Flex Disk / Drive Shaft

[bpossel]

Hi All!

I took a picture of my flex disk in preparation of replacing it this weekend, along with a new drive shaft.  

Look at the old flex disk.  Do you see anything wrong?  It looks like the bolts are not installed correctly?  Am I seeing things?

What do you think?

Bob


Download Attachment: flexdisk_old.jpg
57.01 KB

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[ja17]

Hello Bob,

This is the exact configuration.  This nice photo came from you some time ago. Pay attention that three bolts are longer than the other three. The heads of the three long bolts are shaped differently than the other three. Each bolt assembly has one flat washer next to the rubber surface of the flex disc. All the nuts are on the transmission side of the assembly. Earliest versions had cotter pins and castellated nuts(what a pain). Later versions and all replacement parts use nylock nuts.
Download Attachment: BPossel flex disc.jpg
17.51 KB

Pay special attention that the tab on the flex disc correspond to the flange on the transmission (see photo). Make sure that the sponge rubber grease seal is fitted on the transmission output shaft before re-assembly. The bolts have a long shoulder. During assembly tightening the bolts will snug together the assembly and then the nut will "bottom out" on the bolt shoulder so as not to crush the flex disc.

This is not a difficult job, but the new disc will not last if not assembled correctly.

I am sure your up to the task.


Joe Alexander
Blacklick, Ohio

[bpossel]

Hi Joe,

Thanks for the add'l info.  It really helps!

So, how does my current installation look?  Looks to me that the bolts attaching to the driveshaft are reversed?  The nuts look to be facing the rear of the car vs facing the transmission side?

Maybe this is why I feel a slight vibration at higher speeds?

What do you think?

Thanks again!
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[bpossel]

Merry Christmas!

I confirmed that my old flex disk was installed incorrectly.  See attached pic.  Notice that the bolts that connect the driveshaft are installed backwards.  All bolts should face towards the back of the car, with the nuts facing the front, transmission side...
Download Attachment: old-flex.jpg
64.86 KB

I purchased a new flex disk kit and installed it along with a new drive shaft from Driveline Service.  The flex kit came with new bolts and nuts as well as 2 rubber washers (bushings).  The larger, thinner bushing was already installed in the new driveshaft, so I didnt need  it.  I am not sure where the small, fatter, rubber bushing goes?  When I removed my old flex disk, this smaller, fatter bushing is not present anywhere.

 :?:  :oops:  :?: Where does this one go?  What is it's purpose?

 :oops:  :oops:  :oops: Joe, I just re-read your post below.  You mention a sponge rubber grease seal for the transmission output shaft before re-installing... Looks like this is my mystery bushing...
Can I drive the car w/o this seal until I can get is back on the lift?
Will I do any damage?  My old install didnt have this...

---------------------
Here is a picture of the lift I used.  I was very lucky to be able to use the lift at my sons place of employment.  Made this job a lot easier!
Download Attachment: lift.jpg
47.91 KB

Here is a picture of the new flex disk installed (w/o the above mentioned bushing/washer...)
Download Attachment: newflexdisk.jpg
63.42 KB

Here is a picture of the old and new drive shafts.  I was a bit disappointed with the new shaft in that I thought Driveline advertises the rear having a grease fitting.  Well, it doesnt!  I will call them this week and find out why...
Download Attachment: old-new.jpg
49.66 KB

I also replaced my pinion seal, and will post this as a separate post.

  Hope y'all are having a wonderful Christmas & holiday season!
Bob

[ja17]

Hello Bob,

The thick "hose like" seal slips on the output shaft of the transmission before the driveshaft is hooked up. It prevents the grease from squessing out of the centiering bushing and degrading the rubber flex disc.  Look on page 26-1/7 of the BBB for a good sectional diagram whcih shows the locations of both seals.

Joe Alexander
Blacklick, Ohio

[bpossel]

Thanks Joe!
I guess it will give me another excuse to "play" on the lift this weekend.
Have a nice week!
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[George Davis]

Bob,

I'm glad it went well, and it's nice you had use of a lift.  What a luxury!  Nice car, by the way!

I know I'm probably overly paranoid, but I had a driveshaft get chewed up from one of the flex disk nuts coming loose when I reused then.  The nuts are all-metal self-locking nuts and "might" be reusable, but I don't trust 'em.  If you pull the disk out again, I suggest using some loctite when you reinstall if you reuse the nuts.



George Davis
'69 280 SL Euro manual

[scheutw]

to Bpossel: I just noticed the color of your car and believe to is the same as my 66 230SL. Beige with dark brown interior but with a dark blue top is this right? Mine has a beige soft top instead of the dark one? Original owner says mine was on it when he bought it. But the data card shows it was built with a dark blue top? Could this be?


scheutw   Peoria, Ill.
66 230SL
97 E320

[bpossel]

Hello scheutw. Actually the top is dark brown.  The lighting makes it appear blue?  Car color is light beige (181) with dark brown soft top and cognac (140) interior.  A PO installed the side door guards , which will be another future project, removal... and repaint .
The color combo you mention .. light beige, dark brown interior and blue top sound odd, but if your data card reflects that, that is what it was.
Regards, Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[scheutw]

Bob, thanks for your input. The original buyer of my 230 swears it came with the beige top and not a blue one. A blue top with this color just does not fit. Don't know how to resolve it. The beige top number is very close to the blue one so wonder if factory misprinted the data card? Oh well. Thanks again.


