Homokinetic Joint Disassembly - 300SD W126

[Richard Howard]

After searching and looking at many threads here on rear axles and their boots, I need to ask for information I've not found so far...

The rear axles on my 82 300SD W126 are the homokinetic type and still had the original boots in place as oil drained when I cut the boots off the shafts. I've decided to reuse these original joints as they're noise-free and apparently still have much of the factory heat-treated surfaces intact where the balls ride. After disassembly of the joints and a thorough cleaning of all the parts in mineral spirits, I plan to reassemble with four of the Astoria Flexx boots - chosen because of their supposedly extreme flexibility and durability. For lube, I plan to use the supplied molybdenum disulfide MoS2 grease; the boot kits appear to be from somewhere in the EU.

Question: How are these homokinetic joints taken apart? I've found no snap rings and when looking at the ends of an axle shaft itself I think I see the ends of splines where they enter the "three-arm" castings that contact the housing when the joint is flexed to its limit.

I've used a brass drift and hammer to try to drive the "three-arm" casting away from the shaft (secured in a large vise) but haven't had any success so far. Does this joint disassembly require the use of a press? I have one available.

Thanks for any information on this disassembly precedure...

[nlines]

I do not think it is easy to disassemble these axles. I have seen a video on Youtube I think, which shows how to use a funnel to help slip the boot over the joint. it seems to work good.

[Diesel911]

I believe the FSM shows using a Hydraulic press to press them apart. I also believe it shows that you un-crimp the tapered part (the part where the Boot clamps to) of what I call the Cans and remove them to get inside.
They sell kits that have new Cans that you have to find a way to crimp over yourself.

I think you are going into near virgin territory. I only read one post where a member used a press to take apart their axle. Don't forget to post some pictures.

If it was me and I was dead set on reusing the Axles and re-botting them I would buy a gallon of solovent (like mechanics use) and a solovent sprayer (cheap at Harbor Freignt). I would leave the Axles intack a shove the solovent sprayer inside the Cans and spray out all of the old oil.
After the solovent has completely dried I would find someway to pack the grease up into where the balls are in the joint. After which I would do the re-booting.

I did the above to a Chevy Citation and put on a Split Boot over 10 years ago and that CV joint is still OK today.

I also believe that if you do take the Joint apart it is a good idea to keep the same Balls in the Same space that the came out of and both parts of the Joint indexed to same place the came aprt from.

[Nashvillecat]

I am facing the same situation with an 85 300SD. I was going to upgrade to the newer axles but could not find the stub axle to install on the differential so I decided to clean, grease and reboot the original homokinetic axles.

I so far have not been able to get the axles out of my car. They will not compress enough to clear the wheel bearing. Does anyone have any suggestions for this increasing the clearance?

Also I found a product by Dorman UNI-FIT and Multi-Fit that are supposed to allow installation of the boot without disassembly. Part number 614-040 and 614-050. Around $75 saw on their website.

[Richard Howard]

Nashvillecat: I had a tedious time getting the first axle out... intend to do one first, reinstall on the car, then do the other. I also had almost no clearance between the outer splined end of the axle and the wheel bearing's grease seal.

Finally after raising the differential slightly higher I was able to get the axle end past the seal, got it to clear by going towards the parking brake's cable jacket and not towards the spring. I did produce some distortion at several places on the outer "can's" lip, where the shaft contacts it at its limit of flex. I expect to be able to reform the lip with careful use of a small adjustable wrench or small ball pein hammer.

I did not disconnect the lower shock attachment but will do so before the reinstall - it may, as other threads indicate, allow a bit more drop of the swing arm to allow the splined end to get past the seal and enter the hub a little easier.

Maybe some of the more experienced people here will soon post information on the actual disassembly of the joint. If this procedure seems too questionable, I may then flush out the old lube as mentioned above with solvent and relube the parts. It would however be great to be able to disassemble only one joint on each axle and install both new boots without the use of the expensive stretching tool. I also don't look forward to using gorilla-tactics along with a quart or so of silicone spray to stretch the Flexx boot's small end over the joint's housing/can - it seems like it's beyond the laws of physics!

[Diesel911]

Decided to look up some stuff in the FSM.
The big part of the "Can" on the Axle is called the Protective Sleeve and the the part of the Can that the Boot clamps onto is called Stop Sleeve.
In the FSM they show a tool to cut off (the crimp that holds it to gether) the Stop Sleeve. After the Stop Sleeve is cut off you can pull the Axle apart.

At this point with the FSM method of replacing the Boot you would put the Axle into a Hydraulic Press and press off the Spider from the Axle. Slide the new Boot on. Press the Spider back onto the Axle.
Of coures int is not necessary to press anything off if you have another way to expand the boot but if you want to take apart the Axle CV joint to take a look you need to cut off/remove the Stop Sleeve.
If you cut the Stop Sleeve Off you will need a new one and have to find some way to crimp it back on.

It maybe possible with a lot of careful work to uncrimp the old Stop Sleeve so that you can reuse it; but, i have not read anythig as to how to do this.

[burford]

Richard, These joints are big. Use twice the amount of grease. MB says use 310
grams I think. Anyway, I did this job with the flexx boots developed some noise after 3k miles, used more grease and no more problem.

[waybomb]

I cut my cans off when I needed to replace cracked boots and tig welded the new ones together. I ground the flange off, and welded. No need for special tools.

[Diesel911]

Originally Posted by waybomb

I cut my cans off when I needed to replace cracked boots and tig welded the new ones together. I ground the flange off, and welded. No need for special tools.

A Tig Welder; not a special tool???

I one of the Posts I read they crimped on the now Stop Sleeve with a Channel Locks.

[waybomb]

Ok, it is special, but can be used for many things. That's what I meant - not a dedicated one-use tool.

When I did the job, I though about using a pliers, but I was concerned about getting the crimp tight and consistent. The welder is always available, so, went and welded it together. For sure it will not leak nor come apart on its own.

[Diesel911]

Does anyone out there know if Homokenetic Axles for a 126 are fatter that then 123 Axles?
Here is the a site showing how to replace the boot; uses a different tool but you can see how much the fb3001 will stretch about 11 pics down from the top.
http://www.dieselgiant.com/mercedesaxleshaftbootreplace.htm

[Diesel911]

The Homokenetic axles rebuilt or new seem to be more available and less expensive.

So far I have not read anything about the Annular ones functioning better than the Homokenetic ones.

The New made in China Axles are Homokenetic.

[SD300]

I think mines are the anular type, since it has a large disk similar to a disc brake rotor there.

are those less hassle than the homokinetic style?
anular type no need to pull the back cover of the diff to remove the C clip?
TIA