How tight should the speedo cable 13 mm bolt at the back of the transmission be?

Bmachine

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While doing an oil change yesterday, I noticed some oil drips at the back of the transmission. Upon further inspection, it looked like it was coming from the speedo cable entry point. I checked the 13mm bolt there and it was very loose. I started tightening it up, and it felt strangely soft as I did it. Not stripped, mind you but it felt like it was going into some thing soft. How tight is that bolt supposed to be?

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Ohmess

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My recollection is that the bolt fits into a groove and only needs to be tight enough to keep the cable from coming out.

I just looked at this on my 635csi barn find. Your leak is coming either from the o ring for the speedo drive, or the shaft seal inside the speedo drive unit. Replace the o-ring first. The shaft seal is small and difficult to replace.
 

TomHom

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For what reason ever the left screw did mot come with a hole
 

Ohmess

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The one on my 635csi does not have a hole. Haven't climbed under my coupe to see if that one has a hole, but I know I did not put safety wire on it when I installed it.
 

Cornishman

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My recollection is that the bolt fits into a groove and only needs to be tight enough to keep the cable from coming out.

I just looked at this on my 635csi barn find. Your leak is coming either from the o ring for the speedo drive, or the shaft seal inside the speedo drive unit. Replace the o-ring first. The shaft seal is small and difficult to replace.
I have three transmissions, one has a hole, two don’t. If yours does not I suggest that you drill it and wire it.

The seals, O ring is thicker than normal, but easy to change, the shaft seal is a PITA, suggest that you buy two or three seals, they are easy to damage. Or, pay someone who knows what they are doing with these, it might be cheaper.
 
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