What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Help! Wrong Hinges On Rudder ?

Toobuilder

Toobuilder

Well Known Member
Based on the problems with the elevators last flight, this morning I removed the rudder to lube/inspect. Found two GMM-3M-670 rod ends and one -670. This can't be right according to plans, right? The -680's were barely hanging on with only 3 threads engaged in the nutplate! :eek: At least the jam nuts were tight.

2132ozn.jpg



So, assuming this is NOT according to plans, where are the shorter -670's used so I can go hunt for my two missing -680's?

Otherwise, I'm ordering a new set from Spruce.

Thanks
 
From my experience. What you have is correct. Sometimes it is noticed that the vertical is not trimmed enough forward at the top so the bearings in the rudder are not installed in as far in as they should be. The bottom bearing is longer so to accommodate the rudder horn. Some builders have installed the longer bearings in the top and center because of the issue you have come up against. Larry
 
I just finished the rudder on my RV-7. DWG-7 calls out MD3614M rod end bearing for the top 2, and a larger MD3616M at the bottom. At each location there is a unique spar web-to-bolt-center dimension. You need a set of plans to determine the proper rigging. I don't know the details of your RV-8, but I wouldn't be concerned about different hardware in different locations.
 
OK, weird.

However, these top hinges are only catching a few threads and that is a major problem in my book. Going to have to look at this more carefully, because there is not much room to bring the rudder forward. Certainly not enough to get the threads fully engaged, anyway.

Thanks much for the heads up!
 
larharris2 said:
I just finished the rudder on my RV-7. DWG-7 calls out MD3614M rod end bearing for the top 2, and a larger MD3616M at the bottom. At each location there is a unique spar web-to-bolt-center dimension. You need a set of plans to determine the proper rigging. I don't know the details of your RV-8, but I wouldn't be concerned about different hardware in different locations.
Click to expand...

Just for a data point. My 8 plans show the same set up. 14s for the top and middle and 16 for the bottom.
 
Toobuilder said:
OK, weird.

However, these top hinges are only catching a few threads and that is a major problem in my book. Going to have to look at this more carefully, because there is not much room to bring the rudder forward. Certainly not enough to get the threads fully engaged, anyway.

Thanks much for the heads up!
Click to expand...

Each is set at a specific distance from the attach bulkhead. I made a couple wood jigs with a bolt inserted in a hole to get them near that distance. Later today I will find that specification if you need it.
 
I'm at a disadvantage without plans, but is there any reason why the longer rod ends are not used on the top? Is there some structure aft of the rudder spar that the longer shank would interfere with? In other words, if you had say a half inch of thread protrusion through the nut plate, would that be bad (aside from dead weight)?
 
I recommend getting and having plans on hand so that the issues that come up can be addressed properly. If the parts are assembled per plans and the correct measurements are obtained from the plans, the supplied parts should work just fine. I have and others as well have seen your scenario pertaining to the rod end bearings way to many times. Please get a copy of the plans and go from there and maybe ask a seasoned builder to look it over. :) Larry
 
FWIW ... I put those rod end bearings in my -7 rudder a few months ago and I had to run them in until the threads were nearly invisible to make the dimensions called out in the plans. I only had to tighten the jam nut a turn or two to lock it down.
 
Last edited:
Rod End Bearing Length

If you feel uncomfortable with how many threads are engaged, I recommend purchasing a couple of the longer ones and simply replacing them. It's a small price to pay for "peace of mind" don't you think? :rolleyes:

Good luck.
 
wjb said:
FWIW ... I put those rod end bearings in my -7 VS a few months ago and I had to run them in until the threads were invisible to make the dimensions called out in the plans. I only had to tighten the jam nut a turn or two to lock it down.
Click to expand...

