I just installed rudder pedals in my Smith cub. The left side front has a lot of friction even after adding washer shims stacked 2 high on the spring side. Seems to be some kind of interference with the spring tang going forward on the bracket rubbing the side of the clamp. The spring pushes the pedal forward with a nudge, but it sure has a lot of friction in the process. Can anybody describe how free the rudder pedals should be? Any opinions appreciated.
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Cub Rudder Pedal Friction..how much is too much?
- Thread starter bsantana
- Start date
Rudder Pedal Return
Thanks T.J. It doesn't seem like Piper gave much thought to this lash-up!
I don't have any lateral movement in the rudder pedals. I'll see what I can do to free it up. I had one suggestion of beating on the clamp with a rubber mallet as it is installed. The spring tang is flat on the top of the clamp in the left pedal installation. That may be causing the spring to be too low in the gap.
Thanks T.J. It doesn't seem like Piper gave much thought to this lash-up!
I don't have any lateral movement in the rudder pedals. I'll see what I can do to free it up. I had one suggestion of beating on the clamp with a rubber mallet as it is installed. The spring tang is flat on the top of the clamp in the left pedal installation. That may be causing the spring to be too low in the gap.
Bugs66
Registered User
Spokane WA
I am in the same position as Barry was over a year ago. My rudder pedals have some friction. If I pull back on them they do spring back but with some resistance. What is the right amount of play? Should they be totally free spinning or is some friction normal? I haven't shimmed any yet.
Thanks for any help.
Thanks for any help.
Fortysix12
Registered User
RanchAero Grand Vista, Brooksville
They should be loose enough that when you pull it back with your index finger it should spring back with a snap. But not so loose that you could shake them up and down with play.
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
Had the same problem. The spring is being pinched between the mounting plate and the pedal tube which then binds the tube and prevents free movement. The spring is about 30 thousandths thick and the gap is about 10 thousandths. Used washers to increase gap and VIOLA it works fine no binding at all.
Bill
Bill
behindpropellers
Registered User
NE Ohio
I had to grind some of the weld off of the peddle to get mine to fit. The new univair springs have a bigger wire dia. than the original ones.
Tim
Tim
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
Tim
I purchased springs from Stoddards and after getting binding I followed some advice and purchased a set of springs from Univare. Turns out they are the same. But, according to the Northland plans the coils are further apart than the original Piper spring making the spring wider which is contributing to the binding. I spoke to Steve Tubbs and he said that this had not been a problem for him, soooo....I am doing something wrong or have some incorrect parts or something.
I called Wayne at TCOW this afternoon and am working with him to see if we can find a good solution. TCOW has been excellent to work with so far.
Bill
I purchased springs from Stoddards and after getting binding I followed some advice and purchased a set of springs from Univare. Turns out they are the same. But, according to the Northland plans the coils are further apart than the original Piper spring making the spring wider which is contributing to the binding. I spoke to Steve Tubbs and he said that this had not been a problem for him, soooo....I am doing something wrong or have some incorrect parts or something.
I called Wayne at TCOW this afternoon and am working with him to see if we can find a good solution. TCOW has been excellent to work with so far.
Bill
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
Update
Well.....turns out a welder at sometime in the past had a bad hair day and welded my rudders up a bit askew. TCOW offered a new set no charge and was super nice to work with. I think it will be faster for me to fix this one.
Chris, what I was doing that I did not feel good about was putting washers between the fuselage mount tab and the saddle. This enlarged the gap enough for the spring to go under the mount tab. It workes but is not the right way to do things. I will reweld the pedals to get things right. The right pedals are close enough that it will be easy to fix the left pedals will require a bit more work. Note in the photo how the left pedal does not have enough room for a spring.
Hope this helps you folks out there
Bill
Note that the spring is under the tab. Not good.
No room for a spring. Will reweld the rudder to move it to the left.
This is the right pedal. Note the room for a spring.
Well.....turns out a welder at sometime in the past had a bad hair day and welded my rudders up a bit askew. TCOW offered a new set no charge and was super nice to work with. I think it will be faster for me to fix this one.
Chris, what I was doing that I did not feel good about was putting washers between the fuselage mount tab and the saddle. This enlarged the gap enough for the spring to go under the mount tab. It workes but is not the right way to do things. I will reweld the pedals to get things right. The right pedals are close enough that it will be easy to fix the left pedals will require a bit more work. Note in the photo how the left pedal does not have enough room for a spring.
Hope this helps you folks out there
Bill
Note that the spring is under the tab. Not good.