66 230SL beige paint, browm interior, beige soft top.

[KevinC]

Does this look like your combination?

Download Attachment: MB Top Down 6.JPG
83.54 KB

quote:Originally posted by scheutw

Bob, thanks for your input. The original buyer of my 230 swears it came with the beige top and not a blue one. A blue top with this color just does not fit. Don't know how to resolve it. The beige top number is very close to the blue one so wonder if factory misprinted the data card? Oh well. Thanks again.


66 230SL beige paint, browm interior, beige soft top.

Kevin Caputo
Boca Raton, FL
1967 230 SL Automatic
670 Light Ivory
113 Bronze/Brown MB Tex

[Tom Colitt]

Hi Bob

At first glance it looks correct to me...


Tom Colitt

[merrill]

Joe,
I just received a flex disk kit from K&K
it came with new hardware and one o ring and the sponge rubber seal.

the o ring is rather large.  

do i need this o ring ? if so where does it go.

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[bpossel]

Hi Matt,

When you disconnect the front shaft from the flex disk and pull it back, there is an inner plate that sits between the main shaft and the flex disk.  The large rubber seal sits between these two (2) plates.  The small rubber hose slides onto the end of the trans shaft.

Good luck,
Bob

quote:Originally posted by merrill

Joe,
I just received a flex disk kit from K&K
it came with new hardware and one o ring and the sponge rubber seal.

the o ring is rather large.  

do i need this o ring ? if so where does it go.

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[JPMOSE]

Bob,

Why did you need to replace the drive shaft?  I thought they last for the life of the car and only the u-joints and flex disks are replaced.  Educate me!!!



Best Regards,

J. P. Mose
1968 250SL
1987 560SL

[bpossel]

Hi JP,

I was experiencing a "humming vibration" while driving highway speeds .  At closer inspection of my driveshaft, it appeared that a PO had welded a couple of weights to the shaft [!](2 small flat pieces of metal).  Just didnt look right...

 :oops: Not being sure exactly what it would take to fix the hum/vibration (new flex disk, new center shaft rubber donut, new shaft?), I just decided to replace the entire unit.  I only wanted to do this job once!  I am getting tired of doing things twice.. ie, taking apart the same pieces to get to the next area of repair.  Items that I should have just repaired while doing the first job.

A year ago, when I replaced my power steering pump, I recall Joe A. telling me that it would be a good time to replace my front crank seal.  Well, should have listened to him :? !  I didnt replace it because it was just seeping back then.  Now it has more of a leak, and this is another job on my Winters list of engine leak repairs. This requires pulling the hood, radiator, visco fan, ps pump, [!]Again!

Note: When I replaced my drive shaft, I also replaced my rear pinion seal.  So hopefully wont need to pull the shaft ever again...

JP, hope this helps answer your questions.

Regards,
  Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[glennard]

Bob,  Are the 'welded on metals' the weights to balance the shaft?  Seen them on most drive shafts.  Be Good.

[glennard]

Bob, Left out 'as built'.

[George Davis]

Agree on the balance weights, these are normal.

The early cars' driveshafts have replacable u-joints, so replacement of the entire driveshaft should not normally be necessary.

The 280 SL driveshafts do not have replacable u-joints (at least not easily replacable).  The u-joints are staked in place and machine work is required to remove them.  The driveshafts provided by Driveline Service are modified to have replacable u-joints.  So, with a stock driveshaft, 280 SL owners must replace the entire shaft to get new u-joints.

I don't know off-hand where the break-point is for this change.  I would guess one can tell by inspection: if the driveshaft has circlips retaining the u-joints, it's either the early type or a modified replacement.  A shaft with no circlips should have staked u-joints and is not servicable.

George Davis
'69 280 SL Euro manual

[bpossel]

Hi Guys!

Where these "factory" driveshaft weights?

Download Attachment: Factory-Weights-or-not.jpg
46.05 KB

Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[glennard]

Bob, Don't remember any that big!  Postage stamp size, or so, on the drive shaft at various locations.

[awolff280sl]

JA17 writes: "Pay special attention that the tab on the flex disc correspond to the flange on the transmission (see photo)."
In the flex-disc kit that I got from MB, both sides of the flex-disc itself appear to me to be identical, and all of the holes appear identical on both sides. I am not sure what is meant by the "tab"?

[waqas]

Andy, are you sure this is a 113 flex disc?  I've seen this type of disc only once before when dismantling a 108 sedan, and I remember noting how different it was from the 113 version.

This is good picture from Bob Possel clearly showing the tabs Joe is talking about:
http://www.sl113.org/forums/uploaded/bpossel/2006122571530_newflexdisk.jpg

[awolff280sl]

Waqas,
The part number for the flex-disc for 113, 108, & 109's, as given to me by MB is 108 410 0115. This is the same part number Gernold has been using, although the last one he did awhile ago did have tabs. This leads me to think that MB may have recently made a change.
My MB parts dept told me that the design with the tabs is more flexible since it has a kind of thinned out area between the bolt holes. He said this was to make manual shifting a little softer. The "latest available" (at least to me) flex-disc does not have any thinned out sections and may last longer. Who knows?

[waqas]

My understanding is that the rubber between consecutive bolt-holes in the flex disc are designed to alternate between resisting compression and resisting expansion. The orientation of the disc thus becomes important, and the tabs are there to aid correct installation.

Perhaps this differently designed disc that you now have does not differentiate between compression and expansion forces? (and hence no aid to orientation is provided)