O rings for Scott 4200 parking brake valve

[Supercop0184]

My Scott 4200 parking brake valve on my 64 M20C is leaking - the service manual gives both AN and Mooney part numbers for the needed o rings - I am having a very hard time finding these o rings - anyone have any suggestions?? Any help would be appreciated it. 

[carusoam]

See @Skates97 writing regarding parking brakes... There was some extensive insight on parking brakes related to that...

Best regards,

-a-

[DualRatedFlyer]

@Marauders time to shine

[N201MKTurbo]

https://www.aircraftspruce.com/catalog/appages/orings.php

 

[Skates97]

33 minutes ago, carusoam said:

See @Skates97 writing regarding parking brakes... There was some extensive insight on parking brakes related to that...

Best regards,

-a-

If you are rebuilding yours take the opportunity to lube the cable. It should slide nice and easy when operating it. I don't think mine had seen any lube in 50 years. (Something I wish I had known...)

It's a long thread, but some of the guys offered some great insight.

 

[Prior owner]

Might also want to flush out your reservoir. I too am rebuilding my parking brake this weekend- and my reservoir was full of black crud in the bottom after 54 years.

I’m wondering if it’s from not wiping the filler plug before removing it, or from pressure bleeding the system and sending crud up from the bleeder nipple into the reservoir... I think the latter is more likely.

[Andy95W]

Supercop- the Service Manual shows 2 different parking brake valves, the 4200 and 4500.  You'll need to put your eyes on whatever is installed in your plane to see which one you have.

If you have the 4200, life is good- simple o-rings to replace.  The 4500 is a different animal, and then it depends where and how it's leaking.  If it's dripping on your carpet, it's not too bad.  If it's no longer holding your brakes, it's probably the seat assembly from the parts list- and those are pricy, if you can find someone to sell you one.

[Marauder]

My Scott 4200 parking brake valve on my 64 M20C is leaking - the service manual gives both AN and Mooney part numbers for the needed o rings - I am having a very hard time finding these o rings - anyone have any suggestions?? Any help would be appreciated it. 

If you are certain that you have a 4200, buy the O rings from Aircraft Spruce.

Don’t forget to sacrifice something before you begin working on your brakes. It will help ward off the evil spirits.


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[Supercop0184]

5 hours ago, Andy95W said:

Supercop- the Service Manual shows 2 different parking brake valves, the 4200 and 4500.  You'll need to put your eyes on whatever is installed in your plane to see which one you have.

If you have the 4200, life is good- simple o-rings to replace.  The 4500 is a different animal, and then it depends where and how it's leaking.  If it's dripping on your carpet, it's not too bad.  If it's no longer holding your brakes, it's probably the seat assembly from the parts list- and those are pricy, if you can find someone to sell you one.

I for sure have the 4200, but these model numbers aint matching aircraft spruce. LASAR has a 4500 overhaul kit that he says he is sure will work, to the point that, if it doesn't, he will refund the cost of the kit (six bucks - not worried about it). 

[Andy95W]

If it's only 6 bucks, I need to give them a call!  My 4500 hasn't held for years.

[Supercop0184]

4 minutes ago, Andy95W said:

If it's only 6 bucks, I need to give them a call!  My 4500 hasn't held for years.

Stand By, if this one doesn't provide the same O rings (im skeptical that it will), consider it yours lol. 

[Marauder]

I for sure have the 4200, but these model numbers aint matching aircraft spruce. LASAR has a 4500 overhaul kit that he says he is sure will work, to the point that, if it doesn't, he will refund the cost of the kit (six bucks - not worried about it). 

 

The 4500 kit won’t work for you. Those O rings are much bigger. Aircraft Spruce has the ones you need. I circled the ones you need. Disregard the B in the number.

 

The new guy at Lasar told me the same thing about my brake master cylinder kit and it was the wrong one.

 

 

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[Marauder]

I for sure have the 4200, but these model numbers aint matching aircraft spruce. LASAR has a 4500 overhaul kit that he says he is sure will work, to the point that, if it doesn't, he will refund the cost of the kit (six bucks - not worried about it). 

 

And please post a picture of it installed in the plane and when you have it apart. Curious to see if the Scott’s is a better built one than the one I had.

 

 

 

Also note that the big O ring (the -015 one) sits loosely on its seat. Not sure why, but it does.

 

And one final note. The drawing that Gerdes had for my parking brake called for 2 different sizes O rings on the shaft. The Lasar kit only contained the -01 ones. The drawing for mine called for the -01 and -05, yet the Lasar photo for their seal kit shows and -01 and -06, but they sent two of the smaller ones. I would follow the manufacturer drawing for what O rings you need.

