What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Brakes weak

FNG

Member
I have an RV-9A with Cleveland brakes. Both linings and rotors were new 25 hours ago when I purchased the aircraft.

The pedals are firm (no air in lines) but the brakes are ineffective. Hardly can hold aircraft at full power, and don?t seem capable of locking the wheel on landing (this may be a good thing).

I thought they would ?break-in? , but not there yet.

Any suggestions? Is this common on RVS? Are the linings maybe glazed?

Thanks

Tom

Dues paid
 
If you've gotten any brake fluid contamination at all on the pads, the pads are nerfed and will need to be replaced. I did that once...
 
I have an RV-9A with Cleveland brakes. Both linings and rotors were new 25 hours ago when I purchased the aircraft.

The pedals are firm (no air in lines) but the brakes are ineffective. Hardly can hold aircraft at full power, and don?t seem capable of locking the wheel on landing (this may be a good thing).

I thought they would ?break-in? , but not there yet.

Any suggestions? Is this common on RVS? Are the linings maybe glazed?

Thanks

Tom

Dues paid

My RV-6 with 160 HP and Constant Speed prop will be 22-years old. The brakes are not strong enough to hold the airplane at full power.

I do NOT use the Cleveland recommended procedure for brake break-in. Our light aircraft with lots of power will create too much heat. I typically just taxi the aircraft to run-up using some light braking. I do my runup, fly around the pattern, then when all three wheels are on the ground, use the brakes to stop as fast as I can. I do a hard stop after landing using brakes about once a month to keep the brake pads conditioned.

Why do I not do a fast taxi with the brakes on? One friend almost caught his RV-8 on fire with a brake fluid leak that caught fire. It destroyed his wheel pant but his son was at his hangar, grabbed the fire extinguisher, put the fire out before anything else got damaged.
 
1900 RPM Max

Since brand new (I built it), my RV-9 with Matco breaks has not been able to hold the aircraft above 1900 RPM. If I persist in exceeding 1900, the airplane skids along the pavement.
Didn't take but a couple of times at that to realize I was never going to be able to do a full-power, breaks locked, short-field take off.
But with these planes that's just not a worry - for me at least.
 
Breaking in your Brakes.

I agree with Gary.
I have seen a lot damage due to overheating brake disks & linings as well as crystallized O-Rings in the caliper?s & resulting leaks due to heat damage. If your brakes are to powerful you may just end up on your back suspended by your 5 point harness.
 
I have an RV-9A with Cleveland brakes. Both linings and rotors were new 25 hours ago when I purchased the aircraft.

The pedals are firm (no air in lines) but the brakes are ineffective. Hardly can hold aircraft at full power, and don?t seem capable of locking the wheel on landing (this may be a good thing).

I thought they would ?break-in? , but not there yet.

Any suggestions? Is this common on RVS? Are the linings maybe glazed?

Thanks

Tom

Dues paid

I recently purchased an RV-9A. One of the first things I noticed and continues to bother me is the weak braking, as compared to my Cessna 172. I pulled out the plans tonight to look at the geometry and I can immediately see why they are much weaker than expected. I am going to work on some ideas to improve them. I am surprised after so many iterations of the RV design that they are using such a poor brake and pedal geometry. The RV-12 looks to be even worse.

This is my first post on the forum, so I fully expect to get flamed for this one.
 
Beats me what's up here. You guys all have 300 HP or something?

Case in point: RV-6A (not at gross weight), fixed pitch, 160 HP... absolutely no problem holding stationary at full power on a paved level surface. Just did that yesterday. No inordinate brake pressure required. Stock pads, stock calipers, stock fluid.
 
Beats me what's up here. You guys all have 300 HP or something?

Case in point: RV-6A (not at gross weight), fixed pitch, 160 HP... absolutely no problem holding stationary at full power on a paved level surface. Just did that yesterday. No inordinate brake pressure required. Stock pads, stock calipers, stock fluid.

