Diff-difference differ differently? E21 LSD vs. Stock -75 02

[GreenSwede]

I have searched but, I´m not satisfied.

I´ve got the std 75 2002 diff, and I am about to replace it with a E21 LSD. Not sure of year, maybe 79. It has M10 holes in the flanges.

Anyway, I have two stock 75 02 shafts with one cv replaced with a 79 E21 cv, to maintain the M10 cv fitting the LSD. And, I thought, achieve the appropriate length. But the length of the shafts seems to turn out the same.

Another thing is - I´ve read about a difference in width of 1/2” (12,7mm), thus requiring a 1/4” spacer each side.

But the difference between the stock diff I have and the LSD is just 5/8 (8mm). What the heck is this? Should I fabricate 5/16” spacers? With that little I could almost go with washers..

Or just leave it, the car is lowered and stiffer so theoretically it should never stretch that far anyway, right?

[c.d.iesel]

order the correct spacers and screws from member JFPRO bmw here

[oscar94]

I just made this swap. If you can find the matching half shafts to your LSD you won't need the spacers.

[GreenSwede]

Thanks, but he´s probably, like the most of you, in the other side of the great ocean, and the cost of sending would be stupid regarding the goods. Maybe I´ll just have two 4mm spacers machined and be done with it.

[GreenSwede]

I thought I had. But is the different actually in the shafts, and not the cv?

You don´t have the measures of you LSD and/or shafts?

Parts catalouges, not realoem but aftermarket, list 411 and 417 mm shafts for E21. But from what I gather, I´ve already got the 417mm shaft. E21 seems blurry. Almost Volvo-like, parts wise. And I don´t like that.

[TobyB]

M10 holes = later style.

The answer is somewhat convoluted- the 320 diff is narrower, the 320 subframe

is wider, the 320 trailing arms are 'wider', as in the stub axles are longer,

and all by differing amounts.

The ways that are proven are, in order of MY preference:

1- later 320 halfshafts with a 2002 end on the outboard side. The splined halfshafts from the later 320 are, indeed, the right amount longer with this combo.

1.5a, change the diff output flanges to early (8mm holes) and:

2- 5/16" spacers (yeah, 1/4" also works) with 2002 halfshafts

3- nothing at all (I did this before I knew better, and it works) with 2002 halfshafts.

Yep, its all been hashed out before, but not all of us agree on the details.

I got ahold of all the variants and measured 'em before I converted the

race car to all- late- 320 parts...

t

[GreenSwede]

M10 holes = later style.

The answer is somewhat convoluted- the 320 diff is narrower, the 320 subframe

is wider, the 320 trailing arms are 'wider', as in the stub axles are longer,

and all by differing amounts.

The ways that are proven are, in order of MY preference:

1- later 320 halfshafts with a 2002 end on the outboard side. The splined halfshafts from the later 320 are, indeed, the right amount longer with this combo.

1.5a, change the diff output flanges to early (8mm holes) and:

2- 5/16" spacers (yeah, 1/4" also works) with 2002 halfshafts

3- nothing at all (I did this before I knew better, and it works) with 2002 halfshafts.

Yep, its all been hashed out before, but not all of us agree on the details.

I got ahold of all the variants and measured 'em before I converted the

race car to all- late- 320 parts...

t

Yep, it just hadn´t been hashed out to my satisfaction=)

Most annoying is the fact that my diffs seem do differ with other measures than those I´ve read about, thus buying the spacers recommended for a difference of 1/2" would be wrong.

And I have 4 02-axles and one 79 E21 (with the thick cv´s, so probably the short axle anyway).

From what I´v come up with the up-to august 79 323 E21 axle has thick cv´s, and the september 79 323 E21 has the thinner cv´s - meaning longer splined axle(?). The splined axle with 3 "ribs" on it, on the picture above. The later 320/E21 splined axle you´re referring to, Toby.

I got the idea that it was the cv that did the length, I got that from Jeff´s article about diff´s in the FAQ.

Anyway, I´ve got the M8 and M10 issue sorted, so I´ll fabricate spacers. With the thickness responding to the difference of MY diffs.=)

Thankful for all replies!

[eurotrash]

'76 output flanges without the bolt in the center are the ticket. they are longer than normal, and have the correct hole sizes for 2002 axles. They just slip into the 320 diff.

I have been running these for two years, nary an issue.

Just found this thread, hadn't seen it yet, myself..

http://www.bmw2002faq.com/component/option,com_forum/Itemid,0/page,viewtopic/t,304652/highlight,/sid,18e2d27a5c2de894747ae768ca844529/

[visionaut]

'76 output flanges without the nut in the center are the ticket

+1

[GreenSwede]

Thanks!

Well, I´ve got three stock diffs by now. And they all have flanges with nut..=)

Going with spacers. Already installed E21 cv´s. Also, M10 is tougher than M8, right?=)

[GreenSwede]

Bought the bolts at the hardware store and had alu spacers made = 36$.

[TobyB]

If you're going to m10 bolts, make sure you also go to the torque spec for them.

When I made this change, I had a pretty good handle on what it took to get the

m8's to stay fastened- and it didn't work for the m10's at all, as they loosened

up very quickly.

The 10's want to be a LOT tighter than the 8's-

I'd give numbers, but they'd be wrong...

t

[GreenSwede]

Will do! I think I´ve got the specs for E21 somewhere..

Thanks a bunch!

[GreenSwede]

Will do! I think I´ve got the specs for E21 somewhere..

Thanks a bunch!

But I didn´t. Anyone? 2 short and one long grunt?

[c.d.iesel]

output shaft to final drive flange:

M 8 cap screws = 24...27 ft.lbs.

M 10 cap screws = 63...74 ft.lbs