 

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[Marauder]

If it's only 6 bucks, I need to give them a call!  My 4500 hasn't held for years.

 

The $6 kit is $6 plus shipping. I ended up buying the O rings from Spruce and have spares now. The cure life is in the 2025 range.

 

 

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[Supercop0184]

17 hours ago, Marauder said:

 

And please post a picture of it installed in the plane and when you have it apart. Curious to see if the Scott’s is a better built one than the one I had.

 

 

 

Also note that the big O ring (the -015 one) sits loosely on its seat. Not sure why, but it does.

 

And one final note. The drawing that Gerdes had for my parking brake called for 2 different sizes O rings on the shaft. The Lasar kit only contained the -01 ones. The drawing for mine called for the -01 and -05, yet the Lasar photo for their seal kit shows and -01 and -06, but they sent two of the smaller ones. I would follow the manufacturer drawing for what O rings you need.

 

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Thanks for the pointers - I’ve got it removed and will take pictures of it Sunday when we go to working on it. FYI, I did similar to you I suppose - I ordered the lasar kit, hasn’t gotten here yet, but also took the service manual numbers to the local aircraft supply store - they had both o rings - oh well. Learn a little bit everyday lol. 

[Supercop0184]

On 1/23/2019 at 7:55 PM, Marauder said:

 

The 4500 kit won’t work for you. Those O rings are much bigger. Aircraft Spruce has the ones you need. I circled the ones you need. Disregard the B in the number.

 

The new guy at Lasar told me the same thing about my brake master cylinder kit and it was the wrong one.

 

 

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The B was what wasn’t throwing me way off! I had to be reassured by the local folks that it didn’t mean it was the wrong thing 

[Supercop0184]

On 1/23/2019 at 7:21 PM, Andy95W said:

If it's only 6 bucks, I need to give them a call!  My 4500 hasn't held for years.

I’m being told the 4500 is incorrect for me - if so, are you interested in the rebuild kit? Looks like I have a brand new one I cannot use. 

[Andy95W]

7 hours ago, Supercop0184 said:

I’m being told the 4500 is incorrect for me - if so, are you interested in the rebuild kit? Looks like I have a brand new one I cannot use. 

The part that I need is #2, below.  It is the Stem and valve assembly.  I'd be really surprised if your kit has that piece, but if it does- sure!

[Marauder]

49 minutes ago, Andy95W said:

The part that I need is #2, below.  It is the Stem and valve assembly.  I'd be really surprised if your kit has that piece, but if it does- sure!

Sorry Andy, these Lasar kits are typically nothing but O rings. I think the 4500 kit includes the cotter pins. Is the shaft scored?

[Andy95W]

Thanks, Chris.  Mine has an internal leak at the head of the stem where it meets the valve seat, so it doesn't hold the brakes when I pull the knob.  The replacement parts for the stem and seat is about $400 and even LASAR wasn't sure where to get them.  I'd be better off buying an old 4200 off of eBay and just rebuilding it myself.

Or just leave it the way it is and not use the parking brake.  Hmm...

[Marauder]

40 minutes ago, Andy95W said:

Thanks, Chris.  Mine has an internal leak at the head of the stem where it meets the valve seat, so it doesn't hold the brakes when I pull the knob.  The replacement parts for the stem and seat is about $400 and even LASAR wasn't sure where to get them.  I'd be better off buying an old 4200 off of eBay and just rebuilding it myself.

Or just leave it the way it is and not use the parking brake.  Hmm...

I rebuilt mine but needed to trim the smaller O ring to get it to seal. They never chamfered the edge leading to the sealing chamber and the O ring was difficult to get in. After I put it together and verified it wasn't leaking, I am not using it. Haven't used in 28 years because it never worked.

[Captnmack]

Ok..anyone actually was able to remove oring at -5? I’m at a loss..going to take patience...

[Andy95W]

Ask your dentist if you can have a few old probes that he can't use anymore.  Getting it out isn't a big deal, so long as you don't damage the threads or score the aluminum surfaces.

Installing the new one without it getting rolled is the problem.

[Captnmack]

Yeah...I got it out and actually had that oring in stock...flushing reservoir out now....Mack’s Mooney Service Center..

[Marauder]

Ask your dentist if you can have a few old probes that he can't use anymore.  Getting it out isn't a big deal, so long as you don't damage the threads or score the aluminum surfaces.
Installing the new one without it getting rolled is the problem.

I have a set of those dental probes and also bought a brass one.




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