keithl1967

Hello all:

My speedometer was not functioning. I narrowed the issue down to an internal transmission problem--the drive gear.

After getting the tail housing off of the transmission, I found that the drive gear was not in the proper place, and the clip was non existent.

The odd thing is that the drive gear almost seems to be press fit--it does not slide easily (or at all) past the smooth portion of the output shaft.

Is this just a matter of "tapping" it along to get it in the right place?

i don't want to start tapping or pounding on anything without checking with some experts!

thanks!

keithl1967

OK--so I got the new gear on the shaft with a light tappping. In the process, I broke the clip that is supposed to hold it in place.

2 Questions:

1. How do I get it back off of the shaft to try a reinstall (there is no way can get in there to tap it in the opposite direction...
2. how do I get it re-installed, without breaking the clip?

69L46

Did you ever solve this issue? I've unfortunately run into the same problem, the internal plastic drive gear in my M-21 sheared in half.

I'm not relishing the thought of yanking the tranny to replace the gear, but it seems like doing it with it in the vehicle is going to be a bear...

keithl1967

I did...
I had to clear some extra space to work--once I did, it was way easier than I thought.

The crossmember has a plate bolted to it, to which the trans is bolted.

I put a jack under the the trans, and removed the plate....all the room needed to remove the rear housing, and get appropriate tools in to tap the gear either way, as needed.

69L46

Thanks for the quick reply. Would you mind posting a bit more detail on the process as as whole? Which tranny/year is yours?

Being a '69, mine has a welded crossmember, so finding the extra space to pull this off in car might pose a challenge. Thanks.

keithl1967

Mine is a 77 with a TH350...

I at first thought I was going to have to remove the crossmember (autos have a bolt in crossmember).

I found that the trans does not bolt directly to the crossmember on mine. There is a plate held to the crossmember by 4 bolts (2 on top, two on the sides), plus 2 bolts to the trans mount.

Not sure of the configuration on a '69, though....I suspect it would be similar.

69L46

Thanks for the info!

kkEdlund

When I took the speedo gear off my '79 TH350, I was able to slide a open-end wrench over the output shaft just in front of the gear, and gently tapping the wrench with a mallet drove the gear off the end of the shaft. I didn't have to unbolt the crossmember or mounting bracket, just the tailhousing.

The gear was not marred by the wrench, but I think I might have been more hesitant if I planned to reuse it.