Auto-Manual Tranny swap in need of advice - Page 2 - PeachParts Mercedes-Benz Forum

jaysun9 · #16 05-06-2008, 11:54 AM

So just out of curiousity (because I was thinking about how nice it would be to have the manufactured mount for this chassis) where would one look to find that part.....On the good side I had a driveline service modify the shaft and did a killer job on the DS so I'm feeling pretty good about that piece....

bgkast · #17 05-06-2008, 12:51 PM

The dealer could probably order it for you. Do you have a part # on yours Winmutt?

winmutt · #18 05-06-2008, 01:05 PM

Someone with EPC access can pull it up. I believe the correct parts can be found on some 116 chassis and *maybe* 126 coupes. It has 4 bolt points like the auto xmember but sits further up.

KarTek · #19 05-06-2008, 01:30 PM

A universal joint is not a "constant velocity" joint which is to say that when it's transmitting power through a bend, the speed of the output shaft rises and falls a couple times per revolution even though the input speed is constant. The more severe the angle, the more the output speed fluctuates. This is why most driveshafts have them in pairs because the input joint introduces the speed fluctuations and the output joint cancells them out and you end up with constant speed. In a single joint system, the input shaft and the output shaft (before and after the joint) must be as straight as possible to one another or you get vibration - sometimes bad enough to break things, loosen mounts, bolts, etc... if the rest of the drivetrain isn't compliant enough to absorb it. Since the Mercedes has a IRS, there's not much flex in the dif. mount to absorb any vibration and you 'll feel it right through the body of the car.

Bajaman · #20 05-06-2008, 02:21 PM

Jaysun, You said that you dialed into a sweet spot, or drastically reduced the vibration, can you tell me what exactly you did? I have the manual 240D trans x-member and I tried lowering it two washers or about 3/16".

jaysun9 · #21 05-07-2008, 12:37 AM

So been playing around and have found a solution that dialed the driveline with from what I can tell no vibration! Pulled the trans mount, cut two 5/16" steel strips about 2.5" by about 3.5", layed them across the top of the mount and welded to form a nice flat new mounting surface......Drilled out new mounting holes, re-attached trans mount, got back in car and hoped for the best....Took a test drive through all gears and came back with a big smile.
Worked out much better than the washers and fits nice against the chassis. Officially and claim the veg-burning 84 300CD manual trans....Thanks for all the help out there as I'm finally feeling accomplished on this one.

barry123400 · #22 05-07-2008, 01:06 AM

It's starting to sound like a critical alignment job on the driveshaft. I guess two targets with holes could be fabricated and a cheap laser bolted to the driveshaft to get it running on the same exact plane. . Would allow minute adjustments to be preformed that escaped the human eye.

jaysun9 · #23 05-07-2008, 01:30 AM

Yea it's definately crucial to line up the DS as precise as possible....Bajaman let me get back to you on the exact measurements I'm not sure if it was 5/16 or other....I'll double check that one

winmutt · #24 05-07-2008, 10:56 AM

If you can use the thicker mount as well.

Bajaman · #25 05-07-2008, 11:54 AM

Quote:

Originally Posted by winmutt

If you can use the thicker mount as well.

What?

winmutt · #26 05-07-2008, 12:03 PM

There are a variety of trans mounts made. Those people who are using the the 240d cross member have 2 options, one that is solid and another that has a rod through it. There is also a wider thicker one used for automatics and turbos if you are using the automatic cross member there are two widths as well. You'll want the thickest one available or go solid as some members have.

jaysun9 · #27 05-07-2008, 12:46 PM

With the 2 choices of mounts related to the 240D, Is the difference in choices dependent between the earlier models and the late models?

Bajaman · #28 05-07-2008, 12:55 PM

I only found mounts that have the hole? One round and one oval? Didn't see a solid one.

winmutt · #29 05-07-2008, 01:08 PM

Quote:

Originally Posted by Bajaman

I only found mounts that have the hole? One round and one oval? Didn't see a solid one.

The solid one would have to be fabbed (solid metal). Personally I would go with the auto one as it is heavy duty.