Brakes for use with ABW 26" tires

[RDavidson 183]

Another Question...

I'm planning on putting 26" ABW tires on my Magnum. I currently have Cleveland brake calipers and disc style brakes. Are these sufficient for use with the big tires?

Also, I saw that some guys were upgrading their brake pedals. Any suggestions on which pedals to buy?

Thanks,

Ron

[SuberAvid 617]

Most Cub guys running 31's use the Cleveland double puck brakes.  If you have double puck brakes I am sure they are ample.  26's are a lot smaller than 31's so  single puck's may be adequate but don't know for sure.  They will probably work OK but may not put you on your nose.  Sometimes that's a good thing as least until you get used to the plane.

[ChrisBolkan 130]

I was running 2 inch single puck Cleveland's on my Magnum and they would not stop ABW 29's effectively. I was in the process of looking for double pucks. If you have the big 2 inch puck singles they might work OK with 26's. I'd try it before getting something new. If you have smaller than 2 inch puck singles it probably wont be effective enough. But still, it is easy to try before switching!

[EDMO 1078]

Ron,  I have a set of double-puck Cleveland calipers, and the heavy disks for sale.  The calipers may need new O-rings and pads.  You should have the heavy disks with the 2-puck brakes, they generate more heat.

EDMO

Edited 14 Apr 2014 by Ed In Missouri

[RDavidson 183]

I checked, I do have the 2" single puck Cleveland's.

Ed, I am interested in your double puck brakes. How much would you need for 'em?

Ed you mentioned that I would probably need different discs, what would you suggest?

Thanks Randy and Chris. Am I screwing up going with 26" tires? I want to be able to land just about anywhere. I thought that 26" would be plenty big, but I have seen guys talking about 29" and 30" being great! Let me know what you guys think.

Thanks again,

Ron

[C5Engineer 1170]

Tires are never big enough! I think you will be fine on the 26s unless your doing a lot of rocky landings. Don't be afraid to air them down. It's night and day difference with the Nancos between 8 psi and 5.

[EDMO 1078]

Ron,

      The set I have (calipers and disks) came off of a Piper Seneca Twin - The disks are probably a little thicker than you need, but dispel heat without warping like the thin disks.  If they need refinishing at some time, you have material there to turn off and don't have to buy new ones like you would with thinner disks.  Am I making sense of this?  They are a matched set.

EDMO

[SuberAvid 617]

26's will be good but your Magnum could easily handle bigger tires.  The trade off between the 26's on my Avid+ and the 30's is about 4 to 5 mph in cruise.  It depends of what you want to do.  If you already have the 26's then just use them.  If you haven't bought them yet then you may want to go bigger if your main mission is to never touch pavement and to spend as much time as possible exploring new landing spots.  I am on the 5th set of tires for my plane; they keep getting bigger.  26's are very good but 30's are more for fun for me than real need, (they will just about land in water without leaving a print though).  If you plan to land in 6" to 8" rocks with occasional larger ones I would recomend the bigger tires.

 

Like Joey said, air pressure plays a big part.  At 5 psi they can roll over a lot of stuff without damaging your plane and also barely leave a footprint in real loose sand so you don't have to worry about getting back out of it.

[RDavidson 183]

Ed, that sounds good, let me do a little research to get smart on those. I understand what you are saying with the thicker disc. I'm sure that the good braking trade off is a little more weight added, but sounds like it could be worth it.

Randy and Joey, thanks again for your input! I'm going with 30s since I haven't bought the 26s yet and since my gear is the same length and height as Randy's.

Randy your plane looks great! I love those tires! I hope you don't mind me stealing all of your ideas? I have copied your gear, want the same tires and I even looked at the boat seats in cabelas that you have in your plane! I feel like an internet stalker! Ha!

Thanks again guys!

[RDavidson 183]

Randy,

I just re-read your post...those are 26" tires in your pic. Sorry I got confused there for a minute.

Your 26s look great, well proportioned.

So, I'm going to use 26s as a minimum, but I think I'll probably go with the 30s, sounds like they will do what I want them to.

[akflyer 1427]

Ron,  I am pretty sure those are the 30" in the pictures.  They left a much smaller footprint in the sand at that same spot than my 26" good years did.  I am hoping to see how the 30" look on my Avid later this week.  I just have to get the skis pulled off and get them bolted on.

 

If your running an 0320 look for an 82X41 or an 81X42 prop.  The pull you will get with it to get you out of tight spots is well worth cruising a little slower.

 

[ChrisBolkan 130]

The only AWB tires I thing you want to consider for the Avid are the light sport 26's or 29's. Any of the other AWB offerings will be way too heavy. Just one guys opinion. I don't think you could go wrong with either of those though.

[akflyer 1427]

I put the 30" air streaks on yesterday. With the updated brake pedals and mc4d masters, I can only hold it to 3800 rom on run up. If your going to put on big tires, get double pucks! On landing these single pucks are about as effective as the old cable operated band brakes..

[saskavid 47]

As far as the magnum top end of it's brake system goes, I've only studied it in pictures and from what I can see the brake pedals suffer from some of the same flaws as the smaller avids even though it is completely different in appearance.guys with mc-4d masters and the modified 2 piece pedal are able to make 600 psi, which in an ac setup is about all you want in most cases.But as Leni's current setup with 30 inch airstreaks shows there are limits to what a single piston internal caliper bottomend can do even with maxed psi.To my eye the magnum brke pedal would make 400 ish psi or less stock, with the leverage and flex issues I'm seeing though this is just a guess.Only way to really tell is to plumb a pressure guage onto the top end with the caliper out of the picture.

