Master Cylinder

Friday was the day to travel to Rapid Racing in Clermont to see Greg Wright about some brake kits.  Dad and I had a good time talking with him about the old days, health problems, and, umm, karting.

Rebuilding the brake master cylinder was the main topic of discussion.  To rebuild or let it go?

If you rebuild, do you get the whole kit or just buy o-rings from an auto supply store?

Since the kart has been dormant for 40 years, all the old timers say to rebuild everything.  So we better rebuild.

First, was figuring out the mechanism.  The set screw on the outside needed to be removed, but it was a challenge.  I selected the wrong screw driver (needed a wide, thick blade, not a thin regular blade.) and promptly slightly stripped the slot.  But with some vice grips, pressure, Blaster, and Dad's persistence, it finally started moving.

Here it is with a "little" wear.  It might need to be replaced.

The set screw sits in the hole at top of master cylinder and holds in the top-hat-looking thing, which is actually the piston.

Here is the piston and spring.  Notice black scum on the piston.  The "cup" gasket is on the right end with a tiny metal plate inside it.

The reservoir was full of a mix of new clear fluid and old, grimy gunk.  After dumping that out, I discovered a good layer of gel on all the surfaces.  That took some cleaning.

 Here is the cylinder housing.

Notice the scalding on the sides.  That cleaned up just fine.

After that we headed up to the Autozone to pick up some o-rings and seals.  Rebuilding is for next time.

Brakes

** Click on the images to see them at a larger size**

What do the inside of Airheart brakes look like?  

We all assume that brakes that have been unused for nearly 40 years need to be upgraded.   Should be easy.  Pull out the the piston and change what ever is included in a "brake kit."   Dad said we needed brake kits. Guys on the forums said we needed brake kits.  I don't know what's in a brake kit, but I ordered two from Greg @ Rapid Racing.  

Here is the piston half of the brake, prior to cleaning.  Piston in the middle.  Gummy, but pretty simple.

Here it is after cleaning.  We tried to remove the piston by blowing compressed air into the system, like Dad had done while he was active in karting.  Nope, the piston was stuck solid. We gently "persuaded" the piston back into the cylinder, but the compressed air would not move it back out.  

Finally, we decided to put the brake system back together and let hydraulics do the work. 

Here is the master cylinder being cleaned.

Reassembling the brake system on the kart.  Always good to check where the rods go... in relation to the tie rods. :-)   Also notice the clothing... it was 80 degrees!  Check out the last post when it was 30 degrees, and I had my long johns on.

A short section of tubing was used to connect the brake housing to the master cylinder.  Finally, after bleeding the air out, the piston moved out.  BUT not all the way.  

 The back seal was broken so we were sucking air.  I happened to put my thumb over it while Dad pumped the pedal.  BINGO!  Fluid, dirt and the piston went flying!   The second brake was in the same condition, but with this knowledge was apart in just a few minutes.

That allowed us to clean everything with gasoline and get the hard stuff off with emery cloth (which Dad has had since using it to hone the cylinder of this same engine...in the early 1970s!!  Seems he knew he would use it again.)

So that is what the inside of Airheart brakes look like!  This was Dad's first time to tear down the brakes. They had always just worked.  Piston, O-rings.  So what is in the brake kit?  Just a couple 0-rings for that price?  Well, we looked a little deeper and found all kinds of good stuff.   So, yes, the kits are necessary! 

Nuthin' like a wheel brush to clean the hard stuff off of brake rotors!

Next up was the tanks.  I cleaned the dust with gasoline and gently pulled off the 200mph tape and #24.  Nice of Jeffie to used Dad's last race number.  Dad will display it in the tool locker.

Reminder, there are rubber grommets in the holes that attach the tanks.  Without proper lubrication (or forethought), they can be hard to move.

 One.

 Two.  I found out that fuel is only put into the tank near the engine.  No need for fuel in two tanks.  the dummy tank is just a bumper.

 

Finally, we ended the day with the throttle mechanism.  Only took us 2-3 tries, but we got it.  The throttle link to the spring goes under the tie rod.   AND don't put the tiny cable clamp allen bolts, which are the size of a grain of rice, down on the tank!  They will roll away and are hard to see.  Thanks goodness for thick, rough welds!

That leaves just a few things to do... the really fun part!