Metzman510

wayno, I couldn't agree more. The 21 tooth is to correct the odometer, up 2 teeth from the 19 tooth that is in there currently. The speedometer definitely has a date with the cleaning, inspecting, and adjusting folks, I just wanted to try and get the odometer on the correct page also. Its a 2 sided attack, one to correct the odometer, the other to calibrate the speedometer.

Wayno, I'm going to need a purple 21 tooth...

Datzenmike, Thank you.

Thank you!

Can somebody post a picture of a series 63 speedo drive as a reference?

That would be super helpful!

Mike, my speedo drive looks like the longer one from the picture in this post, picture at the top of page 4 shows  speedo drives side by side. The longer unit with the black gear on the left. Only mine has a white 19 tooth gear on it.

https://ratsun.net/topic/19081-speedometer-gear-issues/page/4/

What year is an s12 200sx? Do you have the pn? I have access to a full machine shop and can modify as needed if possible. 

Ok, so here's where I'm at...

Speedo is marked MPH, clearly on the face.

On a 10 mile loop as laid out in my bone stock Ram pickup, my odo reads 11.3 miles, off by 13%. So my 19 tooth speedo pinion needs to be a 20 tooth. 10% correction per tooth right? Maybe 21 would be better but sounds like it's very difficult to get...

Once l get that new speedo pinion in the car I can start working on the speedo accuracy, which as Mike suggested is likely a magnetic adjustment issue.

Any comments are appreciated. 

Ok, first, that explanation of the speedometer function is over the top helpful! Thanks!

Second, how would I know if I had a metric speedo? Would there be a KPH designation somewhere?

Going for an odo run to check it shortly...

Loving the help!

Crashtd420, Excellent info, thank you so much! Will call on Monday and now have a great reason to go for a drive!

Any information or documentation floating around on adjusting the magnets in the speedometer? The needle on the gauge reads steady BTW.

Does anyone know what the thread sizes are on either end of a Datsun speedometer cable?

So you think I should work on the speedometer gauge to try and correct the indicator vs actual speed issue? I need to check, but I think the odo is running fast also which makes me think the speedo drive gear is causing the problem. 

Does anyone still make those geared correction units that you run inline on the speedo drive cable?

That is the transmission in my 510. So can I assume that is the FS5W71B "shorty" from a 1984(ish) 720 pickup?

Yes, when I  bought the car the speedo cable was in the trunk, when I connected it, this is how it reads.

Going out to check th trans pic against what's in the car.

Okay, I'll get under there tonight and put a tape measure to it, thanks Mike!

Yes, on the left as you are sitting in the car.

I found a thread discussing speedometer pinion drives here:

If you go to the top of page 4, in the picture are the 2 speedometer drive assemblies. Mine looks like the one on the left. Mine has a white 19 tooth gear on the end of it. I am trying to ID the trans, as my speedometer is way off (100 mph indicated is actual 65 mph GPS). So I was hoping to get a correction on the speedometer pinion. My diff is an open R-180 front unit from a 4x4  pickup with 4:11 gearing, tire size is 195/60-r14.

All guidance is appreciated!

New to the forum, but have been using it as a resource for a while, it is a real help!

My 69 510 sedan has a 5-speed in it. Due to packaging restraints in the car, I am having trouble identifying it. The serial number on the top of the bell housing is 7202575, there is not a number cast into either side of the transmission housing (60 or 60A as an example). The tail housing is marked #1, and the trans case has "L1 NMCA" cast in the side of it. The speedometer drive is in the tail housing, on a downward angle, pointing to the left side, and the screw to hold the speedo pinion drive in is at 6 o'clock.

L-series engine in the car. Trans is definitely a wide ratio unit, standard 5-speed H and a half pattern (not the dogleg).