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-   -   Brake question (http://www.vansairforce.com/community/showthread.php?t=150545)

Adam W 06-17-2017 07:21 AM

Brake question
 
Hello all

I have just put together my brake rudder pedal assembly. After bolting in the Marco master cylinders I find the brake pedals not returning all the way to neutral. The hinge bolts are not binding. Is this something that will improve when the system has fluid in it? Is this why I see many have used an upgraded cylinder? Is it normal?
Just wondering before I bolt this assembly in the fuse and it's way harder to work on.
Also does it pay to replace the Vans plastic brake tubing with higher end braded lines?

BillL 06-17-2017 07:31 AM

Quote:

Originally Posted by Adam W (Post 1181057)
Hello all

I have just put together my brake rudder pedal assembly. After bolting in the Marco master cylinders I find the brake pedals not returning all the way to neutral. The hinge bolts are not binding. Is this something that will improve when the system has fluid in it? Is this why I see many have used an upgraded cylinder? Is it normal?
Just wondering before I bolt this assembly in the fuse and it's way harder to work on.
Also does it pay to replace the Vans plastic brake tubing with higher end braded lines?

They should return. Remove from the assy and determine if they are sticky. I used a little air pressure (less than 1 psi) to ensure mine returned. I did remove the rudder pedal assembly to replace the forward skin, so, it can be done. That is when I found the non return issue, long bolts completely fixed it. I have additional return springs and collars on hand just-in-case. Those pedals have to have ZERO friction or they will impede the master return.

BTW - You will learn to work under the panel. A barrier to things on the firewall sticking holes in your head (1/4" plywood), several pillows and you are fine, as long as you are flexible.

DGlaeser 06-17-2017 07:43 AM

Do a search for 'brake return springs'. A number of builders, including me, put return springs on the brake piston rod to solve that problem.

JonJay 06-17-2017 09:40 AM

Quote:

Originally Posted by DGlaeser (Post 1181060)
Do a search for 'brake return springs'. A number of builders, including me, put return springs on the brake piston rod to solve that problem.

You should resolve the binding issue before resorting to springs. Binding means wear and tear on bolts and weldments. If you still want the springs as a backup, fine, but the internal springs are adequate (barely) when the system is installed and bolts aligned properly.

Robert Anglin 06-17-2017 12:04 PM

Yes.
 
We see this far to much. The Matco master cylinders work well if they can return to the top every time. If not there will be a slight back pressure on the system and the brakes will drag a little. These cylinders have a return spring in them that pushes up on the plunger, if the plunger gets to the top of the cylinder the poppet valve will open and be ready for the next push down.
What we have done to get these pistons to return all the way back to the top is install the same return spring that is inside the cylinder also on the outside around the rod of the plunger. It is a nice fix that works very well. You buy the rebuild kit from Van's, put the new spring that comes in that kit inside the cylinder, take the old spring, put it around the shank of a drill bit that is 1/64" bigger than the rod " 3/8" "and peen it with a small hammer, while rolling it on a steal plate or anvil. This opens the spring up a little tell it slides over the rod nice and easy. Then put a thick nylon washer at the bottom under that spring and a 3/8" caller with a set screw in it at the top of the spring, slid down over the rod. You don't have to press it down to hard, just enough to get it moving back to the top each time. I think our set screws were locked down about an inch or inch and a half down from the top of the rod to get it to work. This also makes the brake pedal feel much better out on the move. Just what we have found that works for us.
Yours, R.E.A. III #80888

snopercod 06-17-2017 12:40 PM

The old-style matco master cylinders (old, as in 20 years ago) with the internal reservoir would stick like that and cause the brakes to drag (ask me how I know). I replaced them with the latest version and haven't had any problem since then.

gasman 06-18-2017 12:48 AM

Any hardware store will have springs, collar and nylon washer
that will fit.... Take some measurements and go shopping. It will cost you less than $5 for all needed parts.

Adam W 06-18-2017 04:56 AM

A couple more questions re brake rudder pedal
 
Thank you for those answer everyone

Does anyone know roughly for far off firewall i would want to set the pastic bushing blocks for someone 5'4" tall i have made 4 settings starting at 3" off firewall and 1 inch increments from there

os it worth upgrading the Vans brake lines?

snopercod 06-18-2017 05:57 AM

Quote:

Originally Posted by Adam W (Post 1181169)
Does anyone know roughly for far off firewall i would want to set the plastic bushing blocks?

On my Lancair, I drilled a series of holes in the "floorboards" and installed nutplates so the location of the plastic blocks could be moved.

Lemmingman 06-19-2017 09:46 AM

Quote:

Originally Posted by Adam W (Post 1181169)
Does anyone know roughly for far off firewall i would want to set the pastic bushing blocks for someone 5'4" tall i have made 4 settings starting at 3" off firewall and 1 inch increments from there

What I did was set the holes as far aft as I could (I'm about the same height as you) I'll adjust as needed when the time comes. Remember that another part of the equation is the length of the rudder cables. When the time comes you'll have that to use as well to get the angle that suits you.


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