What are my diff ratios?

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J

Jamesyboy

New Member
Posts
114
Jacked up the rear axle on my 1988 Def 90 yesterday. Wheels are on drums so don't spin for long but they turned nicely. A bit of sideways play there ie knocking a bit when tyre pulled back and forth - bearings?

I worked out that one tyre revolution produced 1.75 turns of the diff flange.

Found same ratio was on the front flange with a single wheel station jacked up - the front prop is off - so it was easier to see the movement.

Reading another forum I am told it is definitely 3.54 revolutions of the diff flange for every single revolution of the tyre.

Am I doing something wrong?
 
Im not sure if your doing anything wrong, but your landy wouldnt move very fast with 1:1.75 ratio!

coincidently, if you double your original figure, you get the 1:3.5 ratio... confused? me to!

I wouldn't worry.

G
 
Griffdowg said:
Im not sure if your doing anything wrong, but your landy wouldnt move very fast with 1:1.75 ratio!

coincidently, if you double your original figure, you get the 1:3.5 ratio... confused? me to!

I wouldn't worry.

G
Click to expand...

Tiz simples, Griff - it is because he is only turning ONE wheel. The diff splits the output to both wheels - as one wheel is stationary, the other wheel is going twice the speed (rotations of wheel to prop) and therfore gives only half the ratio. ie 1:1.75 instead of 1:3.5.

comprehende?
 
So if me and my mate spin a rear wheel forward each at the same time - that diff will turn at the stated correct ratio?
 
yes.............
but why bother - ever time yo mate tries to turn the wheel forward, yours will try and turn backwards at the same rate - just do what has been done - one wheel in the air and turn the wheel 10 full revolutions and count the number of turns of the prop. better still turn the wheel 35 complete turns and see wot the prop turns.
 
Not pointless when you think the last assh-le to own the vehicle, based on other discoveries, might have put a different diff in each axle. I am checking because my props are getting chewed and t boxes worn out.
 
Checked it again. One wheel in the air at any time - ten rotations of front tyre then back tyre - 17.75 rotations of each respective diff flange. I guess that works out at the right ratio if you factor in the other axle wheel as a mulitplier (x2).
 
This is helpful

[nomedia="http://www.youtube.com/watch?v=i_Enyf67KTs"]YouTube- How to Calculate a Rear Differential Gear Ratio[/nomedia]
 
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