Inverting the brake Master Cylinders?

DrHolling · #1 06-17-2008, 01:46 PM

Anything wrong with mounting the brake master cylinders inverted from the plans orientation? I think it would minimize the line movement when the brakes are applied and released and moves the fittings away from your feet. Has anyone heard recommendations against mounting them upside down?

Dave

videobobk · #2 06-17-2008, 06:38 PM

Standard bleeding procedure is to backfill the reservoir from the wheel cylinders. I would think that filling the master cylinders in that way might trap bubbles, causing soft brakes. It would seem you could fill from the reservoir, but that would cause bubbles in the wheel cylinders. This, IMHO, is a case where Van's instructions make pretty good sense. I haven't heard of flexing of the lines being a problem, and the cylinders don't get in the way of my size 14's.

Bob Kelly

Dennis Madden · #3 06-17-2008, 06:47 PM

I inverted mine, and put those A-600 reservoirs on each peddle. It did trap some air, but I pumped them full from the bottom (wheel fitting) and it worked out great. Shorter lines, no return lines. Just an all around cleaner install. Less parts is less failure points. ;-)
Ps
it an RV-4 I'm talking about.
Dm

cguarino · #4 06-18-2008, 12:12 AM

Mine were inverted. I think that is the way the -4 plans showed them a few years ago. I had so many problems getting the air out that I had to install a bleeder valve in the brake line. Finally, I turned them over and have never had a problem bleeding them since. From my limited experience (one airplane) I do not recommend inverting the MCs. They are just too hard to bleed that way. Just my.02.

gasman · #5 06-18-2008, 02:02 AM

Quote:

Originally Posted by DrHolling

Anything wrong with mounting the brake master cylinders inverted from the plans orientation? I think it would minimize the line movement when the brakes are applied and released and moves the fittings away from your feet. Has anyone heard recommendations against mounting them upside down?

Dave

And I have never had a problem bleeding the brakes. Rebuilt all five (parking brake) cyls. and it took me about five minutes to bleed the entire system from the top down...... My 6A will be done like PIPER did it....

REHughes · #6 06-18-2008, 08:40 AM

Quote:

Originally Posted by gasman

And I have never had a problem bleeding the brakes. Rebuilt all five (parking brake) cyls. and it took me about five minutes to bleed the entire system from the top down...... My 6A will be done like PIPER did it....

As per Piper Club instructions, take a short piece of tubing and put one end on the brake bleed fitting, and immerse the other end completely in a cup of brake fluid. Crack open the wheel brake bleed, fill the system from the top down, and press the brake pedals 10 or 15 times. Make sure the reservoir never gets emptied as you do this.

Putting the tube end into a cup of fluid prevents any air from being sucked back in as the brake pedals are repeatedly pressed.

DrHolling · #7 06-18-2008, 11:06 AM

Thanks for the replies. Matco indicated that they could be mounted in any orientation but cautioned that bleeding might be an issue (he suggested 'vacuum' bleeding).
The 'Piper' method sounds like the same technique we used for automobiles (in my previous life I was a mechanic). Not a problem.
Sounds very do-able to me just uses a different method of bleeding.

Thanks again,
Dave

videobobk · #8 06-18-2008, 11:14 AM

If you pump in fluid from the top, it may be possible to reverse the connections on the wheel cylinders so that the bleeder valve is on the top. I can't say it is possible, but it would allow any air there to vent through the bleeder instead of being trapped at the unvented top.

Bob Kelly

todehnal · #9 06-18-2008, 12:06 PM

I never was fond of the brake lines on RV's being toward the pilot. Glad to hear that someone has successfully managed to get them on the forward side of the peddles!

Man, a picture sure would be terrific!

Tom

gasman · #10 06-18-2008, 01:38 PM

Quote:

Originally Posted by todehnal

I never was fond of the brake lines on RV's being toward the pilot. Glad to hear that someone has successfully managed to get them on the forward side of the peddles!

Man, a picture sure would be terrific!

Tom

You will need to fit it by grinding off the red part. You will see when you go to install the cyl.

What is really nice , is when you need to rebuild the cyl, you just remove the lower bolt swing the cyl to you and remove the snap ring, then pull out the valve from the body without removing the cyl or any brake lines........