RV-6A wheel installation issue (Jurassic problem)

[PaulvS]

Installing the main wheels on a -6A, the first step is to fit the U-403 flange brackets onto the axles to mount the brake calipers and the wheel pant brackets.

The gear legs have the holes already pre-drilled in the axles for the 5/16" bolt that pins the U-403 in place, and the U-403s that I just recently bought were also pre-drilled.

When the U-403s are mounted onto the axles the position appears incorrect and instead of being oriented vertically they are rotated forward by 27 degrees. The plans indicate that the bolt hole should be horizontal, however it is inclined 27 degrees, causing the flange to be in the incorrect position.

Normally in a situation like this I check to see what I did wrong. However, the gear legs are in the correct sockets L&R. The axles are also aligned, so the gear legs are oriented correctly in the sockets. The only thing I can think of is that the gear legs were drilled incorrectly at the factory. Anyone recall this happening before, mid 90s?

I've contacted Van's support over a week ago but no response yet, I guess they are busy dealing with the laser cut parts problems.

As for the remedy, I'm hoping to be able to re-drill the holes in the flange brackets to match the holes in the axle. I stripped off the powder coating and took the parts to a local TIG welder for him to fill in the existing holes. I'm hoping that there won't be any interference between the bolt and the caliper!

 

[AlexPeterson]

SNIP However, the gear legs are in the correct sockets L&R. The axles are also aligned, so the gear legs are oriented correctly in the sockets. The only thing I can think of is that the gear legs were drilled incorrectly at the factory. Anyone recall this happening before, mid 90s?SNIP

It's been about 24 years...but, how are you sure the L/R is correct? It's probably obvious when handling them, but I don't recall and I can't visualize the geometry just now.

 

[hgerhardt]

the U-403s that I just recently bought were also pre-drilled

Early 90's, none of those holes were drilled from the factory. So it looks like someone match-drilled the gear legs with the original U-403's and then lost those parts, causing you to buy new ones?

Rather than drill new holes in the gear legs, I'd try to match those holes to your new U-403's via Bridgeport mill. Or contact Van's engineering and see what they think about a second set of holes in the gear legs.

Also, I wouldn't worry about TIG-filling the existing U-403 holes. That will probably warp the tubes causing grief on assembly.

 

[PaulvS]

It's been about 24 years...but, how are you sure the L/R is correct? It's probably obvious when handling them, but I don't recall and I can't visualize the geometry just now.

The gear legs have the letters "L" and "R" stamped into the ends from the factory and I installed the L on the pilot side and the R on the co-pilot side. They also fit OK into the matching gear leg mount sockets.

 

[PaulvS]

Early 90's, none of those holes were drilled from the factory. So it looks like someone match-drilled the gear legs with the original U-403's and then lost those parts, causing you to buy new ones?

Rather than drill new holes in the gear legs, I'd try to match those holes to your new U-403's via Bridgeport mill. Or contact Van's engineering and see what they think about a second set of holes in the gear legs.

Also, I wouldn't worry about TIG-filling the existing U-403 holes. That will probably warp the tubes causing grief on assembly.

I'm the original owner and the gear leg bottom holes in the axles were drilled by the factory. The top holes were left for the builder to drill.

The U-403 flange brackets were nowhere to be found in the kits. I reviewed the shipping documents from when I did the receival checks and the u-403s were not listed at all on the picking list, for some reason, so I did not notice that they were missing. Same goes for the aluminum axle nuts. So I just ordered and paid for new ones.

I really don't want to drill another hole in the axle. In the email to Van's support I requested undrilled U-403s, in case the welding distorts the old brackets. I didn't want to leave the holes open because they are adjacent to where the holes should be, plus that would allow in dirt and moisture to rust the axle.

 

[hgerhardt]

Interesting on the factory holes...when was your kit produced?

My -6 is 21622 and I'm the 3rd owner of the parts so I don't know exactly when it was first sold. Would be interesting to know when the factory started drilling holes. Your kit must be one of the first ones.

 

[PaulvS]

Interesting on the factory holes...when was your kit produced?

My -6 is 21622 and I'm the 3rd owner of the parts so I don't know exactly when it was first sold. Would be interesting to know when the factory started drilling holes. Your kit must be one of the first ones.

My kit is 22320, emp/wing/fuse kits produced 1993-1994. Finishing kit was from 2000.

