What gears do i have?

[MattTHEe30GURU]

Im driving at like 65-70 mph and it revs at 3100-3200 rpm. What rear end gears do i have?

[lambo]

I'd say around a 3.73 with an M20. There's a tag on the diff that should tell you your ratio.

[Rsully70sev]

3.73 is my guess.

Model? Motor?

[FunfGan]

Ironic name is ironic.

[Rsully70sev]

Lol

[woodisgood]

http://www.csgnetwork.com/gearratcalc.html

[MR 325]

So should we assume you have a 1984 318i with an auto transmission?

Or is it a 1991 E30 M3 with a 2.5L stroker and a dogleg trans?

Maybe it's a 325e with a 454 Chevy big block?

[FunfGan]

I very much like the 3rd option.

[325ix]

I very much like the 3rd option.

I'll take option two or three.

[MattTHEe30GURU]

no i have a 91 318i 5 speed all stock. and there was no tag on the diff

[Quadrajet]

You should have a small case 4.10, or is it 4.11? I have noticed on my 318is that my speedo reads about 5mph slow, but my odo is dead-on, have you verified yours?

[MattTHEe30GURU]

no my odo is non working and i have noticed that the speedo feels or looks alittle slower

[Jaxx_]

no my odo is non working and i have noticed that the speedo feels or looks alittle slower

speedo indicates speed at the diff, not your traveling speed. It will read correct. If you are going faster than the speedo says, your tires are a bit big. Use your phone's GPS, or a standalone GPS to tell you your speed.

[FunfGan]

That seems low for a 4.10 on an m42... I wasp pulling ~3500 @ 70mph.

[ButtJuice]

Its a 3.73. My dad owns a 91' 318is and swapped a 3.73 lsd, that RPM rate is close to his.