Rb25 Gearbox Speedo Conversion For R32

[32_Dave]

RB25 Gearbox Speedo Conversion for R32

Intended Audience: Rb25 R32 Converters

Technical Level: Medium

Duration: 30-60 mins

Disclaimer:

If you f**kup don't blame anyone. Myself or SAU are not responsible for injuries, poor workmanship and product failure. This tutorial is a guide of how to convert the Rb25 gearbox to mechanical Speedo. All instructions are to be done with care, if you doubt your skills seek out someone like a mechanic or machine shop. If you read this and think WTF do not attempt this tutorial.

Tools Required:

Now before you start thinking I'm going to need some crazy mill or lathe, you don't, I made this with very basic power / hand tools that most people would have around the house.

• - Bench or 100mm Grinder
  
• - Assorted Files
  
• - Blowtorch or Fire lighter
  
• - Pliers, Screwdrivers
  
• - Rule, Sewing measuring tape (or flexible tape) and engineers square
  
• - Fine tip felt pen
  
• - Battery Drill, Drill bit (metal, suitable size)
  
• - Tap / Die kit (not required, but helps)
  
• - Glue (araldite or cyno)
  
• - Nylon or Rubber Mallet
  

Items Required:

• - R33 Speedo Assembly (you just need the red cog 21T)
  
• - Screw / Washer (suitable size)
  
• - VL Turbo Speedo Assembly (part number: 32702-02G17 )
  

Background:

My names Dave, I'm a sparky so in no way think I'm some car genius, cause I'm not, and if you pick up on something wrong in this thread please don't gloat, pm me or post up and ill add the information in. Now let's get on with it...

All crazed 32 enthusiasts some stage want to ditch the Rb20 or Rb20 gearbox and seek more power, and stronger internals. As you all know the standard R33 Rb25 gearbox uses an electronic sensor to communicate with the ECU / Tacho, whereas the Rb20 gearbox uses a mechanical drive to communicate with the ECU / Tacho. With this issue creates problems, such as having a working Speedo is a RWC requirement, however, with some basic modifications / fabrications a working Speedo can easily be achieved.

Comparison of the 3 Speedo Drives. As you can see the R32 on left R33 in middle and VL on right. The R32 / VL are mechanical as the R33 is electronic (mine you won't be able to notice, because itself destructed removing it from the gearbox – alloy grows over time). As you can see they all differ allot. The Gears are all different sizes, and cut different ways. This picture of the three drives it just to show you how different they all are.

NOW LETS START

• - Step #1
  

Take the VL Speedo.

Remove the Retainer pin, so you can slide the inner shaft out.

• - Step #2
  

Take the R33 Speedo

Remove the red gear by removing the C-Clip at the top of the shaft (can either use C-Clip pliers of a screwdriver)

Note: See how to two inner shafts differ

• - Step #3
  

Take the VL Speedo.

And proceed to melt the black gear off the end

Note: See now how the two inner shafts differ with no gears.

• - Step #4
  

Take the VL Speedo.

Grind / File a flat spot in the VL shaft 13mm long and 2mm deep

• - Step #5
  

Take the VL Speedo.

Heat up the inner shaft once you are happy with the flat section you have just created. Make sure you don’t go over heating the shaft (red hot)

[32_Dave]

• - Step #6
  

Take the VL Speedo.

White it is still hot, line up the flat spot on the gear and shaft and push together. (this will create a spline inside the gear). The aim is to get the shaft and top of the gear flush, don’t worry if you do not succeed the first time, just redo step 5 then 6.

To remove the gear, gently tap the inner shaft with a punch.

Once you’re happy with the gear position, remove it. Mix up some araldite and coat the inside of the gear and the shaft, and press together. Allow ample time to dry.

Note: If you do not have a TAP / DIE kit skip step 7

• - Step #7
  

Take the VL Speedo.

Find the centre of the shaft, and scribe, and then proceed to drill a small hole down the centre. Once you have done this find a bolt / screw and washer suitable to the size hole you drilled. Then tap the hole. Then take the screw / washer add some loc tight and tighten.

Put your new centre shaft / gear to the side, we are about to modify the housing.

• - Step #8
  

Note: Due to the housings centre hold being off centre, the VL housing needs a new locator groove cut 180deg opposite to the original.

Take the VL Speedo Housing.

Take your flexible tap, line it up with one side of the original groove and make a mark 36.5mm on the other side. Then take you tape and measure 10mm either side of this mark. Take a square and measure 3mm from the base of the housing and mark. Then again at 7mm. This will create a square box 20mm long and 4mm wide.

This is what you want to end up with.

• - Step #9
  

Take the VL Speedo Housing.

Cut along both lines that you have marked, and another in the middle.

• - Step #10
  

Take the VL Speedo Housing.

Grab a file and neaten up the groove. (Try your hardest not to make the groove bigger or longer)

Edited June 9, 2009 by 32_Dave

[32_Dave]

• - Step #11
  

Note: CLEAN BOTH SHAFT / HOUSING BEFORE CONTINUING

Take the VL Speedo Housing and Shaft.

Coat the shaft with some grease. And slide into the housing.

• - Step #12
  

Take the VL Speedo Housing and Shaft.

Take the locator pin and punch it back in. (the piece of paper is the indication of the play between shaft / gear)

• - Step #13
  

Take the VL Speedo Housing and Shaft.

Admire what you have just created. (However you’re not done yet)

• - Step #14
  

Take the VL Speedo Housing and Shaft.

When you go to mount the new Speedo drive in the box, make sure you put heaps of lubricant on, because they can be a bitch to remove. Once lined up, gently tap the gear in with a nylon or rubber mallet. If you can test that the Speedo rotates when you spin the output shaft of the gearbox.

The aim of the game is to line up the bottom of the groove to the gearbox housing.

