915 output flanges vs. 944 cv joints

[trevorbrady]

Does anyone have a good knowledge of the output flanges of 901 and 915 transmissions and the CV joints of the Porsche 944?

I have 2 pairs of output planges (both coarse splines at gearbox end, I think 17 splines or so)

one pair have 6 holes on a PCD of 94mm, only 4 of which are drilled through and tapped. The o/d of the flange is approx 110mm



the other pair have 6 holes on a PCD of 77mm, and all 6 are drilled and tapped. The o/d of this flange is approx 88mm, and there is a "lip" folded down towards the cv side.



I am trying to mate these to 944T drive shafts, but the 944 CVs have a PCD of 6x86 and an o/d of 100mm. Since neither of these pairs of flanges suit the CVs, are there CVs out there that will suit either of the flanges or are there flanges out there that will suit the CVs?

This is a bit of a head scratcher for me, any help appreciated.

[canibugu]

looks like nobody knows.

I have the same question

[Wally]

Well, I'am no 'output flange' connaisseur, but the above pair is most likely 915 late style. The 110mm CV flange diameter is typical, as are the 4 x M10 bolt holes and the two dowels. Useless for any VW-type vehicle as 110mm CV joints only come with Cv's that have porsche axle inner splines, unless of course if you can also use the porsche CV's at the wheel end, then a porsche axle of the right length can be used.

The 90mm (your 88mm) CV's are most likely VW bug CV's, so those flanges are probably from an IRS bug anyway.

I have rounded of your measurements as there are only 3 relevant CV sizes: 90mm: bug
100mm: T2/T3 busses and 944. 944 has probably different (porsche) inner splined axle size then VW busses have!!
110mm: late 911 (most, not all!) 915 gearboxes.

Simple.

[boygenius]

The turbo 944 has 28 spline axles so the turbo CVs won't fit. The n/a 944 has 33 spline axles and the type 1/ type 2 CVs will fit them. At least this is true for my 1987 n/a axles. I thought the 930 had 108mm CVs.?

[Michael Ghia]

Trev,
The 94mm flanges are stock for late 901 transmissions, code 911/** and also early 915 transmissions up to 78.

The 77mm flanges are stock for 914's and early 901 transmissions code 901/** and are stock T1 size.

The ones you want for T2/944 CV's are fitted to 911SC's only from 1978 to 1983. They will bolt into any 901 or 915 transmisison.

MG

[GS guy]

Or... you can have your output stubs modified to accept the T2 100mm CV's. I just did that for a 914 box - some of the original smaller (914/T1 size) flange was machined off, new custom machined chromoly T2 size flange fitted and welded to the stub. Finished up with nice black oxide coating - awesome work!
Work performed by Todd at Precision Alloy:
www.precisionalloy.com
Jeff

[LOAF]

BG,

Question for you.. FYI, I have been cross posting.. but I am lost...

See if you can help me out here.. As far as a conversion with the following.. 901 (911) tranny to 944 late N/A arms.. what do I need once I have everything on the ground..

As I mentioned my not so unique situation is the following..

I am doing the 944 late conversion with sigle piston brakes.. I have the following parts that I would like to reuse as part of this conversion..

The have the 944 Stub axles.. which I am not sure I can swap out..
The 944 Axle that is conected to the Stub..
and shortly within a week a 901 (911) tranny...901 trans from a 66-68 912/911

The seller has different output flanges, but for starters I am not sure which flanges to even ask for.. man I am confused..

I am not sure what can mate with what.. If there is a simple solution out there.. I am not looking at Big Hp numbers.. 100-150 at most..

What is your recommendation?

As far as the tranny T2, or is there a stock 901 part?

Which axles. 944 or T2.. will these mate to the 944 stub axle.. I will check how many splines and if it has a part number..

What CV Joints do I use?

Do I have to replace the 944 Stub axle?

Help
Alex

[Michael Ghia]

Alex,
If you want to use 944 arms, no matter which arms they are (steel, narrow ally or wide ally) then use the driveshafts complete with CV joints which come with them.
In order to marry those driveshafts up to the 901 tranny, you will need output flanges from a 911SC 915 tranny.

The early 901 comes with small (T1 size) output flanges and the late 901 comes with 930 size output flanges. The 914 box comes with T1 size output flanges.

Another way to make stuff work would be to use the early or 914 output flanges (T1 size) and swap the CV joints over on the end of the driveshafts with T1 CV joints... that said I have never tried this so you'll be the guineapig! I suspect that the splines on the shaft will be the same but that you'll have to use an extra spacer on the splines before you put the cv joint on as the T1 CV joints are narrower than the Porsche ones.

Good luck, if I lost you please say so and I'll try to explain again.

Mike

[LOAF]

MG,

The first part makes sense, a little lost on second half..

As fas as sourcing 911SC 915 Flanges.. Is this a hard thing to come across..

I will do some investigating.. but for now this seems like my best choices..

Thanks again Michael.

ALex

[LOAF]

Michael,

I just got done with an email and got asked about the SC flanges..

The Sc Flages came two way corse spline and fine spline. Which do I need?

Thanks
Alex

[boygenius]

Alex, I'm not a real transmission expert so I can't be of any real help. The early and late aluminum trailing arms use the same axles and are interchangable. As long as they are 33 spline the type 1 CV joints will fit them, That is what Zen is using on his car right now. You should just be able to bolt up the axles using the type 1 inner CV's like Micheal Ghia suggested if you can't get the drive flanges you want.

[trevorbrady]

Originally Posted by boygenius

The early and late aluminum trailing arms use the same axles and are interchangable.

BG, is this a FACT, or second hand information? I don't mean to doubt you, but I want to be 110% sure!
I need to get drive shafts for my project pretty soon (i'm making do with type1 shafts and CVs as the type1 arms are still in place at the moment), and I need to know EXACTLY which ones, as mistakes in buying Porsche parts are costly mistakes!

I have early aluminium arms. I thought I needed early-late (make sense?) drive shafts to suit, but the early aluminium arms were only in production for a short while and are rarer compared to the late-late arms. If I knew for a fact that late-late drive shafts would do, I could get them pretty easily.

Just a thought, but how do type 2 drive shafts measure up, length-wise, against the various type1/924/944 drive shafts?
I know blind chicken has a page with comparisons between shafts/cvs, but I don't remember them comparing overall lengths of shafts. Anyone ever definitively document the differences in lengths?

[zen]

early and late arms both use 21" axles. i had a set of early arms on my bug first and then switched to late. there is a thread on here somewhere with good detail and pics as i was going through it. the difference in the width between the arms occurs at the hub. compare a rotor for a early and late and you will see what i mean. in fact, there is also a pic somewhere on here where i stacked the two arms and took some pics.

[boygenius]

What Zen said, plus make sure that you get the 33 spline axles and not the 28 spline axles. 33 spline count is what VW uses so type1 type 2 CV's will fit. The turbo cars came with the 28 spline so get some N/A axles. I use places like www.pelicanparts.com to cross reference part numbers in their online catalog. Look up what year your rear suspension is from to check on the axle assemblies and there will be a description of what other models and years those axles fit.

[Michael Ghia]

All the flanges which I have delt with have 18 splines. These are known as the course splined flanges and the teeth are about 2.5mm across.

I can't remember how many splines are on the fine splined flanges.

MG