AA Disc Brakes

nknobil · 30 March 2020, 05:31 AM

Hey All,

Has anyone fabbed up a system to use disc brakes with the AA heavy-duty wheels that Robert B puts out?

I'm specifically scratching my head over the caliper bracket and how it attaches to the axle...of course any particular insight as to successes and failures with various calipers and discs would also be welcome.

FWIW, I'm not looking to incorporate differential steering, just to have a "johnson bar" setup like old Pipers used to have...

N28 · 3 April 2020, 06:34 AM

Quote:

Originally Posted by nknobil

Hey All,

Has anyone fabbed up a system to use disc brakes with the AA heavy-duty wheels that Robert B puts out?

I'm specifically scratching my head over the caliper bracket and how it attaches to the axle...of course any particular insight as to successes and failures with various calipers and discs would also be welcome.

FWIW, I'm not looking to incorporate differential steering, just to have a "johnson bar" setup like old Pipers used to have...

If you poke around our “Culpeper Nieuport, again” thread you will find photos and descriptions of how we mounted our calipers. Our method was designed to keep the brake torque from bending the axle’s center hinge bolts. We started with cable actuated but could not achieve the needed mechanical advantage to operate the brakes and so changed to hydraulic. Our setup provides differential braking as our tailwheel does not steer. A johnson bar setup should allow for cable actuated. Run the cable through Bowden housing to eliminate the need for pulleys.

I will see if i can find out whose calipers we used, they are an ATV product, and Bill made the discs from 4130 sheet. We have had a change to our builder ranks and it may take a while to find the info.

nknobil · 8 April 2020, 04:30 AM

Thanks Tom!

I've been shuffling through the web, looking for brake rotors...

If you can find/share that info I'll send you a box of lobsters! (we build those here, and we need to support those guys).

Thanks

nknobil · 8 April 2020, 01:52 PM

Those rotors weren't a Bendix product, were they?

I'm looking a half-dozen, solid rotors with a 5-hole, 100mm bolt diameter that might work...they seem a little on the large size, though...

N28 · 14 April 2020, 07:11 AM

Quote:

Originally Posted by nknobil

Those rotors weren't a Bendix product, were they?

I'm looking a half-dozen, solid rotors with a 5-hole, 100mm bolt diameter that might work...they seem a little on the large size, though...

Lobsters? Now that's incentive!

The rotors were made in house. 1/8" SAE 4130 annealed was used. We had access to the advice of engineers at a large automotive brake manufacturer who recommended mild steel. We chose 4130 for corrosion resistance. Thickness was a compromise between weight (thick) and warpage from use (heat). The brakes are not intended for short stopping on landing but ground maneuvering so use is light allowing 1/8" to be used. If 1/8" proves too light we can easily increase the thickness.

Making our own discs allowed for fitting the attach bolt pattern to the AA wheel. I will try to post some photos showing the process. It was not difficult.

Sorry for the slow response, I'm in the thick of a major rework on my WACO and it's burning up a lot of my time.

N28 · 14 April 2020, 07:19 AM

nknobil · 15 April 2020, 04:34 AM

WOW!

I was way over-thinking this (not unusual). We have a full metal fab shop here were I work, so fabbing something like that up would be a snap.

What did you use for calipers?

And (being a safety-oriented guy) I would point out that your method of cutting out the center hole of your disc might be considered risky, even among well-trained mohels.

PM me your address and we can organize your lobsters! You'll want to have the water a-boil when they arrive!

nknobil · 15 April 2020, 04:38 AM

BTW -

I had the good fortune to visit the airport in Culpeper back in 2015 as a part of the mob with the Texas Flying Legends...what a blast.

N28 · 15 April 2020, 06:50 AM

Quote:

Originally Posted by nknobil

WOW!

And (being a safety-oriented guy) I would point out that your method of cutting out the center hole of your disc might be considered risky, even among well-trained mohels.

Thanks. We do like living on the edge

N28 · 15 April 2020, 07:06 AM

Quote:

Originally Posted by nknobil

WOW!

What did you use for calipers?

PM me your address and we can organize your lobsters! You'll want to have the water a-boil when they arrive!

The calipers are from an ATV/ four wheeler type vehicle. I'll look for the receipt to get some sourcing info. If I recall one reason for selecting the particular caliper, other than braking effort, was the source provided a package; hoses, calipers and a master cylinder. No buying parts from different sources or experimenting out of a parts catalog. The second reason was the master cylinder, this being a dual type. On the original vehicle one cylinder powered two front calipers and the second the single caliper on the rear axle. We used the front wheel calipers connecting each to a single cylinder in the dual master. I think we plugged a port on one cylinder. This configuration provides for differential brakes, essential to our setup.

Rather than ship how about the next time I'm in Maine I'll stop in to see your project and enjoy some lobster?