When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Well now that the W204 C300 is running well, noticed that at around 60-70MPH there is a fairly consistent rather strong vibration in what feels like the floor/rear of the vehicle. If you accelerate through it under load it seems smooth. The vibration appears during light acceleration and constant speeds only.
Tires have been balanced but figured that would be constant not changing under various loads.
Checked out the suspension and it all seems solid.
Drive shaft and flex discs appear in good shape.
Motor mounts are good.
Transmission mount appears good but looks original. Have a new one on order.
Can just a blown out transmission mount cause this?
At times the vibration feels almost violent. But then at times is vastly reduced.
About 133,000 miles presumably everything from the transmission back is original.
Transmission has been serviced recently new filter and fluid. It shifts fine besides what appears to be a standard delay from reverse to drive. No delays on upshifts or downshifts. Very smooth.
Also under any kind of acceleration or constant speed there is no vibration at all below 60MPH.
Rear diff has been serviced and had no metal in it
Inspecting the tires may be a good way to check for issues, whenever i have the wheels off working on the car which is often im always closely inspecting the tread for any abnormal wear. Last year I was getting an odd vibration on the front drivers side as well as the suspension felt hard hitting bumps, turns out the tires were old and worn, cracking everywhere. New tires all around made it ride like new again.
Have you inspected all of the control arm silent blocks/bushings for wear/cracking. Inspect the rear differential bushings for wear/cracks.
How does the suspension look, the springs and shocks?
inspect rear axles, look for torn/cracks boots.
May be worn wheel bearing, though would probably be a loud noise associated with it.
When I did my original inspection for the vibration I did not see any cracks in any of the bushings. The previous owner put the wrong size tires on the rear. It's a sport so has the staggered wheels. Instead of 245 they put 225. The tires are from 2021. They could totally be the culprit. It seems like it's almost like it gets in a rhythm and goes away and comes back as if out sync then back.
I'm going to inspect again. I've been hesitant to put new rear tires on it before ruling everything else out but it very well could be the tires
Took a gander underneath from the back and low and behold the differential bushing is completely ripped all the way around. That should be a fun job. I'm going to guess this is the source.
The more I think about this it reminds me of a bad u-joint. I don't hear any noise from the center bearing. However the vibration is so strong now. The diff feels solid despite the worn bushings. The u-joints aren't serviceable on these shafts?
When I grab the center of the drive shaft it moves up and down maybe 1/4 inch less than 1/2 for sure.
Thinking of dropping the shaft out and just refurbishing it. Can't seem to find a new one for less than $500.00.
So basically new flex discs and center bushing/bearing is all we can service?
Took a deeper look and found the center support bushing is resting fully compressed on the bottom of the center ring. Also the transmission mount is also very compressed. Overall the actual bushing itself does not look bad at all. I don't even see cracking. The only thing of concern I saw was that the boot over the splined shaft was ripped and you could see the splined part of the shaft presumably where the missing part of the boot should be. The flex discs show stress cracks on the surface but not actual deep cracks. Doesn't make sense I know. It almost looks like splatter paint. Looking at this job. I am really hopping to avoid having to pull the entire exhaust. If I can get by with just the tail section it shouldn't be too bad. Looking at the bolts it doesn't appear anyone has touched the bolts. Was thinking maybe someone did the center bearing before and didn't line up the splines correctly causing the shaft to no longer be balanced. U joint seems solid.
I'll report back after changing the transmission mount first. Really don't want to pull the shaft for no reason if that's enough to cause the vibration.
Swapped just the transmission mount and the difference is drastic. There is still some vibration but that feels like tires now instead of the entire chassis.
The new transmission mount brought the center carrier back in line. The trans and shaft were about an inch lower than it should be. The mount was completely ripped and was original.
Some time ago I had almost exactly what you described...after (like you) going round and round and round...well, found out a rear wheel was out of round. Slightly bent rim.
Hello. Got all four new tires today and happy to report the issue is resolved. Seems like the rear tires had a slipped belt or some kind of failure. Thanks for everyone's input.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
