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Brakes

Browncbr1
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Browncbr1 Grand Master

Browncbr1

Posted
Posted

ive read that some people have said that mooney brakes are not the most robust or lack some authority compared to other planes. Im not sure if those accounts are the standard or the exceptions.

I installed new brake pads and bled lines thinking it would help. They don't feel spongee. But, they don't stop my plane very well at all. I was trying to make a turn off today and I was stomping as hard as I could and it was just slowing down at a comfortable rate, not representative of how hard I was pushing. . Other planes I've flown would have locked up the wheels had I been pushing that hard. Does this sound like a problem or just how the mooney brakes are? There is literally no way I would be able to lock up the wheels with these brakes. This is all with just me... Wondering how it would be at gross

gsxrpilot Grand Master

gsxrpilot

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Yeah, somethings not right with those brakes. Mine will stop the plane short or lock up the wheels if I don't dump the flaps.

cliffy Grand Master

cliffy

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How long has it been since the wheel cylinders were apart and cleaned, new orings and bled?

How old are your brake discs?

Do the wheel cylinders slide easily on the slider pins in the mount?

 

Hopefully the answer to these questions will fix your problem

You should be able to lock them up.

Hank Grand Master

Hank

Posted
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How long has it been since the wheel cylinders were apart and cleaned, new orings and bled?

How old are your brake discs?

Do the wheel cylinders slide easily on the slider pins in the mount?

 

Hopefully the answer to these questions will fix your problem

You should be able to lock them up.

The brake fluid will turn to gel over time, too. Check yours, you may want to flush it all out and put in new, then bleed them all over again.

I routinely make the 2500' turn off with little braking.

Browncbr1 Grand Master

Browncbr1

Posted
  • Author
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It just came out of annual and my mechanic said he replaced the left slave cylinder seal due to some moisture showing. He also installed brake pads on both sides and bled the system at my request. It seems the same as before. I can't imagine him doing all that and not greasing the slider pins. It brakes evenly. That is to say that one side isn't stronger than the other. Are the right and left systems completely independent of each other? It's odd that they would brake very evenly poorly.

carusoam Grand Master

carusoam

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Breaking is at best 'not good' compared to modern autos....

This is a function of their tiny size and where the brakes are located. Only on the two back wheels.

Realistically, when you brake too hard, they will lock-up.

A set of brakes that is working properly will be controllable from light braking to full braking.

If they lock up, let up, then reapply.

If you apply full force to the brakes and only slow gently, you get an uneasy feeling and post a question on MS.

Some thing is not right. But it is usually easy to make right.

+1 on the replace old gunky red gel with fresh cherry juice...

Go Mooney!

Best regards,

-a-

MB65E Grand Master

MB65E

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I don't think the pads have broken in yet. Give it some time and they will improve. However, I'd have your tech looks at it again with a fresh set of eyes. Make sure the fluid is topped, and double check the pads and rotors. I just taxied a 36'' wheeled Huskey that had new pads on it. It was a miserable Taxi.

-Matt

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Alan Fox Grand Master

Alan Fox

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I would lean towards a new set of rotors , these are overlooked a lot , when they wear they do not wear evenly , and they get a glaze over years of use , that is not conducive to good friction.....If you have a good solid pedal(s) I don't think that it is a fluid or slide issue.....although fresh fluid is a great Idea from preventative maintenance standpppoint....p

Browncbr1 Grand Master

Browncbr1

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  • Author
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I can understand how pads may need to be broken in if the rotor isn't perfectly smooth. Perhaps it will get better, but will check everything again first. But, this was somewhat how it was with the previous pads that were quite worn already. I didn't do any break in procedure and wasn't advised by anyone until now. And I just had one landing on these pads before the above described scenario.

bonal Grand Master

bonal

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New pads on mine and if all goes as planned annual should be done tomorrow and I will be doing my imitation of a fearless test pilot. Will note brake performance. Some brake pads require a run to fully hot to break in so we shall see how they perform but of corse there will be a number of things that will be tested on this flight.

Guitarmaster Veteran

Guitarmaster

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There was a post here on MS a short time ago regarding bleeding.  I'll see if I can find it.

 

Basically, he had trapped air where the flexible line is connected to the hard line.  He called it an "old motorcycle trick" to bleed at the fitting.  

 

I have had the same problem with, and still do to some extent, my brakes.  Bleeding doesn't help and new pads (mine were worn to the rivets) helped a little, but not a whole lot.  My next step is to try this "trick."

 

Good luck!

Andy95W Grand Master

Andy95W

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I can understand how pads may need to be broken in if the rotor isn't perfectly smooth. Perhaps it will get better, but will check everything again first. But, this was somewhat how it was with the previous pads that were quite worn already. I didn't do any break in procedure and wasn't advised by anyone until now. And I just had one landing on these pads before the above described scenario.

The break-in procedure (brake-in?) is actually called "glazing", and while it's bad for car brakes, our organic brake pads actually need it. You basically taxi the airplane at about 1800 rpm or so for about a mile, then let them cool and go fly.

If that doesn't work, check the thickness of your brake discs. If they are well within spec, bleed per the aforementioned Mooneyspace post.

Good luck! When you get them right, you'll appreciate the effort you put into it.

Yooper Rocketman Veteran

Yooper Rocketman

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I changed the pads on my Rocket during my recent annual and forgot about the break-in procedure.  Thought I was going off the runway the first landing.   I complained to my hangar partner (an A&P) and he asked if I did the break-in procedure?.  I'm thinking there's more to this that just breaking them in.  Well, that fixed the problem.

bonal Grand Master

bonal

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Thanks for the correction in terminology yes "glazing" haven't heard the term in ages. I used to run Ferodo pads on my race bikes and had to glaze them to smoking hot twice (2 heat cycles) before they would function. I'm glad this subject came up because I no doubt would have forgot to glaze my new pads before my test flight.

bonal Grand Master

bonal

Posted
Posted

Annual done test flight complete and yes new pads were real weak at first. After a handful of hard stops during taxi they improved some and with a full stop on runway after landing they felt ok but I think will need some more glazing.

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