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Removing the left Brake Pedal and master cylinder

P

Philly5G

Registered User
England
On removing the P1 seat to change the harness, we've noticed the Master Cylinder Bracket is cracked and needs a weld repair. Looks like the unit is bolted through the floor board to the frame tubes and looking like another tricky job to remove. I've searched the forums and can't find a post on the best way to do this, can anybody help please? :)

And as a secondary question to this, I'm guessing removing the floor board means removing the control sticks and connecting rods? Is this correct and is this a very big job?

Thank you!!

Philly
 
Last edited:
I had a similar question about removing the floorboards 10 plus years ago on this web site. I remember it took dozens of questions from myself before the penny dropped. The floorboards are put in before the fabric and the rest of the aircraft and that's not an option. To remove things like your master cylinder bracket you have two options. Very young flexible arms, and hands, or cut a new inspection hole underneath for access.

Best of luck.
Texmex.
 
texmex said:
I had a similar question about removing the floorboards 10 plus years ago on this web site. I remember it took dozens of questions from myself before the penny dropped. The floorboards are put in before the fabric and the rest of the aircraft and that's not an option. To remove things like your master cylinder bracket you have two options. Very young flexible arms, and hands, or cut a new inspection hole underneath for access.

Best of luck.
Texmex.
Click to expand...

Thanks for this Texmex!! Sounds like another access panel then!! Shame about the floorboard as that could definitely do with a refresh!

On the access panel topic, the Port and Starboard access panels abeam the rear trim mechanism have been cut exactly over a sloping cross tube, is this the standard place for them? as it means I can't get my (far from massive) hands in to access anything. I'm considering cutting at least one new access panel forward of these so I can actually access something :)

Cheers

Philly
 
The master cylinder brake frame is cast. I never thought it was a good idea to weld an aluminum casting but I could be wrong. Here is the grommet placement drawing from Piper.
 

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I welded a broken ear on mine 30, maybe 40 years ago, and it has held up fine. Not data though, just an anecdotal info - - -
 
Steve Pierce said:
The master cylinder brake frame is cast. I never thought it was a good idea to weld an aluminum casting but I could be wrong. Here is the grommet placement drawing from Piper.
Click to expand...

You can weld cast, but it's not as strong as original, hence why you see larger aluminum weld beads. Or so is what the instructor told us back in 80's. Maybe things have changed?


Sent from my iPhone using SuperCub.Org mobile app
 
Steve Pierce said:
The master cylinder brake frame is cast. I never thought it was a good idea to weld an aluminum casting but I could be wrong. Here is the grommet placement drawing from Piper.
Click to expand...

PERFECT!! Thanks for posting the grommet drawing, the forward of the 2 rear trim access panels is EXACTLY where i planned to make my new ones!! and the 2 under cockpit panels look pretty much like the brake cylinder ones, although maybe a little forward.

Thanks!!

Philly
 
Replace it. Search ebay. Many people going to steves aircraft brakes and Dakota brakes. Should be plenty used ones out there.


Sent from my iPhone using SuperCub.Org
 
texmex said:
I had a similar question about removing the floorboards 10 plus years ago on this web site. I remember it took dozens of questions from myself before the penny dropped. The floorboards are put in before the fabric and the rest of the aircraft and that's not an option. To remove things like your master cylinder bracket you have two options. Very young flexible arms, and hands, or cut a new inspection hole underneath for access.

Best of luck.
Texmex.
Click to expand...

I've obviously got young and flexible hands Texmex!! I got one bolt out fairly easily (having looked at removing the bungee doors first) then unfastened and secured the brake hose out of the way and then used a small socket spanner to hold the under tube nut and managed to undo the remaining 2 bolts!!
 
I just poke 3 holes under nuts. Use a small univair grommet glued on first at each location. Then patch over them when done or put a 3/4" ? snap cap in them when done. Your 3/8" socket will fit through them


Sent from my iPhone using SuperCub.Org
 
Last edited:
What Mike says.

I have been messing with Cub brakes for 56 years, and both my Cubs have a single rectangular access plate with two U shaped holes on the front for the protective grommets. I can swap out a master cylinder in 45 minutes. I am running the Grove 95-1 and -2 reservoir masters for the last 3 years under a field approval, and I smile every time I depress a brake pedal.

I did break a casting once. I fixed it on my mill with two 8-32 cap screws. It was the pivot ear. Worked for over a decade. Still works, but I will never go back.
 
Another option at the covering stage is to install anchor nuts onto the brackets. I've just removed my brake master cylinder having done that 3 years ago when we recovered and it took only 10 minutes, including removing the stick and front seat :) of course metal belly panels is another solution.


Sent from my iPad using SuperCub.Org
 
kiwicubber said:
Another option at the covering stage is to install anchor nuts onto the brackets. I've just removed my brake master cylinder having done that 3 years ago when we recovered and it took only 10 minutes, including removing the stick and front seat :) of course metal belly panels is another solution.


Sent from my iPad using SuperCub.Org
Click to expand...

This is what I was hoping I'd find when I started to unfasten the mounting bolts :)
 
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