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HomeTech Articles > 914 Five Bolt Pattern Conversion

Pelican Technical Article:

Five-Lug Rear Wheel Conversion

Gill Paszek

Diagram 1

     Well, old Bee Jay has again roped me into helping him work on his 914, the freshly painted and upholstered Non-Leaky Tikki.  It looks so good now, he just couldn’t stand to run the Minilite knock off wheels any more.  (The wheels aren’t held on with knock-off hubs, they are cheap reproductions of the Minilite magnesium wheels.)  So, we converted his rear hubs to accommodate five-lug wheels.  This article will show you how to cobble together a makeshift tool out of inexpensive pieces from the local hardware store, and use it to reseat the hubs.  Even if you don’t want to change hubs, you can use this procedure to remove and replace rear wheel bearings.  Rookie mechanics, be aware this is not an elementary procedure.  It is less complicated than a transmission rebuild, but definitely not a good first project.

     There are several reasons to convert a 914 from the four-lug to the five-lug wheel pattern.   Most folks do it for the sake of appearance – classy Porsche and aftermarket alloys fit the five-lug pattern.  It can also benefit performance.  Many of the five-lug wheels are wider and lighter than those available in the four-lug pattern.  There are also many high performance brake components that are compatible only with five-lug wheels.   The actual conversion entails swapping the four-lug rear hub for a five-lug hub.  Sounds easy enough, but it seems the entire rear suspension must be disassembled to get access to the hub.  OK, I exaggerate, but you will see everything that must be removed and re-installed during the conversion.

     The other complication is the rear wheel bearing. The bearing is a press fit into the trailing arm, and supports the hub.  It is a sealed unit that lasts 100,000 miles with no maintenance.  The problem is, driving the hub out of the bearing trashes the bearing.  Driving the hub back into the bearing can also trash the bearing, if you don’t do it right.  The trick is to pull the hub into the bearing by exerting force only on the inner race of the bearing.   Using a mallet to whack the hub into the bearing transfers excessive loads through the inner race and balls into the outer race.   This fatally damages the bearing.

     There are three reasonable choices for converting the rear hubs to the five-lug pattern.  The first way is to use 914-6 hubs.  This is a very sanitary approach, but it requires installing 914-6 stub axles, also. The 914-6 stub axle is unique to that model, but the 914-6 hub is the same one used on 1969-1973 911s (part number 901.331.065.09).  The 914-6 used 28-spline hubs and stub axles; 914-4s used a 37-spline configuration.

     The second option is to use hubs from a 1970–1971 914-4, and have them drilled and spot-faced to accommodate five-lug studs.  The 1970-1971 pieces are desirable because they have bosses cast into the hubs in the right places to support the five-lug pattern.  This gives good support to the studs and makes the finished hub very strong.  There is no need to change the stub axles.  Bee Jay wisely chose this option.

     The third choice is to use hubs from a 1972-1976 914-4.  These have no bosses for the five-lug pattern studs.  The studs will therefore be mounted into thinner metal than on 1970-1971 hubs.  However, garages that have done this conversion report no problem with the hubs failing.  Again, the existing stub axles can be used.

     In addition to the hubs, you will need brake rotors that are drilled for five lugs.  You can order new 914-6 rotors, or have 914-4 rotors redrilled.   Bee Jay bought the 914-6 rotors because his existing rotors were in poor shape and couldn’t be reused.

New parts you will need:

- 2    Brake rotors (914-6 or redrilled 914-4)
- 4    Rear brake pads
- 2    Hubs (drilled for five lug)
- 2    914-6 stub axles (ONLY if you use 914-6 hubs)
- 10  Wheel studs
- 2    Wheel bearings
- 2    CV joint gaskets (forget these and the CVs sling grease all over)
- 2    Cotter keys (for castle nuts holding the hubs onto the stub axles)
- 2    Five lug wheels (you will probably want two more for the front!)
- 10  Lug nuts

Tools and supplies you will need:

