901 ZF LSD Question

[MarkL]

I bought a 901 ZF LSD a number of years ago (part #901-332-053-13) and am trying to figure out the proper axel flanges. We are using a 1970 901 trans to mate with my 1969S axels but they are not compatible.

I was told that this LSD was designed to accept Lobro axle “Joint flanges.” I think these Joint flanges are peculiar to this version LSD only. Is this the case? Anyone know where I can source the proper Lobro axels and flanges?

Best,
Mark

[chris_seven]

I thought that this LSD was designed for the later 901 type box (911?) and was the same unit that was fitted to the 914 and the early magnesium 915.

The coarse spline 915 flange should fit.

The part number of the flange in 1969 and 1970 was 901.332.209.21

The part number for the flange for the 915 was 915.332.209.21 and I believe that they interchange.

The flange for the 68 911S without an LSD is quite different and the LSD in the ealry 901 box, which had a 904 part number, had an output to suit a Nadella. The part used to convert this diff to work with a Lobro was totally different.

904 diffs look similar to this unit:



The adaptors to suit CVs are like this:



This diff would't fit the 911 box as bearing sizes are wrong and length over flanges is different.

[911quest]

I know I shouldn't offer these but I have a set of correct flanges for the 69>901 LSD. If interested let me know.



You can see the difference between the two flanges The first picture is the NOS LSD flanges. The second is the LSD next to a 69-74ish open diff flange.

[MarkL]

Tony,
You have a PM.
Mark

[MarkL]

Thanks Chris,

I think Tony may have what I need.

Best,

MarkL

[gled49]

coarse spline drive flanges like those pictured came in two lengths. 56mm and 61mm. measuring from the end of the spline to the end of the skinny part of the drive flange. 56mm open diff. 61mm LSD. there were some early open diff flanges that were 61mm. 911 flanges have a big bell look to CV part and the 915 look a lot flatter. the total length of the various drive flanges do vary a bit. gordon

[MarkL]

Gordon,

Thanks for posting. Tony is sending me out a couple of Flanges to try. I'll let you all know what ends up working.

Early ZF LSD's seem to be a black science. Parts book shows that a std. flange should work yet have not yet found one that does.

MarkL

[gled49]

forget the early alu. LSD pictured second. the LSD pictured first fit in all the mag transmission 911-914-915. there are 7 drive flanges for the 911s alone up thru 74 before they changed the carrier offset in 75. 901 332 209 15 is for lobro alu.(like 68). 209 21 is early mag. 209 00 >71. 209 04 is sporto. again 209 21 is for >70 LSD (that is the open diff drive flange that goes both ways. 915 332 209 01 is open diff 72> and 915 332 209 21 is for LSD. short and long drive flanges snouts with the hollow end were both coarse and fine spline to I think 1977 in 911 and turbo. with the introduction of the flat bottom fine spline drive flange (no hollow end) the open and LSD drive flange became the same circa the SC's. Gordon PS I've seen lots of early LSD's dammaged because of wrong drive flange. short flanges try to turn the diff into a locker.

[Grady Clay]

Guys,

Can I get some good high resolution and high quality images of the flanges. Precise measurements are also very worthwhile.

None of this has been well documented.

Please email me in high res.

Best,
Grady

[911quest]

Grady,

Sorry but your about 6 hrs to late there already on the way to Mark he might be able to help you out once he gets them.

Tony