Brake Return springs - Page 3

Sunriver Ken · #21 02-20-2011, 09:01 PM

I did the Home Depot springs and washers and they work great. HOWEVER, the longer bolts did just as much or more than the springs. Suggest you do them both. The corect dimensions for the bolts can be found via "search". This really does help as does building up the bottom of the brake pedals is also a good idea.

alpinelakespilot2000 · #22 02-20-2011, 09:10 PM

Quote:

Originally Posted by Sunriver Ken

I did the Home Depot springs and washers and they work great. HOWEVER, the longer bolts did just as much or more than the springs. Suggest you do them both. The corect dimensions for the bolts can be found via "search". This really does help as does building up the bottom of the brake pedals is also a good idea.

Thanks, Ken. I tried that, but to use the long bolt you have to have drilled through originally with a long drill bit and/or been perfectly straight as you drilled through the thick brake pedal angle. Getting the holes on both sides of the pedal to align perfectly is a must, otherwise the long bolt merely binds up the pedal more than individual bolts on each side do.

gasman · #23 02-21-2011, 12:56 AM

Quote:

Originally Posted by alpinelakespilot2000

Thanks, Ken. I tried that, but to use the long bolt you have to have drilled through originally with a long drill bit and/or been perfectly straight as you drilled through the thick brake pedal angle. Getting the holes on both sides of the pedal to align perfectly is a must, otherwise the long bolt merely binds up the pedal more than individual bolts on each side do.

This is one place where a sloppy bolt fit is OK. Just file the holes out till the long bolt slides through without any drag.

Bevan · #24 02-21-2011, 11:37 AM

What is the correct bolt length to order?

Bevan

N9331v · #25 02-21-2011, 05:44 PM

The bolt size I'm using is AN3-56
Expensive $45.00 for both sides from Spruce.

Jekyll · #26 02-25-2011, 08:24 PM

I added springs to my brakes tonight. I used 3, 3/8 stainless washers from ACE and 3 x 19/32 x .054 springs from McMaster-Carr. These springs have 7.49 pounds of compression under load. I went with lighter springs because my hinge bolts are long, through bolts and are very smooth. I did it like Alpinelakespilot2000.

My hinge bolts are AN3-60 bolts from Spruce ($10.90 ea) and I needed 2 washers under the nut. My brakes are very smooth and free. These bolts are fairly dear but, you get a nice, smooth hinge with a single bolt.

The springs come in a bag of 12 so, I have 8 extra springs if anyone wants them. 90 cents for each spring and $5.20 shipping (US); send a PM. The springs cost $10.41 with shipping from Mcmaster-Carr so, you can save a couple of bucks if you want my extra. I'm just looking for my cost and the Post Office's cut. I schlepped all over for an afternoon and didn't find suitable springs locally.

Definitely best to do this before riveting the top skin. Even with that, it took some contortions to add the springs.

Jekyll
7A Slider

RV9A Bill · #27 02-25-2011, 09:32 PM

I will take four of your extra springs. I think that adds up to $8.80. let me know your address.
RV9A Bill

ccryan · #28 02-26-2011, 06:39 AM

I have brakes that drag slightly when there is pressure applied to the bottom of the rudder pedals. Unless I am very careful, meaning, I taxi with my feet OFF the pedals, just tapping them whenever I need correction, there is no problem. On takeoff, with both feet on the bottoms of the pedals with slight pressure, my brakes drag. I talked to Van's and Ken S. mentioned how some builders were machining the holes 1/8" larger on the master cylinder to add some "slop", and give a little leeway so the problem I'm having doesn't occur. I know myself and one other RV-8 on my field have this problem. My question is, would this spring setup fix our issue?

sf3543 · #29 02-26-2011, 10:53 AM

The geometry of the RV8 rudder/brake pedal makes it very easy to apply brake drag while using the rudders to taxi. I think this is what you are referring to. Its is a well known issue and you can probably search on this forum to see different types of fixes. One popular fix is to replace the two short axle bolts, at the base of the pedal, with one long AN bolt that spans the entire pedal. This allows you push on the rudder only without actuating the brake at all. (You are actually using the bolt as the rudder bar, which does not apply any pressure to the brake.)
Another fix is to attach something onto the base of the pedal itself to keep from pushing the brake on. This is what I did. I used a piece of delron, about 1/2" x 1/2" by whatever the width of the pedal was and just attached from the back of the pedal with two #6 screws. It works great and the mod does not have any effect on flying at all. If you look at the pedal, from the side, you'll see that this method actually pushes the rudder and tends to put a little opposite pressure on the brake. (You could use a piece of wood, etc.)
There are probably other fixes that would work, but these do for sure.
I would guard against drilling the holes out too large and letting things slop around.

sf3543 · #30 02-26-2011, 11:00 AM

I forgot to mention that the brake masters can still cause a slight drag, even after making the above mentioned mod, but not always. If it persists, then the springs need to be added.
you can test it by just trying to pull the plane forward on the ground. If the brakes are dragging, you'll be able to tell. (Actuate the brakes several times while testing this, since they can stick intermittently.) This means you probably need the springs. If they do not drag, then you are inadvertantly using the brakes while taxiing.