- ” all thread  (This is a steel rod, ” in diameter, that is threaded its entire length.  It is available at your local hardware store, usually in 3-foot lengths.  You actually need about 15 inches.)
- 2 nuts and 4 washers (to match the all thread)
- Socket set (1/2” drive, ” drive also helpful)
- 30mm (or 1 3/16”) socket
- Long, stout flex handle to match 30mm socket
- Torque wrench
- Screw drivers
- Metric combination wrenches
- Pliers
- Metric hex (Allen) wrenches
- 12-point CV joint wrench
- 3” outer diameter (OD) iron pipe, or a socket the same size
- 2” OD socket,    or  ” drive
- Iron bar or pipe, 1.5” OD
- Molybdenum disulfide grease
- Anti-seize grease
- Blue Loctite


1.   Remove cotter key from stub axle castle nut.

[Click on Photo]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

2.   Set parking brake.  Loosen stub axle castle nut.  This baby is 30mm across the flats, but a 1 3/16-inch socket also fits beautifully.  The nut should have been torqued to 217 to 253 ft-lb, if the previous mechanic followed the specs.  If he grabbed a pneumatic impact wrench and got medieval on the nut, there’s no saying how tight it is.  I have a  -inch drive socket set that helps in situations like this.   If jumping on the end of the flex handle (see photo 1) doesn’t loosen the nut, feel free to put a four-foot cheater bar (pipe) over the flex handle and stand on the end.  Needless to say, I’m not a fan of using impact wrenches to tighten nuts.

3.   While you’ve got the flex handle out, loosen the wheel lug bolts.

4.   Chock the front wheels, jack up the rear of the car, and rest it solidly on jack stands.

5.   Remove the lug bolts and wheels.  Stash the wheels under the car.  That way, you don’t trip over them, and if the car slips off the jack stands, it crushes the wheels rather than your skull.

6.   Remove the castle nut and washer from the stub axle.

7.   Release the parking brake.  Disconnect the parking brake cable from the lever on the brake caliper (see photo 2).

8.   Remove the brake pads.  To do this, pull the clips holding the pad retainer pins.  Back off the venting clearance on the inner and outer pads.  “Venting clearance” is the space between the brake pad and the rotor when the brakes are not applied.  On 914s, you can (actually, must) manually set venting clearance because the rear brakes aren’t self adjusting (mainly because the parking brake is integrated into the caliper).   To back off the venting clearance on the outer pad, remove the plastic cover over the adjusting screw and loosen the lock nut.  Use a 13mm box wrench.  On the outboard adjusting screw, insert a 4mm hex wrench and turn the screw clockwise to loosen the venting clearance.  Yes, I know this sounds backwards.  The inboard adjusting screw is accessible through a hole in the trailing arm.  Remove the plug, insert a 4mm hex wrench in the adjusting screw, and turn it counterclockwise to loosen the clearance.  If you still have the old inboard plugs with the hex wrench hole in it, I strongly recommend buying the new plugs that have a raised hex head, so you can use a 10mm socket to remove them.  The plugs tend to stick, and the tiny internal hex hole strips out when you try to remove them.  A pair of new style plugs costs about $10.  Now drive out the pad retainer pins, remove the centering spring, and pull the pads out.

9.   Remove the brake caliper.  The service manuals say you need to disconnect the hydraulic brake line first, but you don’t.  What you need to do is to remove the clip that holds the brake line to the bracket on the trailing arm.   It is located about a foot forward of the caliper, right where the flexible brake hose meets the rigid line (see photo 3).  Then you can remove the two bolts holding the caliper, using a 19mm box wrench and penetrating oil.   Don’t let the caliper hang from the flex hose; support it on a block of wood or hang it with a piece of wire.

10. Remove the two flat head screws holding the brake disc in place, and remove the disc (see photo 4).  These screws are often grossly overtorqued, and are hard to remove.  A hand impact screwdriver is very helpful.  This is a heavy screwdriver device you hold against the screw, and whack with a ball peen hammer.   The impact forces the screwdriver blade against the screw and gives it a tiny but forceful twist.  Great for removing stubborn screws.  Everyone who works on old cars should have one. 

