Brake Return springs

[Jekyll]

Originally Posted by RV9A Bill

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

Check your PMs

[mannanj]

Oh my! Here I am coming up on 5 years and 400hrs., WITH NO BRAKE SPRINGS and I didn't know I had a problem!!!!! ???Wonder why I still have the same tires I started with??? (No wonder they're going bald----)

[rleffler]

Originally Posted by LifeofReiley

RV Brake Spring Parts List

I used the following from McMaster Carr
www.mcmaster.com/

(1) Pkg 6389K625
Nylon Bearing Flanged, for 3/8" Shaft Dia, 1/2" Od,
3/8" Length, Packs of 5 $1.97 Pkg

(1) Pkg 9657K115
Steel Compression Spring Zinc-Plated Spring-Tempered, 3"
L, 1/2" Od, .047" Dia, Packs of 12 $5.29 Pkg

(4) Ea. 9946K13
Aluminum Set Screw Shaft Collar 3/8" Bore, 3/4"
Outside Diameter, 3/8" Width $1.82 EA.

for a total cost of about $19.62 with shipping.

Resurrecting an old thread. It appears that I'm experiencing dragging brakes, so I'm going to try putting springs on to see if that helps.

So here's a dumb question, based upon the above parts list. How are you getting the spring which has an inside diameter of .406 over the flange that the outside diameter of .5?

I didn't pay attention to the dimensions and blindly ordered them off McMaster Carr. When I got the springs, they appear to be too stiff (or I'm too weak) to uncoil the ends a bit to get them over the flange end.

For the folks that used these parts, how did you accomplish getting the spring over the flange?

I've got .5 ID springs on order, but since this was a long thread several years ago, I'm curious on how people accomplished the task.

thanks,

bob

[Robert Anglin]

If you have the Matco cylinders as we use on the two seat'ers, we have just been using the repair kits from Van's. They have a new spring in them along with all the new seals. I take the old springs and put them around a bolt, then roll them on a steel plate or such and peen them with a small ball peen hammer while rolling them to let the spring swell to the size that goes around the piston shaft. Then we put a 1/8" thick nylon washer down at the bottom of the shaft on top of the cylinder top. And then use a set screw caller to hold the spring with some ( just a little ) pressure on it. So it will return to the top of the travel every time. Just kid of what we found to work and it does very well.
Yours, R.E.A. III # 80888

[maus92]

I found that when I rebuilt my Matco master cylinders last year, I no longer needed the external shaft springs I had installed the year before. I assume that the cylinders were original to the build in 2000; I didn't find any documentation that they had been changed or rebuilt. I also found that the shaft had deformed, which caused the leak at the top of the assembly that was the reason for the rebuild.

[tgmillso]

After a recent post in another thread from someone asking about brake return spring mods, I thought I should finally update this thread with my brake modifications. I assembled my Matco master pistons with the springs recommended in this thread and there was only a barely perceptible increase in return force. I subsequently took some measurements of the spring force in the matco's, ran a few calcs, and came up with an alternative spring solution that will double the current spring force. The original spring upgrade was a maximum of 6lb in compression. This one is 30lb. I've tested them out over the past week during my taxi tests and they feel perfect, with no risk of dragging brake, even if your toes are naturally leaning on the pedals, but not too much force that they become an incomberance when you want the brakes. I also modified the collar sleeve arrangement so that even at full brake compression, there is no way that the spring can rub on the ram. The sliding collar is also a self lubricating polymer, which should help with longevity. Just make sure when you assemble things that the collar is low enough to just clear the top mounting tab, but not so low that you restrict compression of the ram. My aircraft is an RV-7, and I would absolutely recommend the long-bolt (single axis) mod to the brake pedal to eliminate binding, in addition to the spring upgrade. You'll also see in the photos some another mod I did to make some standoffs. These are just aluminum split collars and a piece of tubing cut into thirds, then riveted in place with some long AN470AD4 rivets (the collars are countersunk on the inside and I back riveted it against an appropriate diameter bolt shank). I've also stacked two more short pieces of the cut tubing in between to give myself a little further distance.
Anyway the McMaster Carr parts list is as follows.
Spring 9657K435
Lower nylon sleeve bearing: 6294K441
washers (for seating the lower nylon sleeve bearing) 90295A470
Top nylon sleeve bearing: 6389K625
Set screw shaft collar: 9946K13

For the standoffs:
Two piece collar: 6436K136
Aluminum tubing: 9056K79

Hope this helps.
Tom.

[Mike S]

Tom, great info------I took the liberty of copying it over to the sticky thread on brake problems in the " RV Ongoing Maintenance Issues" forum.

Will be much easier to find in the future, instead of only in the RV 8 forum.

[JonJay]

Springs are a bandaid around a problem. Fix the problem and you don't need springs. Most people won't accept a system in their airplane that doesn't work properly. This seems to be an exception as folks readily go through the effort to add springs to a system that doesn't need them and wasn't designed for them.
I doubt the added springs will cause any issues, but why not get your pedals, bolts, etc... properly aligned so you don't introduce excess wear to those parts. You then won't need any additional springs.
Lots of help in the forums on how to do this right.

[rocketman1988]

One thing you overlooked with the addition of springs is brake feel. Even with perfectly adjusted pedals, linkages, etc., the return pedal force is minimal. The addition of springs gives a greater tactile "feel" to the brake pedals.

Of course, you are also entitled to your opinion, too...

[JonJay]

Originally Posted by rocketman1988

One thing you overlooked with the addition of springs is brake feel. Even with perfectly adjusted pedals, linkages, etc., the return pedal force is minimal. The addition of springs gives a greater tactile "feel" to the brake pedals.

Of course, you are also entitled to your opinion, too...

Wow... is that necessary?
Most are installing springs to fix ?dragging brakes? rather than fix the underlying issue first. Your the first I have heard of that installed them to get ?greater tactile feel?. I would still recommend fixing the system before adding to it.
Perhaps it?s all my years flying antiques that had near zero ?tactile? feel, and near zero brakes