I also suspect it was one of the first to be drilled, at Langair who made the legs for Van's.
Perhaps they put the gear legs on a flat surface and drilled a plumb hole in the axle. The leg should have been tilted at 27 degrees instead, so the hole would be horizontal when the gear leg is installed.

 

[AlexPeterson]

The gear legs have the letters "L" and "R" stamped into the ends from the factory and I installed the L on the pilot side and the R on the co-pilot side. They also fit OK into the matching gear leg mount sockets.

Thanks - maybe since you are "down under" they are mis-marked

Just for sport - you have tried them swapped left/right?

 

[lr172]

I
I really don't want to drill another hole in the axle. In the email to Van's support I requested undrilled U-403s, in case the welding distorts the old brackets. I didn't want to leave the holes open because they are adjacent to where the holes should be, plus that would allow in dirt and moisture to rust the axle.

As long as you have adequate edge distance for the new holes, I would not weld the old ones shut. There are several methods to keep corrosion at bay. Just use grease on the shaft before installing it. That is not an interference fit part, so moisture can get in there, even without the extra holes. Welding the holes shut is likely going to create some work to get the part to fit on the axle.

 

[PaulvS]

As long as you have adequate edge distance for the new holes, I would not weld the old ones shut. There are several methods to keep corrosion at bay. Just use grease on the shaft before installing it. That is not an interference fit part, so moisture can get in there, even without the extra holes. Welding the holes shut is likely going to create some work to get the part to fit on the axle.

There's not enough edge distance for the new holes, unfortunately. The holes will be filled with some 5/16 discs rather than full build up using welding rod. I'm hoping Van's will respond with undrilled U-403s in case the welding distorts the fit. The welder guy is very good and is going to try and minimise distortion.

 

[PaulvS]

Thanks - maybe since you are "down under" they are mis-marked

Just for sport - you have tried them swapped left/right?

Maybe!

I haven't tried swapping left/right, too hard because the plane is on the gear and the axle bolt holes L/R are the same position (whereas they should be unique).

 

[rvbuilder2002]

The standard install of the gear legs on all of the airplanes with round legs results in the bolt that attaches the brackets being oriented such that it is parallel with the ground when the airplane is level at the longerons.

It looks to me like that would be the case if the were swapped from how they are now.

 

[PaulvS]

The standard install of the gear legs on all of the airplanes with round legs results in the bolt that attaches the brackets being oriented such that it is parallel with the ground when the airplane is level at the longerons.

It looks to me like that would be the case if the were swapped from how they are now.

It appears that both legs have been drilled the same since the bracket holes are perpendicular to the axis of both the leg and the axle, if that makes sense. In order for the bolt holes to be parallel with the ground the gear legs would need to be at a right angle to the fuselage and the resulting toe in (or out?) and camber would be extreme.

Swapping them over now isn't feasible because the socket mounting holes at the top won't line up, though it might prove the legs have been mis-labeled and the punch marks L and R are reversed?

 

[PaulvS]

Fixed by welding

This is just to close this out. The brake support flange brackets U-403 have been re-drilled in the correct position, after welding closed the existing holes.

The response from Vans Support about the gear legs was "Perhaps the L and R are incorrectly stamped?"

It seems this is a very isolated problem and it's highly unlikely that anyone else is going to be affected by this, now.

 

[KeithO]

Great to see you are making progress and working through all the "issues" on your scratch build...

 

[gasman]

I'm the original owner and the gear leg bottom holes in the axles were drilled by the factory. The top holes were left for the builder to drill.

The U-403 flange brackets were nowhere to be found in the kits. I reviewed the shipping documents from when I did the receival checks and the u-403s were not listed at all on the picking list, for some reason, so I did not notice that they were missing. Same goes for the aluminum axle nuts. So I just ordered and paid for new ones.

I really don't want to drill another hole in the axle. In the email to Van's support I requested undrilled U-403s, in case the welding distorts the old brackets. I didn't want to leave the holes open because they are adjacent to where the holes should be, plus that would allow in dirt and moisture to rust the axle.

I think Van's included them with the brake and wheel package.

 

[PaulvS]

Brake mounting

FYI the drawings and construction manual lack some detail for how the brake itself is mounted to the axle. Here are a couple of pics in case anyone else gets stumped. Fortunately I did not encounter any parts interference due to the non-standard hole position in the axle.
In hindsight, I think the U-403s could have been re-drilled on the other side, because they are symmetrical and there is a chamfer built into the brake that would slide over the welding bead.