[akflyer 1427]

Mike,

 

What size brake lines do you run?  I had the 1/8" lines when I was using the MC1 masters.  Would it do me any good to run bigger lines?  I wouldnt think it would really make much difference, as pressure is pressure and once its compressed to XX PSI its not going to matter if I am running bigger lines or not.. but theory and reality sometimes butt heads and if the bigger lines sem to work better I could give it a try pretty quick.

 

[marksires 484]

If your brake pedals don't have the 2.5x1 geometry that Matco says you need, then fixing that will make the biggest improvement in braking over anything else you can do.  My 'stock' avid wouldn't hold at 3000RPM, let alone 5000-5500rpm needed for runup.  It had the MC5 cylinders with the built in reservoir.  I tried the augmentation kit that matco sells, which made a marginal improvement - maybe I could hold 3500RPM.  So I bit the bullet, put in MC4G (really short) cylinders, an external reservoir, and built new pedals that gave me the 2.5x1 geometry.  Now I can hold 5500rpm for runup.  Same calipers, lines, etc.

Mark

[ChrisBolkan 130]

When I said my 2 inch single puck Cleveland brakes would not stop my AWB 29's, it probably needs to be said that the entire brake system is stock Magnum as came from Avid at the time. I have done nothing to increase the mechanical advantage of the cylinders.

[Av8r3400 1178]

Just as another thought…

 

I've seen airplanes, Just Highlanders in particular, that have two Matco single puck calipers per wheel.  To do this with Clevelands may require some custom backing plates.

[SuberAvid 617]

Ron,

 

Those pictures of my plane are with the 30" Airstreaks.  I have the stock pedals on my plane but changed to the MC4 masters with remote reservior and redrilled the brake pedals to bring them in close to the pivot point.  I have the stock 1/8" plastic lines but switched to the triple puck matco calipers.  I can run my plane up without moving; not sure it it would move at full throttle.  I can taxi it with the tail up and I have to be a bit careful on landing so it doesn't do a nose plant.  You will probably want to change to the double puck Clevelands on your magnum eventually if you go with the 29's or 30's.  It is nice having adequate brakes.

 

I would recomend the 29" ABW Airstreaks if your going to buy a new set; they are plenty big (probably cannot tell them from the old 30" Airstreaks Leni and I are running) and they are lighter than the regular ABW's like Chris said.

 

Leni, those look pretty huge on your Avid!  How do you like them?  What did it do to your cruise speed?

[saskavid 47]

Mike,

 

What size brake lines do you run?  I had the 1/8" lines when I was using the MC1 masters.  Would it do me any good to run bigger lines?  I wouldnt think it would really make much difference, as pressure is pressure and once its compressed to XX PSI its not going to matter if I am running bigger lines or not.. but theory and reality sometimes butt heads and if the bigger lines sem to work better I could give it a try pretty quick.

 

I'm running quarter inch Joey is running 1/8 inch doesn't seem to make much if any difference..If you look at a cross section of 1/8 vs 1/4 and do an area ratio of the material wall to the orfice the fluid passes thru then in theory the 1/8 inch should be much stronger or rigid than the 1/4.My test stand does have the quarter inch line attaching the mc to the guage and it still allows me to wrap the 600 psi guage.One thing I've noticed wen it is 50 as opposed to 90 above, mucheasier to make pressure at lower temp.rigidity of the line does play a part in performance with temperature. Provided you don't have any air left in the system after the swapout from wheels to skis, then you should be at 600+ psi. You can't feed a matco or most any ac brake bottom end any more.With oversize tires it is real easy to over heat things in continued panic/ hard stops and the friction coeffecient goes to hell because you've cooked all the resisns out of the pad. 

[RDavidson 183]

Leni, the tires look great! Ok, sounds like I need to look into getting the MC4 masters. What are you guys using for different brake pedals? What makes the originals not so good? If I need to change them I'd like to do it now while I still haven't Fiberglassed the boot cowls or riveted the firewall in place.

Also Leni, I went big and bought a used O-360 for it, so I'm sure it will swing the larger prop. What brand prop makes the 81 or 82" you are talking about? I have a 78" ground adjustable Whirlwind prop that I use on another plane and I love it. I can only imagine wat another couple of prop inches will do! Probably leave the prop still and spin the airplane instead!

Mike, I'm running 1/4" too. Is it brake pedal leverage that the original pedals are lacking?

Randy, where did you mount your remote Resevoir? Thanks again for your gear leg dimensions! I am loving how the gear looks...minus my current wimpy tires!

[saskavid 47]

Ron with regards to toe brakes it is more a matter of mechanical reallity that no mechanical system is 100% effecient.Basic leverage mathmatics doesn't take this into account.The original hydraulic brakes on the non magnum avids were lacking in leverage and flimsy to the point of where you could pour as much leverage into the top end as yu wanted it wasn't going to turn into line psi just get obsorbed within the system.

http://www.avidfoxflyers.com/index.php?/topic/530-go-kart-to-matco-brakes/

this is a thread Joey did when he installed my 2 piece pedals , mc4d masters, and swapped out his cable bottom end to hydraulic. 

[EDMO 1078]

Ron,

       If you are going with the Cleveland Calipers, why not use Cleveland Master Cylinders with them?  I think they work at higher pressure than Matco MCs.

I have either 2 or 4 of them.   PM me if you want them cheaper than buying new Matco.

EDMO

[dholly 718]

Ron, you must have paid too much for that O-360. I see your wife has you sleeping under the plane!

[RDavidson 183]

Ha! The dog bed definitely is mine!