Rear Axle Bearing Issue

[ShelbyPower]

I brought my rear axles to my mechanic yesterday to press on the bearings and retainers and we both thought it was going to be a 10 minute job. He was able to press on the bearing with no problem but as we tried to seat the retainer we couldn't get it to go all the way down. To get it even close he really had to crank on it with the press. After some head scratching, he removed the retainer and when we inspected it the inner surface had developed a ridge suggesting that the OD of the axle had not been machined correctly (too big).

This is a standard 9" rear from the 9InchFactory purchased through A&C. My mechanic (very experienced with Cobra builds) suggested I ask for new axles. Anyone else have this experience? I posted a couple of pictures to my gallery showing the bearing retainer after removing it from the failed attempt to press it.

[venum14]

ShelbyPower- As you mentioned the bearing change should be straight forward. A few thinks to investigate.

1. The bearing /retainer press fit area should only have two diameters. One for the fit of the bearing/retainer and a smaller diameter for the axle seal. The bearing and retainer should slide (no press fit) over the seal diameter.
2. Verify that the fillet radius on the axle, this is where the bearing diameter meets the larger diameter near the flange. The corner radius of the bearing must be larger than the fillet radius of the axle so the bearing face fully seats on the shoulder of the axle. Note, bearing quality varies greatly with many top names being made in China!
3. With calipers verify the inside diameter of the bearing and retainer. The ID of the bearing should be roughly .002" -.005" smaller than the axle diameter and the retainer will be .010" or more smaller. Only the retainer holds the bearing and axle in place, that is why there is such an interference. You don't want the axle coming out of the diff. housing when you go around a corner!
4. For installation, apply a small amount of Never Seize or bearing grease to the axle diameter and inside of the bearing, press it on first. Then apply the Never Seize to the retainer and press it on as well. It will take much more pressure to fully seat to the bearing.

Jeff

[Jerry Clayton]

where is the axle retainer plate that bolts to the end of the axle housing???

Heat the retainer ring a glowing red and drop it on the axle next to the bearing--as it cools it shrink fits to the axle--the interferance fit is much more than you can/should press on.

I believe that Jeff's measurements are off---

[ShelbyPower]

Jerry - The axle retainer plate is a C-plate so it can go on after the bearings are pressed on. I am going to measure the axle OD and compare to the retainer ID. What should the difference be? Is the heat method generally OK--will I need much pressure to press on a heated retainer?

Jeff- Thanks for your info. I am still trying to figure out if I have a machining issue with the axle or if the retainer is out of tolerance.

[Jerry Clayton]

the retainer, when heated will expand enough to fall over the axle and only needs to be gently seated against the bearing--it will shrink fit itself to the axle tight enough that it won't come off--

[ShelbyPower]

I measured the diameters of the bearing retainer and axle. The ID of the bearing retainer is 0.006 smaller than the OD of the machined surface of the axle shaft so it should go on. I will order new retainers and have them pressed on while hot.