how do i find out what my gears are

[low76swb]

i wanted to know what my stock gearing would be in my 76 swb with a 4bbl 350

[BigRed]

The ratio should be stamped on the ring gear. Or, you can resort to counting the teeth. Every once in awhile, somebody will get lucky and find a stamped tag on the outside of the gear cover that has the ratio on it. If you find the numbers, you should be able to divide them and get your answer.

[Prerunner1982]

http://www.quiknet.com/~ke6vut/axlecalc.html

this will get you close, not exact.... if you know at what RPM you are doing a certain MPH, in 3rd gear and your tire size you should have your rear end gear ratio.

[Frank-id]

A quick method of finding rear gears ratio is.. Jack up rear of vehicle, so as to be able to look at and touch rear u-joint or pinion yoke. Make a white mark on yoke or u-joint facing toward ground. On one rear wheel make a white mark on tire facing ground. Have helper turn wheel one turn , while the u-joint is watched. The driveline will turn 3-4 turns as the wheel turns just once. Usually the driveline will turn 4 and a little , which is a 4.10 ratio.. A driveline that turns less than 4 turns is a 3.73. This is a quick and easy ratio check, with out any disassembly....... Frank

[CHEVYJEFF]

look at the codes on the build sheet on the inside of the glovebox door should start with a G designation example GT5, G80 ect. Then do a search for glove box codes on the internet. This will work assuming its the original set up.

[Slonaker]

Mine actually says 3.08 on the sheet in the glovebox. I have seen an older truck that had the build info on a sticker under the hood. I want to say it was on the inner fender, but I am not sure.

Again, this assumes that you can find the info, and that it has not been changed.

Slonaker

[PHOENIX]

Go to checker or autozone buy a gasket ($6) and gear lube.
Take the cover off with a pan under it to catch the gear lube.
Count the teeth on the ring gear and the pinion and divide them to find the ratio.
Clean old gasket off and install new gasket.
Put cover back on and tighten with hand tool as evenly as possible.
Remove side "fill" plug and fill with new gear lube until it spills out of the fill hole (then its full).
You may want to buy a fluid pump (under $10) or buy at least one of the smaller gear lube bottles with the pointed tip.
The pump and pointed tip bottles make it much easier to fill.

This way you have new gear lube in (which it probably needs), you know the ratio for sure, and you know what condition your gears are in.
You may have some damage inside you were not aware of.

You could do this in a couple hours for a few dollars.

[1974StepSide]

Originally posted by Prerunner1982
this will get you close, not exact.... if you know at what RPM you are doing a certain MPH, in 3rd gear and your tire size you should have your rear end gear ratio.

This is the method I used to guess-timate that I have 3.08 gears... I played around with the calculations, and I'm pretty confident that I have that gear ratio.

[onetoncrewcab]

I posted this question a few months ago and Phoenix replied with the same suggestion. After thinking it over and the fact I wanted to know exactly what I had, I pulled the covers. I used my brother's air wrench to knock both covers off (front and rear). I didn't have to put mine back together so, I saved the time on that part of the project.
It really isn't that big of a deal to pull them and count the gears if you want to be sure what you have. Like Phoenix said, it probably needs to be done anyway.
MJ