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Goodyear Brake MC Parts


Trevor Edie
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Hello! I've been having issues with the Goodyear brakes on my -0. Specifically, the left pedal requires "pumping up" in order to get any pressure. One idea from the General Service Manual is to replace the ring seal in the master cylinder, which is given part number AN 3227-2. Anybody know where one of these could be found? Seems like this PN doesn't lead anywhere.

 

Trevor


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lawheelock
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Posted by: @trevorjediegmail-com

Hello! I've been having issues with the Goodyear brakes on my -0. Specifically, the left pedal requires "pumping up" in order to get any pressure. One idea from the General Service Manual is to replace the ring seal in the master cylinder, which is given part number AN 3227-2. Anybody know where one of these could be found? Seems like this PN doesn't lead anywhere.

 

Trevor

Trevor,

I don't understand why you still have and trying to maintain GoodYear brakes on a Stinson 108?  Though expensive, the Cleveland conversion kit from Univair could save you thousands in repair costs if the Good year brakes take you on a trip through the weeds and maybe a fence or ditch!  The goodyear master cylinders work just fine on the Cleveland conversion.  I know, that is what I did on my 108-0 more than 20 years ago. And I have never had to replace seals in the master cylinder. 

However, I really doubt that the seals in the master cylinder are the culprit.  Most likely is leakage at the wheel cylinder and that somehow air has gotten into the system.  Have you tried bleeding that left side system?  If the fluid in the master cylinder ever gets down, it can suck air and cause this problem. The wheel cylinders are magnesium and after 75 years usually get very pitted and you cant keep them sealed.  Goodyear parts are mostly unobtanium.

Try bleeding that side just like an automotive brake of yesteryear.  It takes one person pushing the pedal and holding it while a person at the wheel opens the bleed valve and lets fluid out, close the valve and the pedal allowed to go up.  Repeat opening the bleed and then have the pedal pushed and held and close the bleed valve before pedal is allowed to go up.  Repeat until you have a brake without pumping.  Be sure and keep master cylinder filled so the fluid does not get down and allow air to be pumped,. Be sure you are using Mil 5606 hydraulic fluid.  You can get it from Spruce.  An alternative way to bleed is to buy a good squirt oil can and outfit it with a hose and bleeder fitting.  Pump all the air out of the line and then attach to the wheel cylinder bleed valve and pump until fluid comes out the master cylinder without bubbles.  You have to fit a fitting in the fill port of the master cylinder to attach a hose to catch the fluid pumped out to keep from making a mess.  This works, but I have been more successful using the old two person method. 

Also, when I remove a wheel cylinder for service, I cap the line coming to it with an AN cap then fill the repaired cylinder and attach the already filled line quickly and not allow any air into the assembly. 

I can often work on a wheel cylinder using that technique without having to bleed afterwards.

Good Luck!

Larry Wheelock

 

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer


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lawheelock
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Posted by: @lawheelock
Posted by: @trevorjediegmail-com

Hello! I've been having issues with the Goodyear brakes on my -0. Specifically, the left pedal requires "pumping up" in order to get any pressure. One idea from the General Service Manual is to replace the ring seal in the master cylinder, which is given part number AN 3227-2. Anybody know where one of these could be found? Seems like this PN doesn't lead anywhere.

 

Trevor

Trevor,

I forgot to mention that you can get an assortment of  Buna N O rings from McMaster Carr that will have O rings in it that will fit your master cylinder if the trouble persists after bleeding the brake.

Larry

 

 

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer


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Trevor Edie
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Hi Larry,

 

I should've been more clear--I have the Cleveland conversion, just with the Goodyear cylinders. We've given bleeding it a try, and after not too long (one 20min flight or less) it comes back. I still appreciate all the good info. Someone wiser than I has recommended flushing the entire system of old fluid, which I also intend to try. However if I have things apart, replacing that seal seems like an easy thing to do. Thanks for the pointer, I'll start looking there!

 

Trevor


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resto108
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I don't know what a AN3227 is, but a AN6227-2 is a MS28775-007.


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Trevor Edie
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@resto108

 

I thought it was odd that all I could find was that number you mentioned. Anyway, here's where I got it:

20210327 192509

 


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lawheelock
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@trevorjediegmail-com

Trevor,

I still think you have air in the system someplace.  As long as the master cylinder has plenty of fluid, it should not "pump up"  The seals on the master cylinder would remain immersed in fluid, I think, and the only way it would go down all the way is if it is pumping against air.  If it was only the master cylinder seals, I don't think it would "pump up".   Are you sure you don't have a leak in the maybe 75 year old hose under the floorboard that connects the hard line from the master cylinder to the hardline that goes down the gear leg and it then connects to the flex line that goes to the wheel cylinder.  I have also found that some conversions to the Clevelands do not clear the fittings for the wheel pants if you have them.  The wheel cylinders have to be free to move back and forth on the pins without restrictions.  In 53 years and over 3500 hrs in my 108, I have never needed to change the goodyear master cylinder seals.  But, I have had some problems getting a good bleed sometimes.  Just something to think about.

