Speedo gear -21 or 22 tooth sets available?

[shaddai]

I finally got my speedo working - first time since I bought the car 10 months ago... and it's about 25% over (60 mph is really 45). I pulled the thing out of the five speed transmission the PO put in and it has 17 teeth. Looks like one can find 17-20 tooth things easy, but 21 and 22 are NLA. Thoughts from the Ratsun brain trust?

[KELMO]

Gonna guess 280ZX 5 speed?

19T is the most I can find in the catalog. 32703-78103. If you are able to find a 21 or 22 pinion you may need the housing also.

Not sure what vehicle this would come from.

[datzenmike]

 

21 is purple and 22 is orange.

 

22/17 is 29.4% reduction in speed to 42.36 MPH

 

21/17 is 23.5% reduction in speed to 45.9 MPH   .... this one is much closer to your 25% error.

 

 

32702-E9821 is the 21 tooth pinion assembly for the '86 model year S12 with the CA20E engine.   Over $30. You can get just the 21 tooth spindle but the 17 tooth sleeve won't be eccentric enough for the larger diameter 21 tooth and the plastic gear will crush against the drive gear in the transmission. Each sleeve will allow the use of 2 or maybe 3 gears before they become too large or small a diameter.

 

Pretty sure you can get them in Japan for sale on line.

 

https://zparts.com/index.php/2016/10/16/speedo-gears-illustrated/

 

20 tooth...

https://www.thezstore.com/page/TZS/CTGY/classic22c09

 

R31/R32 Skylines used 21 tooth pinions. Don't forget you want the sleeve as well not just the gear

https://www.ebay.ca/itm/Genuine-OEM-Nissan-Speedometer-Pinion-Gear-R31-R32/283890699512?hash=item4219344cf8:g:XC4AAOSwN~Rey3k6

 

Here's one from Japan 'https://www.ebay.ca/itm/OEM-NISSAN-3270258S21-PINION-ASSEMBLY-SPEEDOMETER-32702-58S21/383021982489?hash=item592de3a319:g:3CQAAOSw2QtdENFt&vxp=mtr $115 US

 

 

[shaddai]

27 minutes ago, datzenmike said:

 

21 is purple and 22 is orange.

 

22/17 is 29.4% reduction in speed to 42.36 MPH

 

21/17 is 23.5% reduction in speed to 45.9 MPH   .... this one is much closer to your 25% error.

 

 

32702-E9821 is the 21 tooth pinion assembly for the '86 model year S12 with the CA20E engine.   Over $30. You can get just the 21 tooth spindle but the 17 tooth sleeve won't be eccentric enough for the larger diameter 21 tooth and the plastic gear will crush against the drive gear in the transmission. Each sleeve will allow the use of 2 or maybe 3 gears before they become too large or small a diameter.

 

Pretty sure you can get them in Japan for sale on line.

 

https://zparts.com/index.php/2016/10/16/speedo-gears-illustrated/

 

20 tooth...

https://www.thezstore.com/page/TZS/CTGY/classic22c09

 

R31/R32 Skylines used 21 tooth pinions. Don't forget you want the sleeve as well not just the gear

https://www.ebay.ca/itm/Genuine-OEM-Nissan-Speedometer-Pinion-Gear-R31-R32/283890699512?hash=item4219344cf8:g:XC4AAOSwN~Rey3k6

 

Here's one from Japan 'https://www.ebay.ca/itm/OEM-NISSAN-3270258S21-PINION-ASSEMBLY-SPEEDOMETER-32702-58S21/383021982489?hash=item592de3a319:g:3CQAAOSw2QtdENFt&vxp=mtr $115 US

 

 

Daaaaang you're helpful!

 

but... is my math wrong? 60*17/22=46.36... 21 is more like 48.57?

 

if 21 is indeed the right one, I'll snatch that purple gear thing up (last link) and that should be the entirety of what's needed?

 

and yes... 280zx five speed. Wide ratio allegedly, based on the dust shield, two ears, and the screw thing securing the assembly is on top.

[shaddai]

[datzenmike]

9 hours ago, shaddai said:

Daaaaang you're helpful!

 

but... is my math wrong? 60*17/22=46.36... 21 is more like 48.57?

 

if 21 is indeed the right one, I'll snatch that purple gear thing up (last link) and that should be the entirety of what's needed?

 

and yes... 280zx five speed. Wide ratio allegedly, based on the dust shield, two ears, and the screw thing securing the assembly is on top.

