300sdl Shake - PeachParts Mercedes-Benz Forum

TED JENNINGS · #1 03-01-2004, 07:29 AM

MY 1986 300 SDL HAS 203K ON IT- THE FRONT END HAS A SHIMMY AT 60+ MPH- IT IS WEARING THE OUTSIDE OF BOTH MY FRONT TIRES- I HAVE REPLACED BOTH TIE RODS,CENTER LINK,STEERING SHOCK AND HAVE HAD COUNTLESS ALIGNMNETS & WHEEL BALANCINGS- AT MY LATEST ATTEMPT TO GET IT FIXED- THE TECHS FOUND NOTHING WRONG WITH THE CAR BUT BLAMED IT ON THE TIRES- CONTINENTAL CH90'S- BUT WHY DO I HAVE THE SAME PROBLEM WITH MY SET OF STUDDED SNOW TIRE ON THEI ON SET OF RIMS?

TX76513 · #2 03-01-2004, 11:09 AM

Ted, how are the Chassis Front-end support rods? This was an issue with my SDL but was looking at everything else.

TED JENNINGS · #3 03-01-2004, 02:02 PM

WHAT/WHERE ARE THEY EXACTLY- I'VE HAD THIS CAR FOR 13
YEARS SO I SHOULD BE ABLE TO FOLLOW YOUR DISCRIPTION

Q · #4 03-01-2004, 02:06 PM

If your tires are already worn out of round, you will still get vibration no matter what you change. Take one off and roll it on a flat surface. If it wobbles, there's your vibration.

Some tire places will shave them true for you.

psfred · #5 03-01-2004, 02:27 PM

Ted:

Track rods go from the lower control arm to the frame. The bushing at the rear can go bad (so can the bearing up front, but that's rare). This will allow the control arm to twist backwards under load. You can check them by lifting the rubber boot on the frame and inspecting them. Wear is usually obvious.

You will also get groans or creaks going over bumps when they are bad, and they usually also clunk on braking. When they are really bad, they thump something terrible.

YOu also need to make sure the alighment shop is using a spreader bar to load the tires on the front outwards while doing the alignment. If not, they will spread on their own, causing excessive toe-out while driving -- this wears the tires funny and they usually vibrate as they wear -- no way a Continental is going to wear perfectly balanced (or any other tire, either, for that matter).

Shimmy at 60 mph or so makes me thing loose parts, though -- check wheel bearings, tire balance, rotor runout, rims for out of round or runout, and all the bushings for condition. Bad ball joints may cause problems too! And, the ilder arm bushings can get loose -- check by attempting to move the idler arm vertically. If it moves, replace the bushings.

Peter

TX76513 · #6 03-02-2004, 08:10 AM

What Psfred said is correct. I believe the specs call for 800+#'s of spread on alignment. Don't want any flames here so if you don't spread em

that's fine too.

TED JENNINGS · #7 03-02-2004, 09:31 AM

WHAT DO YOU MEAN BY 800+# ?

TED JENNINGS · #8 03-02-2004, 12:09 PM

HOW WOULD YOU RATE THE CONTINENTAL CH90 TIRES?- SOME OF THESE ALIGNMENT SHOPS TELL ME THEY ARE NOT THAT GREAT AND THEY ARE MOST OF MY PROBLEM- WHY SHOULD I HAVE TO PAY 100.00/TIRE FOR MICHELINS JUST TO GET A GOOD TIRE?

TX76513 · #9 03-02-2004, 01:57 PM

Quote:

Originally posted by TED JENNINGS
WHAT DO YOU MEAN BY 800+# ?

The way it was explained to me is 800# or 800 pounds of force to simulate the position of the tires at 60mph. Possibly someone can chime in with the exact numbers - but I caught on to what was being described. This all came from a discussion at a tire store that didn't have the spreader bar or the ability to apply that much force for an alignment.

psfred · #10 03-02-2004, 03:09 PM

Well, you get what you pay for.... BAsically, yes, you must pay good money for good ride and no vibration.

MB recommends V rated (130 mph) tires, and I won't put less than H rated tires on my cars -- after all, they DO go that fast (or almost).

H or V rated tires will be balanced enough to run that fast -- lower rating tires won't necessariy. If the tire itself isn't round and/or isn't marked to indicated the low spot, or isn't perfectly round, it's gonna vibrate.

I use Firestone Affinity LH-30s -- nice tires, plenty of tread, good traction dry, wet, and on ice and snow (although not exactly snow tires), wear well, and run quiet as fast as I plan to go. About $75 each.

If the tire shop doesn't use a spreader bar, you will have perpetual alignment and vibration problems, along with severe road surface "tracking" and crosswind sensitivity.

Peter

JHZR2 · #11 03-02-2004, 03:58 PM

I have found that these cars do tend to wear the outside edge of the tires a bit faster than the inside.

Do you use the same wheels for your summer and winter tires? If so, you might have a slightly out of round wheel.

Id have to suggest you utilize an MB shop for alignment... They know these cars best.

Conti tires should be quite good. Ive seen them as OEM on many BMW and MB cars.
Im not sure that MB reccomends V rated (which are up to 149 MPH by the way, H rated is up to 130) on these cars... My w123 reccomends s speed rated tires. I run H rated with very good success, but will probably drop to T rated next time so I can try those michelin rain tires, or the goodyear aquatred 3s.

JMH

TED JENNINGS · #12 03-04-2004, 01:26 PM

I JUST READ THAT THE REAR SPRINGS ON MY 1986 300SDL ARE ADJUSTABLE- IS THAT TRUE? THEY DO SEEM TO BE A LITTLE WEAK AND THE REAR DOES SAG SOME- ALSO-ISN'T THE TRANSMISSION
IN THAT CAR ADJUSTABLE IN SOME WAY?