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81 300TDT WAGON , 82 300DT SEDAN, 84 300TDT WAGON(retired),
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Discussion Starter #1
I inspected the flex disc using a flash light under the car, and I saw no cracks at all before.
Last weekend, I was trying to replace the center bearing support according to that nice w123 center bearing replacement step-by-step guide.
After I took off the 6 bolts and using pry bar to try to move the D/S out of the flex disc, I discovered there were cracks on the flex discs between metal and rubbers. I stopped the work. And I ordered two flex discs.
Before I start this work again.
I would like if anybody can help me with the following questions
1, Should I still take off the front piece shaft first? Then the rear piece? Or take them as a whole after unscrew the flex disc bolts?
2, Do I have to lower transmission to access the bolts connecting disc to transmission?
3, what is the torque for bolts connect to the flanges and the 13mm bolts for center support?
4, How to remove the parking brake spring / line/cable?
5, Other advices?
 

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When I did the center bearing, I learned one very important step: mark with paint or something else permanent in one of those grooves (there are three) on the female end of the driveshaft so that when you put it back together, you get the exact same spline. You'll see what I mean about the grooves when you remove the nut.

I found that you had to disconnect both flex discs first. Then I decoupled the driveshaft using a large adjustable wrench to grab the nut. It did not take much effort.

Once the driveshaft was decoupled, I pushed and rotated the front half such that I was able to move it far enough forward to the side of the transmission to get the two parts of the shaft to separate. Then I disconnected the bearing support and pulled the rear half of the driveshaft complete with the support out of the car. Then I was able to get the front part of the shaft out of the tunnel.

You'll just need some patience and an assortment of wrenches/sockets to get the bolts off the flex discs. You will have to put the transmission in neutral to spin the discs so you can reach all of the bolts. It takes a while to get them all off because you get 2-3 clicks of the ratchet at a time.

You do not have to remove the parking brake hardware. I torque the flex disc bolts down about as hard as I can without straining myself which is probably 100-125 lb/ft? I don't know.

I also removed the four rear exhaust donuts so I could lower the exhaust out of the way. I have a lift, so I held up the exhaust with a bungee cord while I worked.
 

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81 300TDT WAGON , 82 300DT SEDAN, 84 300TDT WAGON(retired),
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Discussion Starter #5
When I did the center bearing, I learned one very important step: mark with paint or something else permanent in one of those grooves (there are three) on the female end of the driveshaft so that when you put it back together, you get the exact same spline. You'll see what I mean about the grooves when you remove the nut.
Did you replace the flex discs as well? I tried to do the same thing by following the step in the following links PeachPartsWiki: Driveshaft Support (carrier) Bearing Replacement.

I found that you had to disconnect both flex discs first. Then I decoupled the driveshaft using a large adjustable wrench to grab the nut. It did not take much effort.
Once the driveshaft was decoupled, I pushed and rotated the front half such that I was able to move it far enough forward to the side of the transmission to get the two parts of the shaft to separate. Then I disconnected the bearing support and pulled the rear half of the driveshaft complete with the support out of the car. Then I was able to get the front part of the shaft out of the tunnel.
I don't know that to rotate the front half will move the half forward. I follow the steps descibed in the guide using a pry bar and found the cracks in the flex discs.
This is a good tip:). do you still use pry bar on the rear half.

You'll just need some patience and an assortment of wrenches/sockets to get the bolts off the flex discs. You will have to put the transmission in neutral to spin the discs so you can reach all of the bolts. It takes a while to get them all off because you get 2-3 clicks of the ratchet at a time.
Actually I took all 6 bolts last weekend then I found the cracks on the discs. I decide to order discs and replace all of them.

You do not have to remove the parking brake hardware. I torque the flex disc bolts down about as hard as I can without straining myself which is probably 100-125 lb/ft? I don't know.
I also removed the four rear exhaust donuts so I could lower the exhaust out of the way. I have a lift, so I held up the exhaust with a bungee cord while I worked.
Thanks a lot for those tips.
is the rear half easy to get off after rotate the front half as far as possible?
 

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Rotating the shaft does not make it move forward. You will rotate with the whole shaft to get the front three-spoke bit wedged in alongside the transmission to give you a little extra space to decouple the shaft. Once you get it wedged up there, you should have just enough space to get the two parts of the shaft apart and then just enough space to get the rear portion of the driveshaft out of the rear differential. I used the peach parts tutorial as well as a starting point, but there was no way on my car to get the shaft apart without moving the front half forward. I had to get the two apart to get enough room at the back to get the rear portion of the driveshaft out of the differential. I should have taken pictures, but my hands were covered in slime.

I also would recommend a set of gloves when you work around the transmission mount. I slipped off a nut with the ratchet and sliced deep into my finger on the sharp edge of the transmission mount, which is like a razor edge.

I try to avoid pry bars or anything else that increases my leverage unless I am breaking a bolt loose or I've exhausted myself trying to get it apart by hand. Otherwise things get bent, and with so much aluminum on Mercedes, things can also crack instead of bending. I like rubber mallets before anything else. I don't use air tools to replace bolts anymore either since the bolts are usually steel and the piece they go into aluminum. Guess what strips out first... Aluminum. But that doesn't really apply in this area.
 

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82' Euro 240D 84' 300D 01' SLK320 6 Speed Sport!
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Thats what I will be working on today and tomorrow..Yeh!!:mad: I actually had to order a whole new rear drive shaft $400 from MB dealer..Ordered a new trannny mount, scouted everywhere to find Febi or better and ended up ordering a Febi, got it in and its MADE IN CHINA!! :bs:
 
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