Preparing to replace both flex discs...and center bearing/carrier.... - PeachParts Mercedes-Benz Forum

pawoSD · #1 08-27-2007, 08:24 PM

I was under my car last friday dealing with a rattle my bracket on my straight pipe was making, when I decided to check my flex discs. And am I GLAD I DID.

The front one is visibly breaking apart. Many cracks...and around a few of the bolt things the rubber is actually torn and breaking apart!

Explains the driveline vibrations I've been getting. The rear one has a couple tiny cracks....nothing major....but I'm taking the whole shaft off so both are going to be replaced. I'm also changing out the center bearing/carrier etc, as I already have all the parts in my inventory, and the stuff on the car is likely old/worn out anyways. Today I got a pair of big channel locks to get the sleeve nut loose on the shaft...and I think I have most other tools. The flex discs should be coming in a couple days....then I will have all parts I need.

Thanks to the helpful postings of tobybul I understand how it comes out/fits together....so I am not too worried about the project.

The dealer wanted $350....I say no way.

My biggest questions are: Any special tools needed to get at the flex disc bolts? And, in the FSM it specifies Molykote grease or something for putting the two halfs of the shaft back together....do I need this? Or is there another suitable grease for the center bearing/splines that I could use that'd work just as well? As for pulling the bearing off the shaft....will a normal bearing puller work? I think I can rent one at autozone....if not I'll just buy it at sears....I read that to put it back on all you need is a rubber mallet and maybe a 2" piece of pipe...sounds pretty straight forward.

I will probably be doing this later in the week....as soon as my parts come and I have some free time. I think I might try to take some pictures...if I am up to it.

In the meantime I have been driving around in our bought-in-january-but-not-yet-driven 300D. Its a fun little car...slow as heck off the line then it burries you in your seat with power/torque. The throttle pedal is like squashing a sponge....and shifts are a bit quick....but they're rock firm and the engine/entire driveline is in perfect shape. Interior is nice. Klima is messed up...vac locks don't work (they're disconnected) takes 15 seconds to shut down....(every time)

but it has little to no rust...and the price was right. It even has working cruise! I did 130 miles at 82mph over the weekend and it drives straight and smooth....no vibration at all. Its a nice little car. I still prefer the W126 though....its just not the same....

94mgm · #2 08-27-2007, 08:33 PM

no special tools needed besides a 14mm hex wrench for the drain plug. i JUST finished the exact same job + oil change

pawoSD · #3 08-27-2007, 08:56 PM

Quote:

Originally Posted by 94mgm

no special tools needed besides a 14mm hex wrench for the drain plug. i JUST finished the exact same job + oil change

By drain plug do you mean the one on the engine?

My oil change is about 1,800 miles away....so I am good there for a while yet.

Some have mentioned that its hard to get at the bolts on the front flex disc....anyone have specific tips on getting those off?

I'll probably be replacing my rear CV axles too....(or just the boots) in the next year or so....as they are quite cracked.....we'll see how long they last. I already have a diff mount ready in my inventory so I can replace that too.

deerefanatic · #4 08-27-2007, 09:27 PM

Yah, I just pounded the driveshaft out of the bearing with a brass hammer. Mushroomed it a little, but not enough to effect anything.... I didn't even bother to line the halves of the driveshaft back up...... didn't know you had to until too late.... No vibrations or anything......

guess I'm just lucky?

winmutt · #5 08-27-2007, 10:54 PM

Changing the front flex disk with the 300d dampener for the manual drive train was a PITA, the old bolts were allen which was pretty easy the new ones are 15mm but I only have 1 of half a dozen 15mm that will fit it.

pawoSD · #6 08-27-2007, 11:03 PM

I read that the allen key style ones (Lemforder) are easy to round out....so I didn't buy those. which kind is actually easier? Hex or Allen Style bolts? All our cars have the hex style ones....and its what I ordered....so I guess I'll have to manage....but for in the future....is one of the two types easier to install or remove than the other?

pawoSD · #7 08-27-2007, 11:56 PM

Also, I am still wondering on the best type of grease to use when re-assembling the driveshaft and center bearing assembly....do I need the special german MolyKote stuff....or is there another grease that will do an equally good job? Anyone?

Jeremy5848 · #8 08-28-2007, 12:18 AM

Quote:

Originally Posted by pawoSD

I read that the allen key style ones (Lemforder) are easy to round out....so I didn't buy those. which kind is actually easier? Hex or Allen Style bolts? All our cars have the hex style ones....and its what I ordered....so I guess I'll have to manage....but for in the future....is one of the two types easier to install or remove than the other?

My wrench would definitely go for the hex style -- I found him cussing over a stripped Allen head cap screw on a water pump a couple of weeks ago. The hex head has a larger surface area to grab onto.

toomany MBZ · #9 08-28-2007, 06:24 AM

In relation to the Moly part, check into this, may help. http://en.wikipedia.org/wiki/Molybdenum_disulfide

pawoSD · #10 08-28-2007, 06:22 PM

Quote:

Originally Posted by toomany MBZ

In relation to the Moly part, check into this, may help. http://en.wikipedia.org/wiki/Molybdenum_disulfide

Ok....so do I need to get the german version of the stuff? or is there an american made equivalent I could use?

kerry · #11 08-28-2007, 06:29 PM

In my uninformed opinion, just about any grease should work. In a pinch, lard might even get you by. It's not like the joint gets a lot of action since the differential and transmission are much more relatively fixed than in a solid axle system where the differential goes up and down.

Mister Byrnzoil · #12 08-28-2007, 08:00 PM

crows foot for the front flex disc, made the job much easier on my 84

toomany MBZ · #13 08-28-2007, 09:44 PM

I think tobybul means 46mm. I've heard a 1 13/16 inch equivalent. pawoSD, don't think German origin necessary, marking drive shaft on flex disc parts is a good idea.

Hatterasguy · #14 08-28-2007, 10:22 PM

Make sure to mark the driveshaft and put it back together the same way it came out. I used white out.

Use any grease for the splines, they hardly move. I think I used wheel bearing grease.

The flex discs tend to stick, I needed to use a large screwdriver to pry them off the output shafts.

Its a messy job, but not a hard one.

pawoSD · #15 08-28-2007, 10:30 PM

Yeah we have a tub of good quality castrol bearing grease....I'll just use that. I think I will try to do the job Friday night....if it has to be an all nighter....so be it.

I'll be sure to mark the shaft before disassembly as it is an early '82....produced exactly 4 months before they began putting a mark on the two halves. I know my shaft has been out at least twice....it has some red stripes and blue stripes on it.

I will probably use neon orange or something

I miss my car....a W123 (that needs some work) is no match for the ride and feel of a W126.....

Tomorrow morning I am changing the diff oil on the 300D....as it whines around 50-60mph under acceleration.....it is....dirty on the bottom. So I hope there's at least some oil in there still!

I'll be putting some Mobil 1 synthetic diff oil in there.....maybe that will quiet it down. At the very least I'll know there's new/proper level of fluid in it!