HOW TO: Convert to real 5-lug in the rear using 944 CVs Options

[SirAndy]

Convert to real 5-lug using 944 CVs

This Article describes how to convert the rear axles on your 914 to give you real 5-lug hubs using a mix of 914, 944 and 911 components.

Tools and Supplies:

• BFH
• Two new 914 rear wheel bearings
• Four new 944 100mm 6-bolt CV joints including mounting bolts, boots and grease
• Two 911 ('75 - '79) 100mm 6-bolt coarse spline transmission output shafts
• Two output shaft seals
• Two 911 ('75 - '79) 100mm 6-bolt stub axles
• Four 911 100mm CV gaskets
• Two 911 ('69 - '73?) hubs, must have same bearing surface width as the 914 hubs
• Access to a lathe

Step 1: Preparing the axle shafts

Remove the CV joints from your old axles and machine both ends of your axle shafts to allow the wider 944 CVs to slide on.
You'll have to remove 4mm of material to make up for the wider 944 CVs.


4mm of material removed:


Stock 914 CV on the left and a 944 CV on the right




Step 2: Putting it all together

Grease up your new 944 CVs and slide them on the machined axle shaft *without* using the stock spring washer behind the CV!
Make sure the CV slides all the way on and don't forget to put the circlip back onto the shaft to prevent the CV from sliding off.
Note: Make sure the "groove" on the outside of the new CVs always points away from the axle (see picture with the complete axle).
Remove the old stub axles and hub. Remove the old wheel bearings. Install the new wheel bearing in your trailing arms.
Make sure the bearing surface on your new hubs is clean and press in the new hubs. Install the new stub axles and tighten the axle nut.
Remove the old output flanges from your transmission, replace the seals and slide in the new 911 flanges.
Grease up both, the output flange cup and the stub axle cup and install your new axles. Don't forget the CV seals!
Tighten everything to spec and enjoy!


911 coarse spline output shaft and 911 stub axle:


944 CV on 914 axle shaft:


Test fitting the output shaft on the 944 CV:


And at last, the completed axle. The top shows the original 914/4 axle, the bottom shows the new axle:


Mounted on the car:



Info compiled by SirAndy

[Richard Casto]

Andy,

Thanks for the write up. I will probably be using this exact method on my car.

I do have a question. I don't understand the differences in the various transmission output flanges. I am assuming that the course (33 teeth?) flange you mention works with 901/914 transmissions. Does that also work with early 915 transmissions that I think also used a course flange? I think that later 915 transmissions used a fine (43 teeth?) flange. Will this later 915 flange work with this setup?

Overall with the 915, I am concerned if the CV still bolts up (hole pattern and bolt size) and about the output flange to stub axle distance (is the distance the same regardless of which transmission and flange you use. In short, will the 914 axle length always be correct)

I would like to do exactly as you have described, but with my 914 transmission today and then in the future switch to a 915 transmission with hopefully the only potential change is in the output flange.