Rebuilt a master cylinder and bled the brakes today. Ask me anything!

“Rebuilt” a Cleveland 10-30 Master Cylinder today (internally bypassing) and bled the complete left/right brake system afterwards.

Utilized a oil can/gun to pump the 5606 thru the calipers and up thru the master cylinders to the brake reservoir on the firewall.

Noted that a lot of the displaced fluid had the consistency of honey having been in the system for so long. (change the brake fluid more often)

Also noted that the master cylinders MUST be at FULL extension to be able to pump fluid back thru them with the oil gun and properly bleed the system. Remembered this only after getting frustrated with the right brakes not properly bleeding.

Ended up with all four pedals “high and hard”. Very little lost motion with good braking action.

I’ll answer any questions or take any advice.

Thanks for reading, I hope this helps or inspires someone else to do some brake work.

Repair kit part number

Very timely post. I just saw my 10-30 master cylinders are leaking where the piston pin exits the top of the master cylinder. What was the repair kit part number you purchased?

Repair kit part number 199-512

Picked it up from Aircraft Spruce for $36. Really quite quick and easy to do. Slowed it down a touch while explaining/showing everything to my son. He likes the idea of being an aircraft mechanic.

Here is a link to overhaul instructions...

https://www.parker.com/parkerimages... Brake Division/Kit Documents/199-512 Kit.pdf

This link has the specific written instructions on how to overhaul the Cleveland cylinders with important information.

Worth the read.

Good friend uses this with his air compressor. Swears by it.
Lots of similar products on the market.
Tom

TS Flightlines said:

Good friend uses this with his air compressor. Swears by it.
Lots of similar products on the market.
Tom

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I made something similar to this from an spaghetti sauce jar. It works very well, but requires a pressure regulator for the air.

Bendix Brakes

We pulled the left brake today for seeping at the top. We sourced the “0” rings from TacAero on the field. Less than $5.00 for two brake cylinders. With the cylinder out we filled it from the bottom of the cylinder and it was very firm when installed. We plugged both the clear plastic Line and the bottom black line when removed. Hardest part is removal. I don’t bend like I once did.

texdog said:

We pulled the left brake today for seeping at the top. We sourced the “0” rings from TacAero on the field. Less than $5.00 for two brake cylinders. With the cylinder out we filled it from the bottom of the cylinder and it was very firm when installed. We plugged both the clear plastic Line and the bottom black line when removed. Hardest part is removal. I don’t bend like I once did.

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Can’t speak for the Bendix cylinder, but it is generally recommended that the shaft be replaced with the seal. Vans brake pedal design side loads the piston/shaft which then scores and damages the seal, or the seal damages and the shaft scores? Both?
Some folks get away with polishing the shaft but for the cost of a rebuild kit, including the piston, vs time,…..

You may find those seals you replaced don’t last as long as they should if the shaft is damaged. It doesn’t take much.

JonJay said:

Can’t speak for the Bendix cylinder, but it is generally recommended that the shaft be replaced with the seal. Vans brake pedal design side loads the piston/shaft which then scores and damages the seal, or the seal damages and the shaft scores? Both?
Some folks get away with polishing the shaft but for the cost of a rebuild kit, including the piston, vs time,…..

You may find those seals you replaced don’t last as long as they should if the shaft is damaged. It doesn’t take much.

Click to expand...

It is not hard to polish out the light scratches. mounted shaft to drill and used 600 grit paper. Looked brand new in 4 minutes.

OK. Challenge accepted.

There are infinite black and white dots on a plane. Prove that the distance between one black dot and one white dot is one unit.

....says the guy that can't keep bubbles out of his CF resin glaze coat. Many of you had the thought. Somebody with a low level of maturity had to respond. Enjoy your day.

Try This

Now you’re an aircraft brake expert. Can you the bleed brakes on a Piper Cherokee and get all four high and hard?