 

That's what I used to get my differential/tire size to read correctly in my 710 with 4.11 gears and 195/60X14 tires. I managed to find a Red 20T which got it closer but still reading about 33 MPH at 30 or 10% too fast. 22/21 is bang on 10% difference. Charllie69 was able to sent me up with one (again thank-you Charlie, it's the little things like an accurate speedo that makes driving more fun)  

 

 

This is not a close ratio 5 speed. They were available from '80-'83 and this transmission was made before '80. It could be from a 280zx as the first zx was made in 1979 but would be a mid ratio box with a 13.6% over drive 5th. This transmission was also used in the '77-'78 280z, 810 and 620. Have a look for switches on this side other than the reverse lights just to the rear of the clutch arm. If there is only the reverse lights then from an EFI car like the 280z, 810 or first year '79 280zx. They did not require top gear and neutral switches for emissions like the truck

 

8 hours ago, shaddai said:

 

[shaddai]

2 hours ago, datzenmike said:

 

That's what I used to get my differential/tire size to read correctly in my 710 with 4.11 gears and 195/60X14 tires. I managed to find a Red 20T which got it closer but still reading about 33 MPH at 30 or 10% too fast. 22/21 is bang on 10% difference. Charllie69 was able to sent me up with one (again thank-you Charlie, it's the little things like an accurate speedo that makes driving more fun)  

 

 

This is not a close ratio 5 speed. They were available from '80-'83 and this transmission was made before '80. It could be from a 280zx as the first zx was made in 1979 but would be a mid ratio box with a 13.6% over drive 5th. This transmission was also used in the '77-'78 280z, 810 and 620. Have a look for switches on this side other than the reverse lights just to the rear of the clutch arm. If there is only the reverse lights then from an EFI car like the 280z, 810 or first year '79 280zx. They did not require top gear and neutral switches for emissions like the truck

 

 

The prior owner was a little... strange... but he said it was from a 280zx, so it's probably the 79. I wasn't sure (before researching all this speedo gear stuff) about any of this transmission stuff, only that the difference between fourth and fifth is incredibly small. I'm used to close ratio gearboxes (all of my other cars have been close ratio 6 speeds from 2000+)... but that seems ridiculously close!

 

Thanks for the help!

[shaddai]

This just arrived from Japan ... 

[DanielC]

"only that the difference between fourth and fifth is incredibly small. I'm used to close ratio gearboxes (all of my other cars have been close ratio 6 speeds from 2000+)... but that seems ridiculously close! "

 

This is a beautiful thing.  It allows the engine to keep pulling, without dropping too low in RPM to fall below the torque peak on the engine when you shift.  In the 1970's, Datsun was very serious into racing, rallys, and competition.  Why do you think they made the 510's with independent rear suspension?   Very close ratios in the higher gears is perfect for competition.

[shaddai]

Okay... so I tried to install this sucker. Turns out... it doesn't fit if I put the assembly in with the clip slot facing up... but it fits 180 degrees so the slot (green arrow) is at the bottom of the transmission (where there is no way to secure it). Completely unrelated... I accidentally pushed it too far in to the transmission and I haven't yet been able to get it out. Oops. Pic of that later 😕

 

[DanielC]

If you can, put the speedometer cable on the pinion threads, to protect them.  Then grab the speedometer cable nut with a pair of Vise grips.  The "O" ring fits the pinion carrier very tightly in the hole.

[datzenmike]

 

This is because of pre '80 transmissions and after '80 pinion sleeve. Just nick with an angle grinder to make a new keyway.

 

Can you screw the speedometer cable end on? Then just pull out. The plastic gear is eccentric so if in too far and turned it will hit the worm gear inside on the mainshaft. You should be able to see the little tab where my finger is pointing. Turn it to the bottom? and pull straight out.

 

[shaddai]

5 hours ago, datzenmike said:

 

 

This is because of pre '80 transmissions and after '80 pinion sleeve. Just nick with an angle grinder to make a new keyway.

 

Can you screw the speedometer cable end on? Then just pull out. The plastic gear is eccentric so if in too far and turned it will hit the worm gear inside on the mainshaft. You should be able to see the little tab where my finger is pointing. Turn it to the bottom? and pull straight out.

 

To be honest... I can't get the speedo cable off the old assembly... but I will try harder. 😄

[datzenmike]

Grip the pinion sleeve with pliers but don't crush the O ring. I turn the threaded part on the cable with vice-grips but not set too tight. It's pot metal casting. Once it's loose it turns all the way off by hand.

