LettersFromFlyoverCountry

Well Known Member
I burned my finger last night reaching inside the wheelpants of the RV7A. I touched the bracket holding the wheelpants on. Yeow!

I think it's because the brake pedals don't fully retract, so the taxi back to the hangar after landing has one brake drum rubbing.

On my shutdown checklist before getting out is "reach down and pull the brake pedals back" so I can more easily push it into the hangar. But this, of course, isn't possible just off the exit taxiway of the runway. (although I've briefly considered flying without shoes to better accomplish this)

It's not much...perhaps 1/8 to 1/4" of travel. But it's enough.

I've seen various mentions of springs and such to accomplish this, but -- being the visual type -- I need to see images of how people are installing various contraptions.

If you've got some, can you post or refer to a link.

Also, I put the wheelpants on and everything is fine (ball centered, etc.) , but it *feels* like the nosewheel shimmies a little bit on rollout, although I don't know for sure since I've never felt a nosewheel shimmy before (which I could stand near a runway and watch me land my plane sometime. :eek: ).

I didn't have that problem before I put that nosewheel pants on. I've checked the clearances and they're fine (although I do plan to enlarge a tad).

Has anyone else encountered a difference in taxi quality when putting wheel pants on?
 
The brake cylinders I received on my kit (shipped April 2009) have springs inside them for retracting the cylinders back to full-open position - I guess this is a new addition?
 
Other side?

Did you notice if both sides were hot? Did it taxi straight? Just wondering if you have a hung-up brake caliper.
 
Concerning the nose wheel shimmy: How much air pressure are you running? Try 45#. Keeping it on the high side works wonders.
 
Did you notice if both sides were hot? Did it taxi straight? Just wondering if you have a hung-up brake caliper.

It is hanging up, but releases when you reach down and pull the pedal. I've taken the caliper apart a few times and readjusted tie bolts etc.

and, of course, it taxied like **** yesterday.
 
There are photos on VAF that show the spring/collar set up for the brakes. This is where I stole the idea and they work great. I got everything at the hardware store. I don't have any links for you but I'm sure you'll find something if you do a search.

Regarding nose wheel shimmy, I don't have it but I don't give it much time to shimmy. During takeoff, I pull the nose wheel off as soon as I can and on landing, I keep it off for as long as I can.
 
Be sure to check that the brake calipers are free. Any slight pressure from the wheel pants will cause that brake to drag and produce a lot of heat. You should be able to stick a finger inder the pants and move the caliper easily.

I had to add a little "bubble" on my wheel pants to get what I felt was sufficeint clearance between the pants and the calipers.
 
Here's a thread showing how to make your own master cylinder return springs:
http://www.vansairforce.com/community/showthread.php?t=22130&highlight=brake+springs&page=2

There have been several cases of RV brake fires, so you definitely do not want to have dragging brakes! :eek:

Mine are similar but at the top of the spring I added a collar with a set screw. This allows you to add more or less spring tension as required. Want more tension? Just move the collar down. Less? Move it up.

Yes, brake fires are to be avoided!
 
There are photos on VAF that show the spring/collar set up for the brakes. This is where I stole the idea and they work great. I got everything at the hardware store. I don't have any links for you but I'm sure you'll find something if you do a search.

The VAF search function isn't very good and as near as I can tell it doesn't allow for exact wording matches. That's why I asked. I'm a good searcher.

Regarding nose wheel shimmy, I don't have it but I don't give it much time to shimmy. During takeoff, I pull the nose wheel off as soon as I can and on landing, I keep it off for as long as I can.

And that's what I do too. Maybe I should've gone in more detail about the problem but rest assured I'm aware of the need to handle a nosewheel airplane properly.
 
Be sure to check that the brake calipers are free. Any slight pressure from the wheel pants will cause that brake to drag and produce a lot of heat. You should be able to stick a finger inder the pants and move the caliper easily.

right. And they don't. But it's not because of the wheel pants, as near as i can tell. I'm pretty sure getting the brake pedals to fully retract will alleviate the problem.
 
Bob make sure that you did not over tighten the bolts that the pedals pivot on.
I had slight brake drag and I added the return springs which did nothing until I loosened the pivot bolts.
 
