Roy Thoma
Well Known Member
This applies to Parker brakes that were supplied in my RV-7A kit. I think newer kits may have Matco wheels and brakes.
My brake disks were past the wear limits with about 1100 hours on my RV-7A. I use the brakes to make turn-offs rather than coast on a runway to a subsequent turnoff. I taxi a short distance for take off and landing at my home airport, KHIO. My nose wheel break-out force is high. Reading posts from DanH and other's I decided to install thicker disk's to get higher kinetic energy rating (search VAF for "kinetic energy rating" for more discussion).
My worn brake rotor weighed 1.313lbs and were just under 0.15" thick.
A disk from a friend with about 100 hours on his similar plane weighed 1.449lbs and measured 0.178" thick. I've read on VAF that new stock rotors are 0.187". I did not find spec's for the weight of new rotors, I'd guess new weight at 1.5lbs. The new Rapco rotors are about 0.300" thick (I measured 0.294") and weigh just under 2lbs (1.986).
I made spacers for the caliper from 1/8" thick 6061T6.
I replaced the pair of AN4H15A's that hold the caliper's together with AN4H16A's to allow for the spacer and for the thicker rotor. I also had to replace the three bolts that hold my wheel plant mount bracket with longer bolts and added washers so the pant mount bracket would not interfere with the new thicker disk.
Cost comparison, from Aircraft Spruce. The stock RAPCO brake disc (RA164-01700) is $83.75, the thicker RAPCO brake disk that I'm using (RA164-09900) is $96.75. The four bolts for the caliper are about $3, add another $5 for the bolts and washers to adjust the wheel pant mount. Total difference for the upgrade if the disc needs replacing is about $20 and about a pound increase in weight.
I have made a few flights with the upgraded disks. My old disks smelled HOT after most landings. The new disks do not. I'm glad I have Viton O-rings and MIL-H-83282 brake fluid (higher flash point).
My brake disks were past the wear limits with about 1100 hours on my RV-7A. I use the brakes to make turn-offs rather than coast on a runway to a subsequent turnoff. I taxi a short distance for take off and landing at my home airport, KHIO. My nose wheel break-out force is high. Reading posts from DanH and other's I decided to install thicker disk's to get higher kinetic energy rating (search VAF for "kinetic energy rating" for more discussion).
My worn brake rotor weighed 1.313lbs and were just under 0.15" thick.
A disk from a friend with about 100 hours on his similar plane weighed 1.449lbs and measured 0.178" thick. I've read on VAF that new stock rotors are 0.187". I did not find spec's for the weight of new rotors, I'd guess new weight at 1.5lbs. The new Rapco rotors are about 0.300" thick (I measured 0.294") and weigh just under 2lbs (1.986).
I made spacers for the caliper from 1/8" thick 6061T6.
I replaced the pair of AN4H15A's that hold the caliper's together with AN4H16A's to allow for the spacer and for the thicker rotor. I also had to replace the three bolts that hold my wheel plant mount bracket with longer bolts and added washers so the pant mount bracket would not interfere with the new thicker disk.
Cost comparison, from Aircraft Spruce. The stock RAPCO brake disc (RA164-01700) is $83.75, the thicker RAPCO brake disk that I'm using (RA164-09900) is $96.75. The four bolts for the caliper are about $3, add another $5 for the bolts and washers to adjust the wheel pant mount. Total difference for the upgrade if the disc needs replacing is about $20 and about a pound increase in weight.
I have made a few flights with the upgraded disks. My old disks smelled HOT after most landings. The new disks do not. I'm glad I have Viton O-rings and MIL-H-83282 brake fluid (higher flash point).