Gearbox Identification - HELPP!!

[Changi558]

Hey guys,

So I have a 1991 Nissan 1via with an RB25DET engine swap (believe it's a series 1 RB25det). I've been trying to get the speedo in the dash working. I've put two rb25det speed sensors in the gearbox now and both times it's been getting chewed out in a concave shape centrally on the sensor gear.

The only reason I can think of the reason is that the gear box I have either isnt an RB25det gearbox, it is a different RB gearbox from a different car, or is there a difference in an RB25 series 1 and 2 gearbox that might be the cause of my sensor gear getting chewed up.

Is there a way to identify the different types of RB gearboxes from the outside with cracking them open?

Any help or advice is appreciated!

[DiscountPirate]

I really know nothing about RB but I assume there are numbers of some sort somewhere on the tranny, whether a VIN or casting numbers, those might help.

[gaz_moose]

it might be a 300zx or a 2WD pickup truck gearbox. does it look like its been apart?

I know for the 300zx they have 2 different sensors (probably for turbo/non turbo) which are identified by the colour of the gear on the speed sensor. the speed sensor gear is driven by a worm gear on the output shaft so the fact yours is stripping the middle off the gear does suggest something might not be right, or that your worm gear is knackered.

[smoked240]

A 300zx speed sensor works in the RB25det transmission. I cannot remember off hand which one it is(turbo or non turbo). The 300zx speed sensor is used to help with the speedo problem from the s13-RB25 trans.

Gaz moose might be onto something. I would pull the speed sensor and inspect inside there and see if anything is off.

Some people have used an RB20 transmission on an Rb25. Maybe this is the case here?