Good data point! There's no way I could do that here. The rudder would be jammed against the fin long before that. I suspect regardless of the hardware callout on the plans, I'm now stuck with a "custom" solution. I'll consult the plans, but I suspect replacing the upper rod ends with a longer version will get me where I need to be.
 
grayforge said:
You may already know this, but you can purchase individual plans pages from Vans for $3 apiece.

http://www.vansaircraft.com/cgi-bin/store.cgi?ident=1376236170-120-186&browse=gifts&product=ppset (Bottom item on the page)

I ordered replacements this way when fiberglass hardener leaked onto and gummed up a dozen pages of mine. :-(
Click to expand...

I was not aware of this, thanks for posting it.

I took the liberty of copying it into the "RV Building Tips/Techniques" forum, so it can be found easier.
 
Because of this VAF thread I checked my rudder Heim joints and found that the bottom one was only threaded in three threads also! The others were five threads. The bottom one was the wrong p/n but all three had no more room to turn them in further with the lock nuts. Not having them at least extending through the plate nut will not be acceptable to me. I'm ordering three MD3616's.

I'm not the builder of my plane so I may have over looked this problem.

Michael, I'm glad you posted when you did. This sort of info. saves lives!
 
Zero4Zulu said:
Because of this VAF thread I checked my rudder Heim joints and found that the bottom one was only threaded in three threads also! The others were five threads. The bottom one was the wrong p/n but all three had no more room to turn them in further with the lock nuts. Not having them at least extending through the plate nut will not be acceptable to me. I'm ordering three MD3616's.

I'm not the builder of my plane so I may have over looked this problem.

Michael, I'm glad you posted when you did. This sort of info. saves lives!
Click to expand...

Something doesn't make sense ... just did a visual on my -7 rudder; the bottom rod end bearing is the only one visible from both sides. I have at least 3 threads above the lock nut and 3-4 threads protruding from the *back side* of the nutplate ..this seems like a great engagement to me for the MD3616M rod end bearing! I remember a similar "deep" engagement for the other two 3614's as well. Did you guys get shorted (literally) on your rod ends?
 
Beats the heck out of me what is going on there, but I did find an acceptable, if not perfect, compromise. I have the "small" rod end back in the top and I can just barely get full thread engagement. I did have to sand the fiberglass tips due to a slight interference, however. I had to use the "large" rod end in the middle though. Not super happy about this because the ball end is slightly wider than the hinge brackets and does spread them out a little. At least it's rigged straight and I don't feel like the rudder is going to fall off now!

...and to think of all the times I've had this airplane to VNE... :eek:
 
Toobuilder said:
Beats the heck out of me what is going on there, but I did find an acceptable, if not perfect, compromise. I have the "small" rod end back in the top and I can just barely get full thread engagement. I did have to sand the fiberglass tips due to a slight interference, however. I had to use the "large" rod end in the middle though. Not super happy about this because the ball end is slightly wider than the hinge brackets and does spread them out a little. At least it's rigged straight and I don't feel like the rudder is going to fall off now!

...and to think of all the times I've had this airplane to VNE... :eek:
Click to expand...

I'll be doing the same thing. I can live with the top bearing engagement. The bottom rod end was the 3614M. No idea why the builder did this but with everything else I have found wrong on this plane I'm not too surprised.

For the middle bearing, I can put the 3616M on my surface grinder with a fixture and reduce the width of the bearing .015 per side.
 
RV9 rudder

I am installing the same rod ends on my 9 rudder 14s at top and mid. 16 on the bottom.
My problem is I don't see any starting dim for the rod ends on my plans page 7 as the instructions say to use
Can someone give me the dim.
 
By memory there is a measurement from the forward face of the spar web to the center of the hole in the rod end! I've checked mine and they have plenty of engagement. DWG 7 will have the call out's.

Gibbo
 
Rudder hinge bolts

I am doing my first tail section. I found that the nut plates and hinge bolt take way too much force to put together. My part members are k1000-6 and md3614m . Do the plate nuts need to be taped? What is up? Thanks CHS
 
You must log in or register to reply here.
Back
Top