No room for a spring. Will reweld the rudder to move it to the left.
This is the right pedal. Note the room for a spring.
Bugs66
Registered User
Spokane WA
Thanks for the photos Bill. I made some 5/8d x.032 SS washers as per the Piper drawings. You are permitted to shim up to .032 (as far as Piper says). My pedals have nice movement now. When I welded my tabs I used a jig that was to Piper spec. No problems with my tabs.
Stealthchicken
Registered User
Friendswood, TX
What are the rest of you doing for the pedal shims? The AN960-10L washer is the right thickness (~.032) but its O.D. is too small (according to the drawings). An AN970 washer just won't work. So for those that don't want to fabricate their shims--do you cough up roughly $2 per washer?
I didn't take much notice when I dismantled, took a hundred+ photos, but not a single one shows the pedal spring installation.
I reckon I've got it wrong. Should the spring go outside of the mounting lug?
It looks as though the lug flange needs bending back a tad. As it is, the spring gets trapped between the pedal bearing tube and the lug unless I use many more washers than I took out.
Thanks
Bill
I reckon I've got it wrong. Should the spring go outside of the mounting lug?
It looks as though the lug flange needs bending back a tad. As it is, the spring gets trapped between the pedal bearing tube and the lug unless I use many more washers than I took out.
Thanks
Bill
mike mcs repair
Registered User
chugiak AK
S2D said:
and? are you going to offer them for us yet?
Ok, mods apart, how did the Piper factory fit them? I couldn't find anything in the archive to show this. I've tried squeezing one up to go outside, but it's not happy about it.
Bill Rusk's picture above shows it fitted inside the lug. But unless the saddle is spaced more than 94 thou wire thickness, it's going to bind when the clamp is tightened.
S2D, your spring looks good with the coils closer together. Looks like they'll fit so the straight parts are outside the lugs. Double-sided and one less turn will give more than 2 times the stiffness, if it's the same wire. Guess that doesn't matter as left and right pedals balance each other out.
Bill
Bill Rusk's picture above shows it fitted inside the lug. But unless the saddle is spaced more than 94 thou wire thickness, it's going to bind when the clamp is tightened.
S2D, your spring looks good with the coils closer together. Looks like they'll fit so the straight parts are outside the lugs. Double-sided and one less turn will give more than 2 times the stiffness, if it's the same wire. Guess that doesn't matter as left and right pedals balance each other out.
Bill
Nice to see some improvements in this area. I always thought that a delrin busing through the center of the petal tube with a bolt like a Axel would work much better, no drag at all on the petal, there would be some fab involved and weight would probably be a wash vs the 4 bolts a shims ect. Then you could use those 2 holed straps for what they were designed for Holding Up Conduit.
NimpoCub
Registered User
Nimpo Lake, BC . . . AKA "the Floatplane Capital o
I love STD's spring, wish I'd seen that when I had mine apart.
Fitting those springs & getting rid of the pinch points wasn't my best day in the refurb. process, but I did 'er.
I also noticed just barely enough tension to pull the front pedals back, so I bent the spring ends (the 90* bend) over the front bottom cross member & covered it with a piece of hard plastic to prevent chafing. Helped a lot, now my pedals keep that cable nice & snug.
STD, that's a saleable invention. Oh, and how did your adjustable elevator tensioner work out??
Fitting those springs & getting rid of the pinch points wasn't my best day in the refurb. process, but I did 'er.
I also noticed just barely enough tension to pull the front pedals back, so I bent the spring ends (the 90* bend) over the front bottom cross member & covered it with a piece of hard plastic to prevent chafing. Helped a lot, now my pedals keep that cable nice & snug.
STD, that's a saleable invention. Oh, and how did your adjustable elevator tensioner work out??
Stew
GONE WEST
Haywards Heath, UK
Rudder Pedal Return Springs
I have the correct shim washers (3 thicknesses) and assembled the pedals without the new Univair springs and all free and good.
Thought it would be a matter of adding the spring to the front LH pedal and move on to the next pedal.
Four hours later I knew it was time to walk away and think about it as I just couldn't seem to get the spring to look and sit correctly plus operate smoothly.
This is an old thread and saw that Bill was not happy either so it must be an issue, anyone got any good steers on what way to go on this.
Kind regards
Stew
I have the correct shim washers (3 thicknesses) and assembled the pedals without the new Univair springs and all free and good.
Thought it would be a matter of adding the spring to the front LH pedal and move on to the next pedal.
