Mercedes SLK World banner

1 - 8 of 8 Posts

·
Registered
Joined
·
89 Posts
Discussion Starter #1
This is sort of a weird issue, and I’m not quite sure what to make of it. I’ve noticed an intermittent shimmy at speed – 3-4 seconds on, 3-4 seconds off, generally around 65 mph. Feels like the rear driver side. It would not be noticed except for the recently paved road that I take to work – it’s subtle, to the point that I thought it might just be my imagination. It’s not the paving job – I tested that with other vehicles and different roads with new pavement – still feel it. The tires are Pilot Super Sports – 1 year old, but I suppose they could be the problem. They are not road force balanced, but with other cars I’ve had, it was a constant shimmy that RF resolved. It doesn’t appear to be getting worse, no sounds or anything, and not really noticeable below 60. Anyway, I’ll probably let my mechanic take it for a spin before it goes into storage – that unfortunate day is quickly approaching, but I’d certainly appreciate suggestions. Thanks for your time!
 

·
Administrator - Founding Member
Joined
·
92,876 Posts

·
Registered
Joined
·
88 Posts
If tires are the same size front and rear swap wheels front to back and see if shimmy moves to new location.

If tires are not same size swap from left to right and see if it moves.

When swapping the wheels just do two at a time. Otherwise you will get confused like I did and have to start over. It is also a good idea to mark each tires position (LF, RR, etc.) before you start moving them around.

When I bought my car it had a bad 30 mph shudder that shook the whole car and it turned out to be a bent rim on the left front. This was probably the reason it sat on the dealers lot for 280 days and I got a steal on the pricing. The wheel only had about .060" runout. The tires were Continental with about 30% tread left.

Just swapping the wheels/tires from left to right on the front cured my shuddering and made it completely vibration free on a smooth road.

If you don't feel like messing with it do a 4 wheel alignment and tire balance. Ask the tire guy to check the rims for runout when they are balanced. Even if you find the issue you should still do this.

The members of this forum helped me solve my issue - Hope this helps.
 

·
Registered
Joined
·
152 Posts
I have had the same issue and it was a tire out of balance but just like it fixes itself and then starts again. Turns out the tire slips on the wheel. Its good after balance but starts again if I get on it much. Tires were marked to wheel and the tire had moved. The same weight but just a small distance further on the rim. Was told the only way to fix was replace tire or rim. Tires are coming due replacement so have waited since its not bad unless you want a glass like ride. The roads here are not that good to start with. My tires are AS 3s.
 

·
Registered
Joined
·
89 Posts
Discussion Starter #5
Thanks for the replies! I'll look over the tires and rims. Last summer I took a hit from a hidden pot hole - hence the new tires. I though I had it sorted out, but the roads around here are in disrepair, so it was hard to tell. The passenger front and rear took some damage, but maybe the rear rim was also compromised. The front was a little easier to tell. I'll have it tested. The on - off squib was new to me. Thanks again for your help! Regards.
 

Attachments

·
Registered
Joined
·
1,684 Posts
^ - ^^

For anyone driving over pot-holed roads, raise your tyre pressures to give your rims a fighting chance! Will also reduce the likelihood of slippage on the rim.
 

·
Registered
Joined
·
152 Posts
Your are right very easy to tell on that one. If I read right, you new tires are still in warranty so they should fix it. Mine are still under the 6 year warranty but I am not ready to just replace one tire for the little shimmy that I have. They removed my tire and I took the rim down to the car wash and really clean it up and then use a brown pad inside on the ridge and double clean that. They put something on the tire also and mounted it back and mark it. Drove it around the block and came back and it had moved. Michelin stated there was too much stuff used when they mount it. I am not rough on tires so I can live with it for another six months. If it get worse then will replace both rear and they will check if it does not set to the rim. Could be they both vehicles are Red.
 

·
Registered
Joined
·
88 Posts
When tires are mounted the stuff they put on the bead is a rubber lubricant which makes it easier to mount and inflate.

I found the following quote in an article about a Camaro spinning the tires on the rims - mainly from braking.


It was a perfect combination, but engineers quickly found that when the Z/28's capability was tested, the wheels were rotating – slipping – inside the tires. They sought the root of the problem by marking one of the Pirelli P Zero™ Trofeo R tires at the beginning of a lap with a chalk line relative to the valve stem on the wheel. At the end of the lap, they recorded where the chalk line ended up and noticed the tire had rotated at least a full 360 degrees from where they started.

Racers use an abrasive paint around the bead of the wheel, where the tire meets the rim, to combat the problem on race cars. The Z/28's engineers tried it, but it wasn't strong enough to prevent the slippage, so other approaches were tried. Finally, they tried media blasting, which involves shooting a gritty material through an air gun at the wheel's surface, adding texture to the paint for the tire to grip.

"Media-blasting the wheel created an extremely aggressive grit on the rim, which finally got the tire to hold," said Stielow.
Here's a thought - The next time your tires are mounted advise the installer of your problem and ask him to clean off all of the rubber lube on the side of the bead that blows out to contact the rim. You could also take him a baseball pitchers resin bag and have him dust the contact seal surfaces with the resin.
 
1 - 8 of 8 Posts
Top