Brake upgrade

[Jeff1smith]

I found this earlier post. I have been having constant brake issues with leaks, scored rotors and just feeling that I didn't have enough stopping power.
I visited the Matco booth at OSH a couple years ago and the rep told me the same thing in the post. The stock brakes were just barely adequate.
It's time to upgrade ... anyone have suggestions? Like to stay with Matco and not go Grover so I don't need any further mods and they are twice as much.
Anyone have dual calipers?
Matco upgrade part number?

 

[JonJay]

Old Tailwheel airplane mantra -
“If your brakes hold for run up, you have more than enough”.

 

[edhunter]

Jeff - I bought a set of brakes off a rv14 for my 9a. Easy swap and much better braking. My stock brakes would not hold an IO-320 w fixed pitch prop, static 2200 rpm during run up. Probably no more than 135hp.

 

[JonJay]

Jeff - I bought a set of brakes off a rv14 for my 9a. Easy swap and much better braking. My stock brakes would not hold an IO-320 w fixed pitch prop, static 2200 rpm during run up. Probably no more than 135hp.

Something wasn’t right.
At least you can’t put an A model on its nose.

 

[DanH]

What is the subject aircraft?

The kinetic energy values noted above might mislead a brake shopper. An RV-8 at 1800 lbs and 60 mph (52.174 knots) results in a kinetic energy of 108,531 per brake.

I've attached Cleveland document 50-76. You'll find the kinetic energy calculation at the upper right. I don't know what is supplied with current kits, but a Cleveland 199-102 package was the standard for 7's and 8's, rated at 117,500. They really are a bit undersized for the A-models, because they tend to get hot steering for taxi, but they are fine for the tailwheel airplanes with 500-5 tires, assuming reasonable landing speeds.

The disk is an energy storage device. A thicker disk stores more energy for the same temperature. The kinetic enegy rating of a 199-102 can be increased to the 199-93's 155,000 ft-lbs just by swapping disks. You'll need a set of Rapco RA164-09900 disks, four longer AN4 bolts, and an easily fabricated spacer in the caliper.

 

[Walt]

I sugget you look at Grove.

 

[mstrauss]

You may want to check out this Grove RV upgrade: https://www.groveaircraft.com/rvwheel.html

 

[RV8JD]

I've attached Cleveland document 50-76. You'll find the kinetic energy calculation at the upper right. I don't know what is supplied with current kits, but a Cleveland 199-102 package was the standard for 7's and 8's, rated at 117,500. They really are a bit undersized for the A-models, because they tend to get hot steering for taxi, but they are fine for the tailwheel airplanes with 500-5 tires, assuming reasonable landing speeds.

I see that Grove recommends their dual-piston calipers for the tri-gear RVs:

 

[TS Flightlines]

I see that Grove recommends their dual-piston calipers for the tri-gear RVs:

View attachment 58846

All due respect to everyone here, including my friend Dan who comes up with all the technical documentation !! If you are having issues with stock brakes not responding properly, might I suggest that it isnt the manufacturer, but most probably the install or maintenance. MANY RVs are flying with the stock brake package that Vans engineers chose. Little attention to details make sure to get all the energy out of those brakes. Before spending a bunch of money on upgrades, go back to basics and start checking little things. Proper pad compound, caliper misalignment, loose mounting, thin discs, heavily glazed discs, slight amount of air in the system, not necessarily a spongy pedal, but one with a longer travel.
Check the master cylinders for piston to bore wear at the end of the travel. And the piston size themselves, vs the stock diameter--yes there have been cylinders that were shipped with the wrong bore size. And if you wanted to verify the brake pressure you can install a high pressure gauge at the caliper and measure it. Then determing if its really a manufacturer issue. Just my .02 worth.
Tom

 

[DanH]

I see that Grove recommends their dual-piston calipers for the tri-gear RVs:

View attachment 58846

Yep. Just polishing the pins here, but note that kinetic energy rating is not necessarily indicative of brake response. Generally, more "braking power" means less pedal pressure is required for a given response.

Example...assume the disk upgrade I mentioned in a previous post. The thicker disk will result in a higher kinetic energy rating (more ability to store heat), but given the same caliper, line pressure, and tire diameter, the initial braking response will be the same as with the thinner disk...the disk and tire diameters did not change. Brake response later in the rollout may be better with the thicker disk, because its temperature did not rise as much, i.e. less brake fade.

Different example..I'm currently flying the thicker disk with the standard Cleveland single piston caliper, paired with 380-150-5 tires. The 380 is about 1" taller than a 500-5, so radius is 1/2" greater, which requires more pad pressure (i.e. more pedal pressure) for the same braking response. However, note the required kinetic energy absorption is the same regardless of tire radius.

