterry99]

Originally Posted by Broxin

I too have been quite unsatisfied with the ride of my 94 SL500. My tires are quite old, so that may be part of it. I did improve the ride by replacing front cracked strut mounts.

Bobterry99, I see that the first part number refers to a "Strut Assembly Heavy Duty" and the other is "unavailable." How do I know if I am getting a softer strut when ordering from Phil or Bilstein directly?

Has anyone here replaced their shocks with 'softer' shocks and experienced improvement?

Both of those struts in Fastlane are the stiffer variety. I think you would have to call Phil and give him the 129-320-14-30 and 129-320-01-31 part numbers.

I have a '99 car to compare against a '90 car, and the ride of the newer car is better. But it still isn't as good as I would like it to be.

By the way, I owned an R230 for four weeks earlier this year. And I made several comparisons between this car, a '99 SL500, and a '96 SL500.

The higher starting torque of the '99's engine compared to the '96's engine was noticeable, to my surprise. The other comparison I made was in ride, of course. I drove a 5-mile circuit over a variety of surfaces near my house. There were times when I experienced cowl shake/jiggliness in the R129, but the ride in the R230 was always fantastic.

[GregE240]

I took my hard top off about 4 weeks ago, just in time for the British summer. I must admit I've noticed a little more scuttle shake with the hard top off, but its not that bad.

Saying that, my car has ADS, so I don't know if that makes a significant difference? Also, mine rides on 18" AMGs.

I too have driven an R230, which was fabulous (fitted with ABC). However, the trim felt a little more plasticky than the trim in my car.

[bobterry99]

Originally Posted by GregE240

However, the trim felt a little more plasticky than the trim in my car.

The car magazines and anyone with an objective opinion all agree with you on this -- except for one person. Me! Ironically, I have the exact opposite impression. I don't won't to get off topic, so I'll start a new thread.