• - Step #15
  

Now it’s up to you to make a retainer for the gearbox / Speedo drive. I used a small piece of aluminium that was 20mm wide and 4mm thick to fill the groove, proceeded to drill a hole and bolt it up to gearbox.

THE END

[B0oStEr]

Interesting tutorial with really useful pics.

I did this mod a couple of years ago.

Just a couple of things anyone trying this might find useful.

When I went to my Holden dealer to buy a vl turbo speedo drive my mate that works there said to take the part no. to nissan and ask for a navara speedo drive. It was only a fifth of the price for the same part.

Instead of filing a flat on the new shaft I used a round file to make the hole in the gear perfectly round.

It then pushes onto the splines very firmly.

No need for heat or glue or a retaining screw.

[32_Dave]

When I went to my Holden dealer to buy a vl turbo speedo drive my mate that works there said to take the part no. to nissan and ask for a navara speedo drive. It was only a fifth of the price for the same part.

Instead of filing a flat on the new shaft I used a round file to make the hole in the gear perfectly round.

It then pushes onto the splines very firmly.

No need for heat or glue or a retaining screw.

that part number is indeed a nissan part. there about $35 bux or something like that. ive hurd of many a gears falling off so went for the safer option.

thanks for kind words.

Dave

[GTRsean]

You could also use an R32 GTR speedo drive and pop it into the r33 box, just do the last couple of steps.

I'm sure that it should work?.....maybe or it would be completely different due to the drive being in the transfer case instead of the extension housing.

[B0oStEr]

You could also use an R32 GTR speedo drive and pop it into the r33 box, just do the last couple of steps.

I'm sure that it should work?.....maybe or it would be completely different due to the drive being in the transfer case instead of the extension housing.

People have used the gtr drive with but it costs more and you still have to fit the r33gtst gear because the gtr gear teeth slant the other way.

[DCVNR32]

I NEEDED to know about thread ALONG time ago

Since then, Ive tried 2x R32 GTR Speedo drives and snapped both.

I attemped to make these 'custom' drives, but wasnt informed about

the offset of the 'spacer' that holds it in.

So 3x custom drives later, I gave up.

I had problems with the shafts breaking, the gears turning but slipping

on the shafts, The last 2x broke on Queensland Race way and decided

to go walk about the gear box...:S

Got lucky, the gears are made of a stronger compound then the speedo shaft. =D

And yes, take the part number to Nissan and they will give you a navara

speedo assembly. Was about $36 off the top of my head.

Well on that note, I might make another call to Nissan and attempt this again...

Just sad that the 'red' RB25 speedo gear alone is $70 from Nissan.

[2gceffy]

iv done this Aand it worked for about 10min then the shaft broke and is now sittin inside my gearbox, what i cant understand is why would it break ?

the gtr unit whats the difference between it and the navara unit?

also does anyone have the part number for the red cog thats on the r33 gear? and the gtr speedo drive ?? cheers

also whats the need to cut another groove in the top ?

Edited October 10, 2009 by 2gceffy

[Vinesh]

hey i used a b14 speedo panel and made it fit in my c33 instrument panel its very accurate. couldnt source the navara speedo so i did this. to me i also think its safer and you get bk features like door lock

[2gceffy]

what is B14?

[JonnoHR31]

iv done this Aand it worked for about 10min then the shaft broke and is now sittin inside my gearbox, what i cant understand is why would it break ?

the gtr unit whats the difference between it and the navara unit?

also does anyone have the part number for the red cog thats on the r33 gear? and the gtr speedo drive ?? cheers

also whats the need to cut another groove in the top ?

probs meshed too hard against the gear inside the box. if you look down from the top of the drive you'll see the gear is offset from the centre, insert it into the box the furthest away from the gear inside the box then slowly turn it until it meshes with the gear inside and then back a touch.

i just grinded the vl cog off myne and shoved the 33 cog on with some superglue, slid it in the box and left it sitting (not bolted) and its always worked perfectly. the drive wont fall out of the gearbox unless its seriously loose

[Gerry Giraffe]

Hay mate just wondering would u do this same conversion for me?? how much would u charge if i supply all the parts?? where abouts do u live??

[Sheriff Wan]

Hey mate,

Firstly what a terrific tutorial! Its people like yourself that make SAU a great knowledge base and kudos to you for sharing!

Just keen to know if this is still working? and also if it has caused any other issues with regard to steering or specifically HICAS etc?

Cheers

[32_Dave]

Hay mate just wondering would u do this same conversion for me?? how much would u charge if i supply all the parts?? where abouts do u live??

sorry mate, its really not hard to do yourself

Hey mate,

Firstly what a terrific tutorial! Its people like yourself that make SAU a great knowledge base and kudos to you for sharing!

Just keen to know if this is still working? and also if it has caused any other issues with regard to steering or specifically HICAS etc?

Cheers

i have not personally tested it yet as i haven't finished building my car, however a mate ran this in his race car with no issues, since then its changed owners. ill be testing mine within a few months i hope.

[nisbne]

my mate has been looking for this info thanks will pass it on

[45LDE]

What will happen if you just use the VL Cog and dont change it besides the speedo will be out?

[bubba]

What will happen if you just use the VL Cog and dont change it besides the speedo will be out?

Nothing.

I used an untouched Navara sender and it turned out the 17T cog (I think it was 17T) on the Navara sender suited my 3.9:1 diff gears pretty nicely!

[45LDE]

Nothing.

I used an untouched Navara sender and it turned out the 17T cog (I think it was 17T) on the Navara sender suited my 3.9:1 diff gears pretty nicely!

did u still install it 180deg out?

how long have you used it like that for?

[bubba]

Nope, didn't install it 180deg out.

Was running like that for a couple of years until I took the car off the road in September.