Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Metal shaving in rear drum
I have been using the Bodsy Bible and videos to work on my rear brakes on my new to me LR3, 162,000 miles. A nasty screeching noise prompted the investigation. Left rear looked great inside, just lacked grease on the six rubbing points for EPB shoes, which I remedied. I adjusted the shoes tight, backed off 8 clicks.
When I got to the right rear, I pulled off the disc/drum and out came a significant metal shaving (pictured). Further inspection revealed more metal shavings up inside the brake assembly, as well as a "nugget" that I think was a long shaving rolled up onto itself and welded by the heat. They very clearly came from the backer dust plate which had been rubbing against the drum. That back plate has slight damage to the bottom, like it got pushed inward or up.
Click image to enlarge
Click image to enlarge
Click image to enlarge
Click image to enlarge
But I got curious and thought maybe there was a different reason the disc and back plate were contacting each other. There was also evidence of a previous disc (discs have all been recently replaced) contacting the pad carrier but it was not a lot of wear.
There is *minute* play when I take hold of the hub and try to work it in and out from 9 and 3 (horizontal) and also from 12 and 6 (vertical). Possibly a little more play on the vertical.
You'll also notice the booted bolt on the upper control arm with the casted piece offset toward the rear rather than in the center (as it is on the other side).
Click image to enlarge
Could a failed wheel bearing misalign the disc enough to do this?
16th Apr 2024 3:20 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
It's possible that either a brake component came loose (slipped shoe clip is common) or a foreign object got into the drum causing the damage. The wheel bearing should have no obvious lateral play, but the upper knuckle has very obviously shifted way out of place which it should never do.
If you checked the bearing for lateral play with the wheel bolted on and there is movement the bearing is shot. There is a locking clip on the lower knuckle bush but oddly not on the upper one.
It's not a difficult job to replace the bearing but you'll need a 30 ton hydraulic press. (sometimes you can get away with a 20t) The knuckle bushes will push out easily but I wonder if the upper part is worn (too loose fitting?)
The other thing to look at the the rear tie rod adjustment as it's the only other thing that might cause the bush to shift if maladjusted.
However, if the rear wheel was to suddenly "lock up" I could see how it might cause the knuckle to to be forced forward leaving the bushing behind!yµ (idµ - eAµ) ψ=mψ
16th Apr 2024 12:29 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
PROFSR G, thank you for taking the time to offer up some knowledge as I'm a complete novice on these components (but willing to learn).
I guess it's best to check wheel bearings with wheel on because the movement will be more pronounced than with the wheel off, so I can try that.
I will remove the bolt to inspect the knuckle and bushing. I'm going to lean toward your "lock up" theory for what caused it to shift in the first place.
16th Apr 2024 5:21 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
Mark the upper bolt cam discs relative to their position with the upper arm/knuckle mount. This is the camber setting which you will need when reassembling. yµ (idµ - eAµ) ψ=mψ
16th Apr 2024 5:25 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Could you show me what parts you're talking about marking?
16th Apr 2024 7:41 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
Mark these cam washers in relation to the black upper arm mounting point. When you have it off it will become clearer but you need to mark it first or you will loose the setting!
Click image to enlarge
yµ (idµ - eAµ) ψ=mψ
16th Apr 2024 7:56 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Something like this?
Click image to enlarge
Click image to enlarge
16th Apr 2024 8:35 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
Yes, you can see how the eccentric washer sits inside a fixed "U" shaped section. As a slightly loosened bolt is turned the eccentric washers which are "keyed" to the shank rotate to force the adjustment required.
Hope that makes sense, but it's been a long day. yµ (idµ - eAµ) ψ=mψ
16th Apr 2024 9:24 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
It does, thank you. They seemed offset so when you said "eccentric" a light bulb went off. I will be sure to align my permanent marker marks at reassembly.
I'm usually half visual learner, half technical terminology but I have to admit a good visual wins out for me most every time.
16th Apr 2024 11:11 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Well, upon removing the bolt and doing a closer inspection it is clear that the bushing is tight as a drum. It is by no means a loose fit. Is there a way to compress it into its correct location without special tools?
17th Apr 2024 8:24 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
Move the upper arm out of the way and use a threaded bar with suitable size sockets to pull it back to centre. You could replace it as it's done it's job at 160k miles?yµ (idµ - eAµ) ψ=mψ
17th Apr 2024 8:44 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Thanks for your suggestion with the threaded rod. It worked, but the amount of torque needed was definitely more than I was expecting. A ratchet and two feet of "cheater" bar were needed.
Anyway, I think you're right about the tie rod adjustment. I have the upper control arm adjustment back as it was when undone. On the other side of the vehicle, the knuckle is more or less perfectly square with the upper control arm attachment point, but here you can see it's totally cockeyed. Any tips for this?
Click image to enlarge
19th Apr 2024 6:58 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5093
Is the tie rod actually attached in that pic? They do look skewed sometimes depending on the position the suspension is lying. If the tie rod is maladjusted there should be tyre wear evidence!
If not put it back and have the alignment checked. yµ (idµ - eAµ) ψ=mψ
19th Apr 2024 7:25 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
Alas, the vehicle came with a new set of tires.
But yes, the tie rod is attached in that photo. I haven't done anything with it yet. When I put it all back together I suppose I'll schedule an alignment.
Thanks for your help and advice.
19th Apr 2024 7:43 pm
itsmywheelhouse
Member Since: 12 Apr 2024
Location: New Mexico
Posts: 28
You were correct, sir. I looked closer at the new tire and the outer portion (rim side) has been worn smoother than than the inner, which I think would indicate the tie rod needs to be extended.
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