Speedometer Pinion Gear Installation Help

[z boy mn]

Hey everyone,

I've combed through the archives looking for directions on swapping out the speedo pinion gear, and I found some information but I'm a bit nervous taking on this task as I don't want to wreck anything (cable, gear, etc.) as the parts are so hard to find. I have a 1983 5-speed in my 1971 Datsun, and I finally finished the 4.11 LSD diff (which works great). The speedo gear I have now is 20 tooth, and it's about 10% off, so I'm moving to the 21-tooth version (they don't make the 22 anymore).

(FYI, when I contacted Nissan to order the part, there were only 2 left in the country and it's being discontinued, so if you need one, now's the time to get it!)

My plan is the following...any suggestions?

1) Lift up the rear of the car so I can keep the gear oil in the tranny.

2) Remove the plate and speedo gear housing.

3) Remove the cable from the gear housing.

4) This is where I get fuzzy...will the old pinion gear just come out if I pull on it? I noticed in one of the posts with a picture there was a small pin and the writer said not to lose it...but what does it do? Will it fall out? The link for the post is here: http://www.classiczcars.com/forums/e...ps-needed.html and it's post #4.

5) Put it all back together and drive like crazy as we'll have snow soon!

Thanks in advance for any help you can offer for step #4...

[Darrel]

it's a roll pin, you will need a very small punch to drive it out.

[Zed Head]

I've removed a couple of those gears. As Darrel says, a small drift or punch is needed to get the pin started out. I had to use pliers to finish pulling it. It's pretty tight.

You kind of skipped the step of removing the pinion gear assembly/housing from the transmission. They can get stuck also. A big flat bladed screwdriver in the slot will break it loose but large pliers or vice-grips might be needed to completely remove it. Pad the plier jaws, there are many gear housings out there with ugly teeth marks on them. The metal is soft.

[esprist]

If you could, save the roll pin, as this roll pin is Metric size and impossible to find one in US.

[z boy mn]

Thanks for the tips everyone...I'll definitely try to save the pin. When I had the diff done they swapped from a 19-tooth to a 20, so things have been loosened recently so I hope they're not too stuck. I just want to make sure I don't wreck anything as it doesn't sound like the parts are possible to replace easily. I'll let you know how it goes when the part comes in!

[EuroDat]

Ic you are changing the pinion, you should replace the o-ring seal on the pinion adapter and the lip seal in the adapter. Don't wont to go to all that trouble and have it leak afterwards.
If you don't have a punch the remove the roll pin, you can use a wood nail from the hardware store. Just file the point flat so its square with the rol pin. It should tap out easy.
Chas

[z boy mn]

Wow--those are GREAT pics with labels and everything. I do have the seals (I got them from MSA) and will swap them to make sure I don't have any leaks with the new gear. Still waiting for the pinion gear to come in from Nissan--I'll keep you posted!