7A main gear mount issue

[jmjula]

I know others have had similar issues to what I am seeing, so I am hoping for some advice. My left mount went in quite smoothly, but the right is not. It appears the lower web of the mount is preventing the lower holes from lining up. I am already using a floor jack to help get things into place, but it is not helping much. Any suggestions are appreciated.

 

[frankh]

Try this

Using a tapered drift pin (hardware store bolt, cut threads off and grind a bull nose on the remaining shaft) will pull the holes over. I can't honestly remember if there is a bolt that will hold just the mount in position when you remover the pin though...i don't think there is???...

Anyway, you can pull out the mount and gently bend the lower flange of the mount a little more.

Or try pushing out the side wall of the fuse using a bottle jack and piece of 2*4. Try to push from the LH mount rather than the oppositie fuse side.

My guess is ypu don't need much to get the weldment in there.

I do seem to remember grinding off just fraction of the holes on one of my lower weldment holes on the lower flange.

You might want to call Vans to check on which methods they would find acceptable.

Critical area, go slow.

FRank

 

[thallock]

James,

Yes, these can be a bit of a problem to get to fit. It looks like your problem is that you waited until after the bottom floor was riveted on to do the fit. This looked like it might be a problem to fit later, so I did this while the fuselage was on its back, before the floor was riveted on. It still took awhile to get everything to fit (one side went right on, the other side took a few hours of mucking with). Of course, this doesn't help you now.

What you need to do is to make sure that the hole in the floor and the F-704 flange has clearance all around the weldment where it sticks through the floor. This is a series of "put the weldment on, mark where it hits, take it off, file a little on the hole, put it on, mark, take it off..." One other thing that I did was to use a deburring tool to remove the paint from inside the holes on the weldment where the bolts go through. This helps a little for a few of the bolts that are a little off.

Good luck,
Tracy.

 

[frankh]

Ont he QB you have no option

You have to cut the hole and kind of wing it...There is a template on the drawing though which was approximatly correct.

Frank

 

[thallock]

Frank,

Yeah, that would make it a little more difficult. You still need to make sure the hole has clearance all the way around. It doesn't need much, but you do need to make sure the leg of the weldment is not being held out of place by the bottom skin or flange on F-704.

Tracy.

 

[Davepar]

Make sure the mount isn't interfering with one of the side skin rivets. I had some issues in that area and had to do some tweaking.

 

[David-aviator]

I'd remove the paint in the hole and it will probably go.

It's been a while, but there also is an issue with rivet heads on the floor skin in that area. Seems to me some had to be counter sunk on both sides like the rudder trailing edge wedge to make room for this piece to fit into that corner.

I know Van's does not approve, but I had to use a hand reemer on some of the holes to get the bolts in. And even after that, they were mighty tight. A rivet gun on very low pressure will tap, tap them in nicely.

dd
RV-7A
Troy, MO

 

[Jamie]

As mentioned before, check the side skin rivets.

Also check this rivet:

This picture should really be rotated counter clockwise 90 degrees...but you get the idea.

 

[jmjula]

Thanks for the replies. I had already done everything mentioned, so it was time for a bigger hammer, and better guide pin(s). I decided to make a set of three pins, all with different tapers. I installed the most shallow one first as far as could go, then hammer in a slight more agressive one, and then finally the last one I could get to go in all the way. This weldment is firmly in place now. Now on to fitting the wings....

 

[Pmerems]

The weldments aren't perfect!

I too had some problems with my RV-7A main gear weldments.

If I recall the plans mention opening up the through holes in the weldments if required. These holes are not precise close tolerance holes. Make the weldment fit the center section not the other way around.

I have considered reaming the weldment holes 016"-032" oversize so that the wing attach bolts slip right through the weldment. I believe they are already about .005" over sized right from the factory.

Don't force the bolts into the weldment, it may damage the center section!

Your mileage may vary.

Paul