differential gear swap

[rwd]

if i want to change the gear from 4.1(jza70) to 3.72(ma70) , how my speedometer can have the right speed for the new gearing

 

[mk3_chris]

I've also been wondering about this, and nobody I've asked has any idea. I'm at the point where I'm just going to invest in a Gps and use it instead.

 

[IJ.]

Swap in the correct driven gear at the end of the speedo cable will get you close but you would need to run the stock diameter tires, or if you want it exact get a correction box.

 

[mk3_chris]

Swap in the correct driven gear at the end of the speedo cable will get you close but you would need to run the stock diameter tires, or if you want it exact get a correction box.

Wouldn't it be just as easy and to use a gps, I mean I'd imagine they would be slightly off also. But I don't plan on running stock diameter tires either.

 

[KingCobra]

if i want to change the gear from 4.1(jza70) to 3.72(ma70) , how my speedometer can have the right speed for the new gearing

Best way to do that is, get the speedo gear from the tranny that goes with the same car the diff is coming out of... then you know the ratio is right!

 

[IJ.]

Wouldn't it be just as easy and to use a gps, I mean I'd imagine they would be slightly off also. But I don't plan on running stock diameter tires either.

With a correction box they can get it 100% accurate with whatever tire/gear you use.

I use a MoTeC dash and wheelspeed sensors and set mine up using the GPS to 0 it in.