Z

ZU-RVZ

Member
Hi,

Recently I posted a thread on tire wear that did not solve my problem.

I have a 7A and have managed exactly 76 landings since new on a set of brand new Air Hawk tires. There is canvass showing on the left tire. Tire pressure 40psi.

Today I removed the wheel pants to put the new tires on and noted a severe visible toe-in on the tires, more on the left than the right. The tire wear was also worse on the left than the right.

I calculated a 2.54 degree toe-in on the left and 1.64 degrees on the right.

Measured at a forward datum of 70" forward of LE, and an aft datum in under the tail tie down, the wheel tracks almost 9.6inches off center!!

When the aircraft is pushed backward the tire bends outward as if trying to climb off the rim, and inward when pulled forward.

Obviously my tire wear is not landing related but they wear during taxi, which is a very short distance at a remote airfield.

I have e-mailed Van's and the leg manufacturer and they do not have a conclusive answer. The one thing that Van's did state is that the toe-in should be almost 0.

One theory is that I was supplied with legs for a 9A and not a 7A but I doubt whether the difference between designs could cause this much toe-in.

Has anyone else experienced this and how would you suggest a fix?

I am not keen on spending loads of money on new tires every 40 hours!

I cannot post attachments but will e-mail the measurements on CAD or JPEG if anyone can offer advice.
 
Toe in

2.5 deg seems alot on one leg, make sure you measure with the wheels off the ground. I drilled my mounts using 1/8 inch shim to set .75 deg toe as stated in the plans #$$#@$ oops that should have been 1/16 inch (3 Deg Total Toe-In plans call for 1.5 Deg). I called vans a they said move on. Got about 120 hrs on RV6A and only now am I starting to show any ware, guess I will rotate next inspection.
 
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Old vs. new design

I am not sure this helps and in no way implying this is the case but something to consider.
The gear legs that were sent to me for my 9A were of the "old" design. The only way we discovered this is due to the fact that we are building two 9A's side by side. The toe in was very noticable. We took careful measurements and Van's sent us new gear legs and I sent the old design back. Van's could not figure how I got these from the factory. They did credit the shipping back to my account.
Just a thought. Hope this helps.

Pat Garboden
Ozark, MO
 
Thanks Gorbak.

My kit was shipped in 2003. When was yours shipped?

Vans would probably help me too and have requested that I take measurements of gear leg angles.

This will involve stripping the gear leg fairings and brakes which I suppose I'll have to do.

Any additional comment will be welcomed.
 
Your are right to try and find a fix to this. Toe-in is not good for your tires or the handling/landing qualities of your airplane. The Rocket guys have had to fight this issue as well because of the titanium gear legs and their flexibility.

Generally, toe-in greater than a 1/2 degree is undesirable. For the most part, it is kind of tough to notice the difference until you fly an airplane that has zero toe-in. When landing and taking off, the downwind gear leg, if the maneuver is not coordinated with the wind, will have a tendency to "dig in" due to the toe-in. It makes the airplane handle in a less desirable manner than it is capable. It also affect the way it taxis too.

We measure our toe-in and camber with the airplane in the three-point position fully loaded with fuel.
 
ZU-RVZ

I ordered the fuse and wing kit prior to year end 2003 to save the price increase. Sounds like our kits were delivered near the same time.
Yes, you will need to raise the plane off the ground, remove the wheels, brakes and such in order to get the proper angle measurement. Sounds like you need to remove the wheels anyway to replace the tires.

We would not have noticed this had we not had two nearly identical planes sitting side by side. There was a remarkable difference in how the wheels sat on the garage floor. We just were not sure which was incorrect until we got the correct angles of the gear leg from Van's. Good luck and let me know if this is the issue.

Changing these out did not take much time what so ever. Van's worked with us and immediately got new legs on the way, and asked that we returned the old legs in their crate.

Pat Garboden
Ozark, MO

RV9-A 942WG (reserved) O-235 w/ slider paint stage
RV9-A 942PT (reserved) O-320 w/tip-up wiring stage
 
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