Author Topic: Wobbley brakes  (Read 4167 times)

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Offline nmflyboy

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Wobbley brakes
« on: August 11, 2007, 09:41:29 PM »
I just put new brake pads and discs on my Varieze, I had two landings, one with fairly heavy braking, and now they wobble.  

I am assuming I have warped the rotors.  

I have wheel pants and it was a short taxi to my hangar.  

Any Ideas?  

I am thinking of venting the wheel pants so they cool better.

Can I machine turn the rotors or should I replace them?

Thanks for any help guys!
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Offline GlennBob

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Hot discs
« Reply #1 on: August 13, 2007, 12:52:17 AM »
Sounds like you warped your rotors.  If it were me, .. I'd check into having the rotors turned.  The manufacturer usually has specs as to the minimum size the rotors can be turned down to before they must be trashed.  You may already know this, but that's the way I'd go.  Venting might help, I don't know.  Someone else might.  Is there a reason you had to brake heavy ?  Will this be common practice ?

Glennbob
N600EZ  O-320-E2A,  Hertzler prop, Trio AP, Narco HSI, Custom headers, Oil heat.

Offline GlennBob

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« Reply #2 on: August 13, 2007, 12:54:25 AM »
One other thing to check.  Are you sure your calipers are fully releasing ?  If you just put in all new, .. you wanna make sure it turns free. Otherwise you may be creating heat just while taxiing.

Glennbob
N600EZ  O-320-E2A,  Hertzler prop, Trio AP, Narco HSI, Custom headers, Oil heat.

Offline nmflyboy

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Wobbley brakes
« Reply #3 on: August 13, 2007, 11:55:22 AM »
Thanks Glennbob for the reply.  I will have them turned.  I made sure the calipers were fully open before I put them back together, but as you mentioned, maybe they are dragging a little after brake application.  

I am at VNY and I always request 16R (the longer runway) but sometimes they are busy so I take 16L.  16L is much shorter and that is why I had to brake harder than usual, it wasn't too hard and I really don't think that one time should have warped the rotors.  But like you said, maybe the hard braking and a stuck caliper could have generated enough heat on the taxi.

Again, thanks for the reply!
VariEze
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"I will always be puzzled by the human predilection for piloting vehicles at unsafe velocities!" CMDR Data

Offline easyrider

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Wobley Brakes
« Reply #4 on: August 16, 2007, 07:02:04 PM »
Did you bed the new pads in before flying?
The Repco method is 2 fast stops from 40 mph with a cool down period between runs.To check do an engine run up and check for forward creep.
If the aircraft moves do another taxi with a hard stop and check again.
Easyrider

Offline Bill James

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Wobbley brakes
« Reply #5 on: August 19, 2007, 12:27:48 PM »
While youre at it, you might check the lower strut. Probably not an issue for you but i have helped repair three struts that had failed due to brake heat. Two struts were failed horizontally through the top axle bolt holes and one failed a little higher adjacent to the top of the brake disc. All had wheel pants. Indications included irratic brake shimmy, the gear wanting to spread, and uneven tire wear. None were visible until removing the outside glass wrap on the strut. On two, the damage was such that once the wrap was removed, the lower strut and axle came off.
That i have not had a similar issue is probably due to the brake shields and our 6k ft runway.  Hope having the rotors turned fixes it for you-
Bill James, Fort Worth VariEze N95BJ
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