Doing your own front wheel bearing replacement is pretty straightforward and is commonly done by home mechanics, especially when the front wheels only steer and stop the car. Front wheel drive cars can be a little more difficult, and there are certain models that use something other than “inner/outer bearing” configurations, but Porsche decided to go “traditional” on our cars. Rear bearings are sometimes forgotten and can be a bit more of a challenge to replace.
FRONT WHEEL BEARINGS
Replacement of the front wheel bearings requires the removal of the wheel and brake caliper. Pull the center cap, take off the retaining nut and pull the hub from the spindle. The outer bearing will likely fall out of the hub. The inner (larger) bearing is probably held in place by the inner grease seal, which must be removed, releasing the inner bearing. Clean everything thoroughly, getting rid of any grease and debris that may be hiding on the spindle and inside the hub.
When you pack the bearings, use your hands as shown in this video.
If you don’t want to put the grease in the palm of your hand, use a grocery store plastic bag over your hands or a pair of nitril gloves. Make sure the bearing is completely greased inside and out.
Place the inner bearing in the hub, then tap a new seal into place. I like to also grease the spindle lightly. Then put the hub back on the spindle, seating it firmly. Then place the new outer bearing on the spindle, followed by the clean keyed washer and finally the retaining nut. Preload the bearing with the proper adjusting process – don’t just tighten it up. The bearing has to be tight enough not to move around, but loose enough to allow the grease to flow around it. This video shows a great way to ensure that your bearing are 1) properly seated and 2) properly preloaded.
The trick is to tighten the nut enough to seat the bearings properly, then loosen the nut about a half turn and reset it to the proper torque. While there are a zillion opinions on how much torque to apply, the video and others say something around 20-25 INCH pounds of torque is enough. I have also seen where you should be able to very slightly wiggle the washer – not so sure about that.
Properly greased and installed, your front wheel bearings should last a long time.
REAR WHEEL BEARINGS, 944 SERIES I
The rear suspension/bearings are different between the 1983-1985.5 (Series I) 944 and the 1985.5-1991 944 (Series II) and 1987-1988 924S. We will look at the Series I cars first.
The Series I cars have inner and outer tapered bearings much like the front bearings with an inner, outer and a seal on each wheel. Getting to the bearings requires removal of the outer CV joint, the wheel and brake caliper, then the axle. The nut on the outside of the axle is normally torqued to several hundred foot pounds, so you will need to get inventive on how to loosen it. Unfortunately there is little out there to help you. I have used every method including using the proper tool! Start with loosening this nut on both sides before taking off the wheel or putting it in the air.
- Put the proper size 1/2″ drive socket on a breaker bar, with a section of pipe to increase leverage. Have a partner in the car holding the brake.
- Using the socket, breaker bar and pipe, put the end of the pipe on the floor and push the car forward or back.
- Using the socket, breaker bar and pipe, put the end of the pipe on your hydraulic floor jack and jack up the end of the pipe.
You always run the risk of breaking the breaker bar and/or the socket. Keep that in mind, and also keep in mind that you will need to retorque the nut when you put it back on.
Once the axle nut is broken loose, remove the CV joint at the axle hub. Remove the wheel, caliper and rotor. Remove andy retaining clips and gently tap the axle out. The outer bearing will come out with the axle, the inner will probably end up stuck in the housing. Carefully remove it. Keep track of the various spacers that are part of this assembly, including the order and orientation upon removal. Clean everything, grease the bearings and reassemble.
REAR WHEEL BEARINGS, 944 SERIES II, 924S
These cars have aluminum banana arms and a large single bearing. Disassembly is similar to the Series I cars, but the bearing is held in the carrier by friction (lots of it) and two c-clips. Again, there are many ways to remove the old bearing, including using the proper tools. However, one cheap way is to heat up the aluminum carrier around the bearing with a MAP gas torch, then just tap it out with a hammer. (The aluminum expands faster than the steel in the bearing, so it loosens it up when you heat it.) To put the new one in, first freeze your new bearings in the freezer for a week or so. Sounds strange, but the frozen bearing and the heated aluminum are a perfect match. The cold bearing drops right in place in the hot aluminum carrier with minimum effort, then everything tightens up as the temperatures go back to normal. Reassemble the rest of the parts and torque the axle nut. You can also use bearing pullers and other tools, but the heat-and-frozen seems to work well.
Replacing wheel bearings in the front is pretty simple and straightforward, as long as you don’t mind getting dirty. Rear wheel bearings are a little more complicated and require some more advanced equipment, even though we are only talking about a big socket and a breaker bar. Breaking the axle nut loose is the big thing.
So good luck!
Kevin Duffy is an Associate Professor of Criminal Justice at Daytona State College in Florida and a dedicated car guy. He divides his time between teaching criminal justice topics in the online environment and working on/driving cars, particularly Porsches. Kevin is one of the principals in InspiringLifeOver50.com.