1967 250se coupe diff pinion seal

[grezm0nkey]

started work on the rear end of the car. had the rear right wheel bearing changed out, will work on the left next. i am curious to ask u guys if anyone has changed the diff pinion seal. would it be possible to do so just by removing the drive shaft? or would it have to be done from the insdie of the diff?

oh yeah while i am at it what about the drive shaft center support bearing and rubber mount. any pointers and tips would be grat. thanks in advance.

grez

[MunichTaxi]

Those items are on my 'to do' list, also. I get a small vibration above 45mph (68kmph?).. There is also a brass sleeve bushing at the front driveshaft/ transmission interface that probably needs inspecting (at least). Also check your flex disk for cracks.

[billrei]

Yes replacing the pinon seal is possible by removing the driveshaft. The biggest issue is removing the pinion nut that holds the diff drive flange. Removing the nut requires a special socket with four fingers that interface with cutouts in the nut. I was able to modify an old 1" socket with a dremel and cutoff wheel. Just mark the pattern on the socket face and cut out the sections. I believe Hazet makes the socket for this if you want to go that route.

[billrei]

One other item. When you had the axle bearings out did you repack them with grease? Unlike 99.9% of the axle setups out there the rear bearings in these axles are not lubricated by the hypoid oil in the diff. There is a set of inner seals on the axle that is suppose to isolate the bearing from the oil. I don't think I have yet to take apart any of these axles where the bearings are properly lubricated. There is always a burned smell of over heated oil or dryed up grease!! I believe some small amount of oil does seep by these inner seals but it is not enough to provide proper lubrication. Anyone who owns a 108/109/111 who has not inspected and relubed these bearings is running on borrowed time.

[Arthur Dalton]

Originally Posted by billrei

Yes replacing the pinon seal is possible by removing the driveshaft. The biggest issue is removing the pinion nut that holds the diff drive flange. Removing the nut requires a special socket with four fingers that interface with cutouts in the nut. I was able to modify an old 1" socket with a dremel and cutoff wheel. Just mark the pattern on the socket face and cut out the sections. I believe Hazet makes the socket for this if you want to go that route.

The biggest issue when changing the seal is that the flange nut has to be indexed so it goes back on to the same mark.
There is a crush spacer between the pinion bearings that is set to preload at the factory and if you go beyound this point , the 2 bearings will fail.
The proper way to do it is to jack the axles til the tires are off the ground , and free turning [ no brake drag] . You then put a torque wrench on the
pinion flange nut to check the force it takes to turn the pinion shaft . The spec on this is a preload force of 22-26 inch/lbs. To attain this , you tighten the nut in small increments [ I use 1/8" at a time] til it takes spec force to turn shaft. That will result in correct bearing loading. Go very slow, b/c if you go BEYOND spec, you crush the bearing crush spacer too much and it then has to be replaced
The indexing before removal will save you all this hassle...

[autozen]

Arthur,
I used to hate doing rear pinion seals just because of that crush sleeve. Are you saying to chisel mark the nut and shaft and spin the nut on til tight. Then tighten nut til marks line up? Please explain better.

Thanks,
Peter

[Arthur Dalton]

Originally Posted by autozen

Arthur,
I used to hate doing rear pinion seals just because of that crush sleeve. Are you saying to chisel mark the nut and shaft and spin the nut on til tight. Then tighten nut til marks line up? Please explain better.

Thanks,
Peter

Hello Peter.

