Author Topic: W108 U-joint replacement  (Read 596 times)

dirkbalter

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W108 U-joint replacement
« on: November 26, 2019, 22:59:26 »
Hello All

Due to a vibration I had on my w108 / 6cyl, I am attempting to rebuild the drive shaft. I already have all the parts: flex disk, front bushing, main bearing, rubber insert, u-joints. However, when inspecting the drive shaft, I recognized that the u-joint cap is somehow bonded the u-joint housing. I couldn’t find anything in the BBB that talks about that. A Haynes manual that I also have, states that the u-joints cannot be rebuild and a new prop-shaft is required?  Does anybody know or have done a u-joint replacement? How are the u-joints secured after installation?

As always, thank you for your help.
Dirk
66 230 SL
70 280 SEL
18 C300 COUPE
05 HD FLSTNI

mbzse

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Re: W108 U-joint replacement
« Reply #1 on: November 26, 2019, 23:10:48 »
Quote from: dirkbalter
.../...Does anybody know or have done a u-joint replacement? How are the u-joints secured after installation?
The 230SL type drive shafts have u-joints with needle bearings that can be exchanged w/o welding.
The later type drive shafts have the bearings peened into position. This type can also be refurbished, but that requires knowledge and a workshop.

If you use a replacement u-joint, this is welded onto the drive shaft. The whole shaft then needs to be set up in a machine for straightening and balancing.

Some Forum info for instance in this thread:
https://www.sl113.org/forums/index.php?topic=2833.msg16009#msg16009
« Last Edit: November 27, 2019, 00:25:00 by mbzse »
/Hans S

dirkbalter

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Re: W108 U-joint replacement
« Reply #2 on: November 27, 2019, 00:03:34 »
Hallo Hans,

Good to hear from you. Do you remember talking to me about it in San Diego? You actually suggested to check and change the flex disk. I thought, while I am doing that, I might as well change the u-joints. I did my 230 drive shaft already with no problems. The joints have clips on the inside to secure them. I expected a similar set up on the later shaft and was confused when I didn’t see clips or grooves in the joints.  (Shaft is still in the car)

So, if I understand you correctly, the joint caps are (spot) welded to the housing after they are replaced to secure them in place. The welding or better the heat generated from it does not affect the grease inside? 
Dirk
66 230 SL
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18 C300 COUPE
05 HD FLSTNI

mbzse

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Re: W108 U-joint replacement
« Reply #3 on: November 27, 2019, 00:39:55 »
Quote from: dirkbalter
.../...So, if I understand you correctly, the joint caps are (spot) welded to the housing after they are replaced to secure them in place.../...
Well, a somewhat complex theme...  From factory, the later type u-joints had the bearings peened to keep them in position (as seen on the picture I attached in the previous reply)
What I wrote about welding is, that a whole new u-joint unit (new from factory) is welded onto the drive shaft itself. The worn out u-joint is first cut away.

Quote
The welding or better the heat generated from it does not affect the grease inside?
This would be up to the person/company doing the refurbish of the u-joint to see to. I have only looked at drive shafts refurbished this way; I have no first-hand experience with it or the methods used.
« Last Edit: November 27, 2019, 00:47:05 by mbzse »
/Hans S

dirkbalter

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Re: W108 U-joint replacement
« Reply #4 on: November 28, 2019, 00:30:34 »
This would be up to the person/company doing the refurbish of the u-joint to see to. I have only looked at drive shafts refurbished this way; I have no first-hand experience with it or the methods used.

Yup, got you.
I put the car on the lift and did a closer inspection of the joints. It appears that the u-joints  were changed already and the rebuilder welded washers on top of the joint caps to secure them.. (That’s why I asked the (silly) questions). I didn’t see that initially. Once the shaft is out and if they feel ok, I won’t touch them and limit my work to the flex disk and center bearing assembly.
Dirk
66 230 SL
70 280 SEL
18 C300 COUPE
05 HD FLSTNI