speedometer/tranny question.

[billy]

alright
i am an idiot so here goes.
i am going to be using a c6 tranny from a 1982 econoline van.
if i use the same diameter tires that were stock on that van.
will the speedometer read correctly on my rod?

thank you for your time
bill

 

[the reverend muddy grimes]

are you using the same ratio rear end? If so then it should.

 

[billy]

are you using the same ratio rear end? If so then it should.

i dont know.
too bad i dont know anything about cars huh?[S

 

[CR55]

The gear ratio has a lot to do with the correct speedo reading as well as tire size,......But you don't speed anyway, do ya?[cl........CR

 

[Lightning]

It will only read the same if - 1) your speedometer is the same ratio as the one in the econoline 2) Rearend gear ratio is the same 3) tire size is the same 4) the tranny speedo drive gear is the same for your speedometer. If not then, all of this can be adjusted by the speedo drive gear by reducing or increasing the ratio.

 

[gassersgarage]

No biggie. Just take it to a speedo shop and have the calibration checked/changed. I had it done recently for $60. It was only 5 mph off but now it's perfect.

 

[R Pope]

The industry standard is a cable speed of 1000 rpm @ 60 mph. All speedo's are the same. It is possible to calculate the gear you need, but most guys just buy bigger or smaller drive gears and kinda fake it till they get close enough. A handy trick is an S10 4X4 gearbox that goes on the cable drive boss and changes the cable speed. They are available in quite a few ratios if you find a bunch at a wreckers.