As an aside, I can make the tailwheel skip with the above setup. A little less pedal pressure would be nice, but as a practical matter I already have all the braking power I can use, and it's more difficult to over-brake.

 

[N702PL]

Yep. Just polishing the pins here, but note that kinetic energy rating is not necessarily indicative of brake response. Generally, more "braking power" means less pedal pressure is required for a given response.

Example...assume the disk upgrade I mentioned in a previous post. The thicker disk will result in a higher kinetic energy rating (more ability to store heat), but given the same caliper, line pressure, and tire diameter, the initial braking response will be the same as with the thinner disk...the disk and tire diameters did not change. Brake response later in the rollout may be better with the thicker disk, because its temperature did not rise as much, i.e. less brake fade.

Different example..I'm currently flying the thicker disk with the standard Cleveland single piston caliper, paired with 380-150-5 tires. The 380 is about 1" taller than a 500-5, so radius is 1/2" greater, which requires more pad pressure (i.e. more pedal pressure) for the same braking response. However, note the required kinetic energy absorption is the same regardless of tire radius.

As an aside, I can make the tailwheel skip with the above setup. A little less pedal pressure would be nice, but as a practical matter I already have all the braking power I can use, and it's more difficult to over-brake.

Hey Dan, Can I buy your old Cleveland blank mounting plates/pads if you still have them? I've always wanted to have a back up set to have ready to go in lieu punching out the rivets as I change them. Please let me know. Thanks, Jim Lechleiter in SC!

 

[DanH]

Hey Dan, Can I buy your old Cleveland blank mounting plates/pads if you still have them? I've always wanted to have a back up set to have ready to go in lieu punching out the rivets as I change them. Please let me know. Thanks, Jim Lechleiter in SC!

I'm sorry, but I only have one set.

 

[Taltruda]

What is the subject aircraft?

The kinetic energy values noted above might mislead a brake shopper. An RV-8 at 1800 lbs and 60 mph (52.174 knots) results in a kinetic energy of 108,531 per brake.

I've attached Cleveland document 50-76. You'll find the kinetic energy calculation at the upper right. I don't know what is supplied with current kits, but a Cleveland 199-102 package was the standard for 7's and 8's, rated at 117,500. They really are a bit undersized for the A-models, because they tend to get hot steering for taxi, but they are fine for the tailwheel airplanes with 500-5 tires, assuming reasonable landing speeds.

The disk is an energy storage device. A thicker disk stores more energy for the same temperature. The kinetic enegy rating of a 199-102 can be increased to the 199-93's 155,000 ft-lbs just by swapping disks. You'll need a set of Rapco RA164-09900 disks, four longer AN4 bolts, and an easily fabricated spacer in the caliper.


Dan, I did this mod to a buddies -9a. I also bought a .062 axel shim from McMaster and shaved off .062 from the wheel nut. As for the caliper spacer, I started with .125 alum but milled it down to .013 (the difference between disk thickness)

 

[DanH]

Thanks Tom. Yes, I forgot to mention that the tapered rod gears may need some spacer work, IIRC to keep the fat disk from contacting the wheel pant bracket.

Life is easier when you fly an -8

 

[Dougnabbit]

There are not a lot of voices I listen too on VAF. But Scott McDaniels and Dan Horton are two of them!

Dan, thank you for your insight.

 

[RicoB]

I sugget you look at Grove.

I have the stock setup on mine. if I were to switch to the grove how much modifications would be needed? Would my wheel pants mount the same etc? Is it a straight forward parts swap?

 

[mstrauss]

I have the stock setup on mine. if I were to switch to the grove how much modifications would be needed? Would my wheel pants mount the same etc? Is it a straight forward parts swap?

I thought the Grove wheels and brakes are the "stock" for what Vans provides.

 

[gasman]

I installed the thicker Rapco discs in Aug 2012. They are about .125 thicker than the stock discs. I now have over 600 landings on the discs and pads. I USE my brakes. There is no heat trail on the edge of the disc or on the bell. They look like new. The pad wear is what you see in the picture that shows the thickness strip of a new pad, placed against the used pad.

The .125 spacer that I made from stock ACE aluminum bar stock is a prefect fit for the thicker disc. The spacer to move the wheel out, was from Granger.

More info here.... https://vansairforce.net/threads/anyone-got-a-part-number-for-the-brake-disk.123889/#post-1144203

Picture shows that thicker discs will greatly reduce disc over heating problems. And reduce pad wear.