need help with gear ratio

[jamiebarnesjr3]

i have a 84 k10 swb i blew my rear in the back out and am putting a replacement in my questiion is if i turn my hub 1 full turn and my drive shaft moves a hair under one turn what is the gear ratio i dont want to pull the cover off or anything like that

[Irish_Alley]

Can't help you on turning thing but. Its now a good time to inspect everything in the pumpkin and putting new fluid in her, also to make sure you ratios are the same.

[Lt.Del]

my questiion is if i turn my hub 1 full turn and my drive shaft moves a hair under one turn what is the gear ratio

that would make it a hair between a 4.11 to a 2.73 or thereabouts, give or take a hair or two.

Point is--it's tough to say.  You'd have to get into tenths of turns (on your wheel) and stuff and isn't very accurate. Then you have to divide the numbers by the difference of how many pieces of gravel there are in your driveway and the number of shingles on your roof.  Just too much to calculate.

pull the cover off the differentials and its stamped in there or count the teeth of the ring gear divided by pinion gear -i think. 

[Chevalade]

Put a line on the tire, jack the rear up, mark driveshaft, turn driveshaft 1 full rotation, count how many times the wheel goes around from reference point.

[Blazin]

Pull the cover! Why wouldn't you want to open it?
Good time to clean out the old oil, dirt, crud, metal shavings etc. Inspect the teeth, etc. Clean up the gasket surfaces, spooge some cone on it, pop the cover back on, and top it off with fresh oil.

[Irish_Alley]

yes x2. get dirty

[zieg85]

Love the smell of gear oil in the morning ;-)

[Skunksmash]

Like an old dirty fart.

[jamiebarnesjr3]

ok i went out an double checked the rear its 1 turn of the wheel to 1 and a little over  half of a turn to the driveshaft would it help if i spun wheel 10 times and counted driveshaft turns

[Captkaos]

If you broke the rearend out I would pull the front cover off just to make sure everything is working correctly,  You may save yourself some headache by pulling it and inspecting it. 

What Chevalade posted is how you should do it if you want an estimate.

[jamiebarnesjr3]

ok nevermind with that i got it put in an drivin but when i put in 4x4 the back wheels hop would that mean that the rear is higher or lower than the front

[Captkaos]

if you don't know if the front or rear ratios match, you are going to tear up your driveline by putting it in 4x4.  You can only have a 1% variance for on road vehicles.

[jamiebarnesjr3]

i know they have to match thats why i was tryin to figure out the back rear ratio in this post i cant tear the cover off i was attending a funeral an a buddy of mine changeed the gasket an put new oil in it i told him to count teeth and he forgot theres no way i can afford to do it again i just wanna kno what i need to do to find out the ratio with out taking the cover off

[jamiebarnesjr3]

ok figured ratio out its something tlike 3.23 does this sound right for a stock 84 blazer rear

[Irish_Alley]

The ratio is off that's why it hops. Sounds almost as if the rear is a higher number