Cub expanding tube brake

J

jesse

Touchdown! Greaser!
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Jesse
I'm pretty sure the expanding tube in my left brake failed catastrophically. I haven't completely disassembled to verify but brake fluid pouring out of it suggests to me that is the case.

It's possible I might have gotten a spare with the airplane. I need to go through the spare parts. If I didn't does someone have one? It's the same brake a cub would have.
 
(Funny Q & A!)

I have two expander tubes and brake assemblies left over from the Groves brake conversion on my 1941 J4A. The problem might be that the J4 used automotive brake fluid, although somewhere I've heard that the expander tubes are compatible with either brake fluid or Mil H 5606 petroleum fluid. Somehow that seems like an oxymoron from my background in hydraulics. Maybe Tom D can advise.

They are yours for the postage from Minneapolis. I can get to them this weekend.
 
caution!

Lotta hydraulic fluids been used over the years including old vegetable based oils. I would make certain you got the right stuff.
 
nrpetersen said:
(Funny Q & A!)

I have two expander tubes and brake assemblies left over from the Groves brake conversion on my 1941 J4A. The problem might be that the J4 used automotive brake fluid, although somewhere I've heard that the expander tubes are compatible with either brake fluid or Mil H 5606 petroleum fluid. Somehow that seems like an oxymoron from my background in hydraulics. Maybe Tom D can advise.

They are yours for the postage from Minneapolis. I can get to them this weekend.
Click to expand...

It seems like nobody actually has a clue about what should be in these. The safest option seems to be to flush everything and then put in 5606 which is my plan.

I'll gladly take you up on your offer. PM sent.
 
nrpetersen said:
Maybe Tom D can advise.
Click to expand...

I would advise never repair an expander tube brake..

They came from the factory empty, and either DOT 3 brake fluid or 5606-A can be used in them, but many have been changed to Mil-spec 5606, from DOT 3 and shortly after begin to leak.

IMHO it is time to upgrade to Clevelands disk.
 
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Other than the neat tires you can get for those 800x4's there is no advantage to the cub tires and brakes at all. I'm with Tom on this one, get some real brakes if you need them. I've seen lots of those expander tubes dissolve with any type of brake fluid and no one seems to know what is really supposed to work. I watch 2 of them drain quite a bit of 5606 after just being installed new. Another set disappeared using dot 3 fluid. I did see one set that used some racing silicone based fluid and they lasted for years but never really worked....not even as well as the normal ones do. Having flown J3's and J4's as well as taylorcraft and other Chinn mechanical type braked planes I think the mechanicals work better though none work well. For those of us who had an instructor to pop us in the head and yell "get off the (^$+*@_(_ Brakes!" we found they weren't really all that necessary for anything but runups so maybe they're not a problem for you. I like the clevelands a lot better though because they are there when you need them and you don't have to use them if you don't......


Frank
 
BiffJ said:
Other than the neat tires you can get for those 800x4's there is no advantage to the cub tires and brakes at all. I'm with Tom on this one, get some real brakes if you need them. I've seen lots of those expander tubes dissolve with any type of brake fluid and no one seems to know what is really supposed to work. I watch 2 of them drain quite a bit of 5606 after just being installed new. Another set disappeared using dot 3 fluid. I did see one set that used some racing silicone based fluid and they lasted for years but never really worked....not even as well as the normal ones do. Having flown J3's and J4's as well as taylorcraft and other Chinn mechanical type braked planes I think the mechanicals work better though none work well. For those of us who had an instructor to pop us in the head and yell "get off the (^$+*@_(_ Brakes!" we found they weren't really all that necessary for anything but runups so maybe they're not a problem for you. I like the clevelands a lot better though because they are there when you need them and you don't have to use them if you don't......


Frank
Click to expand...
Other than this one incident I haven't had any problems with them and they've had more than enough force for the Flybaby. Flying without brakes is not an option as they're needed to do a run up, if the tailwheel is unlocked, or if you have to taxi with a significant wind.

I have a brand new set of 8.00x4 wheels and tubes so in not switching sizes anytime soon. The Grove option is attractive but a thousand more dollars is more than I'm willing to spend. Many people have ran these brakes without issue for 50 years. Lots of myths about them. Would like to at least make a swing at fixing them before spending big money.
 
FWIW...

Iffen you do elect to replace them - Matco would work OK for a Flybaby and cost less than Clevelands. Kinda on the wimpy side, but nicely controllable. Parts (bearings, seals, brake linings) are reasonable also.
 
The reason I replaced them in my 1941 J4 was to get away from leaking/spraying brake fluid (DOT3) onto fabric & having it dissolve the dope/paint. Someone at prewar Piper got carried away with pretending cars and airplanes were similar.:mad2:
 
nrpetersen said:
The reason I replaced them in my 1941 J4 was to get away from leaking/spraying brake fluid (DOT3) onto fabric & having it dissolve the dope/paint. Someone at prewar Piper got carried away with pretending cars and airplanes were similar.:mad2:
Click to expand...


:vomit: boy that would get annoying quick!
 
bnt83 said:
:vomit: boy that would get annoying quick!
Click to expand...
So does a stuck brake on landing.

the self adjuster built into the brake gets contaminated with yuck from within the tube and fails.

Many of the Fairchild 24 have this type of brake system. (Different size) and are plagued with problems with parts, and corrosion caused by the DOT 3 fluid, plus the poor performance.
 
nrpetersen said:
(Funny Q & A!)

I have two expander tubes and brake assemblies left over from the Groves brake conversion on my 1941 J4A. The problem might be that the J4 used automotive brake fluid, although somewhere I've heard that the expander tubes are compatible with either brake fluid or Mil H 5606 petroleum fluid. Somehow that seems like an oxymoron from my background in hydraulics. Maybe Tom D can advise.

They are yours for the postage from Minneapolis. I can get to them this weekend.
Click to expand...

I ended up using 5606 fluid which seemed to work well. Thanks to nrpetersen as of today the Flybaby is back in the air.
 
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