scsmith

scsmith

Well Known Member
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?
 
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.
 
scsmith said:
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?
Click to expand...

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
 
its a pretty severe clatter

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.
 
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
 
I checked the wheel, but I will again

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.
 
I had the same thing

scsmith said:
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?
Click to expand...

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.
 
Geoff said:
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.
Click to expand...

Per the guru's at Cleveland, NO GREASE!! Use only a dry lubricant such as Dry Slide on the slidepins.
 
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.
 
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.
 
scsmith said:
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.
Click to expand...

Grease and wax will attract dirt. And when the pins can't float, they will bind and break the casting at the pin. Try the wax to see if it will stop the clatter, but then clean it out and just live with it.

The bevel of the pads help with the squeal of the pads, not the clatter.

THERE IS A REASON FOR THIS STATEMENT........
Per the guru's at Cleveland, NO GREASE!! Use only a dry lubricant such as Dry Slide on the slidepins.
 
Make sure the brake line isn't touching something!

Just another point on this same topic.

After my last condition inspection, I began to hear a rattle at certain taxi speeds that went away when I touched the brakes. A little experimentation led me to believe it was the right brake.

Removing the front half of the wheel pant revealed that the loop in my brake line had gotten moved just a bit so that it could touch one of the nutplates securing the front half or the intersection fairing. A few gentle tweaks of the brake line fixed the problem and certainly prevented a bigger problem with a failed right brake. :eek:

Guy
 
I've noticed a steady increase in the amount of rattle I hear when taxiing over the past several hundred hours. I believe it started, however, when I had the great idea to clean the pins and bores that the brakes ride on...

I don't recall hearing much until about 1000 hours, which is probably about when I cleaned those pins.

Maybe someone else has figured out a new solution not listed in previous replies?

Perhaps some sort of biasing spring? Not a lot of room in there, but it might not take much.
 
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