Larry

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer


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resto108
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The parts book shows it to be a AN6227-7, which is a MS28775-012. Look in 00-25-223, Appendix D. It gives all the dimensions of O rings, but -012 sounds more likely than a -007.


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Trevor Edie
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Thanks guys! I'll be able to give the brake some more attention here in another couple days. 


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Ryan Sherwood
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@trevorjediegmail-com 

Curious to hear what you find. 


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Trevor Edie
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Ryan, thank you for the timely reminder to update.

 

Since my last post, we have tried bleeding the brakes some more. This produced no results. We then overhauled both master cylinders, which essentially involved replacing the single O-ring in the assembly. Following this, the problem showed up on both the left AND right sides, and no amount of bleeding would solve the issue. We tried pumping fluid in from the bottom, from the top, and put enough fluid through to renew the whole system and then some. The issue persisted--first push on either pedal would go to the floor, with the next few being firm as can be. Wait about 90 seconds though, and the pressure is gone.

 

I ended up purchasing another set of Goodyear master cylinders from another owner sadly parting out his aircraft. Using their innards and the exterior of my old cylinders, we believe the best possible setup has been reached. And on initial test, the problem seems solved. But the trip to Oshkosh will be the best test of that, so if it resurfaces I'll be sure to update further. I'm still suspicious of the old spiral tubes further down the line in my airplane, but there's no basis for that other than "well we haven't replaced them yet and I can't see inside them!"

 

Thanks to everyone here for your help so far. See you all at Osh!

 

T


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Trevor Edie
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Post-Oshkosh update--problem still not solved. Going to end up getting new Univair master cylinders and seeing if that fixes the problem. Goodbye money!

 

T


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Dennis Crenshaw
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@trevorjediegmail-com Trevor, have you dropped the pan below the floor boards to check all your hose connections?  If you have replaced your master cylinder seals with different ones as you stated and you still have the problem on both sides, then it doesn't make sense that the problem is the master cylinders.  I agree with Larry that you probably have air in the lines.  Check the line connections under the floorboards--a leak should be evident.  The seal where the coiled line screws into the bottom of the master cylinder is an MS 28778-4 O ring.  That's not what was the original that Stinson used but it fits and will work.  Then you should have a hard line (aluminum tube) connecting to a flex line which exits the fuselage to the top of the gear beam.  Then another aluminum brake line down the gear beam to your brake cylinders.  I would check all these connections before I spent the big bucks!!


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lawheelock
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Trevor,

You have the Cleveland conversion, right.  Have the brakes ever worked correctly after the Cleveland conversion?

Do you have wheel pants?  Often the brackets supporting them interfere with the movement of the calipers.

Did you install the Clevelands according to the drawing that came with them?  Wheel cylinders forward?

 

Cleveland wheel cylinders (calipers) MUST be free to move on the anchor pins in order to operate.  If the calipers (wheel cylinders) are not free to move, you will get the results you are seeing.

 

Often with wheel pants, the cylinders are not free to move in and out against the fixed disc.   When a pedal is pushed the cylinder must move and it must move back when pressure is released.  If it moves back and sticks in that position the next pedal push will not force the cylinder against the disc.

 

Check to make sure the anchor pins are lubricated with silicone grease like Dow Corning DC-4 and that the calipers are free to move on the pins.,  They have to freely float on the pins.

 

Also the Cleveland kit comes with flex lines to connect the cylinders to the gear leg down hard aluminum tubing.,  If you don't have the flex lines at the wheels, that may restrict movement of the calipers.

I have original stock Goodyear Master cylinders along with the official Cleveland kit I bought from Univair in the 1980s and they have been 100% trouble free except for one time one of the calipers got stuck on the anchor pins and that pedal would not activate the brake because the piston moved out far enough that the pedal went all the way down, but the piston was not contacting the disc because the caliper was stuck on the anchor pins and would not move.  Some rust had built up on the pins and after cleaning the rust and lubing with DC-4 the brake worked perfectly even though I had suspected the master cylinder.  No trouble in the last 35 or more years on my 108-0 with original Good year master cylinders, original coiled copper tubing, replacement flex lines in the belly coupling coiled copper spirals to the gear leg hard tubes.

 

Larry Wheelock

 

 

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer


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