The original post from two years ago was revived recently but got off topic so here is a new thread and a link to the old one.

Vibration assistance needed - Manual Transmission Related?

It seems that many auto to manual conversions suffer from some vibration issues. While many of the suggestions dealing with balancing the driveshaft, changing the bearing mount, making sure there is no metal to metal contact, etc, have been somewhat helpful, most of the vibration was still present at least when I tied it.

I found a friend with a european 300D with a 4 speed manual. When I looked at the way the tranny was mounted I was surprised to see that the transmission crossmember/mount was NOT like the 240D manual, nor was it like the 300D automatic. Nautrally, I swaped in the euro cross member and mount into my car and low and behold, 90% of the offending vibrations went away.

There was not much hope is visiting the yard to search for a euro 300D manual, but I thought that, Germans being Germans, mbz might have used the same crossmember on a 240D AUTOMATIC!

It turns out to be true, the 240D Automatic transmission crossmember is the same as the 300D european manual crossmember. The mounts themselves are indeed different, the 240 has narrow mounts, while the 300 has a thick mount, close to twice as thick.

So here is another piece that no longer needs to be fabricated for the conversion. I am still experimenting with different mounts, there are quite a few versions, but even with my old auto trans mount the large majority, but not all, of the vibrations have been eliminated.

Here is a picture of the 3 different crossmember types. (You can ignore the bar that is attached to the auto 300D mount, that was my old mounting solution.)

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Very cool discovery! Thanks!!!

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Never a dull moment at Berry Hill Farm.

Very interesting for sure. As I remember that 4 bolt cross member was also used on the Euro 240D with a 5 speed that I swapped out last year.

Thanks

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Yes, interesting indeed.

I have a crossmember from a 280TE with 5-speed and it looks very much like the 300D auto version except with less "dish"? It's hard to judge in the photo.

I suspect that these cars are very sensative to variations in driveline angles. It is probably not as important with trucks because they have stiffer couplings (less chance to develop high-amplitude vibration) and more vibration in general.

Ted

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1983 240D automatic, Orient Red, 174K
1983 240D manual, Biscayne Blue, sold at 341K

I think this could set off a rash of automatic 240D "cross member" strippings They'l be showing up on eBay soon.

Matter of fact I think I have one out in the trunk of a parts car.

That "2 holer" does look spindely compaired to the "4 holer"

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Since installing the crossmember I tried a couple of different trans mounts with some interesting effects.

Firstly the 300D euro that I originally looked at had a W124 mount (built in safety) Part #124 240 0018. It seemed to give very satisfactory results. Keep in mind that the underlying vibration seemed to be present but its amplitude was dramatically reduced. Its possible that my original setup, with the extension bar, was particularly prone to vibration, which sounded like a hollow drone that resonated in the body of the wagon.

I also tried a 240D mount (with the round hole) with and without using the center sleeve and bolt. With the sleeve and bolt there was some harsh vibration at idle but I thought I could feel the drivetrain tighten up at speeds too. With out the sleeve/bolt there was a bit more vibration at speed, likely due to the fact that the 240D mount is maybe 40% narrower than the 300D or even the 124 body trans mount.

Overall I think the original 300TDT auto mount is a safe bet, but if you have a variety readily available it might be worth trying the different ones. Please post if you find a particularly good one.


The last mount is from a W124.

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