901 Flange Questions

[126coupe]

This is my primary box. It has a 904 75% Limited Slip
You can see by the 2 arrows that the round flange is welded to the another flange from a different kind of axle set up

My question is : I just aquired a "spare" longbox from Powerhaus II, ( no flanges) I would like to replicate the flanges from my primary box in the photo. What are the two flanges from the photo from? Any Ideas how to replicate? Just learning about these transaxles

[126coupe]

Heres the new Transaxle from powerhaus. Same gears as the primary but a "w" 5th instead of a "v" I was hitting 8200
rpm's at the CA speedway with the "v" this should cure it
What we go through for just a little more speed!

[studeb]

those are the old nadello flanges welded to a spacer

the early lsd was meant to be used with nadello half shafts

i am not sure if the splines are the same on your new box as on the lsd, but i think so

[126coupe]

Thanks! are the nedello flanges rare? Can I use something else?

[126coupe]

come on 901 gurus any answers???

[Grady Clay]

Minkoff,

Yes, those are rare.
Yes, those are probably very expensive to remanufacture.

They came on 904, 906, and pre’69 911s ordered with LSD.

If your rules allow, a ’70-’71 911 (901) transmission uses the later LSD common all through 915s (and G50s I think.) There are OE flanges to fit most any axle.
There are some important advantages to the later mag transmission in addition to weight and the later LSD. It is configured to run the wider 2nd and 3rd gears without interference. The LSD clutch components are larger and less subject to wear. There are readily available spare parts in the PCNA system.
I wouldn’t hesitate to use a good mag case transmission (with the aftermarket intermediate plate) with engines to 2.8.

You probably can get a large sum for the good 904 LSDs.

Best,
Grady

[126coupe]

Grady I already have 2 Race 901's Im just need to know what
flanges work w the 901 in the 2nd set of photos

[Grady Clay]

Minkoff,

I looked up your part in PET6.
That part is a “Joint flange” E.904.332.209.01.
I usually interpret the “E” to mean Extinct.
In addition to #14, you will also need #15, #16 & #17 (2 each.)
"

"
(C) 2003 Dr. Ing. h.c. F. Porsche A.G.

I also looked up the LSDs.
The one you have is:
E.904.332.053.00
This can only be used with Nadella axles unless there is a mod like you have.

The LSD for the mid-’69-’70 mag case is:
E.901.332.053.13
I think this will also fit the earlier aluminum case and is designed to accept Lobro axle “Joint flanges.” I think these Joint flanges are peculiar to this version LSD only.

The LSD for mid-’70-’71 911 and the later 915s is:
915.332.053.11 and more.
Designed to fit Lobro axles.
In most cases the Joint flanges are slightly different between the LSD and the open differential.


I find that for track only use, a welded solid open differential is a good solution. It is economical, service free, and more predictable for me.


Best,
Grady

[Grady Clay]

For those who haven’t seen a Nadella axle for an early 911.
The link is to accommodate the necessary change in length
as the suspension moves through its range.
"
"
(C) 1966 Dr. Ing. h.c. F. Porsche A.G.

I found an interesting addendum from ‘67:

“Vehicle types 911, 911S, and 912 are being equipped with NADELLA
half shafts (spare part Nr. 901.332.025.02) and with LOBRO half shafts
(spare part Nr. 901.332.026.10) on an alternating basis.”

Sounds like Nikasil and Alusil.

Best,
Grady

[jluetjen]

Minkoff;
I don't know if it will help or not, but the early 915 flanges will work in a 901 if you have the diameter of the bearing surface taken down by 1mm. That's what I'm running in my car right now. You could most likely pick up a set for just a few dollars from your local dismantler. That's what I did.

[Grady Clay]

John,

The 901 LSD is a peculiar beast. The splines in the LSD are external splines that protrude from the transmission. The axle flange is very short and has internal splines for the LSD and a 4-bolt flange for the Nadella half shaft.

When you ground your axle flanges, did you measure the surface hardness before and after? I had an excess of flanges and never tried that. Good for you.

For those attempting this, the internal length of the axle flange is critical. When the stretch bolt is tight, the axle flange is tight against the spider gear and the threaded piece, it still should have axial free play. If not, under some differential action, it can unscrew the stretch bolt or damage the spider gear and bad things happen. Caution.

Best,
Grady

[jluetjen]

Hi Grady;
I think you are confirming what I suspected which is that the flanges for an LSD equiped 901 are different then for a 901 with a normal diff. In my case I'm using a normal diff, but I figured that I'd offer that up for some lateral thinking about the problem in case someone could take that idea and run with it.

As far as the surface hardness, my machiniest and I considered it and chose to not treat the parts given the fairly large bearing surfaces involved vs. the expense and difficulty. One machinest didn't want to do it since he throught that cutting through the surface treatment would be a pain. The second (a full-time machine shop that did many industrial jobs for my previous employer) didn't have any issues. Consider my road use an endurance test and I'll share what I see when I pull them out. So far there haven't been any issues and I've been using them for about 8-10K miles of weekend driving, but no DE's or track events.