Got the w124 300d Diff mount repaired! - PeachParts Mercedes-Benz Forum

777funk · #1 04-20-2007, 07:05 PM

After several weeks of 1 hour at a time on changing the Differential Subframe mounts (bushings) on my 87 300d I finally got it! Yeah!!!!

Very simple when it comes down to it. And really wasn't that hard to get out using the puller (sir tools sold by performance products)

If you're changing the differential mounts here are your steps:
1. Jack the car and put jack stands under the rear jacking points. Basically get the wheels off the ground an inch or two.

2. Let down the rear half of the drive shaft (the drive shaft has two pieces joined near the center support bearing) so you can push the differential forward so it's outta your way. To do this here's what you need to do:
a. Spray paint or mark a spot on the flexdisc and one of the 3 driveshaft lobes so that you can re-connect the two in the exact same spot again. If you don't you'll have problems with balance later. I've read it'll vibrate like crazy.
b. Unbolt the 3 bolts that hold the flex disc to the differential (You can leave the other 3 that hold the driveshaft to the flexdisc on).
c. Push the driveshaft toward the front of the car to separate it from the flex disc. It needs to push out and away from the flexdisc by about 1 inch. (I removed the two center bearing bolts may be necessary, may not. If it's hard to push the drive shaft toward the front of the car undo these two bolts and try again it should work) Took me about half my strength while under the car to separate the two My guess is about 50-70 lbs pushing force away from the diff. Just grab it and push hard!

3. Take the diff down. Unbolt the two rear bolts (Allen 12mm socket) (in the old diff mounts/subframe bushing), then unbolt the top mount (Allen 8mm socket). There is a 17mm nut that is super hard to reach on the bolt of that top mount. It's between the metal frame above the top diff mount and the floor of the vehicle.

I bent a wrench to the shape of my hand (pretty much just an L with the shorter side being the box end) when touching that nut in order to have a tool to hold the nut steady while removing the bolt. Very hard without the bent up wrench. With it piece of cake! Just blow torch a cheap Wal-mart wrench til it's red hot then bend it with a pliers (you won't use your hand to bend it if you're smart Then cool it in cold water immediately. The wrench size you'll need is 17mm use the box end to hold that nut.

4. Now that the diff's outta the way, put the puller in place. REMEMBER, you want to pull the old Mounts out toward the FRONT of the car. They will come out VERY easily (using the puller) if you do this. They CANNOT be pulled out toward the rear. DO NOT BANG THEM OUT WITH A HAMMER, unless you want to mess up your subframe.

5. Put the new ones in from the front side of the car and push toward the rear (just the reverse of direction 4). PLEASE Note you want to put them back in just like they were when factory installed. Take a picture if you think you'll forget. This means orientation and how far they are pushed in. Just put them back in slowly and check occassionally if you think you're going too far.

Then put it all back together again just like you took it apart and you're set!

If this job is done right I'm sure it can be done by an amateur in about 2-3 hours tops. Good luck!

bellyboy · #2 04-20-2007, 09:31 PM

i did mine today-went great

Jeremy5848 · #3 04-21-2007, 02:57 PM

Quote:

Originally Posted by 777funk

... using the puller (sir tools sold by performance products)...

The only tool by Sir Tools that Performance Products lists on their web site is a "panel removal kit." I'm sure that's not what you used.

Can you provide a better description so I get the right tool?

Thanks for the great description of the project.

Jeremy

777funk · #4 04-23-2007, 07:27 PM

Quote:

Originally Posted by Jeremy5848

The only tool by Sir Tools that Performance Products lists on their web site is a "panel removal kit." I'm sure that's not what you used.

Can you provide a better description so I get the right tool?

Thanks for the great description of the project.

Jeremy

Sure,
Here is the link and item number:
http://www.performanceproducts4benz.com/productpage.aspx?pid=105960&name=Sub+Frame+Bushing+Tool

Item number 58-076

It's also on the Sirtools website. You can buy it a few other places. Some cats on this site even say you can make one. I'm not creative enough with my metalworking skills so I coughed up the $100 and bought it.

Hope that helps.
Nick

777funk · #5 04-23-2007, 07:30 PM

Quote:

Originally Posted by bellyboy

i did mine today-went great

Glad to hear! Hope the steps I gave helped. It's so nice to be able to get give help. Takes away alot of headache!

gsxr · #6 04-30-2007, 04:37 PM

Quote:

Originally Posted by 777funk

5. Put the new ones in from the front side of the car and push toward the rear (just the reverse of direction 4). PLEASE Note you want to put them back in just like they were when factory installed. Take a picture if you think you'll forget. This means orientation and how far they are pushed in. Just put them back in slowly and check occassionally if you think you're going too far.

Excellent write-up! The portion I highlighted in bold, above, is critical. Make sure you install the new ones in precisely the same position, and note that left and right may NOT be pulled in the same distance. The factory tool is much more complex than just a simple puller/extractor, it also measures the forward/back location of the bushing. Here's a link to the service manual procedure:

http://www.w124performance.com/service/w124CD2/Program/Chassis/35-050.pdf

TheDon · #7 06-04-2012, 01:00 PM

bumping this up since I need to do this job.

Good guess is that when working with the differential is to keep a floor jack under the pumpkin and slowly lower it.

The FSM shows two different methods for this job, one involves removing the half shafts and one does not. I am guessing this method leaves them attached.

The other issue I have is the press for the job, I do not want to buy one and I cannot make one so I need to borrow one, does anyone have one I could rent? Thanks

240dddd · #8 11-12-2018, 02:19 PM

Planning to tack this job on a 1987 300TD. I have the aftermarket bushing tool, but I'm still trying to understand whether the diff needs to come all the way out or if there is a way to create enough room without disconnecting the half-shafts and removing the diff?

sixto · #9 11-12-2018, 07:49 PM

On a sedan without SLS, removing the flex disk and unhooking the exhaust should be enough to lower the diff with axles attached clear of the bushings. I don’t know if/how SLS changes the game. Don’t forget the bushings on top of the diff.

Sixto
98 E320s sedan and wagon
02 C320 wagon