Propshaft Flexi disc replacement

[g2000tpembroke]

Happy new year all
I’m trying to replace my Propshaft Flexi disc and I am struggling to remove the centering cross, do I need some kind of special tool or pullers to remove it?  Also when replacing the cross when refitting should it just slide back on or is there more to it? Lots of great info about replacing the Flexi joint but nothing about the removal and refitting of the centering cross flange is this an unusual problem?
Thanks in advance for your help

Gary Tingle

[rwmastel]

What is this centering cross?  Do you have a pic?  I don't see it mentioned in Tech Manual - https://www.sl113.org/wiki/DriveShaft/FlexDisc

[Charles 230SL]

hello, I believe Pembroke is referring to the transmission flange. A special socket/tool is needed to remove the flange nut - several members of this group have made their own tool using a 1 1/8 socket. More information here: https://www.sl113.org/forums/index.php?topic=35192.msg257355#msg257355.

[rwmastel]

OK, I had not heard that term before.  Also, I didn't know you had to remove a flange to replace the flex disk.

[Charles 230SL]

hello, I believe Pembroke is referring to the transmission flange. A special socket/tool is needed to remove the flange nut - several members of this group have made their own tool using a 1 1/8 socket. More information here: https://www.sl113.org/forums/index.php?topic=35192.msg257355#msg257355.

oops, disregard my last. Pembroke is not referring to the transmission flange but rather the "centering cross" on the driveshaft-side of the flex disc,,(please accept my apologies).  Attached is another photo of it - 

[rwmastel]

Looks a lot like a flange to me.  I understand it's on the drive shaft side, but what's the difference between flange and centering cross?  Just trying to learn something new.

Edit:  I think I figured it out.  Looking at the well notated picture of an installed flex disk in the Tech Manual (link I posted above), I do see what appears to be an additional part between the drive shaft flange and the flex disk.  That must be the centering cross??  What is its purpose?  Well, centering of course, but since it appears to be the same shape as the flange, why doesn't one part do everything?  Should additional detail be added to our Tech Manual?

Edit 2:  Attached is a really good pic showing the centering cross between the flex disk and drive shaft flange.  (It also shows the flex disk installed in reverse with tabs on drive shaft side, and drive shaft flange bolts in backwards.)  It is from this old thread.  https://www.sl113.org/forums/index.php?topic=6298.0

Does the centering cross normally just stay stuck to the drive shaft flange when separating this assembly?

@g2000tpembroke (Gary) - Are you replacing yours with a new one, or are you just saying that it came off the drive shaft and your having difficulty placing it back in?  Did it just fall off, or did you have to pry it off, or is it connected with nut or clip ring or something?  Sorry for the questions, I've not done this job before and I don't now how these parts are assembled together.

I learn something new all the time here.

[ja17]

The centering cross (aluminum flange), should remove easily from the driveshaft flange. Start first removing the three bolts at the driveshaft flange. Loosen up the drive shaft slip joint in preparation to slide the drive shaft rearward. I usually remove the two bolts holding the drive shaft center support at the center of the car also. Once the three bolts at the drive shaft flange have been removed, separate the centering cross (aluminum flange), from the steel driveshaft flange. Once split, slide the drive shaft rearward to gain clearance. If the centering flange is stuck, bump it with a plastic mallet, or rotate it with a blunt drift. You can remove the centering cross with the rubber flex disc once all driveshaft bolts have been removed.

[wwheeler]

Be sure to replace the rubber ring in front of the aluminum centering flange. Keeps the grease from slinging on the flex plate.  https://www.authenticclassics.com/Mercedes-Rubber-Ring-Driveshaft-Centering-Cross-p/auth-008851.htm

[ja17]

Thanks  Wallace, and in addition there is a second, smaller, rubber O-ring you can replace that goes between the centering cross and the driveshaft.(also shown in the diagram)

[g2000tpembroke]

We couldn’t split the sliding joint nut as it was seized solid so we disconnected the prop shaft front, Center and rear and slid it back, the centering cross was left on the gearbox output shaft? The only way we could get it off was to use a small 3 legged gear puller!
I take it that the centering cross should just slide on and off the shaft by hand??
I appreciate that the propshaft will need some TLC before being re-fitted.
Thanks for all the reply’s so far

[rwmastel]

... the centering cross was left on the gearbox output shaft? The only way we could get it off was to use a small 3 legged gear puller!

In the images, the centering cross is between the flex disc and prop shaft.  Help me understand how yours would be stuck to the transmission output shaft.

Do these seal rings always come with a flex disc, or always purchased separately?

[TJMart]

We couldn’t split the sliding joint nut as it was seized solid so we disconnected the prop shaft front, Center and rear and slid it back, the centering cross was left on the gearbox output shaft? The only way we could get it off was to use a small 3 legged gear puller!
I take it that the centering cross should just slide on and off the shaft by hand??
I appreciate that the propshaft will need some TLC before being re-fitted.
Thanks for all the reply’s so far

The centering cross slides on and off without any force. You may want to take the C clip off your old one and remove the guts on the inside. Perhaps something was damaged inside that caused the cross to adhere to the shaft.

[TJMart]

In the images, the centering cross is between the flex disc and prop shaft.  Help me understand how yours would be stuck to the transmission output shaft.

Do these seal rings always come with a flex disc, or always purchased separately?

Rodd the seal and o ring must be purchased separately. Seal is part #180-997-10-40 and o ring part #120-411-00-60-64. These numbers are for my 1970 280SL and may be different for other years.

[ja17]

Yes the centering cross should be easily removable. It was probably never greased or damaged during a previous repair. Notice the grease zerk on the drive shaft!

[ja17]

Unless you have the special wrenches for the sliding joint nut, loosening can sometimes be difficult. Some heat can help. If all else fails, disconnect at the differential (as you did).

[wwheeler]

Joe mentioned greasing the centering joint and is usually forgotten. I remember the first time I did that after the driveshaft overhaul. It took about 20 to 30 pumps of the grease gun. It holds a LOT of grease. So don't give up until the grease pushes out the check valve opposite the zerk fitting.

[Benz Dr.]

Joe mentioned greasing the centering joint and is usually forgotten. I remember the first time I did that after the driveshaft overhaul. It took about 20 to 30 pumps of the grease gun. It holds a LOT of grease. So don't give up until the grease pushes out the check valve opposite the zerk fitting.

This is applicable to early cars like 190SL or 220S whereas the 113's use a sealed hanger bearing from what I've seen. The front of the drive shaft has a grease fitting if that's what you refer to.

[wwheeler]

Yes, talking about the front of the driveshaft at the centering cross/flange whatever you want to call it.