I too can hold at full power, but it takes much more brake force than seems necessary to do so. I mostly notice the weak brake force when landing. It is possible, if I were to lift my feet up off of the floor and fully on to the top of the pedals (a couple of inches off of the floor), Perhaps I would have the full power of the brakes, which seem to be missing with my feet on the floor. I don't think that it should be necessary to lift my feet off of the floor to accomplish this. I guess heel rests could accomplish this, maybe something to consider. Maybe I will try that first.

I have started laying out the geometry in SolidWorks tonight and it is clear the arrangement can be improved to increase the braking force while leaving my feet on the floor.
 
I recently purchased an RV-9A. One of the first things I noticed and continues to bother me is the weak braking, as compared to my Cessna 172. I pulled out the plans tonight to look at the geometry and I can immediately see why they are much weaker than expected. I am going to work on some ideas to improve them. I am surprised after so many iterations of the RV design that they are using such a poor brake and pedal geometry. The RV-12 looks to be even worse.

This is my first post on the forum, so I fully expect to get flamed for this one.

I thought mine were weak when I bought mine as well. It turned out to be a combination of factors. The pedals never felt soft, but braking action was less than the warrior. Pads still had plenty of life as they looked to be recently replaced during last annual just before my purchase. After bleeding the brakes with new fluid (Royco 782) throughout and lightly scuffing the rotors with emory to remove some glaze they stop great. Been almost 75 hours and well over 100 landings with no measurable change. Not sure I would want them any grabbier than they are now.

As an aside, I was surprised to see the amount of air bubbles that were between the calipers and the first set of rudder pedals. I would have thought I would have felt soft pedals, but I didn’t. It wasn’t a big slug of air, but still enough.
 
reliable braking is important and it can save your life. check the brake pedal firmness before each startup. note the brake effectiveness each time they are applied to understand if something has changed. if you believe there is a change in brake effectiveness then correct it immediately. learn to minimize the use of brakes during normal operation. hey, you are the one that has to maintain the brakes, why not extend the life.
 
I too can hold at full power, but it takes much more brake force than seems necessary to do so. I mostly notice the weak brake force when landing. It is possible, if I were to lift my feet up off of the floor and fully on to the top of the pedals (a couple of inches off of the floor), Perhaps I would have the full power of the brakes, which seem to be missing with my feet on the floor. I don't think that it should be necessary to lift my feet off of the floor to accomplish this. I guess heel rests could accomplish this, maybe something to consider. Maybe I will try that first.

I have started laying out the geometry in SolidWorks tonight and it is clear the arrangement can be improved to increase the braking force while leaving my feet on the floor.

I'm not moving my feet up in order to hold the plane. I'm a size 9.5" shoe.
Just my opinion, but don't start messing around re-engineering something that is flight critical when I think you have a maintenance problem with the existing installation.
 
One more thing

One more thing... when the rudders pedals are neutral (neither depressed) what is the angle that the brake pedals are at compared to the floor?

There are two ways of adjusting the typical Van's top mounted rudder pedals: 1) shorten or lengthen the links which connect the pedals to the rudder cables. 2) Move the entire assembly fore/aft (at the nylon pillow blocks) into new mount holes (that may or may not exist).

If someone placed the assembly too far forward and compensated for shorter pilot legs by shortening the links... then the pedal angles will be substantial. And thus you'd need to flex your ankles a lot more than is optimal to get full brake application.

Conversely if the pedals are too vertical it becomes way too easy to apply brake when not intending to.
 
Last edited:
I have a similar problem with my RV-9A: very weak braking. Although i can hold in place at full RPM, my landing roll is so long that i overshot the end of the runway on a landing rollout which i could easily have made with my C-150.
This caught my attention; i must do something about it!
I do not think that the standard lining material is up to the job. (Pardon, Van)
I am going to look into different material, with a higher coefficient of friction, and encourage others who want better braking to share ideas and findings with me.

i do not want to do somersaults, but am looking to have a rollout commensurate with the short landing distance of the -9 (or -6, or whatever). And i do not want something highly abrasive to the disk - but am prepared to experiment.
Anyone interested?
Jim
 
Back
Top