Hey guys,

I have been slowly restoring my '91 300E back to it's original, new condition. I just repainted it (black on Alto Grey from Teal Green! and it's gorgeous), after having paid several thousand dolalrs last year on a variety of improvement projects (new cylinder head, blower motor and blower, tensioner, timing chains, radiator). I also personally replaced my headlamp lenses and the entire grill. Anyway, now that it looks absolutely fantastic, my most recent problem is the transmission. It has been making a loud "clunk" or "single knock" sound every time I decellerate from a speed of 35mph or higher. It always happens as the gears drop down from a higher gear (say, 4th down to 2nd). It's been getting louder lately and happens whether I decellerate slowly or a quick stop. Any idea what this is and how much it will cost to repair?

Have you checked the Flex Discs in the drive shaft?

No, I'm not familiar with what that is. How much does that cost to repair? I just have to send it in to a local shop I work with.

Thanks!

There are two flex disks in the drive shaft (front and rear). They are there to absorb any shock to the drive shaft. They wear out, especially the front one.

I had to have the front one replaced on my '91 300E at 60,000 miles. It cost me a little over $300 at an expensive Mercedes dealership. You can probably get it done for less at an independent shop.

I've had both done once (at 70k miles) and the front re-done (at ~125k miles) on my 190. Now at 150k miles and *just* starting to get the clunk on the downshift - I suspect the rear. Each one is ~$100 for the part (basically a big rubber bushing with some metal inserts for bolts). Have a shop do it though - you have to lower the tranny to get at the front one and I think you need special tools for the driveshaft to get at the rear. My recollection was $450 to have both done (labor intensive) and $300 for for the front only. While in there have them check your tranny mounts - this would be a good time to replace them as well and they seem to wear out between 70-90k miles.

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Makakio
1992 190 2.6
lotsa miles

Thanks! It always helps to speak intelligibly with your repair shop. I have a non-dealer foreign repair shop that I go to but I always feel sticker shock from the repair cost. So, at least now, I can go in with an idea of what it is. What you've described sounds exactly like what the problem is. Again. it's always on the downshift, so perhaps it's just the rear and not the front? How much do you think it would cost for the replacement of the transmission mounts while they're there?

Fastlane sells the mount for $33.33 and shows a list price of $38.00. I would think that there shouldn't be any labor involved to change it if you have the front flex disk changed.

I'll take your advice and visit my local repair shop.

If it turns out not to be the flex disks, it could be sticking transmission bands.

This happens to me on occasion, either on initial shifting when acccelerating on the first drive on a cold/cool day, or on deceleration after the engine/tranny is warmed up after sustained driving.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black