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RV-8 rudder pedal mods
I know of two mods for the problem of applying a little brake when wanting only rudder deflection.
One is to replace the the pedal attachment bolts with one long bolt across the face of the pedal. The other is to add small extensions to the bottom of the pedals. For people who have done one or the other, how has this worked out? And would you prefer one method over the other? |
Hi Bill,
I might get corrected on this but in my very very humble opinion, I would leave the pedals stock. I have never had a issue with inadvertent braking but I have had a time or too when I needed brakes NOW, and I personally like being able to quickly give a tap or two of brakes in a strong crosswind. I have overheard conversations where ground loops have happened and the pilots have quietly wondered if they had had better access to the brakes the ground loops might have been avoided??? Its all personal choice All the Best |
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The master cylinder return spring is pretty weak, and a little binding can prevent total return of the piston, which is needed to un-port the pressure relief. |
Leave them stock
I agree with Kirk Groves. I have over 500 hours on my RV-8 with stock rudder peddles and I have had no problems applying brake when I just want rudder. I think that stock peddles work very well. I wouldn't change a thing about them.
Dan Miller |
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I have pedal extensions which I installed before I flew an -8 (based on Randy Lervold's design). I have also flown -8's with stock pedals. I like my pedal extensions because they fit the geometry of my ankles and feet - I fly with my heels on the floor, and the tips of my toes on the extensions. I have no problems with sliding my feet up to tap the brakes when I need them - but again, this is very, very dependent on your personal foot geometry. Fortunately, the rudder pedals can removed with about an hour's work through the forward baggage compartment, so you aren't stuck with how you do them if you decide to change later on. Experiment until you get them right! Paul |
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Just corrects any misalignment that may have crept in due to two bolts being used. |
Bill:
My 2 cents is the issue is the master cylinders not the pedals. Some (like me) have had master cylinders that tend not to fully release and thus drag the brakes. Most posters seem to agree that it is due to weak return springs on the Matco cylinders. No matter how I positioned my feet on the pedals including tips of my toes only on the lowest point of the rudder bar, I still had the problem. I changed to the Grove replacement cylinders and haven't even thought about it since. Chris |
O.K., perhaps I spoke too soon---------should know better than to disagree with Paul:rolleyes:
I was looking around in the archives for photos of the long bolt fix. (scroll down to post 3). And I ran across another thread that shows a -8 setup. It appears that the 8 is not like the units posted in the above link. Is the pivot bolt/bolts in front of the pedal in the 8, or is this just a weird angle that makes it look like it is in front??? http://img147.echo.cx/img147/8898/rv...armockup2t.jpg |
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This a completely separate issue from the "inadvertent braking" / geometry issue. |
Thanks Buck.
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Even with 60+ trips around the sun, still learning. |
I think it may depend on which style of pedal you're using. I had this discussion with Danny King a couple of years ago and it seems to me that this problem of inadvertent brake application is more pronounced on the ground adjustable pedals. I have the ground adjustable (floor mounted) pedals on my -8 and they exhibit the exact same problem I had with my very early -6 which had floor mounted pedals. The geometry between the pivot point of the pedal and the base pivot point of the master cylinder allows for inadvertent brake when you apply rudder. The brake pedal is forced by the master cylinder to articulate back towards your foot. The more rudder input the further the brake pedal articulates back. Your foot is not able to bend back enough to avert applying brake pressure.
I installed Randy's extensions and like Paul I keep my heels on the floor. I can push the extensions with the balls of my feet and not apply any brake. However, it is quite easy to roll my toes forward and apply brake pressure if necessary. I agree with Paul, if you don't like the extensions they're very easy to remove. |
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NO WAY! Never would have guessed that. Hope I look as "young" in 20 years! :cool: Joe PS. Good topic, I've been researching this in the last week or two. |
Hey Rick!!! Laura saw your post and wanted to tell you hello from Bahama Mama:D
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Off topic....sorry
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Mods
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You never accidentally get on the brakes. If you need 'em; they're right there. If you don't like them take them off. I think you will like them tho. |
Unintended consequences
If you put lower brake pedal extensions on your RV-8 pedals, you will not be able to stick your feet through the holes below the pedals, and stretch out your legs on those long flights. Before you do this mod, sit in your plane and put your feet through the pedals and rest your heals on the tubes.
I have flown three RV-8s with extensions including Iron's. I vote to not modify Van's design. |
Bill,
Six years ago during the test period I noticed that the aircraft would almost come to a complete stop when I attempted to do a 180 on the runway. During subsequent flights I noticed that the aircraft accelerated when I took my foot completely off the opposite pedal during the turn. My big feet were causing the brakes to drag. I put a 1X1X1/8" aluminum angle on the bottom of the pedal with two bolts, so the arch of my foot would push on the horizontal portion of the angle. This meant that the force was applied below the fulcrum of the pedal and the brake rod was pulled up, not down. I believe the different opinions are the result of the fact that the standard geomerty works for some and some not. The angle works great for me. If interested email me at jpthornton@fone.net and I'll send you a picture. Jim |
to all
many years ago I installed spacers (two inch nylon rod,drilled,split, then clamped to the rudder pedals) with much success,, when building my 7 I went with a set of the Cleveland pedals,,, I like them but they have two drawbacks, one, they are heavy, second and the worst, one can get a toe stuck in part of the pedal just when you need to get on the brake . don't ask.... but that was one ugly landing at 52f... thanks Rod I'm glad you a CFI |
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