11. Remove the three bolts holding the dust shroud inboard of the brake disc (see photo 5).  Use a 13mm box wrench and a squirt of penetrating oil like Liquid Wrench.  These bolts may have been installed 30 years ago!  Your hub should now look like photo 6.   Note that Bee Jay had installed aftermarket wheel studs on his four-lug hubs, instead of using the stock lug bolts.

12. At this point, the service manuals say you need to remove the heat exchangers, which is a royal pain in the gluteus maximus.  The heat exchangers prevent removal of the axle half shafts, which must come out to pull off the hub.  The ever-resourceful Bee Jay figured a way to remove the half shafts without dropping the heat exchangers.  Read about it in the next step.

13. Use the special 12-point CV joint wrench to remove the four bolts holding the constant velocity joint to the transmission flange (see photo 7).  Remove the half shaft by pushing the stub axle out of the hub.  If you chose not to remove the exhaust system, you will find the inner CV joint hits the transmission, trapping the stub axle in the trailing arm and preventing you from removing the half shaft.  Relax, there is a simple trick to get the stub axle completely clear of the trailing arm.  On the right side half shaft, push the inner CV joint forward and upward, and you will gain enough clearance to pull the stub axle completely out of the trailing arm (see photo 8).  The left side is more difficult.  On the left side of the transmission, the starter occupies the space that Bee Jay pushed the inner CV joint into on the right side.  So, disconnect the battery ground, disconnect the cables to the starter, and remove the starter.  You now have enough space to push the inner CV joint up and forward, and the stub axle will clear the trailing arm.  Bee Jay believes removing the starter is a lot less hassle than dropping the exhaust system.  Decide for yourself.

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

14. The next step is to drive the hub out of the wheel bearing.  There are fancy and expensive pullers to do this, but they are hard to use on a 914 because the trailing arm offers few flat surfaces to push against.  The normal way is to use a 1 -inch outer diameter steel bar or pipe, and drive the hub out from the inside.  We used a 1 -inch outer diameter (OD) socket and an old, beat-up extension (see photo 9).  If you use a new extension for this task, it will soon look old and beat up.  Removing the hub requires repeated heavy blows with a big hammer (see photo 10), because the hub tends to corrode and glue itself to the bearing’s inner race.  The violence of removing the hub will destroy the bearing.  We removed the right side hub with little trauma, but the left one just wouldn’t budge.   I applied Johnson’s Law (don’t force it - use a bigger hammer) but I still got nowhere.  So, we used a 13mm box wrench to remove the four bolts holding the bearing retainer cover, and continued beating on the hub.  We figured we would push the bearing out of the trailing arm with the hub, then we could worry about freeing the retainer cover.  What happened was, the bearing broke apart and the hub came out with half the inner race, the retainer cover, balls, and cage attached.  Bee Jay pried the cage from the hub.  The cage came off easily, ball bearings flew all over the garage, and the bearing retainer cover was free.  We weren’t going to reuse the hub or bearing anyway, so we were happy.  Apparently, corrosion had permanently cemented the inner bearing race to the hub, making it impossible to remove the hub by itself.

15. If you managed to drive out the hub without loosening the bearing retainer cover, remove the bearing retainer cover now.  A 13mm socket or box wrench will do the trick (see photo 11).

16. Remove the bearing from the trailing arm.  The easiest way is to pound it out from the inside, using the Brute Strength and Ignorance (BS&I) method.  Crawl under the car and put a 2-inch OD steel bar or pipe against the inner bearing race. We used a 2-inch OD socket and extension (see photo 12).  Note how the socket is reversed on the extension, so the narrow end of the socket self-centers in the bearing.  Now, grab a ball peen hammer and drive the bearing outward (see photo 13).  Don’t worry about damaging the bearing, you’ve already reduced it to scrap iron by removing the hub.

17. Clean up the trailing arm with degreaser.  The recess on the inside, where the CV joint lives, is usually caked with old grease and mud.  The bearing retainer cover will also need a bath in grease solvent.  The seating surfaces for the bearing must be very clean so the new bearing mounts properly.  My old buddy, Jim Alton, swears by Gunk’s citrus degreaser.

