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Mechanical Speedo drive swap into RB25 Gearbox


Mike Rowe

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Today I just bought from a Nissan dealership the Nissan Navara speedo drive assembly and er I'm thinking it's only suitable for the turbo RB25 box.. I have pictured below all three drives from each gearbox; Navara (extra long), original R31 Skyline electronic drive, and original 260Z drive. The last two are very close I'm just wondering has anyone succesfuly installed a mechanical drive into a non-turbo box? I'm thinking of trying the original drive again but I did have it installed and all I can get from it is internittent movement of the speedo while I'm driving. I'm assuming I haven't meshed the gears properly in the box so the speedo isn't working all the time... This is my last hurdle of the whole conversion (RB25DE);Anyone here had any luck?

speedos_thumb.jpg

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Very odd. My D21 Hardbody speedo (1988) is not nearly as long as the one you show. Also, I have a 1988 Z31 turbo speedo assembly and it is nearly identical in length to the original Z32 assembly.

 

I just picked up a replacement speedo cable and will be installing the assembly this weekend. I'll take pictures of all three side by side as well.

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My mechanic took care of this for me, however, he did not mention having to modify anything to get the speedo to work off the normal rb25 transmission. He actually said I wouldn't need to bother buying a electronic speedo after I'd mentioned it pre-install I can try find out more if anyone would like.

 

Aaron

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Aaron, I'm not sure exactly where or from what car my gearbox is from because the electronic speedo sender isn't an R31 Skyline version and a Holden Commodore VL model with the RB30 has a cable drive (above pic middle speedo drive). I have ordered from Nissan a part #32702-58S17 which I hope will solve my problem. Part is coming from Japan so it's going to take around a week and a half to get here so by then I can say how I went. I would love a pic if you can get one easily just so I know what I need!

 

Any pics of speedo drives are welcome!

 

Thanks,

Dimitri

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Well, strike 3 and I am out. Both speedo assemblies I ordered were too short and the diameters too small. The Z32 assembly is as long as the Navara's. The D21 Hardbody assembly is too short and the diameter is too small.

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I've had some luck this weekend...I went rummaging through the wreckers and removed a speedo drive from a Nissan "Gazelle"..I think in the US market they were called a 200SX 80-85 model with a CA20 motor? Installed it, went for a drive and sure enough...hello speedo! My odometer works again. Its about 3-4 Mph out but who cares? When I installed it, I made sure when I had the ass up in the air, I turned the prop shaft and made sure the speedo drive turned with it completely. Cable went straight on and away I went! I've ordered another one from Japan (part # 32702-58S17) which came in a Holden Commodore VL model 87-88 with an RB30 but non-turbo. That speedo drive should fit also...I'll let you know when I receive it.

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I think that if you unscrew the electric sensor, you will find the standard mechanical drive inside. My Z31 turbo trans had this setup.

 

 

I have two spare FS5R30A trans in my shop. One has the cable type assy, the other has the electronic type speedo drive assy.

They were both sold to me (at different times) as Z31 88-89 turbo Z trans.

 

I can pull them both and take pics if needed?? If that will help, since they are identical to the RB25det trans...

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  • 1 month later...

It looks to me like the 32702-02GXX Mechanical Speedo Pinion Drive for the trucks AND the Z32 tranny, is available with 17,19,20,21 and 22 teeth

 

Replace the XX with the tooth number of the pinion you need.

 

http://mynissanparts.com/parts.html

 

I need to figure out what pinion will work with the Z32 trans and the R200 3.54 rear and stock 280Z speedo.

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Well the conclusion that I came to is I found the perfect speedo drive if you have a non turbo RB gearbox is from a S12 85-86 (or Australian model Gazelle hatchback). Goes straight in with no mods and original speedo cable mounts and works 100%. If you have a turbo RB gearbox you will need a longer Navara speedo drive (as pictured in one of my previous posts and others). I've been wrenching on other things on my zed now trying to make it quicker!

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  • 2 months later...
  • 2 months later...
  • 2 weeks later...

Here are the pinion part no's & colours for the RB gear boxes

 

Nissan Part No

? 21 teeth (PURPLE) Ratio 4.375:1

32703-31G20 20 teeth (RED) Ratio 4.11:1

32702-33G19 19 teeth (WHITE ) Ratio 3.90:1

32703-31G18 18 teeth (BLUE) Ratio 3.70:1

32702-33G17 17 teeth (BLACK ) Ratio 3.545:1

? 16 teeth (YELLOW) Ratio 3.364:1

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I now have the complete list of part numbers thanks to my Nissan agent

 

 

Nissan Part numbers for different teeth counts.

 

32703-31G21 21 teeth (PURPLE) Ratio 4.375:1

32703-31G20 20 teeth (RED) Ratio 4.11:1

32702-33G19 19 teeth (WHITE ) Ratio 3.90:1

32703-31G18 18 teeth (BLUE) Ratio 3.70:1

32702-33G17 17 teeth (BLACK ) Ratio 3.545:1

32702-33G16 16 teeth (YELLOW) Ratio 3.364:1

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I'm doing the opposite in that I am putting an electronic sensor into a tranny that had a cable.

 

If you look closely at the various sensors and speedo drive pinions, you will see most are offset a bit.

 

It seems the manual fs5w71c boxes use a drive that is 28mm in diameter and the automatics (3n71b, 4n71b, and RE4R01a) use a 30mm diameter body while the RE4R03a uses a 28mm body.

 

My speedo drive for a 3.54 280zx turbo 3n71b fits in and meshes into a RE4R01a of a 240sx with no troubles.......of course ratios are off.....and the older drives don't have a replacable gear.

 

It might be possible that the 28mm "short" sensors are interchangable from automatic to manual but not sure of gear mesh.

 

In the automatic world, the sensors and speedo cable drives have the shaft offset and It seems that the offset is there so you can use different gear sizes on the same sensor/drive...............but you have to clock it differently.

 

I tried this by putting a Q45 speedo pinion gear for 3.538 diff. on a sensor for a 240sx which is around 4.08 or so and found that I could make the much smaller diameter gear mesh by clocking it such that the mounting tang was nowhere near where it bolts to the tranny.

 

In this case, it was 90 degrees different so something between these two should be less and a change outside of these will be more.

 

The offset coming from a car with the 4.08 is to the extreme least amount of gear mesh depth so I guess the cars with anything higher than that might use a different housijng with more offset to deal with a larger gear.

 

I'm posting this because these dimensions and clocking may also apply to the mechanical speedo drive pinions..........more later with pics and dimensions.

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Are you saying the internal housing is different or the gear itself? If it's the cog, could you just switch cogs with one of the ones listed above? I wasn't aware of there being any difference between them, but we've only been talking m/t as far as i know. They don't have to be clocked to accept different gears, obviously a gear with different spline count will be a different size, and I'm pretty sure the same transmission could have come with a number of different final drives, thus different speedo gears. The only mechanical speedo that we've discussed was I believe an rb26 awd? It might be in the thread relating to the speedo pinion itself.

 

Yes, pics will be very helpful, keep us posted.

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