find the

Easiest Way to Determine Rear End Gear Ratio on a Limited Slip Differential

you're live I would think it'd be really

hard to shoot it live you know just like

I'm such a foul mouth I couldn't imagine

not cussing yeah yeah because we're good

people just just degraded what's going

on guys you're watching budget build

garage and today I'm gonna show you how

to find the rear diff ratio without

taking anything apart it's important

note though we're doing this on a rear

end that has a limited slip if you don't

have a limited slip I'll put another

video out on how to figure out your gear

ratio for that we're trying to figure

out what rear end we want to use in the

Mustang it's not a Ford nine-inch it's

an 8-inch this is my Pontiac not the

Mustang but it has a nine-inch and we're

kind of trying to convince ourselves

that we should put a nine-inch in the

Mustang that way the third members can

be interchangeable I can switch the

gears from this to the Mustang and the

Mustang gears to this we have two

different gear sets so I'm gonna show

you how to find the gear ratios on this

and then I'll show you on the Mustang in

another video all you really need is

some tape it helps if you have a buddy

but really all you need is the tape or a

marker whatever you're comfortable with

putting on your car all we're gonna do

is make a reference point right there

and then right here on the tire where

they meet so

once you know that these to line up

we're gonna rotate the wheel 360 degrees

back to this spot while we do that we're

gonna put another mark on the drive

shaft and count how many times that

drive shaft spins once we know that

we'll know what the actual ratio is well

know when you hear a gear like if you

hear three point five two one that means

that drive shots going to spend three

and a half times to the one time this

tire spins if you have posi if you don't

have posi the differential works

slightly different and that ought to be

a different video but now that I got it

like this I'm gonna slide under there

and make a mark on the drive shaft and

I'll have Taylor rotate the wheel go

ahead alright here we go

it's so much slow one there's two

there's three be good there all right so

that's three and a quarter look at your

quarter three quarter turns making it a

three point two five two one I'll

explain that

so Taylor spun this wheel around 360

degrees the drive shaft spun three and a

quarter times making this a three point

two five two one rear gear I knew it was

that because I put it in but it's

important to be able to tell what you

have the reason it's important among

many reasons is when you're on

Craigslist and somebody says they got a


you know gear rear end with posi you

want to go buy that you need to make

sure it's a 411 or it's a 325 or it's

whatever you want to be in whatever they

say is gonna be I've used this method a

lot especially when hunting for

differentials and like pull apart and

pick apart each time I go to a junkyard

and I'm thinking about robbing a rear

end from something this is like one of

the easiest ways to do it I'll put out

another video on how to do it with an

open differential cuz that's what you're

gonna be running into a lot so ya look

for that video soon that's really it for

this video if you liked it go ahead and

like subscribe if you have a question

I'll answer it cool thanks