Yes , by marking the nuts previous position before removal, you are assured that you will not go beyond the original setting of the crush sleeve. I just use some white paint and then put a fine line on the paint dabs with a blk marker pen.
The easiest way to explain the way this pinion bearing set-up works is to compare it to a front wheel bearing. As we all know, as you tighten the wheel bearing nut , you are setting the preload on the beaings [ inner/outer]. Too tight and you strain the bearings. too loose and the tire wobbles.
Well, on the pinion, you have the same set up [ an inner and outer bearing supporting the pinion shaft, but ..in between the bearings is this crush sleeve.
So, as you tighten the nut , the sleeve collapsed [ shortens] and while doing so, it puts opposing pressure on the bearings [ they are angular-like the wheel bearings, facing each other]
What Benz wants is a certain amount of preload on these bearings. As you tighten the nut , the load INCREASES.. The BIG problem here is that , unlike a wheel bearing, if you go too far [ crush the sleeve too much] , you can't take it back.. it is crushed and you can not lengthen it back/longer..it is KAPUT....so yu have to go replace it and start all over again..not good !!!!
By indexing , you are where you were before you got in there.
I have some classic cars that use this swing axle set-up and I am fussy, so I actually measure the preload with a torque wrench and set it to spec. The advantage here is that you are not relying on the previous set-up to be correct, but rather , I am resetting the preload to original specs. This is better b/c sometimes the previous setting is off due to normal bearing wear.
So, torque measurement can get a worn diff. back to spec with torque measure. [This is also a consideration for me b/c it takes up any slop]
I have indexed some and then checked them with a torque measure just for kicks and have never found one that did not require a Smidgeon more on the nut.
Don't confuse the tightening torque on the nut with the torque that it takes to turn the shaft .. they are two completely different measures and are on very different ends of the scale.
The turning torque is in the low inch/lbs and the nut tighten torque is in the high ft/lbs.
make sense????????????????/

[autozen]

Thanks. Good write up. I'll remember the index trick if I ever have to do one again. I used to keep a couple of crusd sleeves in stock in the old days. I don't work on these anymore. I still have all my special tools for replacing the sliding jount. It used to be I could do one of those on jack stands by the road side. I use AAA 100 mile tow now. Gettin old I guess.

Peter

[Arthur Dalton]

<<>

Cool..
I have mde up a couple of tool designs for DIYers to centralize the rear pivot pin to the chassis center-line. You prob have the original.
Nobody does these measures anymore , but i sure do...
Lots of guys are using the 4.5 , 3"27 swings on their 113s with good results.. with the added benefit of rear disc modification for the 230sl..
I also agree with your other post on the compensating spring conversions

[autozen]

I have a 67 230SL buried under a bunch of junk in my garage next to a 3.5 Coupe buried under a bunch of junk. I've used the SL for camping trips many times and have never had a problem with the drum brakes in severe use, but the 4.5 rearend intrigues me. How does the power, torque, and fuel MPG work out?

Peter

[Arthur Dalton]

The changeout is only recommended for 113 with 4 speed stick.
You gain top end , lower cruise rpm without too much accel drop.
It also allows for lower profile tires , as the original were 80 profile Euro.
Hard to find..
The 5 speed ZF comes out to the same math as the rpms of the 4 speed with 3:27...

[Arthur Dalton]

Peter
Do you have any 113 NOS parts hanging around???????????

[autozen]

Arthur,
What are you looking for? My 230SL has a K4A025 box. When I rebuilt the engine many many years ago, I swapped the crank to get rid of the aluminum fluid coupling. I have the steel version.

Peter

[grezm0nkey]

thanks for all the info. i placed an order for a flex kit, drive shaft support bearing, bushing and sleeve, and a pinion seal. couldnt find the pinion bearings or crush sleeve. should arrive tomorrow or next day.

since you have mentioned the diff pinion preload on bearing. when i got the rear bearing replaced, i noticed the mech didnt set any preload on the rear cover plate. would that cover plate set a preload too for the rear bearings? and yes i did pack the bearings before setting. oil looked good draining from the diff.

i plan to do the front bearings too, good to know the preload, thanks again. ill post how it all comes together.

grez

[Arthur Dalton]

Originally Posted by autozen

Arthur,
What are you looking for? My 230SL has a K4A025 box. When I rebuilt the engine many many years ago, I swapped the crank to get rid of the aluminum fluid coupling. I have the steel version.

Peter

Mostly trim and chrome parts.
.and FI pumps a that kind of stuff..