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Old June 23rd, 2018, 04:46
WB9YZU WB9YZU is offline
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Join Date: Feb 2004
Location: Madison, WI
Posts: 6,941
Front Brake info

I had the pleasure of working on my front brakes yesterday. We had taken the boat out and noticed that under heavy braking the front left made a horrible grinding sound. I parked it a couple of days on the grass on the side of the house. When I went o move it, it made this shuffling sound, and it again sounded front left.

Brake service time!

I started with trying to figure out what the shuffling sound was. It sounded familiar from my XJ days. It was a rusty dust shield that had flaked off some rust due to the heavy amount of moisture we've gotten lately. Easy fix: Wire brush, rust converter, paint - done.
To get to the shield, I removed:
The Caliper (14mm)
The Caliper Bracket (21mm)
The Disc (it's probably fallen off by now)

I looked at the pads, they were not wore out, but the inner was much thinner than the outer, so I checked the caliper guide pins on the caliper bracket. Sure enough, the lower one would not move and was completely rusted in.

I think a word on Commander brake architecture would help here:
When the caliper receives fluid pressure it pushes the bores out to push the pads onto the disc. Most OEM brake systems have pistons on only one side. To make sure it applies force equally, the caliper "floats" over the pads and puts the same amount of force on the inner and outer pad.

If the pads wear unevenly, chances are the guide pins are not free to slide in and out.

*** Maintenance Note ***
When performing front brake service, at the very least, verify that the caliper guides move in their bores.
If you want to be preventive, pull the guides from their bores (yup, just pull them out!). Re-grease them with silicone grease, and push them back in. If you damage a boot - well they are cheap and easy to replace.

On XJs the caliper bracket is part of the knuckle assembly (Except the AMC models, which had a replaceable bracket).
On a XK the bracket is removable and available as a part, as are the guide pins and boots for the pins. These are apparently high in demand as the O'Reily stores in my area had the parts in stock.

To replace a rusted in guide, you will need:
A Caliper Bracket.
A Boot/bushing Kit.
A Guide Pin Kit.

Assembly of the caliper bracket:
Get some silicone grease if your bracket did not come with one.
Over each bore hole, install a boot.
Push a bushing over each guide pin (pointy end).
Apply grease to the bushing and guide pin and push it through the end of the boot into the bore.
DO 2X

On mine, I did the drivers side first as it was the big issue. When I slid over the the pass side and found I had the same issue. The OEM pins fit the reman bracket, so with 2 good OEM pins, I had enough to populate a new bracket. My job took 2 Brackets, a Boot Kit, and a Guide Pin kit.

Good Luck!!

Last edited by WB9YZU; June 23rd, 2018 at 04:53. Reason: Spelling
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