Gear ratios?

[BQS4]

This was asked of me by another member, but, I didn't have an answer. In fact, it has got me wondering. How, or is, there a way to visually see what axle ratio one has just by looking at the housing. Is it stamped, painted, coded? Is there some difference in the housings? My example would be that since so much of Opels are interchangeable, that PO's can put in say a 3.67 rear in a plain Jane Manta, but, is there a way VISUALLY to tell from the outside, without having to pull the cover and physically count the ring gear teeth and pinion teeth and divide?

[baz]

i use chalk gene ,with the car Jacked up so one wheel is off the ground and the hand brake off , in neutral mark the prop at the gear box and mark the wheel at a point next to the end of the wheel arch , turn the wheel 1 turn while counting the times the prop turns , not a true or accurate way but close enough

2 turns of wheel gets almost 7 turns of prop so a 3.44:1 diff

2 turns of wheel and just over 7 turns so a 3.67 diff

hth

[guyopel]

Gene, When you remove the rear cover the ring gear teeth are marked with the ratio amd the number of teeth on the ring and pinion no math work at all ! HTH
With the cover off you can look for wear and metal and fluid contamination ( water ) .
John

[opelnut10]

There is no outward difference in appearence on 1.9 cars. Like stated in the previous post the ring gear is marked with the ratio, also the carrier flange for 3:67 or higher number ratios is thicker than the 3:44 or 3:18. In other words you need to have a 3:67 carrier to install a 3:89, 4:22 and so on.

[jeff denton]

Baz's way works best if you have both wheels off the ground and a person at each wheel rotates it one turn while another person under the car watches the marks between the trans and yoke. Otherwise you have some differential gear action interfering.
You can use the higher number gear on the lower number carrier if you make a shim to take up the difference, that trick is explained in a thread about that.
I do agree with taking the cover off to see for yourself what gears you have and what kind of shape they are in and what the backlash feels like and how loose the carrier bearings are. There's certainly nothing wrong with a little rear end inspection every twenty or thirty years...

[hrcollinsjr]

Originally Posted by jeff denton There's certainly nothing wrong with a little rear end inspection every twenty or thirty years...

Is a Proctologist required for this?

Harold

[GTJIM]

Originally Posted by hrcollinsjr Is a Proctologist required for this? Harold

After 30 years the gear oil smells pretty bad - so at least latex gloves are required!