Rear Wheel Bearing adjustment

[cmvasquez]

Hey Guys,

Just installed the rear wheel bearings on my 88 911 Carrera Cab and pressed the hubs. I do not have a turbo look car so I pressed the hubs until they were seated fully on the bearings. The bearings run smooth and I do not hear any movement but when I put the rotor over the hub and secure I see a slight difference in the path at which it spins. It seems to me that either the hub or the bearing is not seated properly. I may also be just imagining this since I have not checked for sure. I have seen a setup of a dial gauge pressing on the rotor face and as the rotor is spun any difference in the dial reading dictated an imperfection in the direction of travel. Is this a good method to check the travel of the hub and rotor?

Any thoughts?

Thanks guys,

Cheers,
CMV

[rusnak]

There is no "adjustment" per se of the rear wheel bearing. Depending on which type of nut you have, Bentley specifies 230 to 330 lbs ft of torque to properly tighten the stub axle.

When you install the bearing, you must support the outer race when pressing the bearing into the trailing arm, and support the inner race when pressing the stub axle on. You should hear no grinding or growling when you spin the hub, and it should spin very freely. It's actually very easy to damage the bearing upon installation, and common to damage it the first time you try installing one. The key is to use washers of the correct diameter, and have it positioned precisely before applying torque.

[will hung]

I'll second everything rusnak said about supporting the bearing when pressing the bearing and stub axle. But I'll add 2 other items.

1. Make sure that the stub axle is pressed all the way into the bearing. Even if it is slightly off, you will see play.

2. How hard was it to press the bearing into the trailing arm? If it was easy, you're bearing bore is egg shape and will either need addressed to reuse or replaced.

[hcoles]

as mentioned there is no adjustment, it is a split race angle bearing, the high torque pulls the inner races together and provides the correct bearing play. after this is done if you have runout then you have an issue.
sounds like you have it in already, I heat the arm and freeze the bearing and they slide right in with some light tapping on the outer race to seat fully

[Trackrash]

I had a problem, where I still had some play in the bearing after it was torqued. Turned out there was a bur on the hub where it contacted the bearing.
You don't say what year car you have, that will determine the torque value.
I learned two things when doing mine. First I noticed that the nut on my car really didn't "cinch" down tight until I got to around 250 ft-lbs of torque.
Also, do not use grease on the threads or you risk the nut coming loose. Use oil. Ask me how I know...

[cmvasquez]

Thanks for the response guys,

Used the heat and freeze method in installing the bearings and I thought I did pretty good job at seating it properly but who knows! I did however hammer the bearings in for the first inch or so using a properly sized aluminum bearing disk. Do you think the force of the hammer did any damage?

Also I haven't even torqued down the axle nut to its final torque spec of 332 ft/lbs. Will that pull everything down snug? I have just been checking it with the two screws holding the rotor to the hub screwed in and torqued down. First time doing this.

As always, Thanks for your quick responses.

ps when I do the final torque down of the axle nut and cv bolts, should the car be on the ground or relaxed?

Cheers gentlemen,
CMV

[James Brown]

it helps to hold the hub from turning

[bazar01]

Originally Posted by cmvasquez

Thanks for the response guys,

ps when I do the final torque down of the axle nut and cv bolts, should the car be on the ground or relaxed?

Cheers gentlemen,
CMV

When I did mine, I torqued it in 4 stages.
First step to 100 ft-lbs with car up on lift, wheel hub held in place with a 3 foot long pipe on two of the lugs and against the floor.
Second step, with car on ground and wheels on without the center cap, torqued to 200 ft-lbs.
Third step to 250 ft-lbs which is my max on my torque wrench.
Fourth step, used my 150 lb weight on a 3 foot long pipe on a 3/4" drive breaker. The axle nut only moved maybe 1/8 turn.

[cmvasquez]

What about checking the disks lateral run-out. Is this what I am thinking of? or is this something completely different?

[mnez]

If you are measuring off the rotor, you are assuming that the rotor is true, and mounted squarely. But it may not be. Can you measure lateral run-out on the hub itself, where the studs are pressed in?

[bazar01]

Originally Posted by cmvasquez

What about checking the disks lateral run-out. Is this what I am thinking of? or is this something completely different?

If I understood you correctly, you installed the brake rotor over the hub and secured it with just the two 5mm countersunk screws and rotated the rotor by hand to check the indicated run out and found it wobbling?
That is not a good way to check for run out on the rotor disk. You have to put on some spacers on the lugs and put on the lug nuts and torque them down to at least 50-60 ft-lbs to make sure the brake rotor seats evenly on the hub then check for run out. Or you can put the wheel on and test the wheel for run out.

But to tell you the truth, once you get the axle nut torqued to 330 ft-lbs, everything will get seated properly, the stub axle, hub and bearings will all get seated unless of course the stub axle and the hub journals and shoulders were dinged or damaged causing the bearing to hang up on the dent or burr in the journals.

If you followed the correct way of installing the bearing, you should be good.

[cmvasquez]

checked the hubs lateral run-out and it was good so I torqued down the main nut and torqued down the wheels and everything looks and measured up great. Thanks guys. Now to the front of the car and then ill post some pics.

Cheers,
CMV