[shaddai]

15 minutes ago, datzenmike said:

Grip the pinion sleeve with pliers but don't crush the O ring. I turn the threaded part on the cable with vice-grips but not set too tight. It's pot metal casting. Once it's loose it turns all the way off by hand.

Got it! Thanks a million sir!

[shaddai]

Dremel modified:

 

 

 

[datzenmike]

That's all it takes. I've done several

 

 

I even cut apart a rd and 'glued' two 11 tooth segments together to try and make a 22 tooth. Yeah that didn't work

[G8KeaPoR]

My thoughts are if anyone has a set of these NOS make a silicone mold and urethane copy them 😀. But since that’s unlikely do what Mike said 👍
 

Another option I just thought if is go to a snob that calibrates.  They likely have an aftermarket gear that will fit available plus they can dial it it.

Edited August 13, 2020 by G8KeaPoR

[shaddai]

14 hours ago, G8KeaPoR said:

My thoughts are if anyone has a set of these NOS make a silicone mold and urethane copy them 😀. But since that’s unlikely do what Mike said 👍
 

Another option I just thought if is go to a snob that calibrates.  They likely have an aftermarket gear that will fit available plus they can dial it it.

I bought this one new on megazip.net... seemed legit enough to try... lo and behold it worked great!

[G8KeaPoR]

can you PM me a URL?  I have the same prob in my 510 plus I would like to duplicate that gear 😄

[shaddai]

7 minutes ago, G8KeaPoR said:

can you PM me a URL?  I have the same prob in my 510 plus I would like to duplicate that gear 😄

Done!

[G8KeaPoR]

Sweet thanks!

 

[taijirich]

Hopefully, nobody gets too upset with me reviving this old thread, but this is the closest that I have come to finding out exactly what I need. I have a 1983 280zx GL that I am in the process of modifying. I bought the Autometer Ultralight set of gauges from the Z store and had them installed, they look great, but the speedometer is not even close to calibrated. I understand that mechanical speedometers will only be accurate at one speed, and will be over below that speed, and under above that speed. Mine says 120 mph but according to GPS is only going 100 mph. Everything is stock, so I should have the white 19-tooth pinion gear. I would like to be as close to accurate as possible at 60 mph. From reading this thread, it seems like the purple 21-tooth gear might be right, but would the orange 22-tooth be better?

[Bleach]

Looking at the 280ZX as an example, each color (and number of teeth around) represents one jump in rear differential gears.

So one speedo gear is for a 3.54 diff

The next number of teeth would be for the same car with a 3.7 diff

Then the next is for 3.9 diff

4.11 and then 4.375, ect.

 

So just figure out what speedo gear you have, look at the information available and try to find the gearset that is one jump in the right direction. Your speedometer is reading fast.

This is just an example, but if the speedo gear cog is telling your speedometer you have a 3.54 gear but in fact you might have gearing closer to 3.7 (lower gear, slower speed at a certain rpm in 5th gear)

 

I did a little bit of digging for you. Here is some info I pulled from DatsunzGarage.us

 

YELLOW is the 16 tooth for the 3.36
BLACK is the 17 tooth for the 3.54
BLUE is the 18 tooth for the 3.70
WHITE is the 19 tooth for the 3.90
RED is the 20 tooth for the 4.11
PURPLE is the 21 tooth for the 4.38

[shaddai]

1 hour ago, taijirich said:

Hopefully, nobody gets too upset with me reviving this old thread, but this is the closest that I have come to finding out exactly what I need. I have a 1983 280zx GL that I am in the process of modifying. I bought the Autometer Ultralight set of gauges from the Z store and had them installed, they look great, but the speedometer is not even close to calibrated. I understand that mechanical speedometers will only be accurate at one speed, and will be over below that speed, and under above that speed. Mine says 120 mph but according to GPS is only going 100 mph. Everything is stock, so I should have the white 19-tooth pinion gear. I would like to be as close to accurate as possible at 60 mph. From reading this thread, it seems like the purple 21-tooth gear might be right, but would the orange 22-tooth be better?

No. Mechanical speedos will be fine across the whole band. It's the ratio that people often miscalculate ("my Speedo is 5 mph fast", no it's not, unless it says 5mph at 0mph and 55 at 50). You are 20% high, so you want to go ~20% bigger. It's not exact depending on bigger vs smaller. I'm too tired to do the math properly at this exact moment, but don't assume what you have. Go check (and then refill your transmission oil). Then do the math.