Speedometer odd question

[Ryanotown22]

So I have a black speedometer pinion gear works great but was reading fast on my speedometer so I bought a brand new blue one with the casing. I put it in my car and speedometer doesn’t work. Took it out and put black one back in and it works. Did this process twice to make sure I wasn’t insane. I made sure when I spin the blue cog that the other end spins and it does and yes I put the speedometer cable in the slot. Is there something else that’s not compatible maybe? Both the assemblies are the same size the only difference I see is the color of gear.

[L320-Dale]

I just went through this when I changed my transmission from a 4 spd to a 5 spd. Wish I had a picture, but I don't.
One transmission had the speedo drivegear bolt at 12:00, the other trans had it at 6:00 (Sorry, I don't remember which was which).
When I tried to use the old gear from the 4 spd in the 5spd it wouldn't work. So I ended up switching the gears on the cog itself. Its easy to do by pulling out the roll pin.
These speedo gears are very slightly off set in the speedo cog. Look at the end of the speedo gear and you can see its offset from center slightly. If you use a 6:00 one in the 12:00 trans or vise versa they will not engage the gears in the transmission. Look at the offset between the two closely, I bet you have the wrong drive cog or what ever its called.
Like I said, you can fix by removing the gear and reusing your original cog.
Hopefully my description is clear, I may not have explained it well. LOL..

Dale

[Ryanotown22]

Wow that has to be it I would have never thought to look at that. My transmission is at the 12:00 so I am guessing the part I got is for a transmission that is at the 6:00. I know what your talking about for replacing the gear I did that process when I refreshed all the seals. Excellent thanks!!

[Ryanotown22]

Took your suggestion and thought why not just dremel a notch on the other side of the gear drive so I did.. and it worked perfect so now I have a 2 notch gear drive thing in blue. There was a line on the other side 180 degrees of the original notch so I used that as a guide on where to dremel. Then used the metal keeper to test fit to make sure the notch was wide enough and deep enough.

[L320-Dale]

Took your suggestion and thought why not just dremel a notch on the other side of the gear drive so I did.. and it worked perfect so now I have a 2 notch gear drive thing in blue. There was a line on the other side 180 degrees of the original notch so I used that as a guide on where to dremel. Then used the metal keeper to test fit to make sure the notch was wide enough and deep enough.

Good job, that works too!