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75 speedo adjusment again

Joined
May 6, 2002
Messages
129
Location
Simi Valley, CA USA
Corvette
1975 Red on RED Coupe
Hey guys, I recently took my 75 to a shop and had the transmmission servvice (being on my back for two days was my idea of a fun labor day weekend). They fixed the gasket leak, but the speedo connection still has a bit of a drip. I need to replace the gear there anyway. My problem: What are the procedures for replacing that gear? I know there have been threads on this so I must be searching the wrong words. Thanks for any help. I sure miss the forum, I've been on business in Mexico and no internet access for two months. Don't know how they can do it.
 
R

rpounds

Guest
The speedometer gear housing is held in place by one screw, with a small piece of steel that is used as a retainer. After you pull out that one small bolt (if memory serves me correctly, it is a 1/4-20 bolt with a 7/16 or 3/8 head), the adaptor will pull straight out the side of the transmission. To make the job easier, loosen the speedometer cable housing nut, but leave the cable attached to the adaptor. This gives you something to grab onto to pull the adaptor out of the transmission. The adaptor has an O ring seal. Over time O rings (usually Buna-N material) 'take a set', meaning that the sealing surfaces will flatten out. If this is the case, replace the O ring and you should elliminate the leak. If you browse around at a neighborhood auto parts or hardware store, you can sometimes find an O ring with a slightly larger material size. This can help to seal off the speedometer gear housing.

Anyhow, once the housing is out, finish removing the cable. The gear R+R will be obvious from there.
 
R

rpounds

Guest
BTW . . . make sure you replace the O ring with with an equivalent material. Some O rings are made of natural rubber and will not hold up to exposure to oil.
 
Joined
May 6, 2002
Messages
129
Location
Simi Valley, CA USA
Corvette
1975 Red on RED Coupe
Thanks guys, I'll try to get to that tomorrow. Unfortunatly though, there is still fluid leaking from the front of the pan where the bracket holds the shift cable. I'll have to take it back to the guys that did that repair and let it sit all day so they can see for themselves where the leak is at. What a pain. Thanks again
 
R

rpounds

Guest
The shift cable suffers the same fate as the speedometer gear housing. It is sealed by an o ring . . .
 
Joined
May 6, 2002
Messages
129
Location
Simi Valley, CA USA
Corvette
1975 Red on RED Coupe
Thanks again for the help guys. The seal on the speedo was flat . replaced it and the seal where the shaft exits. Also had to replace the gear (shaft was worn bad). Now waiting for the new section of speedo cable to come in and I'm back in business. Only a slight drip from the exit tube to the radiator. I'll probablly wait and replace the tubes at a later date. So, just wanted to say thanks, again.
 

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