Re: TOY: Differential gear calculation...

[thebeebs@xxxxxxx]

Hi Scott,

I think what you may be looking for is this:

Block the front wheels,
put the tranny in neutral and release the e-brake
jack up one rear tire
spin it exactly TWO rotations while counting the number of driveshaft rotations.

The number of driveshaft rotations is your diff ratio.

Just under 4 rotations = 3.90, just over 4 = 4.10, 4 1/3 = 4.30, 4 1/2 = 4.56,
just less than 5 = 4.88, etc.

If you're not sure and you want to be more precise, then spin the tire 20 times
and 41 driveshaft rotations would be 4.10, etc.

Also, if you have a LSD or locker where the whole axle has to spin, you jack
up both rear tires and only spin the tire ONE time and count driveshaft revs.


HTH!  AFAIK, this isn't written up anywhere yet.  Maybe I should add it to my
Diff Info page.

-- Erik Bibelheimer,  Citrus Heights, CA  
http://home.off-road.com/~bibelheimer
'86 4Runner
'97 T100

> From: "Scott Muir" <wsmuir@islandnet.com>
> Subject: TOY: Differential gear calculation...
> 
> Hi Guys..
> 
> I was hunting around for a method of calculating what gear ratio a diff has

> by testing it..
> 
> I know i've seen this discussed before... But if anyone could either explain

> how it is done or send me a url that would appreciated...
> 
> As i recall there was a formula for counting the rotations of the drive
> shaft against the number of rotations of a wheel if you picked up one side..

> any hints?
> 
> Thanks...
> Scott..