diff tag

[Silver Fox 43]

Diff tag reads, 41:10 04 09 can anyone tell me what it is please?

[E30stz 0]

4.1:1 isnt it ?

[Silver Fox 43]

That's what I thought too Andy, but it has a different drain plug layout on the back to my others?

[E30stz 0]

out of curiousity which car did it come off .. generally the 318i's had small case 4.1's didnt they. My 316i 1.8 had a 4.27 on it.

[Silver Fox 43]

Yeah, my 316 is a 4.27, but my other 318's a 4.45? Is there such a beast?

[Guest Andrew]

The diff tags either say the ratio like 4.10:1 or like yours;

41:10 - 41/10 = 4.1

Like my LSD is 38:11 so 3.46:1

Yes there is a 4.45 and 4.47

[Gus 5]

it is a medium case diff

andy..jump on this. seriously.

[Carl 3]

As Andy said, 41 and 10 is just the number of teeth, 41/10 = 4.1

I'm running a 40:11 = 3.64 (2dp), others are:

3.91 = 43:11

3.83 = 42:11

3.73 = 41:11

Edited October 4, 2006 by Carl

[Silver Fox 43]

so, apart from size, what are the advantages/disadvantages of this diff over a small case one? Do they both fit the same setup?

[Carl 3]

Small case is considerably lighter but obviously not as sturdy as the medium case.

[Silver Fox 43]

Yeah, definately the medium case, just pulled a small case 4.1 out of my spare shell, considerately smaller and lighter.

[Silver Fox 43]

Small case is 28.5 kg, medium case is 37.5 kg, 9 kg heavier. If the medium case is stronger, is it a better choice, the extra weight is low and at the back, no real problem?

[Gus 5]

i would keep the small unless you want to play around with weight distribution..not a bad place to put it. (if you need ballast with e30 series a good idea)

my rationale behind andy using one is that the 325i will not kill a med case open diff (unless misused)....we're kinda unsure about the small case but i would much rather replace now than in the pits during a race.

[Silver Fox 43]

Thanks for that Gus, this diff is destined for my new Series car as I need a 4.1 diff for it. Would be prepared to swap for a small case 4.1 if someone wanted to, but would have to happen in the next couple of weeks for it to work for me?

[Guest Andrew]

Thanks for that Gus, this diff is destined for my new Series car as I need a 4.1 diff for it. Would be prepared to swap for a small case 4.1 if someone wanted to, but would have to happen in the next couple of weeks for it to work for me?

Will exchange a small case 4.1 for your medium.

[Gus 5]

happy famillies?

god...another round of diff swaps for gus!

[Silver Fox 43]

pm'd Andy. You better get the tools out Gus.

Edited October 4, 2006 by Silver Fox

[Silver Fox 43]

Pic showing driveshaft end.

[Gus 5]

that looks odd

whats up with that? normally just a 4 bolt

[Silver Fox 43]

Diff's as I got it, don't know the story behind it at all, same thread and nut in the centre as the small case I took out of my E30. Would think the fittings would just swap?

[Gus 5]

would imagine so

thought you got outta an e30..was mildly confused!

i would hope they just swap..shouldnt be too hard to find out

[Mark Babb 1]

Oh well, while we're on the subject of swapping. I too have a spare Med case 4.1 diff for an E30. Usual thing, read the Regs that state must use 4.1 diff and then set off to the BMW dismantles and asked for a 320 4.1 diff. Yes sir which size? Errrr not sure what you mean, so ended up buying both small case and med case 4.1 diff.

So Med case surplus to requirements as is the original 4.4? small case diff (1990 320 AUTO) Travelled 75,000k. Also have auto Gearbox from same 75k car

[Silver Fox 43]

What cars did the med case diffs come from? E30's or others, and if E30's which varieties? Thanks.

[gmccormack 0]

One of my S.A. assembled 318 wrecks had a CV joint at the diff end of the drive shaft instead of a normal universal joint. The 6 bolt flange on your diff my be to suit that set up or something similar.

[Jazzbass 1]

That horrid, dirty thing is a differential unit?

You mean I have one of those under my car?

Eeeeewwww...