Dual-Puck Brake and Bushwheel Install

[Andy Young]

I've just picked up some used 31" Bushwheels, along with 40-75D wheels, and 30-52N brakes, and the correct torque plates, the last of which were from a donor Maule. Is the install just a bolt-on, in terms of everything fitting and playing well together, or am I likely to have to change the length of the axle spacer and/or shim the brake discs?

Thanks.

[stick_rudder]

Andy, good to put a face with your name now!

Should just be a bolt on application since you have the correct wheel/brake kit. I switched my M4 from the old Cleveland drum brakes to the 30-52N and they bolted right up. May need to adjust your brake fitting and lines to align with the double puck caliper. I plan on putting 31s on in a few weeks too. Tire clearance shouldn't be an issue but I haven't done it yet.

[captnkirk]

I had to shim the disc on my dual puck upgrade. That was with 8.50's . I would give the folks at Alaska Airframes a call they are very helpful.

[Hottshot]

You may need dif spacer.... 4009-2 if memory serves have in stock.

[Andy Young]

Thanks everybody. The consensus seems to be that shims between the disc and wheel are necessary. However, Airframes Alaska said they didn't think I'd need them; that the ABI 40-75D wheel/disc combo that I have would work fine as-is. I decided to mount them up and see how they looked, and add shims if needed. They are now on, and look good to me. The calipers are ALMOST all the way in on the pins, but there is still a little space there, so that seems ok. The caliper will move out on the pins as the pads wear. There also seems to be adequate clearance between the inner pad backing plates and the tire; it's not in front of me right now, but I think it was at least 1/4". Calipers are mounted to front.

[Hottshot]

Make sure you mount the calipers forward and up as well as taking the calipers and rounding or radius in the edge where it would contact the tire will give you more than enough clearance without having to use shims or long Bolt

[Andy Young]

Thanks Wup,

Good reminder. So what's the 4009-2 "dif" spacer? Does that relocate the torque plate on the axle? Or did you mean to type "disc" spacer?

[Andy Young]

Well, you guys were correct; I do need spacers between the discs and the wheels. It all works great now, but there isn't enough room between the backing plate for the inner (closest to the caliper body) pads and the "towers" on the torque plate to allow for wear of the inner pads. After about 2mm of wear, the backing plates will bottom out on those towers.

[Hottshot]

Call me in am I have info you need

[Hottshot]

Second thought shoot me an email I'll send you the drawings you need tonight as I am on the road tomorrow

[andy]

Andy Y, I bought the same setup (40-75D wheels and 31" tundra tires) from Airframes Alaska in early March 2016 and installed them on my MX-7-180. No shims needed as long as you get the 40-75D wheels from them. The rotor and wheel is already assembled. There's a good 1/2" of clearance between the tire and the inner top of the caliper. If you don't get the 40-75D wheels from Airframes Alaska, then you might need shims to push the rotor far enough from the tire to avoid rubbing the top of the caliper on the tire.

[Andy Young]

Andy Y, I bought the same setup (40-75D wheels and 31" tundra tires) from Airframes Alaska in early March 2016 and installed them on my MX-7-180. No shims needed as long as you get the 40-75D wheels from them. The rotor and wheel is already assembled. There's a good 1/2" of clearance between the tire and the inner top of the caliper. If you don't get the 40-75D wheels from Airframes Alaska, then you might need shims to push the rotor far enough from the tire to avoid rubbing the top of the caliper on the tire.

Hi Andy,

I am indeed using the 40-75D ABI wheels (from Airframes Alaska). I have good clearance between the caliper and the tire, but very little clearance between the backing plate on the inner (closest to center of aircraft) brake pad and the tower on the torque plate that the caliper pin slides into. There is enough clearance for it to all work well with new pads, but as the inner one wears, soon the caliper would not be able to move inwards to compensate. Shimming between the wheel and the disc would fix that, but would move the caliper (and pin) out a bit, such that it would not protrude all the way through the tower.

The rawing the Wup so kindly provided (its actually a Maule drawing) shows that the towers are supposed to be machined down from the stock dimension of .500" to .380". This provides the same clearance that the shims would, but without moving the caliper pin outward in the bore of the tower.

I've now done the machining to the torque plate, and it all looks perfect.

Andy Young