Brake master cylinder

[AmigOne]

Looking over my airplane in preparation for Sun&Fun I saw traces of hydraulic fluid inside the left nose gear door and I traced it to one of the brakes master cylinders.  It is part# 850012-501.  Can somebody suggest which is the best place to buy one.  BTW, can they be overhauled? can the leak be stopped by replacing an O ring or does the whole unit have to be replaced?.  Thanks  

[N601RX]

I think that's the original paramount part number. Many of them have been swapped out with the newer cleveland or gerdes pn. If its still the paramount it will be painted black and round. If it is the cleveland or gerdes it will be gold in color and be oblonged shaped with a flat side. Dan at lasar told no parts were available for the paramont other than o-rings. The cleveland/gerdes have parts or new cylinders available for them.

I have an extra Paramount if your is not rebuildable.

[N201MKTurbo]

Unless it is scored, all you need to do is replace the o-rings. They are easy to replace and inexpensive. Well the one where the shaft goes in can be a little tricky, but not that bad.

[AmigOne]

N601RX, thanks for the information, I sent you a PM.

[jetdriven]

I ran an 18mm fine grit flex hone through them about 8 passes to clean the bore, and installed the 5$ o-ring kits supplied by LASAR.

[AmigOne]

I just ordered the kit.  The fittings to the cylinder still have the thread locks so I guess they are original because I doubt today's mechanics bother with that in such hidden location.  If so it lasted 45 years, not bad.

[Openwheeler3]

I realize I'm reviving an old thread, but I just had my mechanic pull the paramount master cylinders to replace the seals and he found that the spring washers that are part of the check valve are broken on both cylinders. Does anyone know of a source for replacement spring washers? Or do you know which newly manufactured cylinders would fit as direct replacements? The p/n for the paramounts is 850012-501 and the p/n for the washer is 3502-1803.

[jetdriven]

I have a pair of serviceable paramount master cylinders.

[Openwheeler3]

Thanks for the offer. My mechanic was able to find a pair in good shape. However, do you know which modern cylinders would fit as direct replacements in case I run into this problem again? Thanks.

[N601RX]

Gerdes A-110-37 or Cleveland 10-49.  Cleveland purchased Gerdes at some point in the late 70's or early 80's.  Mooney also used a Cleveland 10-24D on the later models with dual pucks, but it has a 3/4 bore where as the others  have a 5/8 bore, but I believe the J manual allows it as a replacement for the earlier Paramount and Cleveland cylinders.

[Openwheeler3]

Awesome, thanks for the info!

[DracoA]

Gerdes A-110-37 or Cleveland 10-49.  Cleveland purchased Gerdes at some point in the late 70's or early 80's.  Mooney also used a Cleveland 10-24D on the later models with dual pucks, but it has a 3/4 bore where as the others  have a 5/8 bore, but I believe the J manual allows it as a replacement for the earlier Paramount and Cleveland cylinders.

The replacement numbers seem hard to find. Are there any other master cylinders that are PMA'd for a M20C mid 60s? Thanks in advance for any help

[outermarker]

My dad is having the same problem with the right brake. O-rings were replaced and still no brake pressure. It's like the check valve isn't working properly. Any advice? Anyone have a serviceable master cylinder for the right side? The Paramount type is what he has. I am flying down to visit him and sure would like to be able to fly with him.

thanks,

albert

[smwash02]

I realize this is an old thread, but it came up during my search. I was rebuilding two v1-15-625-1 / 850012-501 masters and one of them came apart with the 3502-1803 "Shake-proof washer" in two pieces.

It's also called "Disc Spring, Curved, 0.25" and can be found with a part number of 1UAN3 from a black market aviation parts supplier. I might have spares.