<< UPDATE >>96 XJS Rear Break Issues - Take a look and listen

Summary: Purchased this 96 XJS this past November. It has 64K miles and came with no service records. I drove 150 miles home and took it to my local service station the following day for state inspection. The tech raised the car and we saw significant “wobble” in left rear wheel. Click on link.

We both immediately suspected a bad wheel bearing. I drove the car home, removed the wheel and discovered the center hub nut was loose. I tightened the nut and could not force any lateral or horizontal movement in the wheel, nor did it make any whining noise when driving. I thought all good until a week ago.

I started to hear some squeaking noise when I applied the brake while slowing down for speed bumps in my neighborhood. Today, I jacked both rear wheels off the ground and removed the left rear tire. I started the engine and shifted into drive at idle speed. With the rear wheel slowly spinning, I could see some serious warp on the disc/rotor. Notice the changing gap between the disc and caliper in link below

The disc also appeared to be slightly non-concentric to the eye but difficult to capture in video. Last, there was also a faint knocking noise that appeared to be coming from the hub assembly. I placed one end of a pry bar on the hub assembly and my ear on the other end. This produced a very pronounced knocking noise coming from the hub assembly. One knock per inner shaft rotation. Take a listen…

Questions:

  • Could all of these issues stem from the hub nut being loose for at least 150 miles?
  • Is the knocking noise the bearing or possibly the outer u-joint?
  • Any recommendations on manufacturers for rotors – pads – bearings? (Centric - Timken)
  • Am I missing anything else?

Thanks & stay safe,

Kevin

My guess - bearing is gone. Replace both sides.

Excellent methods of showing your problem.

These cars are famous for eating differential output shaft bearings. If the entire driveshaft between the wheel and differential can move in and out, then yours are bad too! Rather than replace the bad parts one at a time, might as well replace all bearings…diff output shafts, and wheel hubs, lower fulcrum bearings. For brakes, Centric are fine that’s what I use. For bearings, hit up SNG Barratt. They’re the cheapest when you buy a kit. Usually SKF brand which is good stuff.

Thanks. Did not want to hear “If the entire driveshaft between the wheel and differential can move in and out, then yours are bad too!”

Heading out to the garage to see if there is movement in the shaft. Stay tuned…

Upon further review… Jacked up rear end of car and removed both rear tires. No movement on half shafts in or out on either side so I am hoping/assuming the diff output bearings are good.
I then improvised a dial gauge by placing a screw driver at 12o’clock between the rotor and the ridge of the shield. The left side is definitely non concentric.


The right side is good. Last, I place my hand on the right hub assembly and could feel no knocking. I did the same thing on the left side and could definitely feel some internal knocking taking place.

Conclusion: replace rear rotors, pads and bearings.

Any additional thoughts or comments welcomed!

Thanks - Kevin

I tend to disagree.
The driveshaft would not move in and out because of the loose nut.
The nut keeps the hub to the driveshaft and not vice-versa.
The output shaft bearings fail indeed but for other reasons, one being the inboard brakes.

Kevin,

Only way to find out is to start dismantling.
Remove the brake disc, start the car and verify that your stub axle is absolutely straight.
If it’s indeed straight the rest is relatively easy. If not you need a new one.
Next remove the hub and inspect the bearings and U-joint.
New discs for sure.
And since you will be there, check also you lower pivot bearings and seals.

I would go with Aristides’ more conservative logical approach rather than just assuming the worst and jumping off the cliff. Start with taking the calipers off - look at the calipers for rub marks from the disk, and the disk pads for clues. Plan on replacing brake pads when you replace the rotors. Now, with the rotors and calipers out of the way, you can take the hub nut off, and the hub, check them out, clean things up.replace the hub and torque the hub not to spec. Start the car put the car in gear (both sides up and on jackstands & front wheels blocked - right?) and listen for noises and check stub axle runout. Stop rotation - engine off and check in & out motion of stub axle & dog bones. At this point you can decide if you need to go any further. into the stub axle bearings, dog bones / u-joints, & diff output shafts.

Kevin,
I forgot to add that the disk/rotor has the parking brake shoes working on the inner surface of the rotor (Ala the C3 Corvettes from the 70’s). Therefore, you would need to examine the inner portion of the rotor and the parking brake mechanism for any sign of damage that may be causing the scraping, squeaking, knocking, or other noises that you have been hearing.

Yes it’s a strong possibility that the “tick-tick” comes from the parking brake.

Yup, been there, heard that. It is just a basic drum+shoe set up. After removing the caliper, back off the adjuster, pull off the rotor. Give it all a good clean, replace, and reset the adjuster. Mine was making a ticking noise because one of the shoe springs wasn’t correctly seated.

Khwilm, fantastic videos. OK, on inspection for tag, inspector demonstrated a wheel wobbel and said the left rear wheel bearings needed replacing. I can do a lot of the engine and electrical s but wheel bearings??not familiar with terminology etc. Any ideas of someone near Carolinas that would do this for me. Reasonable! I do not have a garage. My work is all done in 1 day or interiolr or under the bonnet.
Thanks
Harry Simmons
90 XJS 12
48 3.5 saloon

Just disassembled the rear hub/brake assembly. The first issue was easy, need new e-brake shoes.


The second issue is a bit more troublesome. It appears my initial issue with the loose hub nut led to a spun outer wheel bearing which led to a ruined rear axle hub. Note the excess wear and groove where the bearing sits.

Comments - thoughts? I am I missing anything else?

Thanks - Kevin

BTDT, 2nd hand hub and carrier is in your future, just make sure your handbrake is adjusted correctly before you get back on the road, don’t ask me how I know :frowning:

Impressive…
Just curious, what was the condition of the bearing?
Is the hub carrier still good?

The hub carrier was in good shape. The bearing showed some wear.

Wow. I’d actually be happy to have found that. I’d be excited to see how much better the car runs when it’s been fixed.

What’s funny is, the wheel was not loose and did not wobble like it did with the loose hub nut. (first video) The big difference is lack of squealing I used to hear at low speed while driving through the neighborhood.

On another note, I accidentally knocked the cap off of the abs sensor. No big deal until I discovered how much a new replacements costs. Yikes!

Indeed. Is it repairable? I had a yikes! moment with the ABS sensor on my Subaru, similar sort of price. I was able to pull it apart, repair the break in the wiring, and then re-pot the sensor part in epoxy. Worth a try.

Here’s what I started with: