bleeding Duo Discus brakes

Brake cylinder hone?


"Three Uniform" wrote in message
...

Changing topic to "problems with Cleveland Brake Calipers"

Thanks Craig for posting Bumpers's link again.
I called Joe at Sierra Specialty Automotive (brakecylinder.com)
He stated that his insurance company does not allow him anymore to
work on aviation parts.
(The part could of course be from a historic tractor)

But more importantly, he concluded that the composition of the
aviation alloys does not match with his process and procedures of
fitting sleeves.
He had to deal with a number of returns.
So, he is not providing this service anymore.

In talking to Joe, another point came up.
The Cleveland caliper has the O-ring on the piston.
The sealing is against the bore in the caliper.
Therefore the surface of the piston is not that relevant, but the
condition of the bore is very much so.
In his opinion, the bore should have a polished finish.
When I dis-assembled mine, it definitely did not have a polished
finish.
Apart from some corrosion, there seemed to be a fine, regular, ringed
structure in the surface of the bore.

Any ideas on this ?

3U

On Jan 24, 3:55*pm, "Dan Marotta" wrote:
Brake cylinder hone?

"Three Uniform" wrote in message

....









Changing topic to "problems with Cleveland Brake Calipers"

Thanks Craig for posting Bumpers's link again.
I called Joe at Sierra Specialty Automotive (brakecylinder.com)
He stated that his insurance company does not allow him anymore to
work on aviation parts.
(The part could of course be from a historic tractor)

But more importantly, he concluded that the composition of the
aviation alloys does not match with his process and procedures of
fitting sleeves.
He had to deal with a number of returns.
So, he is not providing this service anymore.

In talking to Joe, another point came up.
The Cleveland caliper has the O-ring on the piston.
The sealing is against the bore in the caliper.
Therefore the surface of the piston is not that relevant, but the
condition of the bore is very much so.
In his opinion, the bore should have a polished finish.
When I dis-assembled mine, it definitely did not have a polished
finish.
Apart from some corrosion, there seemed to be a fine, regular, ringed
structure in the surface of the bore.

Any ideas on this ?

3U

I don't think I'd go there unless there is leakage from around the O-
ring. Too much potential for things to go backwards and not much
potential for improvement. The bore surface shouldn't influence how
firm the braking is.

I'd spend my time chasing out:

1. air in the system
2. soft or decayed brake hose
3. flex in the cable bowden leading to the master cylinder

Just my 2 cents,
Craig

On Jan 24, 8:15*am, Craig wrote:
On Jan 23, 10:03*pm, Three Uniform wrote:









I have nearly the same problem on my V2C. 2 seasons ago I noticed
something dripping from the vent hole in the bottom of the fuselage.
Until then mybrakehad been rock hard. Inspection showed that yellow
brakefluid was leaking from the master cylinder and gum had formed
around the master. Fluid probably 14 years old. I could not find a
revision set and decided to buy a new Magura master (from the
motorcycle store, used on many BMWs). Instead of a 20mm master, I got
a 16mm master.
The 16mm master should only give a bit more travel. Re-installed and
had the same described spongyness. Took the Cleveland caliper apart
and observed significant corrosion on the caliper, less on the piston.
Sanded carefully a bit, installed new O-ring and re-mounted. Still the
spongyness, even after pumping a pint of new clean fluid both ways (up
and down).
Part of the problem is that the piston retracts a bit upon release of
thebrakehandle, instead of taking new fluid from the master
reservoir to fill the void.
I need to do more work before the season starts

Question to Bumper:
Can the brass liners and anodized piston be retrofitted ?
Where ?

3U

I saved this link last time Bumper recommended it.http://www.brakecylinder.com/index.htm

Good luck with the brakes. *You may want to look at replacing thebrakeline. *The one SH used was disintegrating & thebrakeworks much
better after replacing it with a stainless braided unit. *The Hot Rod
crowd has great sources.

http://www.jegs.com/i/JEGS-Performan...archCmd?storeI...

Cheers,
Craig

Just came across this tool for brakes on ebay.
http://www.ebay.com/itm/Pressure-Bra...item3f1396596b

No association with the seller at all.

Craig Funston

On Feb 15, 2:47*pm, Craig wrote:
On Jan 24, 8:15*am, Craig wrote:





On Jan 23, 10:03*pm, Three Uniform wrote:

I have nearly the same problem on my V2C. 2 seasons ago I noticed
something dripping from the vent hole in the bottom of the fuselage.
Until then mybrakehad been rock hard. Inspection showed that yellow
brakefluid was leaking from the master cylinder and gum had formed
around the master. Fluid probably 14 years old. I could not find a
revision set and decided to buy a new Magura master (from the
motorcycle store, used on many BMWs). Instead of a 20mm master, I got
a 16mm master.
The 16mm master should only give a bit more travel. Re-installed and
had the same described spongyness. Took the Cleveland caliper apart
and observed significant corrosion on the caliper, less on the piston..
Sanded carefully a bit, installed new O-ring and re-mounted. Still the
spongyness, even after pumping a pint of new clean fluid both ways (up
and down).
Part of the problem is that the piston retracts a bit upon release of
thebrakehandle, instead of taking new fluid from the master
reservoir to fill the void.
I need to do more work before the season starts

Question to Bumper:
Can the brass liners and anodized piston be retrofitted ?
Where ?

3U

I saved this link last time Bumper recommended it.http://www.brakecylinder.com/index.htm

Good luck with the brakes. *You may want to look at replacing thebrakeline. *The one SH used was disintegrating & thebrakeworks much
better after replacing it with a stainless braided unit. *The Hot Rod
crowd has great sources.

http://www.jegs.com/i/JEGS-Performan...153/10002/-1?p.......

Cheers,
Craig

Just came across this tool for brakes on ebay.http://www.ebay.com/itm/Pressure-Bra...-Aviation-Car-...

No association with the seller at all.

Craig Funston

A method for bleeding the Duo wheel brake may be found on the Soaring
Cafe at http://soaringcafe.com/2012/01/duo-d...ke-adjustment/