Had new pads put on about a month ago. Now the front left squeals when braked hard, but not when braked softly. AND, it does not happen all the time!

Any suggestions other than taking it back to the dealer, who put them on? It's a real hassle to get there and they'll probably say it's something else.

2006 XK8 29000 miles

 

All that I can tell you is that I recently had the exact same problem on my other vehicle and when I brought it back they (a reputable dealer that I have used for almost ten years) told me that sometimes a particular type of pad and rotor will do that. I sprayed a tiny (like just a few dots) bit of white lithium grease on that rotor and that seemed to resolve it, but I am NOT suggesting that you do the same without further information.

 

mbates,
It is a relatively straight foreward job to take the pads out and check that the piston side of the pads have been smeared with copperslip grease. 9 times out of 10 this will cure the squeal.
Easy to do and won't cost you an arm and a leg.

Hope this helps.

 

CRC/Disc brake quiet (05017) | Brake Lube | AutoZone.com

If you want to avoid taking anything apart you may be able to get this spray where you need it to go. Ask the guys at the store and follow the directions on the can. If your issue is purely a function of lack of lubricant between the piston and the backside of the pad this will likely do it for you. It has for me. Buy some "Brakleen" as well and spray the rotor when you are done with the lube. If you are thorough it will clean any lube off of the rotor (you don't want that to be slippery!).

If lubing the back side of the pads (as mentioned in other posts or as I describe) doesn't do it the common issues might be: A) A metallic/semi-metallic pad that just needs a thousand more miles to wear flush to the rotor B) a pad that is seating a bit crooked that would merely need to be taken out and put back in squarely or C) possibly a caliper hanging up (not retracting fully when you press the brake hard). You would hear noise from this after you let off the brake typically. Hopefully the easiest path will get rid of the noise.

 

Thanks. Where exactly do I spray the lub? On the rotor?

 

It's not like anybody asked me, but I'd be nervous about lubricating a part of the car whose really, really important job is to generate friction.

Like the other guys, I've had good luck with the type of grease that goes behind the disk pads, away from the rotors.

 

Jacsun ...

"2001 XK8. Titanium (LGL), Oatmeal interior (AGD), Black top, Aluminum thermostat housing, steel tensioners, NAV, 18" wheels, Winter package, Premium sound/6 CD, Lines for top replaced, Trans fluid & water pump changed at 30K, antenna bypass switch, hydraulic pressure reduction for convertible top. Purchased in MD on 9/6/12 with 34K."

I almost went to look at that car, I think. A gal near Annapolis, right?

 

That's what I thought. I'm gonna drive it awhile first, then get someone to re-grease it. Thanks

 

Not to hijack the thread but, yep, that's the one. I felt bad: she was crying her eyes out when she met me at the airport with it so I promised to call her first if I ever sell it. I had the tensioners done in Glen Burnie. The inside of the engine looked like new. This lady was meticulous. She told me how she grabbed her dress when the latch leaked and cupped all of the fluid in it so nothing in the car would get ruined. I drove it home to Chicago on a sunny 75 degree day. Stopped for 15 minutes to get gas and food and smile at the car instead of in the car...then it was back in for the home stretch! Knock on some burled wood, still not a problem with it.

 

I think you got the answer but on the back side of the pads. Its water-thin unlike the grease you would normally use. One would try to get it between the piston and the pad and between any shims and piston or pad. As you and Dennis hinted- you don't want to lube the rotor which is why you want to get something to clean off any overspray. Undoubtedly taking the wheel off and pulling off the pads is the most reliable way to assess and fix your issue. Just wanted to make you aware of a product designed to be used without having to do the disassembly.

 

Gotcha. Remember the product name?

 

? See post #4 above. It has a link to it. Jac

 

Prior to adjusting, greasing or lubing the brakes, has anyone confirmed that all the pad shims have been correctly installed and that the caliper bracket holding the pads next to the rotor has been cleaned of any foreign material before the replacement pads were installed?

From the initial description, it seems the pads are vibrating against the disc under heavy braking and the vibration is being amplified by the caliper pistons into what is described as a 'squeal'.

 

Don't know. They were put on by a Jag dealer here in San Diego. So it could be the pistons making the squeal and not the pads?

 

Let the dealer sort it out then- his problem, not yours.