Weak brakes...

[ccsmith51]

I, and my friends, are stumped on this one.

The brakes on my RV-6 have never held very well since I purchased it last August.

About 20 hours ago I replaced the pads and discs. It still didn't hold very well and I thought that perhaps I had not broken the pads in well. I would have to stand on the brake pedals to the point I was forcing fluid past the master cylinder O-ring and still the brakes would not hold past about 1,600 RPM.

Yesterday I pulled everything apart and sanded the pads per recommendations to remove any glaze, roughed up the discs, and put it all back together. I flew and upon landing got on the brakes good. I taxied back and took off and landed and did the same.

Today I went flying that the brakes are the same, won't hold past about 1,600 RPM.

The pedals feel solid, not mushy. There are no leaks in the system except when I press so hard that I think I might break the pedals.

So, any thoughts on what I can try next? The same brakes on my RV-4 we so strong that a couple of times I almost put it on the nose...

Thanks,

[Larco]

There is a published procedure for breaking in the pads and this sounds like it was not done correctly. Some say that just stand on the brakes when doing the landing roll out but in my experience this does not work. I have the proper procedure written down at the hanger as a hand out but am at home now. Suggest going to the brake pad manufacture webpage and downloading the info. The scenario that you are experiencing is not new to the RV world but seems to go away as soon as people are coaxed into doing the break in correctly.. Larry

[Infidel]

Do both brake sets feel equal when applying pressure? If so, my uneducated guess would be the shoes and or rotor.

[flyboy1963]

thread from a few days ago on a similar problem.

http://www.vansairforce.com/communit...&highlight=ugh





....and if they are Cleveland; possible breakin procedure.

http://www.aircraftspruce.com/catalo...ingprocess.pdf

[ccsmith51]

I have Rapco pads that I purchased from ACS. On their web page it has a PDF with the proper procedure. Below is what it says, and which I performed:

RAPCO, Inc. Brake Disc Wear-in Procedure
The normal break-in procedure for brake discs using the Rapco, Inc. RA164- discs, is to get the friction material hot (Approx. 850 Deg. F.) by performing the following:
? Use proper maintenance techniques by insuring that the friction material is completely clean and dry of all solvents and hydraulic fluid
? Perform a moderate-speed taxi (10-15Kts ground speed), insuring that you have proper braking (There will be very little brake action at first).
? Allow the brake to cool by taxiing across the airport or down field, without using brakes. If you are not going to fly the aircraft during the break-in procedure, then allow the brakes to cool for 45 min. until the next high-speed taxi stop.
? Once you've established positive brake action, you can proceed to a full-stop landing using significant braking. (Short field landing procedure). At this time the pilot should notice the brakes starting to grab more. If this is sufficient braking action, there is no need for another stop cycle.
? Perform another short field landing, leaving the landing gear extended throughout the landing pattern. This allows the brakes to cool properly before the next heat cycle. After this landing you should have significant brake action.

[turbo]

I find if you put your toes to the top of the pedal you will get a bit more power.

Otherwise you may have a strong engine. Results may vary.

[DHeal]

Are your brake disks standard issue or stainless? I seem to recall that stainless discs don't offer the same gripping power (friction) as standard steel discs.

[ccsmith51]

Originally Posted by Infidel

Do both brake sets feel equal when applying pressure? If so, my uneducated guess would be the shoes and or rotor.

Both brakes feel the same. What I have not tried is flying from the right side and using the passenger side pedals. When we bled the brakes last time we tested. It's sides and he felt the same. I will do a run-up from the passenger side next time and see if it is thes same, which is what I expect.

[ccsmith51]

Originally Posted by turbo

I find if you put your toes to the top of the pedal you will get a bit more power.

Otherwise you may have a strong engine. Results may vary.

Tried that but the pressure required is still too much and can't hold past about 1,600 RPM.

[ccsmith51]

Originally Posted by DHeal

Are your brake disks standard issue or stainless? I seem to recall that stainless discs don't offer the same gripping power (friction) as standard steel discs.

Standard steel.