rear gear help

[pow3rwagon]

Ok I'm fairly new to working on vehicles I know the basics and really the only thing I've wrenched on outide of oil and brake changes was a 97 grand prix. Any who I have an 82 malibu wagon with a th350 that is not original to the car and the speedo is all jacked up. From what I have researched In order to find out what speedo gear or gears I need to correct this I need to know my gear ratio. Now I know it's a 7.5 10 bolt and I went looking around on the axle tubes for some kind of code specifically of the drivers side tube on the side that faces the engine. I'm wondering if anyone can help took a quick pic from the rear I know it's not much help but along with the wagon in got a new phone this weekend to so why not. While under the car I also noticed that at some point someone had boxed the control arms......horrible welds but boxed non the less

 

[pow3rwagon]

Also I do know that in the end if I can't figure it out I'll have to pull the cover and count teeth but I don't have the means to do that for the next month or so

 

[theoldsone]

I don't bother looking for codes any more. Sometimes people change the ratio and there is no way to tell if they did or didn't thus making the axle code pointless. I just count the teeth its a sure way to know your ratio....Or if you don't want to pull the cover lift the car up and turn the drive shaft and count how many times the wheel spins compared the drive shaft. Doesn't give you an exact number but you don't have to remove the cover and carrier together. And there are only so many gear ratios available. Here's a chart I found online.

 

[pontiacgp]

when you take off the cover you'll see the gear teeth numbers stamped on the ring gear. Just divide the larger number by the smaller number to get the ratio.

Axle Ratio Tooth Combination
2.56:1 41/16
2.73:1 41/15
2.92:1 41/14
3.07:1 43/14
3.08:1 40/13
3.08:1 37/12
3.31:1 43/13
3.36:1 37/11
3.42:1 41/12
3.55:1 39/11
3.73:1 41/11
4.10:1 41/10
4.11:1 37/9

 

[pow3rwagon]

Thanks for all the help from everyone I looked again and found an axle code 9TY C115. It was onthe passenger side hiding behind an exhaust bend. I don't know what that means as I did not see it on the code this anyhelp would be awesome. Here is a pic

 

[truracer20]

Looks like a Monte Carlo SS rear. And should be 3.73.

 

[pontiacgp]

If you are not sure what gear ratio you can't be sure about the age and condition of the rear end oil. Rear end oil not only saves the rear end it can also give you better fuel economy.

 

[pow3rwagon]

I plan on pulling the cover and inspecting and refilling once I get moved into my new pace

 

[pontiacgp]

It''ll be nice to have a place at home you can work on it...a new place will always give you a new pace..

 

[truracer20]

Depending on year it may be 3.42. Is there a 1 or 2 after the c115?