V

vinodwahi

Member
Dear Folks,
W have finished our RV9a and had our first Sucessfull Engine start.
We found an issue with our Dual brake system. Dual Brakes are installed as per plan. When we release pressure on pedals, brakes dont come back and wheels are Jamed. Has any body an idea on this issue.
All ideas are welcome.
Vinod
 
Make sure the master cylinders are returning all the way up, sticky pedals will cause this.
 
I installed a spring on the master cylinder to help it reset. That was not enough. I also went back and made sure the nuts on bottom of the pedals were set at finger tight only (then cotter pinned). I had mine set to a normal torque, and it prevented the master from coming back up the last 1/16", which was enough to not let the brake release. After releasing a bit of that pressure on the nut, they work fine. Oh, and I put a bit of grease on the bolt.
 
Brakes

Many of our area builders put return springs on the top of each brake cylinder with adjustable collets. These prevent dragging brakes because the cylinders now return to full extension. Springs are approx 3/8" x 3 "

See many previous posts.
 
Just for reference, here is a photo of the springs on my master cylinder. The photo also shows my Blue Sky pedal extension. I have large feet, and these help me use the Rudder and not the brake during taxi.

IMG_4833.jpg
 
pmccoy said:
Just for reference, here is a photo of the springs on my master cylinder. The photo also shows my Blue Sky pedal extension. I have large feet, and these help me use the Rudder and not the brake during taxi.

IMG_4833.jpg
Click to expand...

It also appears in your photo that you are using one long bolt rather than two individual bolts on each peadel. I hight recommend this modificaiton as it prevent any binding on the hinge
 
that looks quite good.
Did you just use the spring for one cylinder, e.g. on the left pedal? What about the right one, and what about the pedals for the co-pilot?

I see that the spring can release the remaining pressure.
However, I am not 100% sure about the reason for that problem.
Can it also be a problem at the break equipment at the wheel?
 
Maybe VANS has changed the cylinder design recently, but my master brake cylinders have an internal spring that pushes them back out.
 
Pedal Extension

Peter,

Do you have the contact information for the Blue Sky pedal extension?

Best regards,

Bill
RV-7
N151WP
 
Here is the link to the Blue Sky Aviation Site

http://www.blueskyaviation.net/rudder_bar_stand_off.html

Yes, I put springs on both L & R, on Pilot and Passenger brakes. I did it just to have a bit more help getting the brakes to reset. I know there is an internal spring, this is just one of those things I saw someone else do that looked like a good idea.

After I started taxi testing, I determined I still had the nuts torqued to tight to allow the brake to reset all the way. Mine pedals were stopping about a 1/16" to soon, which caused the brake to stay tight. I could reach down and pull the pedal back the last 1/16" to free the brake pads. I heated up the rotor before figuring this out. Loosening the nut to finger tight (cotter pinned), seemed to work. The brakes have not stuck since I did that.
 
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I had the same problem as you described. I did the one vs. two bolts and the springs. That did pretty much solve the brake dragging issue. Regarding the JDair rudder petal extensions, I added these but have to admit I would like even more offset. What a ridiculous design....at least for my 5'11" body.
 
Sunriver Ken said:
I had the same problem as you described. I did the one vs. two bolts and the springs. That did pretty much solve the brake dragging issue. Regarding the JDair rudder petal extensions, I added these but have to admit I would like even more offset. What a ridiculous design....at least for my 5'11" body.
Click to expand...

Yup... I've got the return springs, but the single bolt is a MUST add ! :D
 
You replace the two short bolts that the brake pedal pivots on with a single long bolt.

The way things are with the two bolts it is possible for the center axis of the bolts to be misaligned, and cause binding when the brake pedal is moved within the rudder pedal weldment. Using a single long bolt cures this.

Here is a thread where someone uses a brass rod in place of the bolt, but the photo shows you what I am describing. http://www.vansairforce.com/community/showthread.php?t=74371&highlight=long+bolt

And here is a thread discussing the booster springs, with a parts list. http://www.vansairforce.com/community/showthread.php?t=22130

And lastly, here is a photos of the booster springs installed. http://websites.expercraft.com/PHVII/index.php?q=log_entry&log_id=19304

Hope this helps....
 
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Same as Greg with ours!!!!

I understand why it would be ideal to use the single bolt and I thought about it when building, but I went with Vans two bolts because I was on a weight saving mission. Our 9a has been flying for over two years (without the add on springs) and there has been no problems with the brake pedals returning.

Bob
 
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