914 Five Bolt Pattern
Conversion Guide

There are several ways to accomplish this task. Here are some of them, starting with the front suspension:

(1) The simplest way:

Purchase wheel adapters that will bolt on to the existing hub assembly, allowing you to put 5-bolt wheels on the adapter. This leaves everything also on the car stock, including the brakes. I’m not sure what this does to wheel offset or how the tire will fit under the fender. The best bet is to find somebody who has done it and learn from their experience.  Pelican Parts doesn't sell these wheel adapters because we're not terribly fond of the safety of them.

(2) The next simplest way:

Drill your existing wheel hubs to make it a 5-lug. This procedure is almost exactly how it sounds.

Take your front brake discs (or new ones), and have a machine shop re-drill the holes in the 5-bolt pattern that will accept the 911 wheels. This will also require either studs be pressed into the disc, or the disc tapped to accept a screw-in stud, and a suitable wheel nut to hold the wheel on as you will no longer use the bolts that held on the stock 914-4 wheels.  This is shown in Figure 1.

The down side is that when you wear down this set of brake discs, you will have to go through the expense again with the discs and studs.

(3) Convert the front to 911/914-6 front suspension:

You can change just the strut assembly, which will give you the 911 spindle/hub assembly, along with the vented brake discs and the 911 calipers. This is shown in Figure 2, Figure 3, and Figure 4.  You will have to change to a 911 19mm master cylinder if the car was not already equipped with one.

-or-

Change the entire front suspension to 911:

You can install any 911 (thru 89) front suspension as a direct replacement for the 914-4 suspension.

The advantages are:

• A newer steering rack (all 911s, 912s, and 914s used the same steering rack).
• A built in sway bar.
• A lighter, aluminum steering rack mount (on the later suspensions)
• Larger torsion bars (19mm vs. 18mm).
• Larger brakes.

You will need the larger 19mm master cylinder.  Figure 5 and Figure 6 show a 914-6 front end with vented brake discs, and 'M' calipers.

See article on 911 Front Suspension Spotter's Guide.

 

For the rear conversion:

(1) The simplest way:

Wheel adapters (see front suspension above).

(2) The next simplest way:

Drill the rear hubs out for 5-bolts and insert studs. This is shown in Figure 7.  The early cars (1970-71) have bosses where the holes for the five lug pattern were to be drilled.  Figure 8 shows a hub from a later car.   Drilling out the hub on the later cars appears to work fine from a strength perspective. You can also drill out the brake disc, but it is probably cheaper just to buy a new 914-6 brake disc which already has the 5-bolt pattern. This will allow you to use the stock 914-4 brake caliper.

If you have a 70–71 914-4, you probably have a rear hub that has extra raised bosses where the 5-bolt pattern would have been drilled out on the assembly line.

The stock 914-4 rear hub (72-on) is almost 50% thinner where the studs are going to be mounted on the hub than the 914-6 hubs.

(3) Convert the rear to 914-6 parts: (Original 914-6 rear shown in Figure 9)

You will need:

• 2 rear wheel bearings
• two early 911 hubs (69-71), see Figure 10 and Figure 11
• two 914-6 stub axles, see Figure 12
• two 914-6 brake discs

You need the wheel bearings because you will destroy the old ones.

The early 911 (69-71) hubs use the same wheel bearing as the 914-6 (and 914-4), so the fit is correct.

The 914-6 stub axles will fit the splines of the 911 rear hub, and will also bolt up the 914-4 CV/axle assembly.  Note that the 914-6 used a different CV joint, and a different axle.  A 914-6 CV joint is shown in Figure 13

The 914-6 brake disc will bolt right on and allow you to use the stock 914-4 rear brake caliper.  You can also upgrade to 914-6 rear calipers if you want to increase your rear braking ability.  The 914-6 rear calipers are very difficult to find, and are just about the only solution that you can use to increase your rear braking, if you wish to keep your manual parking brake.  Figure 14, Figure 15, Figure 16, Figure 17, and Figure 18 all show the 914-6 rear caliper.

Some people add 911 calipers to the rear, but then you need to add what is known as a hydraulic lock.  This locks the pressure on the caliper when the car is sitting idle.   While perfectly fine most of the time, the system is under pressure for a large amount of time, while the car is parked.  If a leak occurs in the system, then the 'parking brake' will disappear, and your car may roll down the hill.

After you upgrade your rears, you will need some new wheels.  While there are many options for adding wheels, perhaps the best is the deep offset early 911/914-6 15" Fuchs alloys, shown in Figure 19 and Figure 20.  These wheels have the proper offset to fit nicely under the 914 rear fenders.  The standard, later-style wheels have a different offset which makes the wheel ride very close to the outside fender lip.

     There are other ways of converting the rear which allow for use of larger brake calipers and vented rear discs, but those are beyond the scope of this article.  This tech article is meant to be a broad overview of the conversion process, and to give you a clue as to what options are available to you.  If you have any questions, please feel free to give us a call, or send us some email.  Keep watching in the future for a detailed article on the actual conversion process.  Pelican Parts can provide you with everything that you need for your five lug conversion, from wheel bearings to Fuchs alloys.  Your continued support directly aids in the expansion and development of this technical website.  Thanks for your future support!