Talking bout diff...How to tell the ratio

[bwanac]

I dont know if this is possible, but i have found a parts car i may buy with a lsd. the thing is the tag on it is to hard to read, completely worn away. is there a way to see what the ratio on the thing is? is it written somewhere else, or some way to do it physically?

Thanks guys

and this will be my new home from now on i guess. :up:

[MattE30]

To tell the ratio, jack up the car so the ass is up in the air. Spin a rear wheel. If the driveshaft spins a little less than 4 times per wheel roation, you have a 3.73 diff. If it spins a little more than 4 per 1 roation of the wheel, you have a 4.10 diff.

[Super-Eta]

What kind of car?

[Jordan]

What year and model is it (be sure to say 5spd or auto) and I can tell you what diff it should have.

[Jand3rson]

Try FOOL-PROOF method. (Not to downplay Jordan)

- Jack the car up from the rear and get under it on your back. And bring a wire brush with you, you're going to have to clean 15 years of road grime off your diff to see it.

- Attached to one of the bolts on the bottom rear of the diff, I believe it's on the right, there is a small metal tag. This is your diff ratio.

- If there is an "S" before the number, it's a limited slip. If not, and there is just a number, it's an open diff.

- Mr. Anderson

[Jordan]

Re: Talking bout diff...How to tell the ratio

thing is the tag on it is to hard to read, completely worn away.:

Ahem.. josh.

READ before you post.

[UNHCLL]

Re: Talking bout diff...How to tell the ratio

thing is the tag on it is to hard to read, completely worn away.:

Ahem.. josh.

READ before you post.

Should we make that a requirement for membership? Literacy? ;)

[bwanac]

ok.

it is an 87 325. so it is just a basic eta, the story goes like this

i called the towing company that has it. they got it for free bc after they did some work on it for some guy, he was no longer reachable. so all he knows is that it is posi traction. the tag is unreadable, and it is a 5spd. i dont know if it was special factory ordered or "aftermarket". but from what everyone wrote above i will try that method.

[decay]

To tell the ratio, jack up the car so the ass is up in the air. Spin a rear wheel. If the driveshaft spins a little less than 4 times per wheel roation, you have a 3.73 diff. If it spins a little more than 4 per 1 roation of the wheel, you have a 4.10 diff.

isn't there also a 3.91 rear? supposedly this is what showed up at my door last week.