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prkaye

Well Known Member
I have been doing some preliminary cutting of my wheel pants, figuring I'll do the final alignment and drilling after the plane is assembled. In doing the preliminary fitting, I have discovered that my main wheels are not straight, relative to the center line. They are angled in towards the front, one more so than the other. Is this normal? DWG C2 suggests that the tires should be parallel to the centerline. Will this work itself out when I do some taxiing, allowing things to work into place??
 
It won't really work itself out.... It'll wear tires pretty bad, and create a bigger load on the nosegear. I work on a 6a that has this problem. What you are describing is called toe-in.
 
Yikes! So what can I do about it?? The toe-in seems to be permanently built-in to the fuselage-gear leg assembly.
 
My RV-8 instuctions describe a method to measure for toe-in or out and Van's sells wedges to correct this; they go between gear and wheel mounting when you bolt them on. I believe they come in 1/2 and 1 degree sizes. I bought some to correct mild toe in but haven't used them yet. Bill
 
Darn... should have payed more attention to this when I was installing the gear legs!!! ARG!
My VERY rough measurement with the plane sitting on my uneven floor with no wings on - I measured by holding a long straight-edge along the side of hte tire - gives me a little less than 2 degrees toe-in on one wheel (about 1.8) and a little more than 2 degrees on the other wheel (about 2.2).
Can this be corrected later with shims for the -9A?
 
check it again at full weight

Phil,
it is possible that the angles may change with load - camber will change, which I think will affect toe in/toe out - I would be inclined to wait until you have the wings on to see what the final situation is before panicking (not to suggest that you are panicking), and adjust toe-in with the aircraft close to or at a flying weight and rolling attitude.
Bill Brooks,
Ottawa, Canada
RV-6A finishing kit (and not having measured toe in yet, but crossing my fingers)
 
wait

Given the robust manufacturing process, I wouldn't worry about the wheel geometry until the finished plane has been rolled around and the gear legs have moved into their final position.
For your own peace of mind, verify the gear leg mounts are properly attached to the center section and not hung up on a rivet head.

Steve
 
I would not mess with fixing this until you have finished the airplane and filled it with fuel. Leave the wheelpants and gear leg fairing stuff until after you have fixed the toe-in. With the airplane weighted down to your typical landing weight, set to the toe to be as close to zero as you can using grease plates on the floor and axle shims from Van's. Once that's set, then mount your wheelpants or otherwise, they won't fit back the same way.
 
Not sure if axle shims are available for the -9A. They only list them for the -8 on their webstore.
 
nose wheelpant tight fit!

I finding the nose wheelpant is an insanely tight fit around the brackets. I haven't yet been able to stretch it over the brackets for fear of breaking it. Is this common?
 
Once you cut enough material from the bottom of the rear pant half to provide adequate clearance for the tire, it should be easier to stretch onto the brackets.
 
I know that Grove has some axle shims for their axles. Not sure who's axle you are using on the -9A but I'll bet the manufacturer has some type of shim available. This is a very common problem and the typical solution.
 
Yeah, what Jason said. Also do you have the new style brackets? If so, these brackets will allow you to just remove the hex cap screws (that the tow-bar go on) and the wheelpant will slide aft off the fork...no need to spread anything once you're done.
 
if you really want to check alignment

A great way is to use 'grease plates'. Get 4 pieces of scrap heet metal, usually steel and at least a foot square, and on each side make a sandwich of 2 plates with some grease in between...and roll the airplane on that. That truly alows the wheels to float properly and you can measure toe in or out etc. Rolling the airplane back and forth may or may not find a neutral position, I wouldnt shim until you really know where the gear is on greaseplates etc.

Tim
 
yeah, now that I've removed material for tire clearance, it fits.

I tell ya', I'm goign to be glad I spent these couple of days doing preliminary work on these fairings and pants when I'm out at the hangar and have to stop flying to finish these!!
 
f1rocket said:
I know that Grove has some axle shims for their axles. Not sure who's axle you are using on the -9A but I'll bet the manufacturer has some type of shim available.
Click to expand...

Is that even possible with RV gearlegs other than the ones used on the 8? On the other types, the leg and axle are one unit:

20080113_gearlegs2.jpg
20080120_gear.jpg


Seems like the remedy for a misaligned gearleg of this type would be trickier, if indeed it has occurred here.

mcb
 
Phil,

You only need to worry about the pants in flight. They should hang in the same place with no weight on them. When building, the wheels tend to be in the wrong position because of the weight on them.

Also, as you found out, the shims are only for the -8 and are not available to those of us with the tapered gear legs.
 
Wheels in line with load, wheel pants in line w/o load

In regards to the main gear legs, due to the geometry they will flex under load to give you the correct toe. However, as mentioned, you want the wheel pants to be aligned with the airflow when in the air and the gear legs are not loaded. The wheels will not be exactly aligned with the wheel pants due to this difference.

Also, allow plenty of opening clearance to the tires. I set my 1/2" opening with no load and ended up rubbing when finally installed with load on the tires and slightly low in pressure. I had to cut another 1/2" all the way around.
 
The axels on an RV-9 are one piece tubular and not aligned with shims like an RV-8 which has a flat gear with seperate axels and, I presume, shims between them for alignment. The axels on an RV with tubular gear legs needs to be carefully aligned and then the bolt holes marked and drilled.

What I would suggest doing, if the alignment is still off after checking at gross and after taxi tests etc., would be to call Van's and ask if the Piper Factory alignment method on PA-18 Super Cubs could be used to align your axels. A pipe 10 feet or so long is inserted into the axel and the "armstrong method' is used to twist the axel to the correct position. Crude but effective if Van's OK's the procedure. That was Pipers solution on the factory floor.
 
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