Four hours later I knew it was time to walk away and think about it as I just couldn't seem to get the spring to look and sit correctly plus operate smoothly.
This is an old thread and saw that Bill was not happy either so it must be an issue, anyone got any good steers on what way to go on this.
Kind regards
Stew
Last edited:
Stew
GONE WEST
Haywards Heath, UK
Rudder Pedal Return Springs
Further to my previous post, the 4 Univair replacement springs are not working out for me at all. I can fit them and have the pedal all shimmed up correctly but it just does not sit or feel right, so it isn't right.
I contacted a few short run spring manufacturers here in the UK and they will easily set up the CNC machine and form a dozen from the original drawing but there is a significany cost, however, to get a 1000 they are about $1.50 each.
Question is, if they were made exactly to the original Piper drawing, would they be significantly better? Has anyone any experience with the original Piper springs? I am going to accurately measure the Univair spring when I am in the hangar at the end of the week and see where they are different.
It would be a big ask to get the manufacture approved here in the UK, far easier for Univair to just do a re-run of the spring if their offering at the moment is not accurate.
Interested to hear your take on this.
Kind regards
Stew Edwards
Further to my previous post, the 4 Univair replacement springs are not working out for me at all. I can fit them and have the pedal all shimmed up correctly but it just does not sit or feel right, so it isn't right.
I contacted a few short run spring manufacturers here in the UK and they will easily set up the CNC machine and form a dozen from the original drawing but there is a significany cost, however, to get a 1000 they are about $1.50 each.
Question is, if they were made exactly to the original Piper drawing, would they be significantly better? Has anyone any experience with the original Piper springs? I am going to accurately measure the Univair spring when I am in the hangar at the end of the week and see where they are different.
It would be a big ask to get the manufacture approved here in the UK, far easier for Univair to just do a re-run of the spring if their offering at the moment is not accurate.
Interested to hear your take on this.
Kind regards
Stew Edwards
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cubdriver2
FRIEND
upstate NY
Stew
GONE WEST
Haywards Heath, UK
Glenn, Bill, Jim, thank you so much for the input and all very good stuff which I have absorbed.
With the rotating surfaces cleaned back to bare metal, fitted with minimal shims as necessary (0.032"/0.015"/0.010") and torqued up I can get the pedals installed and rotating freely without the springs.
Given that the pitch of the coil windings on the Univair spring is allegedly greater (less coils per inch) than the original, clearly more space is required on the spring side of the pedal between the pedal upright and the fuselage tab than if fitting the original Piper springs.
I am back at the hangar on Friday and armed with your inputs I am going to grind the "stop" off the old pedal and assemble it sliding the upright pedal tube over to give more clearance for the spring and weld a new stop in place and see if that sorts it, and confirm that is where the problem lies. It is my understanding that Bill effectively did this to get a reasonable fit. I will also measure/draw the Univair replacement spring and see where the differences are from the Piper drawing.
I can only assume everybody comes up against this and solves it in their own way, to their own satisfaction/standard.
Kind regards
Stew
With the rotating surfaces cleaned back to bare metal, fitted with minimal shims as necessary (0.032"/0.015"/0.010") and torqued up I can get the pedals installed and rotating freely without the springs.
Given that the pitch of the coil windings on the Univair spring is allegedly greater (less coils per inch) than the original, clearly more space is required on the spring side of the pedal between the pedal upright and the fuselage tab than if fitting the original Piper springs.
I am back at the hangar on Friday and armed with your inputs I am going to grind the "stop" off the old pedal and assemble it sliding the upright pedal tube over to give more clearance for the spring and weld a new stop in place and see if that sorts it, and confirm that is where the problem lies. It is my understanding that Bill effectively did this to get a reasonable fit. I will also measure/draw the Univair replacement spring and see where the differences are from the Piper drawing.
I can only assume everybody comes up against this and solves it in their own way, to their own satisfaction/standard.
Kind regards
Stew
Stew
GONE WEST
Haywards Heath, UK
Hi Mark
Indeed they are new pedals from Univair as the old replacement springs had sawn grooves into the old pedal bottom tubes.
Had an interesting time ordering them as Univair listed only LH ones for a while assuming that the pedals were universal. Have just sent 2 back and they now supply RH ones again.
Kind regards
Stew
Indeed they are new pedals from Univair as the old replacement springs had sawn grooves into the old pedal bottom tubes.
Had an interesting time ordering them as Univair listed only LH ones for a while assuming that the pedals were universal. Have just sent 2 back and they now supply RH ones again.
Kind regards
Stew
