Bigger better breaks required - I can't hold back my runup

[tracstarr]

So to continue with some of the items slowing my fist flight - I can't hold back my full runup. I've got stock cleveland breaks which came with the kit originally 20 years ago. Single piston, single calipers. Problem is I have 26" tires. After doing the break in procedures about 5 times now the most I can get them to hold is about 4000 rpms (912is) - and that's with A LOT of force. I just can't see any way to improve this without an upgrade.

Is this what others have experienced? It's hard to find much info. I have seen those with single calipers and big tires - but no info on if they are poor, good or great - or even if they are single or double piston. Obviously going up to dual calipers is a sure thing ( I think? ). Realistically, what's the minimum I could do here without replacing masters and lines? Or are they possibly part of my problems being 20 years old and being used for the first time?

I'm starting to feel pretty defeated at this point.

[Kitfox Pilot]

Palmer just went to 4 piston brakes and said they were a great improvement so I am guessing you won't have much braking with single pistons and 26'' tires. JMO

Hope you can get in the air soon..

[airlina]

Keith, I have the same brakes as you on my Series 5 , with a 125HP IO-240 for power. The only variable in this equation is my tires are 22" tundra tires so a bit smaller than yours. While it does take toes on top of pedals with force , I can certainly hold the plane still at full power on grass or pavement, so I think there may be other issues with your brakes beyond being single puck. Personally I wouldn't brakes that could put me on my nose if just touch them, I like having to really apply some force if I want to hard brake . As I have told you previously , on wet grass I can look at the tires and see when they lock up with heavy braking .Bruce N199CL

[Cherrybark]

Are the tops of the rudder pedals hitting the firewall and limiting the brake caliper compression? This comes to mind because it was something I checked before resolving weak breaks with a better bleeding process.

[tracstarr]

Palmer just went to 4 piston brakes and said they were a great improvement so I am guessing you won't have much braking with single pistons and 26'' tires.

Yeah, I looked into that - over 3k for that upgrade......

Are the tops of the rudder pedals hitting the firewall and limiting the brake caliper compression? This comes to mind because it was something I checked before resolving weak breaks with a better bleeding process.

No they are not. In fact, I only get about 1/2 inch (MAX if that) movement when fully on my toes pushing so hard I feel the seat is going to pop. I did read something yesterday about possibly a sleeve insert for the masters but also something about a small insert at the caliper for the tube to keep it from compressing when tightening it?

Keith, I have the same brakes as you on my Series 5 , with a 125HP IO-240 for power. The only variable in this equation is my tires are 22" tundra tires so a bit smaller than yours. While it does take toes on top of pedals with force , I can certainly hold the plane still at full power on grass or pavement, so I think there may be other issues with your brakes beyond being single puck. Personally I wouldn't brakes that could put me on my nose if just touch them, I like having to really apply some force if I want to hard brake . As I have told you previously , on wet grass I can look at the tires and see when they lock up with heavy braking .Bruce N199CL

Hmm, interesting to know. Information I saw somewhere indicated that maybe as I do some landings with increased breaking it might slowly improve. Or maybe I'm not getting them hot enough for break in? I also read somewhere they need to reach 600F? I really don't think I got them that hot. I couldn't touch them with my hands, but no way I was frying bacon on them. Maybe I'll run them a few more times and see if they improve after some landings as well before putting more into it. I also agree I'm in no need of breaks that are going to put me on my nose if I'm not careful - especially as I'm just starting with tailwheel.

[109JB]

What is the bore size of your master cylinders?

[tracstarr]

Not sure. Is there an easy way to tell?

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[109JB]

You will get about 50 percent more fluid pressure with 1/2" master cylinders vs 5/8" master cylinders. As far as how to tell, the master cylinder part number would be a start.