What diff do I have?

[Mark 42]

I got the number on the tag on my Diff - it's 4 10 9661
Is that enough to determine whether it is LSD?

I gather it's a 4.10 ratio ring/pinion.

It seems to spin both tires most of the time AFAICT
But it's a 1991 318i (4 door, M42) so I would have thought it has an open diff.

Is there a way to know for sure?

[Pl3wA]

i heard that if you travel at 80 and you are at 3,500 revs you have a 3.9 or something. im not exactly sure.

if you lift the back of the car and turn a wheel by hand and they both spin the same direction, you have a diff. if they spin in different directions, you dont

[Cronopoulos]

Jack the rear-end up, spin a tire....

OR

R3V method - do a burnout, hurrrrrrr

[pandaboo911]

the tag will have an S stamped in front of the ratio, so you have a 4.10 open.

the bottom of the case will also have a big S printed on it.

[Jand3rson]

the tag will have an S stamped in front of the ratio

This is how you tell. Much easier than the rest of the responses.

[CHIF8008]

"S" stamped on it.

or jack it up and spin the wheels

[george graves]

See the opposite end of the arrow? See the metal tag on it? That's what you're looking for - for an "S"

[Robotin]

i heard that if you travel at 80 and you are at 3,500 revs you have a 3.9 or something. im not exactly sure.

if you lift the back of the car and turn a wheel by hand and they both spin the same direction, you have a diff. if they spin in different directions, you dont

ggoing 80MPH, at 3,500 revs.. in which gear?

and i think if i jacked my car up, i would realize if i had a diff or not without spinning the tires..

[peytonracer4]

i heard that if you travel at 80 and you are at 3,500 revs you have a 3.9 or something. im not exactly sure.

if you lift the back of the car and turn a wheel by hand and they both spin the same direction, you have a diff. if they spin in different directions, you dont

:rofl: i'm pretty sure he has a diff regardless. i think you meant to say LSD.

this is correct. if you spin one wheel and the other goes the opposite direction you have an open diff. both wheels must be raised obviously

[Pl3wA]

im so high right now. but seriously, dont bother checking. you will be disappointed

[themoonman]

i heard that if you travel at 80 and you are at 3,500 revs you have a 3.9 or something. im not exactly sure.

if you lift the back of the car and turn a wheel by hand and they both spin the same direction, you have a diff. if they spin in different directions, you dont

what does it mean if you spin one wheel and the other wheel does not spin at all?

[Mark 42]

what does it mean if you spin one wheel and the other wheel does not spin at all?

$1289.50

[Pl3wA]

$1289.50

thats about exactly the amount, yes

[TobyB]

what does it mean if you spin one wheel and the other wheel does not spin at all?

you left it in neutral...

t

[Mark 42]

You left it in neutral...

Good point.:bow:
Or the parking brake is dragging?