Hi sorry if i am being stupid,
I am trying to check my diff ratio while still in the car.
I have locked up one wheel and,
when i rotate the wheel 10 times the prop rotates 17.75 times.
If i rotate the prop 10 times the wheel rotates 5.66 times approx.

Where am i going wrong and how do i work out the ratio?

Thanks
Tony

Hi,

Your problem is that you have one wheel off the ground, it should be both rear wheels off the ground and make sure that the brakes are not binding.

Regards

Bob

Sorry,
I don't see what difference it will make as it isn't a lsd.

[Edited on 28/2/11 by tony.g]

it does make a difference, because the unlocked wheel has to turn about twice as many times to turn the prop the same distance (might not be exactly twice the number of turns, or might be half, which makes more sense)

the way i'd prefer to do it, is with the car on the ground*, both wheels free, and push the car forward (or back) for 1 full exact turn of the wheels, count the number of times the prop turns, and this is your ratio, the prop should turn around 3.something turns,

when written as a 3.4:1 for example, 1 is your wheel, 3.4 is the prop.



* or as said above, both of the ground, and both turn exactly 1 full turn. or 10 turns, and divide the number of prop rotations by 10, to get 1 turn of the wheels


from what you've said above, i think your diff is maybe a 3.55:1, or around that figure. what axle/diff is it?

[Edited on 28/2/11 by blakep82]

If you hold one wheel still then the other will spin at twice the rate on the planet gears so

10 times the prop rotates 17.75 times, so is 17.5/5 = 3.55 ratio
prop 10 times the wheel rotates 5.66, so 20/5.66 = 3.53 ratio

Regards Mark

Thanks for the replies.
It's a ford live axle so it must be a 3.54.
I need something lower.
What axle can i fit to get a 3.3 or around that figure?

if you take the back cover off the ratio is either stamped or written on the crown wheel

It's an Escort axle with the diff going in the front and no removable plate at the rear.
I now know it's a 3.54.
Tony