XJ XJ8 / XJR ( X308 ) 1997 - 2003

Brakes in the wet

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Old 03-06-2017, 04:33 AM
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Default Brakes in the wet

Hi all, I have a nasty problem with my 2001 xjr. When on the motorway in heavy rain the brakes seem to get overwhelmed by the spray, this results in the car pulling sharply left for a second or two when first braking after a period of cruising. Once they have been used and dried / cleared the car brakes straight as usual.

I've recently had the front wheel bearings replaced but hadn't necessarily been in the same conditions before this work so can't say for certain this was the cause / start of the issue.

Has anyone had similar issues? I wouldn't have thought the caliper would retract the pads very far from the disc normally, but can it happen if they get old? I was also considering whether the dust shield was bent during the wheel bearing change and it now doesn't protect as much as it should. Is there anything else I could consider? Thanks
 
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Old 03-06-2017, 11:55 AM
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How old are the calipers?
How many miles on them.

This sounds like a classic caliper problem. When they put the new pads in, they had to retract the piston in the calipers.

Also, what condition are the rotors in?

It is very possible that there was some dirt or dust on the rubber seal that when the caliper was compressed, got into the piston. This could be causing the problem you describe. Rain should not have much to do with it.

Calipers are not expensive and very easy to install on these cars.
 
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Old 03-06-2017, 03:32 PM
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I guess this could happen if one caliper is not moving smoothly, so that the pads are not retracting properly. Then after a period of rain you would have one wet disc (the normal side), and one dry one (the stuck side).

The sticky side will be dry because 1) The disc is getting hot and 2) The stuck pads are wiping the water off the disc.

If this is the case, I would expect that the sticky side would be noticeably hotter after highway driving.
 
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Old 03-06-2017, 04:59 PM
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Thanks for the replies.

It was the wheel bearings that were changed not any part of the brake system - I only added it for full disclosure as the area had been in bits recently.

The pads and discs are quite old, the car doesn't do a great deal of mileage (coming up to 84k miles) there's some wear on the discs but not a lot. The calipers are likely original.

In my head I had thought it pulled left because it was the working side. I'll have to give it another try in the dry, maybe the pulling is still there I just haven't noticed it yet, in the wet it was very obvious it didn't want to slow down.
Cheers
 
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Old 03-06-2017, 07:08 PM
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My suggestion would be to take it for a drive, pull over while braking as little as possible, then feel the wheels to see if one is noticeably hotter than the others.
 
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Old 03-07-2017, 06:48 AM
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At the worse, redo the front pads and clean, grease the calipers including the pins. Sure sounds like a stuck caliper (or maybe parts that weren't reassembled correctly after the bearing fix). Nothing really difficult here, unless you aren't good at bleeding.
 

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