Diff ratios.

I have a 4.88 diff.

My mate has a diff with no tag, i jacked the rear end up.
2.5 turns of the yoke was 1 turn of the wheels.

Is this the same diff ratio?

Were BOTH rear wheels turning exactly the same, or was one wheel staying still (or even going the opposite direction)? You might need to turn the prop shaft 3 times as much to get a more accurate result.

The left side seems to be the drive side. I tried it with both off the ground but they were free spinning at different speeds because off brake drag. So i put the right one back on the ground and got my son to rest his hand on the lifted left wheel so it would not free spin.

Hold 1 wheel still and rotate pinion until the other wheel has done one turn. and then x2 the pinion count. so if you turn the pinion 2.5 times to the one rotation of the tyre. 2.5 x 2 =5:1 diff ratio

The diffs are not the same. Your mates diff is about half the ratio of yours.

A diff ratio is amount of revolutions of the pinion to the revolutions of the crown wheel, so for a 4.88 ratio you will get nearly 5 turns of the yoke for 1 turn of the wheel.

2.5 seems like a super high ratio. Spin the yoke 25 times and see if the wheel turns 10 times.

AT4 353, I think your method is a little "out". Why would you double the pinion count?

Thanks, I need to do more spinning before I start unbolting stuff.

BYF, have a look at the ends of the pinion shaft, it will probably have a ratio stamped into it. Sometimes its on the yoke end, but then sometimes it's on the gear end...

When you are turning 1 wheel only you bring the spider gears into play, this brings another ratio into the equation. You would need to know that ratio to work out the pinion /crown wheel ratio from the turns you have already worked out.

Dieseldog, AT4 353 is right if one wheel is on the ground and not turning and you are only turning the one wheel that off the ground one revolution. To check a 4.88 by turning only one wheel with the other wheel still on the ground you would have to turn the yoke 2.44 turn and have only one revolution of the wheel , Backyard Fixer your 2.5 is very close if you only had one wheel turning.

Colin

....in my professional opinion....









...this topic just seems to be going round and round !