Matco Brakes

[Roger]

Do I need to remove the wheels to change the brake pads? My MM describes the other brake system. 

[Roger Lee]

yes it's much easier. You need to take the screws out of the brake disc. This just allows much easier access. You can either put a block under the axle or put a 6' ladder with a pad under the wing out by the tie down, but not directly on the tie down. If you need a little more lift add some more padding on top of the ladder. If your tanks are full remember that while the wing is up in the air it is slowly transferring fuel to the low wing and could over flow if the level is too high in the low wing. I prefer to use an engine hoist with a tire mounted on top. That way I can lift the one side long enough to remove the tire and then lower that wing to be more equal to the other side while I work on the wheel or whatever I'm doing down there.

[Roger]

Thanks.

The brakes are binding though there’s still plenty of brake pad left. Might just need to disassemble and clean 

[Roger Lee]

When you say binding it could mean the puck that comes out of the caliper is sticking or the pins that guides the caliper or something else? If you don't know just clean it all. 

The two horizontal pins that the caliper rides on can get dirty. These can just be sprayed off with Brake Clean from a spray can and then wiped off or you can remove the wheel and caliper and wipe them off. You can also use some Brake Cleaner or Lacquer thinner and wipe the disc off in case they have something on them. 

You can still see the witness marks on the pads?

[Roger]

By binding, I mean the wheel when lifted off the ground and rotated, does not spin freely but is still in contact with the disc.

regarding the witness marks I’ll check, thanks again.

[Tom Baker]

3 hours ago, Roger said:

By binding, I mean the wheel when lifted off the ground and rotated, does not spin freely but is still in contact with the disc.

regarding the witness marks I’ll check, thanks again.

The Matco wheels should not spin freely as compared to traditional aircraft wheels. Their procedure for setting bearing tension leaves some drag on the wheel. One good spin of the wheel should only go around once or slightly more, and not spin freely. It has to do with the design of the grease seal built into the bearing.

[Tom Baker]

I would also add that I normally replace the brake pads before they get to the bottom of the wear mark. The piston in the caliper does not have a guide pin like Cleveland aircraft brakes. That means the more the brake wear the less support the piston has to stay in alignment with the caliper. That combined to the fact that the force of the piston does not hit the backing plate of the brake pads squarely will allow it to get cocked and cause the brakes to lock up.

[Roger Lee]

I'm with Tom on the binding. The old Marc brakes had round sealed standard bearing so tightening the axle nut had no influence and the wheels turned freely. The Matco's have a tapered roller bearing. That's better, but you have to use the correct amount of axle nut torque for these type of bearings because that's what holds these bearings in the proper place. The old Marc bearings couldn't be grease, but you need to grease the Matco bearings.

So with the wheel off the ground and the disc in place. Grab the tire and spin it fairly hard. It should rotate at least one full turn, but no more than two turns. It is supposed to have some drag and that's normal. What we want here is for the whole bearing not to turn in its position. We are want the internal rollers to move. Over tightening the axle bearing will create too much pressure and then the internal rollers might no rotate properly.  If your wheel turns more than once, but less than two turns put the cotter pin back in.

 

Matco manual:

http://www.matcomfg.com/WHLWI62TechnicalManual-idv-3671-23.html

 

 

[Roger]

Thank you, appreciated.

[24-8003-ms]

Hi Roger. Has there been any change to the design of the Matco system for the CTsw? Is it still necessary to trim the base of the gear for a fit?

[Tom Baker]

The CTSW does not need any trimming. Unbolt the old axle and remove. Install the new adapter and drill fro bolt. Bolt up new axle assembly. The CTLS with Marc brakes requires the corner of the gearleg to be trimmed to clear the caliper. 

[Roger Lee]

What Tom said. Just make sure the new axle is square and parallel to the ground otherwise it will give you a compound angle on your wheel and and you'll lose your easy ability to adjust tow and camber.

[Tom Baker]

12 hours ago, Roger Lee said:

What Tom said. Just make sure the new axle is square and parallel to the ground otherwise it will give you a compound angle on your wheel and and you'll lose your easy ability to adjust tow and camber.

Roger, I think you sent me the axle adapters from when you learned that important note. I of course used the new adapters, and the old already drilled ones are still laying around I think.

[24-8003-ms]

Many thanks Tom and Roger. We'll make a plan ...

We bent one of the tubular axle fittings and bought a replacement from CT. The new part was very badly fabricated. They'd reinforced it by welding on a reinforcing plate - so it's obviously a known weakness. Problems were that they hadn't reamed the tube subsequent to welding which meant it was heat distorted. The action of installing it also meant the powder coating completely flaked off the unit. Very bad engineering - if we hadn't been on the other side of the globe we would have returned it. 

The the bolt hole was not placed accurately which meant alignment was way out and impossible to adjust without distorting the hole. The remedy is apparently to weld a washer over the enlarged hole in the correct location. I know this is possible, but we're talking microns of adjustment required to bring the alignment back to spec ... and even if we manage that, we have the same problem of a heat-distorted tube.

One question I have, which I couldn't find in the Matco manual, was about the mechanism for adjusting camber and alignment. Is that part of a new axle assembly, and if so, does it come as part of the wheel assembly? 

Bottom line - and thanks for the info - is it's clear the best solution is to replace this part with a Matco system. 

[Tom Baker]

The alignment with the Matco brakes is by adding washers to one or more of the four bolt bloting the axle to the adapter.

As far as adjusting alignment, there is an other way of adjusting the alignment of the knuckle without welding. It does require machining though.

[24-8003-ms]

Thanks again