Rear end help! Need smarts!

[Hogsophist]

It supposed to be out of a 79 trans am. Trying to figure out the gear ratio to see if the set up is ok.

Id(s) off housing:

Tag appears to be k129
Six digit code: 254333
Passenger side appears to be: gm 36


I have searched till I'm exhausted. Any info would help.
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[Kabwe]

If you have no identifying tags with the gear ratio writing on it. Open the rear cover of the rearend, look on the ring gear (the big one) turn it until you see a number that looks like this written on the side of it 41 11, the is your teeth count which will give you your gear ratio. Simply divide 41 by 11 and you have your gear ratio which in this case would be 3:73.



Or you a do the guesstimate version. Which is to mark on the bottom of the drive shaft. Then mark the bottom of a rear tire. Rotate a rear tire one full revolution counterclockwise. Make sure the chalk mark you made starts and ends in the same position. Count the number of revolutions the drive shaft makes by watching the revolution of the mark you made on it. You find your gear ratio by using the number of revolutions made by the mark on the drive shaft. So if the mark made three full revolutions and then stopped halfway through the fourth revolution, your gear ratio is approximately 3.5.

Personally I always open the cover and check the ring gear because I don't like guessing.

[Hogsophist]

Thanks Kabwe. Any idea on this codes? The k129 I tracked. The las digit is manufacture year.
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[mr48chev]

Truthfully I'd just do as Kabwe suggested and pull the cover and either count teeth or read the numbers and do the math.

Not only will that let you know what gear ratio you have it will let you see what condition your gears and the case are in. You need to know what the gears look like and if the pin that holds the spiders in is tight in the case. If it will cost you a few pints of gear oil and some silicone sealer or a gasket but is something that needs to be done before you put the truck on the road anyhow.

A couple of years ago I answered a craigslist add for a free S-10 Blazer with no title. I only wanted the rear axle for my 48 and had no issue with taking my ax and torch to the rest of it to scrap it. You got it, the only part I wanted on the whole vehicle was the rear axle and the rear it was missing several teeth off the ring gear. I did end up giving the axle to someone who needed it because their Blazer axle housing was damaged but their gears were good so all wasn't lost. That is one reason to look inside before sticking it under the truck.

[Kabwe]

Originally Posted by Hogsophist

Thanks Kabwe. Any idea on this codes? The k129 I tracked. The las digit is manufacture year.
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I did a little internet search for you and the only thing I could find was this. I don't know if it will help you but here you go.
http://www.novaresource.org/axle.htm

The one below has an axle decoder at the bottom of the page.
http://www.thecamaro.com/Decoding/Ch...-End-Decoding/

[jimig1]

I'd say open it up you can check the condition and put in fresh fluids. My dad got got a rear end in a car that had broken teeth in the case. Luckily he found them before they got sucked up while driving.

[1project2many]

You don't have to pull the rear cover to get the gear ratio. If it's an open rear (non-posi) hold one axle stationary and turn the other two times while counting the number of rotations of the pinion. If it's a posi then you only have to turn the axle once.