18. Install the new bearing.  Bee Jay cooled them down in the freezer overnight, prompting his lovely bride to ask if we were going to defrost bearings for lunch.  Freezing causes the bearings to shrink slightly, so they slide into the trailing arm easier.  Squirt the seating surface in the trailing arm with WD-40, take a bearing out of deep freeze, and drive it into the trailing arm with a 3-inch outer diameter pipe.  Don’t dawdle, or it will warm up and expand.  I actually used a big socket and a mallet to drive the bearings in (see photo 14).  DO NOT drive the bearing in by hammering or pulling on the bearing inner race, or you will trash the bearing!  Make sure you line up the bearing squarely to the seating surface in the trailing arm, and it will go right in.  As the bearing warms up, water will condense on it.  Dry it off, and wipe the exposed surfaces of the bearing with WD-40 to prevent rust.

Figure 15

Figure 16

Figure 17

19. Install the bearing retainer cover with four bolts and washers.  Clean up the bolts and threaded holes with lacquer thinner or brake cleaner, put a drop of blue Loctite on the bolts, and torque them to 18 ft-lb.

20. Install the hub.  Before you do this, verify the retainer covers are in place.  If you install a hub without the retainer cover, you will have to remove the hub, thus destroying the bearing, before you can correct your mistake.  (Not that anyone writing a tech article would ever make a mistake like that!)  We pulled the hub into the bearing with a cheap collection of inch diameter all-thread, nuts, washers, and sockets (see photo 15).  The socket on the inside of the trailing arm pulls against the inner race of the ball bearing ONLY.  This socket should have a 2-inch outer diameter.  The socket on the outside of the trailing arm pushes against the hub.  Its diameter isn’t critical, as long as it seats squarely against the hub.  We used a 1 -inch OD socket. Smear the all-thread with molybdenum disulfide grease where the outer nut will run.  I like to spritz a bit of WD-40 on the mating surfaces of the hub and inner bearing race, to avoid the corrosion that caused us problems (see step 14).  Assemble everything finger tight, and make very sure the hub is square to the bearing.  Then, crank down on the outer nut with a box wrench (see photo 16).  You will have to hold the hub so it doesn’t rotate.   Figure 1 shows a cross-section of the trailing arm, bearing, hub, and installation hardware, with the hub halfway installed.   The hub will be drawn right into the bearing inner race without damaging the bearing.  Slick!  Disassemble the all-thread and socket contraption, and admire your new five-lug hub (see photo 17).  The hard part is over.

21. Install the half shaft.  While the half shaft is out, it’s a good time to repack the CV joints with molybdenum disulfide grease, and check the boots.  This should be done every 30,000 miles.  Use a new gasket where the CV joint mates to the transmission flange, and torque the bolts to 31 ft-lb.   If you are using 914-6 hubs, you need to install the 914-6 stub axle on the half shaft, or it won’t fit into the hub!

22. If you removed the heat exchangers instead of following Bee Jay’s recommendation, install them now.  Use new gaskets where the exhaust pipes mate to the head, and smear the mounting studs with anti-seize.  If you followed Bee Jay’s advice, install the starter and cables.

23. Smear a dab of anti-seize on the stub axle threads, and install the washer and castle nut.  Don’t use molybdenum disulfide grease here; it is so slippery under high pressure, you will overtorque the nut.  You can torque the nut to about 50 ft-lb now, just to get everything seated.

24. Install the brake rotor.  The flat head screws should be torqued to 3.6 ft-lb, which is just snug.  A drop of blue Loctite will keep them from loosening, and will prevent corrosion in the threads.  We found the holes in the 914-6 brake rotors didn’t match the threaded holes in the redrilled 914-4 hubs, so we couldn’t install the flat head screws.  No big deal, the lug nuts will hold everything together.

