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  #1  
Old October 26th, 2006, 11:51 PM
nyikaguy
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Chris Barty
1997 D90 SW
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Question new brake squeal

Recently I had the rotors and pads changed on my 97 D90. I went with DBA slotted and drilled long life rotors from Expedition Exchange and new oem Rover brake pads. the new set up stops the truck very well, i.e. straight and true. However, the brakes have been on the truck for a month now and I still have a very annoying brake squeal at low speeds, particularly when coming to a graceful stop at a stop light or stop sign. I have tried being aggressive with stopping to seat the brakes but the problem continues. If I stop more quickly than I am used to, I can generally avoid the noise. I notice that the pitch of the squeal seems to be constant irrespective of speed. to me this seems to point to some excitation of a mechanical resonance

The question are
a) how long can I expect this to continue or will this end naturally
b) is there something straightforward I can do to rectify the situation now
c) where exactly is the squeal coming from, i.e. the rotors, the pads, the calipers
d) are there better calipers to fit to the vehicle than the original lockheed set and would this help

any help and thoughts appreciated

chris
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  #2  
Old October 27th, 2006, 03:01 AM
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thewap
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Marc
'95 D90 SW#106
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I don't think the OEM pads are problematic, although I not too long ago installed the same rotors, but opted for kevlar
pads, which are reputed more problematic than OEM.

Assuming that the pads were greased (brake grease) appropriately on the back of the pads, and that the pads are not contaminated with oil on the face for any reason, squeal should be at a minimum upon new installation of the DB rotors.

I installed mine over two months ago. They squealed slightly when stopping at lights, or when superheated after highway. I purchased anti-squeal brake pad grease, and it helped a little. Cleaning my calipers helped a little more.

Setting the brakes on kamikaze runs a number of times, did not help.

Not sure if all my fuss had anything to do with really helping the squeal, but after apprx 2 months, very light squeal diminished to zero.

Yu might want to try sanding the pads leading edges (corner( a little to help against juddering-ie squeal. If dirty, sand lightly the surface too. 80 grit or coarser, but just to score the surface out of any glossing. Make sure yur disk were not oil contaminated. The lockheeds are best.

If that doesn't help, patience and earplugs will.
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  #3  
Old October 27th, 2006, 04:51 AM
Cyborg
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Larry Walton
'97 D-90 ST #2066 UK 4X4
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I have just completed install of the exact setup that Chris has... I am having the same squeal at low speeds right as I am stopping. QUestion I have is....

when installing brake pads... what is the purpose of putting the grease on the back of the pads? I guess it is meant to control squealing and keep brakes working well but how?? Not sure I understand the theory behind it.
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  #4  
Old October 29th, 2006, 07:01 PM
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Stephan Laputka
1995 D-90 SW
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Don't go through the mud with those rotors or you will really get a squeal going. It will probably go away after some time, how long depends on how often your truck gets driven. Doing hard stops from high speeds is something you should not do with those rotors, you run the risk of thermal cracking them. Despite the popular misconception, cross drilled rotors atually decrease brake performance and heat dissipation both of which are amplified in LR brake systems. The sqealing you are getting is most likely caused by the disconformity of the rotor surrface (assuming they did use anti-sqeal) caused by the cross drills. The brake pad is going to have to eat away at the rotor long enough to smooth the edges of the cross drills. You might be able to speed that process up by installing more aggressive brake pads but i don't think it's worth bothering. Cross-drilled rotors really don't belong on a truck so if you off-road your d-90 a lot keep an eye on those rotors for damage. Ultimtely the best solution is to install solid rotors and the squeal should go away immediately.
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  #5  
Old October 29th, 2006, 09:45 PM
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Marc
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The grease on the back of the pads (brake grease is black) is to keep the pads from juddering. ie = squeal. That black brake grease should also be lightly used on the fittings as well, sparingly. I cleaned the calipers pad seating area pretty good with a brass toothbrush, and also lightly greased them. Give or take it's going to settle in after about 500 to 1000,
then no more squeal. I agree with the edges having to be smoothed until they quiet. Until that happens, they will heat up.
After they are settled, I do not see a disavantage over solids , on or off road, and don't agree that solid run cooler. As far as beak strength goes, the DBs feel stronger than stock, but more progressive. The Kevalr pads took a little while to settle, and one thing I have noticed, is that they run way cleaner. No more brake soot all over the wheel.
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Old October 30th, 2006, 01:18 AM
Cyborg
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Larry Walton
'97 D-90 ST #2066 UK 4X4
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When I asked about greasing the back of the brake pads and how that is supposed to quiet squealing I guess i simply dont understand the theory. To put it more succinctly I guess i dont know what "Juddering" is and how grease stops it. Is it a vibration of the pad caused by rapidly grabbing and releasing repeatedly for example? Something like that? Does the stickiness of the grease hold the pad to the piston of the caliper possibly? I am totally grasping at straws here trying to understand. Maybe if i can understand why it is supposed to help I can find the best solution for my squealing brakes in the future. Anyone willing to share specific insights would be appreciated.
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  #7  
Old October 30th, 2006, 08:01 AM
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Stephan Laputka
1995 D-90 SW
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The disadvatnage to drilled rotors is that they reduce the contact area between the pad and the rotor surface thereby reducing the stopping power of the brake pad. Before pad technology was what it is today, high temperatures in the brakes caused the brake pad to release gas that would cause the pad to float on the rotor surface. The cross drills eliminated that. Yet, Unless you ride your brakes down a colorado pass, you are not going to get your brakes to that temperature. The problem is that most rotors are cast and then drilled, which is the case in all the ones offered for land rovers that I know of. This drilling weakens the rotors and leaves it proned to cracking. Since there is now less surface area to absorb heat, the rotor heats faster. In order for cross drills to be really effective they have to be created when the rotor is cast. Porsche has a patent on the process and Brembo has some way they do it. Off-road the issue becomes mud. You go through the mud with the rotor the mud gets stuck in the cross drills, then you go on the road heat the rotor up and you have created pottery in your brake rotor. Thats why i thought they were not as good as solids for wheeling.
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  #8  
Old October 30th, 2006, 08:56 AM
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Marc
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Quote:
Originally Posted by Cyborg
Is it a vibration of the pad caused by rapidly grabbing and releasing repeatedly for example?.
Yes. And the grease helps prevent this.
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