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  #1  
Old 01-23-2009, 08:22 AM
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billdianne billdianne is offline
 
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Default 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?
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  #2  
Old 01-23-2009, 12:32 PM
KirkGrovesRV8 KirkGrovesRV8 is offline
 
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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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  #3  
Old 01-23-2009, 01:23 PM
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Quote:
Originally Posted by billdianne View Post
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.
Actually, the long bolt is a fix for the brakes sticking. The long bolt forces the pivot holes to all align up on a single axis----and the two bolt set up can have the axises at a slightly different position, causing binding in the pedal motion.

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.
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  #4  
Old 01-23-2009, 11:00 PM
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cdmiller cdmiller is offline
 
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Default 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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  #5  
Old 01-24-2009, 08:17 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Mike S View Post
Actually, the long bolt is a fix for the brakes sticking. The long bolt forces the pivot holes to all align up on a single axis----and the two bolt set up can have the axises at a slightly different position, causing binding in the pedal motion.
While this is a true benefit of the single bolt mod, most people that do the mod (as I understand it) are trying to prevent the inadvertent braking that can come from pressing on the pedals with the factory geometry.

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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  #6  
Old 01-24-2009, 09:44 AM
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Quote:
Originally Posted by Ironflight View Post
While this is a true benefit of the single bolt mod, most people that do the mod (as I understand it) are trying to prevent the inadvertent braking that can come from pressing on the pedals with the factory geometry.

Paul
Paul, the geometry does not change when going to a long bolt. Same pivot point, same throw, ETC.

Just corrects any misalignment that may have crept in due to two bolts being used.
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  #7  
Old 01-24-2009, 10:07 AM
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chrispratt chrispratt is offline
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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
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  #8  
Old 01-24-2009, 10:18 AM
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O.K., perhaps I spoke too soon---------should know better than to disagree with Paul

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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Flying as of 12/4/2010

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"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."

Last edited by Mike S : 01-24-2009 at 10:44 AM.
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  #9  
Old 01-24-2009, 11:22 AM
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BuckWynd BuckWynd is offline
 
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Quote:
Originally Posted by Mike S View Post
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???
You're correct. In the RV-8, the pivot bolts are on the front side of the pedals. A long bolt doesn't change the pivot point, and doesn't significantly change the way your foot sits on the pedal. According to some people, it may help prevent "stickiness" of the pedal.

This a completely separate issue from the "inadvertent braking" / geometry issue.
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Last edited by BuckWynd : 01-24-2009 at 11:24 AM.
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  #10  
Old 01-24-2009, 11:38 AM
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Default Thanks Buck.

Quote:
Originally Posted by BuckWynd View Post
You're correct. In the RV-8, the pivot bolts are on the front side of the pedals. A long bolt doesn't change the pivot point, and doesn't significantly change the way your foot sits on the pedal.
Thanks, learned something here.

Even with 60+ trips around the sun, still learning.
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Flying as of 12/4/2010

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Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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