CV Axle questions

[Slow Steve]

Hey all. I just want to say that this is a great forum and completely not what I thought it would be when I first jumped on here after picking up my first 911, 74. She's missing lots of parts and is a project for sure, didn't matter to me. I have wanted a 911 ever since I can remember wanting a car and will put in the time to get her back on the road.... and enjoy it along the way.

Let me start with my first question. Are 930 and 74 911 CV flanges the same size and interchangeable? I have done some digging and 930 flanges are 108mm, think the flanges are the same size for my car. Is this correct and are the interchangeable without any modification?

Thanks in advance and I appreciate any help I can get!

[Slow Steve]

I guess a clearer way to ask this is: what is the size of the flanges on a 74 porsche 911?

[timmy2]

One way to check is go to the Pelican parts section and the description will tell you what cars and years the specific part fits.

[mreid]

I believe those are 100mm, but here is the link:

Porsche 911 & Carrera Axles & Bearings - Page 2

Can't you measure the ones you have now?

[Nine9six]

I believe your 74 has 100mm, while the turbo has the 108mm. The 100mm uses 6mm fasteners, while the 108 uses 10mm fasteners.
Go buy a cheapie 0-6" HF digital caliper $9.99 and measure your flange size.

[Slow Steve]

Originally Posted by Nine9six

I believe your 74 has 100mm, while the turbo has the 108mm. The 100mm uses 6mm fasteners, while the 108 uses 10mm fasteners.
Go buy a cheapie 0-6" HF digital caliper $9.99 and measure your flange size.

Thanks, that's the info I was looking for. I'll pick one up on the way home. I have the axles but I'm missing the trans and looking at a couple of different trans options. I just wanted to make sure the combo will work or can be adapted to work.

[spuggy]

Originally Posted by Slow Steve

Thanks, that's the info I was looking for. I'll pick one up on the way home. I have the axles but I'm missing the trans and looking at a couple of different trans options. I just wanted to make sure the combo will work or can be adapted to work.

There's 3 things to worry about; the drive flange on the transmission, CVs/axles themselves, and the stub axle that fits into the wheel hub.

Basically,

* early 108mm flanges (coarse spline) with 4 M10 bolts and two dowels up to '75
* 100mm flanges (fine spline) with 6 M8 bolts 75-84 (and some very early 85)
* late 108mm flanges (fine spline) with 6 M10 bolts, all 85 up.

915's with 108mm fine-spline flanges are a one-year-only thing, because the G50 was introduced the next year. You can apparently adapt G50 flanges, or Albin can supply 108mm fine-spline ones.

Early turbo (74-84) use 108mm flanges but thicker CVs/longer bolts - everything 85 on is standardized (except 930 retained the stub axle, and never used the attached stub axles the '85 911 did).

So although you can mate the later 108mm CV joints on the early transmission (and I believe your wheel hubs will accept the G50 911 type stub axles), the early 108mm 915 flanges will not interchange with later 915's - and 915 fine-spline 108mm flanges are rare.

And as far as I know, 100mm coarse spline flanges simply don't exist unless you get them made.

CV Joint and Axle/Half Shaft Compatibility

[Grady Clay]

Slow down guys. We need the correct info here. Pelican spuggy is 'right on'.

The '74 911s and the 930 Turbo both use 108 mm CV joints.
However …
The ’74 has four M10 socket head cap screws (SHCS) and two 10 mm roll pins.
The Turbo uses six M10 SHCS and the CV joint is ‘thicker’ axially as it must run at a greater angle.
The axle assemblies are not interchangeable as the Turbo axle shaft is much, much shorter.

The 100 mm CV joints were introduced with the '76 Model 912E in late 1975 and used on the 2.7, 3.0 and 3.2 911s through about 1984-5.
They have a 923 (912E) part number and are barely adequate (some say severely deficient) when used with a 3-liter and larger engine.
The 100 mm CV joints use a M8 SHCS which uses a 6 mm Allen wrench.

Starting about 1984-5, the 100 mm CV joints were replaced with the 6-bolt (M10) 108 mm CV joints using the same axle assembly as the V8 928S.
This axle assembly used a tin end-cap and no longer used a gasket between the CV joint and the flanges.

For your ’74, there is no need to do any ‘up-dating’, you already have the ‘good’ stuff.
New axle assemblies are readily available: Axle assembly; Pelican 911-332-033-09-M60.
You can also just buy the grease and new axle boots for a messy DIY job at less cost (but more aggravation).

There are many threads on this subject.
Some searching will yield lots of information.

Best,
Grady

[Porsche84]

Here is a document I use to explain the drive flanges. Hope this help clear up some questions. The 100 mm were used in 84

[Slow Steve]

Thanks spuggy, grady and porsche84! That's good info, it solves my trans limbo. I have the 108mm (4) bolt, (2) pin setup. Thanks again guys. Like I said, I'm pleasently surprised by this forum.

Cheers!

[jsoderbe]

Hi guys,

I have anoter related question; I have two different 108 mm 4 x M10 CV axles. Some of them have much thicker flange, and some narrower. Are the thicker ones 1969 and earlier? They seem to fit my 1973, but I dont like the axial play....


Regards,

Johan