brake rattle/clatter

[scsmith]

I'm hoping this is something that A/P's see once in a while.

When I taxi at brisk speed, or on landing roll out, the right disc brake caliper rattles in its guides. A light touch on the brake pedal stops it immediately. It brakes normally, smoothly. Release the brake, and it immediately goes back to rattling.

I have 13" flex-lines in a gentle half-loop from the gear leg to the caliper. These are brand new Cleveland brakes as supplied in the kit. Stock RV-8 landing gear. The left brake does not do it, despite having very similar play in the guide pins. I can not see any difference in installation or condition between the two brakes.

I can imagine that with the stock set-up of a aluminum tube brake line to the caliper, it would add enough damping to prevent the rattle. I can also imagine that it would fatigue and break the aluminum tube in short order.

Any ideas?

[Jeff Vaughan]

Steve I had a similar issue during phase 1. What helped: I made sure that the pad contacted the wheel at a slight angle and I cleaned the pad with spray brake pad cleaner. I did not take the assembly off. I just sprayed the heck out of it. Result was a decrease in the noise which eventually went away after afew more hours.

[gasman]

Originally Posted by scsmith

I'm hoping this is something that A/P's see once in a while.

When I taxi at brisk speed, or on landing roll out, the right disc brake caliper rattles in its guides. A light touch on the brake pedal stops it immediately. It brakes normally, smoothly. Release the brake, and it immediately goes back to rattling.

I have 13" flex-lines in a gentle half-loop from the gear leg to the caliper. These are brand new Cleveland brakes as supplied in the kit. Stock RV-8 landing gear. The left brake does not do it, despite having very similar play in the guide pins. I can not see any difference in installation or condition between the two brakes.

I can imagine that with the stock set-up of a aluminum tube brake line to the caliper, it would add enough damping to prevent the rattle. I can also imagine that it would fatigue and break the aluminum tube in short order.

Any ideas?

It is a floating caliper. The noise just means that the pads have backed off of the rotor (this is good) and that the pins are not binding. There is not enough movement to give the tubing a problem. What you mostly hear is the piston plate pad clattering on the piston. This is not a problem

[scsmith]

It is enough to shake the airplane when the caliper is rattling around.

Jeff- note that this is occurring when the brake is not applied. Any brake pressure and the brake works smoothly and quietly.

[Ironflight]

Steve -

If it's shaking the whole airplane, are you sure that it's the brake, and not a wheel that is slightly loose? maybe you need one more partial turn of the axle nut to snug up the bearings. If the wheel is moving laterally on the axle, the brake could be stabilizing it when applied.

Paul

[scsmith]

Paul has a good suggestion, and I thought of that too. A car wheel bearing will quiet down when the brake is applied. So I wiggled and tugged on the wheel, I don't feel any play. But I will jack it up tonight and see how it acts with no weight on it. I will also look at disc runout.

Originally Posted by scsmith

I'm hoping this is something that A/P's see once in a while.

When I taxi at brisk speed, or on landing roll out, the right disc brake caliper rattles in its guides. A light touch on the brake pedal stops it immediately. It brakes normally, smoothly. Release the brake, and it immediately goes back to rattling.

I have 13" flex-lines in a gentle half-loop from the gear leg to the caliper. These are brand new Cleveland brakes as supplied in the kit. Stock RV-8 landing gear. The left brake does not do it, despite having very similar play in the guide pins. I can not see any difference in installation or condition between the two brakes.

I can imagine that with the stock set-up of a aluminum tube brake line to the caliper, it would add enough damping to prevent the rattle. I can also imagine that it would fatigue and break the aluminum tube in short order.

Any ideas?

I had the same thing, but it didn't appear until around 60 hours when I remade the brake lines. I then switched to flex lines at the bottom and it helped somewhat, but they still chattered occasionally.

Someone mentioned on another thread here that beveling the leading edges of the pads slightly would help. That worked well for me. Also, you might try some grease on the slide pins.

[David Clifford]

Originally Posted by Geoff

I had the same thing, but it didn't appear until around 60 hours when I remade the brake lines. I then switched to flex lines at the bottom and it helped somewhat, but they still chattered occasionally.

Someone mentioned on another thread here that beveling the leading edges of the pads slightly would help. That worked well for me. Also, you might try some grease on the slide pins.

Per the guru's at Cleveland, NO GREASE!! Use only a dry lubricant such as Dry Slide on the slidepins.

[Steve Sampson]

I am in the middle of doing my annual and mentioned to my inspector (he works on aircraft full time) this same issue of noise from the brakes.

He gave me some very strange grease (not even greasy) which he said to use very sparingly on the guides. Its not like normal grease in that it is really heavy/solid and black with graphite. The name.....??? He was pretty sure it would make a +ve difference.

Clearly keeping it well clear of the discs and pads is important.

[scsmith]

I checked the wheel bearings, fine.
I did bevel the pads as per Geoff's suggestion, no help.
I'll try some wax on the pins this weekend and report back.