Squealing brakes

The DB9 is notorious for its squealing brakes. I was very fortunate that the first set of brakes didn't squeal at all. When this set had to be replaced a couple of years later by Textor pads, astonishingly no squeal was there, either. Wow, great! I thought i had a no squeal car, but boy was i wrong:

For the next maintenance i replaced not just the main brake pads (Yellow stuff) but also the disks. As for the last replacement, i used the pad grease between caliper and pad and was expecting an easy ride. However at the next trafficlights i was greeted by a terrifying squeals at low speed i.e. the last few meters before a full stop. How annoying!

OK, sometines the brakes nead a little break in, so i started with a high speed brake first to burn in the surface, then drove a couple of hundred kilometers and did several hard and soft brakes, but the squealing persisted. So i again removed the pads, put on additional pad lubricant and ... it squealed again!

However, when putting on the lube i realized that there is a major difference between main calipers (cylinders on both sides) and the hand brake calipers (cyclinder just on one side) plus the hand brake pads were sightly used on one half of the pad surface while the other was in not used at all. So very slightly unparallel to the disk.

Might the fact that the hand brake only has a cylinder at one side an the other side is floating at almost no distance above the brake disk be the cause for squealing? Especially with this little unparallelity? That might lead to audible (terrible) oscillation at very low speed.


Update some thousand km later

ALWAYS at low speeds; e.g. when approaching traffic lights or even more annoying: in a parking garage - the same annoying high pitched loud squeal over and over again. However, if you pull the hand brake a little bit right before the car gets very slow, you can overcome the squeal, but that's not a real option.

So today is took of the wheels again, removed all brake pads, checked for the grease (still present) and decided to use give BG Stop Squeal a try:



I purchased it a while ago, but was hesitant to use it, because i generally want to know what the things comprise of, that i use; especially if it comes in contact with safety equipment like brakes. The bottle just states the solvent, but nothing more. However, this seemed to be a last resort, so i gave it a try and used a syringe and cannula to wet soak the surface of the pads. Others pour the bottle contents into a dish and place the pads (disk facing side down) over night into the liquid and let the pads saturate with the liquid. I decided to start a little smaller. All in all for the 12 pads i used around 10ml of that black stuff. It then takes some minutes to disappear in the pads.

Test drive: Gone. YEAH!


By the way: When removing the hand brake pads, i again noticed, that the spring loaded hand brake caliper moves the whole assembly to the inner side; but the move is not a real gentle one, so i cleaned the upper sliding rod (in contrast to the lower one, the upper one doesn't have rubber bellows on both ends and is exposed to dirt) and spent a drop of oil.

But a mere 500km later, the annoying squeal returned. You can only overcome it by using the hand brake instead of the pedal for the very low speeds. Aaargh!

I tried and tried again. Meanwhile the yellow stuff pads have seen not more than 5000km. Same issues over and over again. After checking the break pads for the origin of the noise, chamfering the hand brake pads, lubricating the sides (not the flat back sides) where the brake pad bases touch the caliper, removing the shims etc., and when nothing was successful, i finally decided to exchange the almost new Yellow stuff pads with other brands (TRW front, A.B.S. back, hand brake pads unchanged). Said, sweat, done.

The new front ones come with a textured "soft" shim glued on their back. I didn't remove that. The back ones come with 3 layers of shims. I also didn't remove those. Inserting all of these was a little harder than installing the yellow stuff pads was back then. I had to push the brake caliper pistons back a bit to insert the new pads. Not a big deal, but it means that the yellow stuff ones couldn't have been too tight thus causing noise.

Test drive was nice. The yellow stuff have more fierce grip, the new ones start do bite a little softer, allowing a more dosed braking, making it a little more comfortable. One might find it less sporty, though. I don't care as long as the squealing is gone and the breaking power in general is not compromised. The rims are always catching dust. The yellow stuff didn't bring a big advantage in that erspect either, so i also don't care about brake pad dust residues on the rims.

I chose a short tour with many braking necessities and tried to provoke squealing, that typically occured close to standstill. I wasn't able so far to get the breaks squeal again. At least for now. Will go on a longer tour today and see, what the experience will be...




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