PA30 Brake linings?

[David James]

Replaced the brake disc and linings. Is it right that backer plate uses 66-62 and the pressure plate uses 66-65?? Also has anyone had to ad a shim? Should I also expect some drag or should wheel spin free until the pads wear in a bit?

[David Pfeffer]

David,
Not sure about the brackets, but in general, "some" drag is perfectly acceptable. I don't have much experience on the PA-30 yet, but usually have some drag between the new pads and disk on every other light GA plane. As long as your caliper is releasing when your foot's off the brake and the drag is minor, I consider that acceptable.

[Charles (David) Miller]

Interesting, because at the last annual we inspected the linings and decided they were okay. I didn't pick up on the fact that they were the riveted type used on most Cherokees. This annual, I still had the linings from last year that we didn't use and when I went to put them on, I found that the correct installation is not a riveted lining. It's held in with a pin that's installed on the pressure plate, and the lining is held in place with these pins. I ordered the correct pins from Aircraft Spruce and the job is done. Looks like the linings are slightly larger than the Cherokee linings and cover the surface of the disk to a greater degree. Anyway, breaking seems much improved.

Dave

[Kristin Winter]

David,

I small amount of drag is OK, but if you can't move it easily with one hand, you have another problem. Look at the big shims which are made of aluminum. The part number is 756-148 or Cleveland 68-12. If you see indentations where the back plates contact it, that is likely your problem. Even fairly faint ones that are only a few thousands deep are enough to cause the brakes to grab when new pads and discs are installed. If you muscle through with too much drag, you will trash the disc.

The problem is that no one ever reads the Cleveland manual on the brakes. Cleveland specifies installing those with a torque wrench to 65-75 in/lbs with dry threads. IMX, mechanics tend to tighten by hand, to at least twice that value or more.

[David James]

Great info all. Yes the wheel will turn with one hand and still free turn about 6" or so with a spin one handed. I really think its acceptable for new pads and disc. I also heard that the manual calls out for shims being used if necessary.
I will look at the big shim. I bet that is the case. Seems like I remember a faint indentation.

Hey while I have you guys. How is your fuel gauges reading. I just put new micro switches and still seem to get a little static build up or resistance somewhere in the system on the right. I know those gauges are suggestive on the ground at best but I also hope that the right will behave like the left.
Has anyone ever put a resister between the sending unit and ground nut to discharge the static buildup like I believe I have? If you disconnect the sending unit lead and reconnect the gauge will read right. Up to full.

[Kristin Winter]

If you find a reference in any of the manuals that allow the addition of an additional shim, please let me know. I haven't seen the authorization to do that, but it doesn't seem like a terrible idea. The Twinkie brakes have one thick aluminum shim and one thin phenolic one, normally.

[Douglas Dodson]

I don't see any problem adding shims if necessary. On the other hand, if the brake isn't too tight, it won't take very long for the lining to wear. I say if you can roll the airplane by hand, then it should be OK. If it doesn't loosen up in a landing or two, then I would suggest a shim.

According to the parts manual, my aircraft , (PA30 # 30-780) should have the pinned linings (two 66-062 on one side of the rotor and one 66-15 on the other). In fact, it has 2 each 66-106 linings on each side or the rotor. As a result, I have 2 ship sets of the 66-062 and 66-15 linings for sale if someone wants them. Both sets including shipping for $165. Parts are new, unused.

E-mail me at houdu@pobox.com

[Kristin Winter]

66-62 and 66-65 are the current part number for the brake pads. This supercedes the 66-15 and 66-19 pads.

The 66-106 pads are not approved for the 30-23 brake assemblies on a PA-30. Do you have different brake assemblies on your aircraft?

[Douglas Dodson]

I will have to take a look, but the plates and all were there and everything looked "normal". I'll check the logs and see if someone did a retrofit in the past and check the calipers for the model.

[David James]

Sorry Guys, Has been a busy couple weeks and have not checked in. I ended up with the 66-62 and 66-65 pads with an extra shim. Everything seems to be working fine. As they wear in I intend to remove shim as needed.
Forgot how nice it is to have new braking..