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Speedo gear -21 or 22 tooth sets available?


shaddai

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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?

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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.

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55ZOBr5.jpg

 

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

 

s-l1600.jpg

 

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27 minutes ago, datzenmike said:

55ZOBr5.jpg

 

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

 

s-l1600.jpg

 

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.

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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:

lMndEOG.jpg

 

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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!

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  • 2 weeks later...

"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.

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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 😕

 

7UR19my.jpg

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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.

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MY7CgEK.jpg

 

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.

 

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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. 😄

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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.

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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!

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

 

 

W5RiDKX.jpg

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

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  • 3 weeks later...

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 by G8KeaPoR
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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!

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