Gear ratio rear axle??

[2 Fast 4 U]

How can I find out what the gear ratio is from a rear axle?
is there a number stamped on it??
It's from a 1973 1.6 S Ascona Automatic

[baz]

the manta 1.6 s is 3.67:1, ralley is 3.89:1 orspecial order 3.44:1 i think the ascona would be the same

[2 Fast 4 U]

Originally Posted by baz the manta 1.6 s is 3.67:1, ralley is 3.89:1 orspecial order 3.44:1 i think the ascona would be the same

but how do I find out witch it is ??

[baz]

look for a tag on the rear plate ,if no tag then jack up 1 wheel and put the car in "N" then with chalk of paint put a small mark on the prop where you can watch it from the side that is jacked up and slowly turn the wheel counting the number of turns to do 1 turn of the wheel
3 and a just short of a half will be 3.44
3 and 2/3 will be 3.67
almost 4 will be 3.89
crude but close enough

[azopelnut]

Take off the differential cover and count the number of teeth on the ring gear and divide that number by the number of teeth on the pinion gear.

[guyopel]

The number of teeth are stamped on the ring gear ( For the pinion and ring gears ) HTH

[2 Fast 4 U]

Thank you all for the info, I'll use the way Baz does it

[jeff denton]

I'm not sure baz's way is quite right, the way I learned was jack both rear tires off the ground, chalk a line on the bottom of both tires and index those lines with lines on the floor. Chalk a line on the driveshaft. Have a person at each wheel rotate a wheel forward one revolution while a person under the car counts driveshaft revolutions. Three and almost a half revolutions is 3.44.
See how this method isn't turning the spider gears?

[2 Fast 4 U]

Originally Posted by jeff denton I'm not sure baz's way is quite right, the way I learned was jack both rear tires off the ground, chalk a line on the bottom of both tires and index those lines with lines on the floor. Chalk a line on the driveshaft. Have a person at each wheel rotate a wheel forward one revolution while a person under the car counts driveshaft revolutions. Three and almost a half revolutions is 3.44. See how this method isn't turning the spider gears?

what are spider gears?

[baz]

the small gears inside the diff and i forgot about them (are they not 1;1 anyway jeff)

[Dmcbrass]

Jeff is right. Opels don't have positraction. If you rotate the drive shaft with one wheel held the other will turn at twice the expected speed. A 3.44 will look like a 1.72.

[2 Fast 4 U]

That shouldn't be to hard to calculate, thanks for the info

[baz]

turn wheel so prop turns twice and half the count ???
ps who mentioned posi diffs?

[RallyBob]

Originally Posted by Dmcbrass Opels don't have positraction.

Actually it might have a limited slip, as the person asking is in Europe. And like all the good options, they got them there, we didn't get them here!

[2 Fast 4 U]

Originally Posted by RallyBob Actually it might have a limited slip, as the person asking is in Europe. And like all the good options, they got them there, we didn't get them here!

It's an automatic, so yes, it has a limited slip, does that make it harder to find out the gear ratio??

[Dmcbrass]

That makes it easier. Use Baz's method. It will work fine.

[GTJIM]

Originally Posted by 2 Fast 4 U it has a limited slip

With limited slip when both wheels are off the ground turning one wheel will make the other wheel turn in the same direction at the same speed - so Baz' first method will work. If the other wheel turns in the opposite direction - the diff does not have limited slip.

[2 Fast 4 U]

Thanks alot guy's