Speedometer drive rebuild

[Tru-Craft]

I have a 1970 GT with a 4 speed stock transmission, early type.
The speedometer drive assembly has been leaking for awhile.
Time to rebuild it!
This is how I did it.
*Un -screw the speedo cable from the 90 degree drive.
*Separate the 90 degree drive, use a (22mm) hex wrench, pull out the square steel flex shaft.
*Remove the retaining pin that holds the gear assembly, pliers worked for me.
*Pull the assembly out of the tranny. Fluid will leak.
*Inspect the gear and shaft end, it has a square hole to drive the cable, this is made of a dark brown nylon. My square hole was stripped, so the gear/shaft had to be replaced.
*The shaft seal fits in a groove in the shaft and holds the gear in the steel body. To remove spray some WD-40 on the seal to soften it, and carefully and slowly push out the shaft.
*Clean and remove the O-ring seal, deburr the steel body around the retaining pin hole and O-ring groove.
Re-place parts as needed.
*Coat everything with gear oil and re-assemble the shaft and push seal in, large end first.
*Push assembly in tranny and tap in retaining pin.
*Install square drive flex shaft and 90 degree, and speedo cable.
*Check Tranny oil level.

For parts I got everything from OGTS, all in stock!!!
Thanks Gil.
Mine is working great and no more leaks
Lyle

[khwk508]

Great description on replacing the speedo drive seals, Lyle!! Need to challenge the forum on what to do if the pin breaks off - the one that retains the gear output. Mine was frozen so I very carefully used vise grips but the pin head fatigued and broke off. I tried drilling a small hole in the pin to fit a screw head, but gave up since I would rather have a drip than damage it further. The obvious solution is remove the rear housing and replace everything - is this the only solution ?
Thx for your input - Bill

[Paul]

I know this is an old thread, but its the only one I found that talks about removal of the driven gear retaining pin in the older style housings.

So, this weekend I was trying to remove the driven gear but couldn't figure out if there was a trick to removing the retaining pin. I never got it out, but the IPB Lyle has shown may help.

Has anyone else had to work on one of these "older" style transmissions? If so, by what method did yo use to remove the retaining pin. I hate to destroy it getting it out because what would I put back in its place??? A metric dowl pin???

Any suggestions would be appreciated... oh and the first thing I did was to PB Blaster the heck out of it...

[wayne70gt]

I just happened to take mine apart this weekend to replace seal and O ring. I had a bar with an end that was shaped like a flat bar for pulling nails. I used that to pry the pin out. Mine came out no problem but maybe I was just lucky. Not sure there would be enough room for a regular flat bar. When I got mine apart I noticed that the short piece of cable was starting to unravel. When I was working with it it broke off at the shaft the gear is attached to. Called OGTS and was told I would have to the whole angle drive to replace it. They gave me the name and number of a member here who is looking for a replacement as I am typing this.

Now I have a couple questions.

1. I am going to replace the tranny fluid with Redline MTL. I am assuming I have to remove the pan to drain. Will I need a new gasket and if so would a form a gasket or similar product work?

2. Does the O ring that I got from OGTS replace the one on the steel housing? (forgot to ask them when I had them on the phone)I haven't removed and replaced yet because it didn't look like it was the right size.

Thanks,
Wayne

[Paul]

Thanks for the suggestion. I'll probably head to Harbor Freight tomorrow at lunch to brouse for anything that looks like it could pull that little bugger out...

Answering #1 Usually I just unscrew screws enough to crack one of the corners down enough for it to drain out. Even if you want to remove the pan and clean it out, you probalby will want to drain it slowly first, BEFORE removing the pan. Doesn't cause as big a mess that way...

#2.. if the o-ring is about 1 inch around then it is the one that goes around the body of the driven gear. Not difficult to replace.

[Tru-Craft]

Originally Posted by Paul I know this is an old thread, but its the only one I found that talks about removal of the driven gear retaining pin in the older style housings. So, this weekend I was trying to remove the driven gear but couldn't figure out if there was a trick to removing the retaining pin. I never got it out, but the IPB Lyle has shown may help. Has anyone else had to work on one of these "older" style transmissions? If so, by what method did yo use to remove the retaining pin. I hate to destroy it getting it out because what would I put back in its place??? A metric dowl pin??? Any suggestions would be appreciated... oh and the first thing I did was to PB Blaster the heck out of it...

Paul, my pin was kind of loose.
PB is a good idea.
Try tapping the pin in, then try pulling out.
Maybe a little heat on the pin, then let it cool and try again.
Yes, a metric dowel pin would work if you destroy the old pin.
My pin was loose, so I put some gasket sealer on it when I re-assembled.
Lyle