Speedo Cable Housing - SOS

[bpossel]

My speedometer has been bouncing at lower speeds.  My tach did the same, and replacing the cable solved the problem .

So, today I started to replace the speedo cable.  Having read many good posts on this site, emails to and from Joe, and also reviewing the BBB, I was ready.

Well, didnt get very far !  With the car on ramps, crawled under the car and traced the cable into the transmission.  As I traced the cable closer to the trans, it was very loose.  Turns out the cable was simply hanging there.  The small section that holds the 5mm bolt, which holds the speedo cable in place was broken[!].

I know that the PO had the transmission rebuilt, so possibly the technician bore down on the 5mm bolt and this cracked this section off.

Now what?  Any suggestions on how to proceed?  Does the trans housing need to be removed to replace the entire speedo housing?  Can this small section be jb welded back into place?

Help!  Any suggestions?

Thanks!
Bob

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

[George Des]

Bob,

This is a common problem. I assume you have an MB Transmission and not a ZF. If this is the case, probably the easiest way to permanently fix is to get an old salvage transmission and use the back cover plate from that. As a temporary fix--it might well last quite long--is to do what I did on my ZF 5 Speed. I took a small piece of fiberglass clothe and saturated it with JB-Weld to reattach the broken piece. Fortunatley, mine had broken off close enough to the end that it did not adversely affect the sealing area. On the ZF the bolt does not need to be "gorilled down" tight. Instead the bolt rides throuh a slot in the end of the speedo cable and that is what holds the cable in. The bolt simply needs to be tight enough that it doesn't vibrate off. Some Lock tight would help. I suspect this is the same type set up with the MB 4 Speed box. There are some specialty shops that can re-weld this aluminum casting using a TIG welder. In my case, I may eventually do that as a permanent repair, but that is only because a replacement rear cover plate for the ZF box is just about unobtainable--there aren't many of these 5 speeds in the salvage yards! If you've got the 4 speed MB box, I'm sure someone on the board might be able to help you out w/a replacement rear cover plate. Good luck

George Des

[bpossel]

Thanks George.

Question...  isnt the speedo cable housing a separate piece that slides into the back casing?   See attached pic.  It appears that all I need to do is to somehow replace the housing...  I wonder if I can replace the speedo cable housing w/o removing the back casing?  Looking for a short-cut...

Note: The red arrow points to where mine broke off.  The clamp part with 5mm bolt are in one piece. Broke off right where it protrudes from the casing.

Thanks again!
Bob

Download Attachment: speedo-housing.jpg
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bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[George Des]

Bob,

Best ck with someone more familiar with that type of rear cover. It does not look like any of the ones I've seen on the MB boxes. The ones I have seen are all a one piece rear cover where this "clamping" area is not removeable as it appears here. Joe Alexander or the Dr may be able to help.

George Des

[merrill]

I broke the clamp off of my tranny changing the speedo cable as well.  In my instance I broke the "top" off.  

luckily I was able to hold everything in place and secure the bolt and cable.

gernold at sl tech told me this part could be purchased and replaced but it is not cheap.

if you are lucky you can get it to work without having to replace the clamp

matt

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

[ja17]

Hello Bob,

Your BBB photo is actually of a different transmission from what is in your car. However the speedometer cable connection is similar.

You can replace the speedometer cable clamping mechanism on your tranmission also. This can be done by removing the small cover plate (two 10mm bolts). This cover plate has a pin which locks the mechanism in place. After the two 10mm bolts and the cover is removed you can simply pull the clamping mechanism out. It has an o-ring seal.

I'll try to send some pics.  I probably have some good clamping mechanisms around if you need one.

Joe Alexander
Blacklick, Ohio

[bpossel]

Joe thank you very much!!!

I know exactly the plate you are referring to.  I found the section in the BBB.  See pic

Do I need to drain the trans fluid before I remove the plate?

If possible, can you send me an extra clamping mechanism?

Thank you again!  I'll send you an email.
Bob

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

Download Attachment: speedo-housing-plate.jpg
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[ja17]

Hello Bob,

Here is some photo imformation. Excuse the out of focus, (something not right with this camera). Notice that the plate has a pin which keeps the clamping unit in place.
 
Download Attachment: trans speedo unit.JPG
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Download Attachment: t2.JPG
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Download Attachment: t plate removed.JPG
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Download Attachment: t clamping unit removed.JPG
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Download Attachment: t plate removed.JPG
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After the plate is removed the clamping unit simply "slides out".  There is a thin paper gasket on the plate and an O-ring seal on the clamping unit.




Joe Alexander
Blacklick, Ohio

[bpossel]

Hi Joe,

Thanks for the pictures!!!  Even though a bit out of focus, after laying under the car for hours trying to decide what to do, these pictures are very clear!

I am just so happy!!!  that I can simply remove the plate, and replace the clamping unit.  I was worried that I would have to remove the rear trans plate, which means the drive shaft, and more...

Kind Regards,
Bob

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

[George Des]

Bob/Joe,

Is this an auto or manual box? The rear looks like none of the manual boxes I've seen?

Geogre Des

[bpossel]

Hi George,

Automatic.
Bob

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

[George Des]

Bob--thx--that explains it--Geo