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

[stephenaki]

How does this affect the issue with the parking/emergency brake? I understand that the 911 conversion negates the use of the parking brake; does this have the same problem or is it a non issue based on the fact that your not changing out the entire suspension.

Uneducated minds would like to know.

[Richard Casto]

How does this affect the issue with the parking/emergency brake? I understand that the 911 conversion negates the use of the parking brake; does this have the same problem or is it a non issue based on the fact that your not changing out the entire suspension.

Uneducated minds would like to know.

I believe that e-brake issues are more of a function of moving away from the stock 914 rear caliper than a five lug conversion issue. For example you can do a five lug conversion and use a 914/6 rear caliper ($$$$) as the e-brake solution is the same for all 914 (4 or 6) calipers. But it is common to do a five lug conversion and at the same time move to a 911 (or other) rear caliper that uses a different e-brake solution than the 914 rear caliper does.

[stephenaki]

I believe that e-brake issues are more of a function of moving away from the stock 914 rear caliper than a five lug conversion issue. For example you can do a five lug conversion and use a 914/6 rear caliper ($$$$) as the e-brake solution is the same for all 914 (4 or 6) calipers. But it is common to do a five lug conversion and at the same time move to a 911 (or other) rear caliper that uses a different e-brake solution than the 914 rear caliper does.

OK, got it. My assumption is, correct me if it is wrong, that if I were to do Andy's conversion I would have to re-do the rear brakes or would the stock 914/4 system work with this conversion?

Understand the stopping power is reduced with bigger wheels but if your not racing the car or increasing the power is it required to convert the brakes? I am still a novice at this so am trying to learn as I go along.

[Richard Casto]

I believe that e-brake issues are more of a function of moving away from the stock 914 rear caliper than a five lug conversion issue. For example you can do a five lug conversion and use a 914/6 rear caliper ($$$$) as the e-brake solution is the same for all 914 (4 or 6) calipers. But it is common to do a five lug conversion and at the same time move to a 911 (or other) rear caliper that uses a different e-brake solution than the 914 rear caliper does.

OK, got it. My assumption is, correct me if it is wrong, that if I were to do Andy's conversion I would have to re-do the rear brakes or would the stock 914/4 system work with this conversion?

One can still use 4-cyl rear calipers with 914-6 rear rotors, or one could have 4-cyl rear rotors drilled for 5-lug.

I think John's point above answers your question. Doing the CV and 5 lug conversion does not require you to re-do your rear calipers. You will need to use rotors that have five lugs (either the 914/6 rotors or re-drill the 914/4 rotors)

[Wes V]

First off, thanks!!

Requested additions;

1. I'd recommend verifying run-out of the of the hub prior to installing. Put it in a lath and use a dial indicator (while rotating the hub by hand). If the source car was in an accident, the hub could be bent and you may not see it by eye. If you don't notice it until installed, you will have to buy new bearings when you replace it with a good one. (BTDT)

2. CV bolts should be replaced with longer ones to match the 944's wider width. It may be recommended to use grade 8 bolts that allow safety wire. At least, locktite the bolts.

3. For us newbies, the 100mm reference is the outside diameter of the CV, not the bolt circle. Of course, that's if that's correct.

Wes