25. Install the brake caliper.  The steel mounting bracket for the dust shroud is sandwiched between the caliper and the caliper mounting lugs on the trailing arm.  Put some blue Loctite on the caliper mounting bolts, and torque them to 50 ft-lb.   You will probably need to use a crow’s foot to torque them, because access is tight.  Make sure the crow’s foot is perpendicular to the axis of the torque wrench, or you will get the wrong torque on the bolts. Bee Jay decided not to reinstall the brake shroud.  Instead, we put two hardened washers, about 1.7mm (.067 in) thick, between the caliper and the mounting lugs on the trailing arm.  This ensured the brake rotor was centered in the caliper.  If you are using 914-6 rotors, be aware they are slightly larger than 914-4 rotors.  The 914-6 rotors are both thicker (15mm vice 9.5mm) and greater in diameter (286mm vice 282mm).  Ensure the rotor is centered between the inner and outer halves of the caliper.  If it isn’t, use a spacer between the rotor and the hub, or a hardened washer of the appropriate thickness between the caliper and its mounting lugs.  It may even be necessary to have the caliper mounting surface milled slightly by a competent machine shop.  Check to see that the perimeter of the 914-6 rotor doesn’t drag on the caliper.  We didn’t have a problem, but if you do, have the diameter of the rotor machined down by 4mm.

26. Secure the brake line to its bracket on the trailing arm by reinstalling the clip.

27. Install the dust shroud.  Torque the bolts to 18 ft-lb.  If you haven’t figured this out yet, I recommend a drop of blue Loctite on the bolts.    No, Loctite isn’t my sponsor, I just believe in their products.  Also, their first factory was in my home town in Connecticut, so using Loctite keeps my old friends and neighbors employed.

28. Install the brake pads and retaining pins, but NOT the centering spring.  Set the venting clearance to .008 inches, inboard and outboard.  You will need a 4mm hex wrench and a clean feeler gauge.  Tighten the lock nut on the outboard adjuster, and install the plugs covering the adjusters.  Remove the retainer pins and install the centering spring, then re-install the retainer pins and their clips.

29. Reconnect the hand brake cable.

30. Put a dab of anti-seize on the lug studs, then mount those lovely five-lug wheels. Torque the lug nuts to about 40 ft-lb.

31. Lower the car to the ground, and set the parking brake.

32. Torque the lug nuts to 94 ft-lb.  I recommend tightening in several increments, like 70, 85, and 94 ft-lb.  Go in a circular pattern, skipping every other nut until everything is at final torque.

Figure 18

Figure 19

Figure 20

33. Torque the axle castle nut to 217-253 ft-lb.  Shoot for the middle of the torque band, 235 ft-lb.  Put a socket and sturdy flex handle over the nut, with the flex handle to the right of the nut, parallel to the ground (see photo 18).  You now need to do some simple math.  Divide 235 by your weight; the quotient tells how far from the nut you must stand on the flex handle.  Example:  Bee Jay weighs 200 lb.  Dividing 235 ft-lb by 200 lb gives 1.175 ft, or 14.1 inches.  So, Bee Jay centered his foot 14 inches from the nut, stood on the flex handle, and torqued the nut to the correct value.  Look at photo 19 and photo 20 to see how gracefully he did it – just like Barishnikov.  This method is much more accurate than a pneumatic impact wrench, much cheaper, and much quieter. 

34. Install the cotter key in the castle nut.  You may have to slightly tighten or loosen the nut to get key to fit through the slots in the nut.  This is why we torqued to the middle of the allowable band.

35. You’re done.

Bee Jay grinned at his classy new wheels, then decided he needs to convert the front hubs to the five-lug pattern, ASAP.   With those stereo amplifiers and CD changer in his trunk, he barely has room for one spare tire, let alone two.

Comments and Suggestions:
frankiec Comments: Got a question. I was told that if I put spacers in the original 914 calipers I can put 911 rotors in the back and still have an E brake. Has anyone done this? Does anyone know of someone making spacers for the 914 calipers??? If so, you can contact me here or email me at frankiec@outrageous.net Any info would be greatly appreciated.

Thanks for your help.
June 16, 2013
  Followup from the Pelican Staff: I opened a post in our forums. A Pelican community member may be able to answer your question. - Nick at Pelican Parts  
Bill Comments: Thanks Guys, I'm a professional mechanic and I could not have done any better. Huge help to read before attempting
February 17, 2012
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts

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