Is your airport taxiway setup conducive to taxiing while someone drives along a parallel roadway? This is how I checked if there was shimmy at varying speeds and tire pressures. That said, it seems to come and go. I've tried 45 lbs, 40, 35 and 30. It gets really hard for me to muscle around in and out of the hangar below that and I'm not so comfortable with lower pressures on landing for fear of a flat. I'm at 190hrs on the original tires, rotated once on the wheel halves.
 
Mine are similar but at the top of the spring I added a collar with a set screw. This allows you to add more or less spring tension as required. Want more tension? Just move the collar down. Less? Move it up.

The only big issue with the set-screw collars is that when the time comes to put new seals in the master cylinders, you have to spend some time de-burring/smoothing where the set-screw has dug into the shaft, else the ridges can damage the new rubber seal when you slide it together for reassembly.

BTW, in one of the threads (search keywords like brake, springs, mcmaster), somebody had posted the exact part numbers for the springs, collars, nylon bushings, etc, to order the components from McMaster-Carr, and they were pretty inexpensive too.

EDIT: found the post here: http://www.vansairforce.com/community/showpost.php?p=159656&postcount=2
 
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Searching VAF

Warning: Thread Drift!

The VAF search function isn't very good and as near as I can tell it doesn't allow for exact wording matches. That's why I asked. I'm a good searcher.

This is how I search in Google. Copy the entire line below and paste it into a google search window:

site:www.vansairforce.com "exact wording matches"

Substitute your exact wording search inside the "". Or, remove the "" and put any key words you want:

site:www.vansairforce.com I burned my finger last night
 
The only big issue with the set-screw collars is that when the time comes to put new seals in the master cylinders, you have to spend some time de-burring/smoothing where the set-screw has dug into the shaft, else the ridges can damage the new rubber seal when you slide it together for reassembly.

BTW, in one of the threads (search keywords like brake, springs, mcmaster), somebody had posted the exact part numbers for the springs, collars, nylon bushings, etc, to order the components from McMaster-Carr, and they were pretty inexpensive too.

EDIT: found the post here: http://www.vansairforce.com/community/showpost.php?p=159656&postcount=2

thanks for this. Ordered the parts and will proceed accordingly. In the meantime, sorry for the folks in the pattern but I won't be making the first turnoff. :D
 
Hey Bob-----just for GP----if its just one brake thats hanging up----check the pedal to make sure the master cylinder piston isnt slightly depressed. If so, it could be keeping some residual line pressure against the caliper piston, keeping it from retracting.
tom
 
Oh, yes, that's exactly what the problem is. That's why I have to physically pull the brake pedals back. I just ordered the McMaster Carr parts to put a spring in there. I'm sure that'll fix things.

And I'll give the nut another turn on the nosegear to see if that changes the shimmy on the NG.
 
Bob...

Just what you'll want to hear - consider changing the brake fluid from MIL-PRF-5606H to MIL-PRF-83282D. It has a higher flash point and thus more resistant to the potential for a fire problem. The fluids are compatible so it's not terrible to change.

Dan
 
Bob...

Just what you'll want to hear - consider changing the brake fluid from MIL-PRF-5606H to MIL-PRF-83282D. It has a higher flash point and thus more resistant to the potential for a fire problem. The fluids are compatible so it's not terrible to change.

Dan

Way ahead of you, Dan. It's the original "equipment" on my plane, I *think* as a result of a thread you had on the Yahoogroup a few years ago.
 
I just remembered something else -- as I was just about to fall asleep last night. I tightened the axel nut on that right wheel last week to remove some perceived play. I bet that didn't help things. Think I'll back off on that a few flats today and see what happens.
 
Bob make sure that you did not over tighten the bolts that the pedals pivot on.
I had slight brake drag and I added the return springs which did nothing until I loosened the pivot bolts.

Same problem I had during phase 1, Bob. Make sure those pivot bolts or whatever they are called are not causing any friction at all. That's why they have a castle nut and cotter pin so you don't have to tighten them. Once I backed mine off just a little bit, the pedals returned completely and the problem was solved. Been fine ever since.