lsd question

I believe 3:64s were installed in automagic gearbox cars, but I might be wrong. Most CSs had 3:45s while CSIs and CSLs had 3:25 rear ends.

Perfect combo with a 5spd is 3:45 IMO. I have a 3:25 in the CSL now, and it's got longggggggggggggggggggggg legs, maybe too long if that's possible.
 
CS Diffs

US 3.0CS all came with 3.64 diffs. Limited Slips were an expensive option, but it seems like a lot of US E9s came equipped with them, especially the 73s and 74s.

The same diff case was used in several BMW models besides E9s:
E3 sedans (2500, 2800, Bavaria, etc.)
E12 Sedans (530i, 528i, etc.)
E24 6 series up to 81 (or 82, I can seem to remember this)(630CS, 633CSi)

These are all straight bolt-in replacements, limited slips or not, and offer ratios of: 3.07, 3.25 and 3.45
 
Re: CS Diffs

US 3.0CS all came with 3.64 diffs. Limited Slips were an expensive option, but it seems like a lot of US E9s came equipped with them, especially the 73s and 74s.

The same diff case was used in several BMW models besides E9s:
E3 sedans (2500, 2800, Bavaria, etc.)
E12 Sedans (530i, 528i, etc.)
E24 6 series up to 81 (or 82, I can seem to remember this)(630CS, 633CSi)

These are all straight bolt-in replacements, limited slips or not, and offer ratios of: 3.07, 3.25 and 3.45
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The 4 speed 2800CS came with a 3.45 LSD. And for combining with an OD 5 speed, I'd vote for a 3.64 -- that's what I have in my e12, and it's a great combination for acceleration and cruising.
 
Great thread.....

What type of marking, if any, are on the caseing for identification?
 
LSD's in CSi?

My understanding is that every CSi did not have a LSD.

I have no documentation to back this up. Others ( the guy who restored mine, and a BMW specialist garage ) have in the past mentioned that my car does have one, said in such a way as to make it appear that this was not always the case!

I would be interested to hear from the experts in here.
 
Re: LSD's in CSi?

My understanding is that every CSi did not have a LSD.

I have no documentation to back this up. Others ( the guy who restored mine, and a BMW specialist garage ) have in the past mentioned that my car does have one, said in such a way as to make it appear that this was not always the case!

I would be interested to hear from the experts in here.
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As would I. I was of the understanding, possibly from this board that all of the CSI's did have the LSD. What are the external markings on the case to distinquish LSD or non-LSD?
 
There is a giant S painted on the case, and the PNs are different.
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Couldn't the S have come off over time or simply forged by someone? What PN's is there a number range?
 
The PNs are on realoem.com. If I recall right, there is also a S stamped on the ratio tag, which is on the lower left or right side of the diff case.
 
The documentation that I have read (various old road tests from road and track and others of that ilk) states that the lsd was infact an option on CSis and not standard equipment. I'm not sure if it was standard equipment on CSLs but I know that it was fitted as standard to E12 M535s.
The only sure fire way to tell if you have a lsd is to rotate one of the drive flanges, if the other one rotates the SAME direction then it is lsd if it goes in the opposite direction then it is a standard unit. I have heard it said that in older (read worn) units it is possible to turn the drive flange and have the other flange rotate in the opposite direction. In my oppinion this isn't possible as the unit would have to be so badly worn out as to offer no lock up what so ever, if this was the case the bearings would have collapsed long long ago with all the crap that would have been floating round in the oil.
 
The documentation that I have read (various old road tests from road and track and others of that ilk) states that the lsd was infact an option on CSis and not standard equipment. I'm not sure if it was standard equipment on CSLs but I know that it was fitted as standard to E12 M535s.
The only sure fire way to tell if you have a lsd is to rotate one of the drive flanges, if the other one rotates the SAME direction then it is lsd if it goes in the opposite direction then it is a standard unit. I have heard it said that in older (read worn) units it is possible to turn the drive flange and have the other flange rotate in the opposite direction. In my oppinion this isn't possible as the unit would have to be so badly worn out as to offer no lock up what so ever, if this was the case the bearings would have collapsed long long ago with all the crap that would have been floating round in the oil.
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Where exactly do I find the painted S? Also is there serial numbers on the case?
 
Couldn't the S have come off over time or simply forged by someone? What PN's is there a number range
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Yes the S could have come off which is why I suggested turning one of the drive flanges, sorry I can't help you with the part numbers at the moment but if I get chance I'll have a look at mine to see if there is anything stamped on the casing other than the axle ratio numbers.
 
Ratio:
Based on this stamp, it is 38/11.

Stamp location:
If looking at the unit such that the unit it upright and you can read the S, the stamp is towards the front on the bottom right side, if I remember right.
 
Ratio:
Based on this stamp, it is 38/11.

Stamp location:
If looking at the unit such that the unit it upright and you can read the S, the stamp is towards the front on the bottom right side, if I remember right.
Click to expand...

OK let's say the diff is stll on the car, is the stamping on the rear of the diff (on the bottom) or closer to the driveshaft?
 
Diff indentification

Great picture. E9s diffs had the stamped numbers like this, on the left side under or in front of the axle drive flange. The painted "S" didn't come til later models. None of the diffs had serial numbers.
 
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