Speedometer problem

[galantrevolution]

I have a problem with my speedometer it reads 5mph more than actual speed , already replace the gear at the trans, what could be the problem ?

 

[clevr4]

Running stock wheels?

 

[galantrevolution]

Stock wheels all 195/60/15

 

[fuel]

Couldn't help but notice you have an 'RS swap' - does that mean you're running the 3.909 rear diff and matching transmission?

 

[galantrevolution]

I just got the trans and engine , no rear end

 

[fuel]

what's your trans code? if it's from an October 1989 RS with the W5M33 transmission, it's going to be expecting a 3.909 rear diff ratio.. if you have a KM225/C50/C51 trans then you have the earlier 3.545 trans.

 

[holeshotmoe]

It will wear your VC out pronto if it turns out the rear ratio is incompatible with the trans. 89Patches has the 3.909 gears if you need them... LINK

 

[OpticalPhenom]

Super useful information.

 

[galantrevolution]

Here the transmission code Kw5m332npxv
Rb7291 so is this a JDM trans and what differential to I need to match that transmission

 

[fuel]

That's not a JDM RS transmission - that's a 1G DSM AWD trans which would match your stock 3.545 rear end. I think the DSM runs taller tyres stock than the GVR-4 so maybe that's where your inaccuracy comes from.

 

[thomcasey]

A DSM transmission is set to run with tires that are just over 1/2" taller than the stock GVR4 ratio. So, you will have speedo issues unless you run a ratio that equals the 1g DSM standard of 205/55r16, or a 631.5mm tall tire.

 

[fuel]

Or you could swap in the GVR-4 speedo drive unit

 

[holeshotmoe]

GVR4 speedometer cable drive gear has 30 teeth