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Main Gear Axle

T

todehnal

Well Known Member
I'm hoping to find a builder with a main gear axle available, who could take a few measurements for me. My 12 is flying, and I hate to take things apart right now. Since they come in the finish kit, they are usually not installed until late in the fuselage build sequence. I need the axle flange dimensions, and the bolt pattern. You guessed it. I would like to see if I can make my own axle shims, and I want them to be full flange shims. The measurements, or a print would be fantastic. Just think of what dimensions you would need to make your own.
Thanks for your help

Tom
 
Well. I decided to go ahead and remove my wheel pants and see if I could take some measurements. It was no problem. It looks like the axle base is 2" X 2" and the hole pattern has 1 3/8" center to center spacing, is located equal distance from the center and parallel on each side. I also took a measurement of the wheel camber. It measures a full inch from being perpendicular to the floor at the outside of the tire. Even with 2 aboard and full fuel, it still has a lot of camber, and my plan is to reduce that to a point where the tire will have a fully centered foot print at 1320 lbs............Tom
 
hard landing

Tom
I believe that the gear is stronger before it reaches the angle where the tires are vertical.
The gear needs to take up the force of a hard landing.
The tires need to get farther apart for the gear so spread.

On a hard landing the tires are not turning before touchdown, they have to slide sideways to let the gear absorb the load.

Interesting geometry

I would not change this without talking to the people at Vans.

my view

Joe Dallas

todehnal said:
Well. I decided to go ahead and remove my wheel pants and see if I could take some measurements. It was no problem. It looks like the axle base is 2" X 2" and the hole pattern has 1 3/8" center to center spacing, is located equal distance from the center and parallel on each side. I also took a measurement of the wheel camber. It measures a full inch from being perpendicular to the floor at the outside of the tire. Even with 2 aboard and full fuel, it still has a lot of camber, and my plan is to reduce that to a point where the tire will have a fully centered foot print at 1320 lbs............Tom
Click to expand...
 
Last edited:
Hi Tom,

While building my RV-12 the EAA tech councilors consulted to do periodic inspections during the build gave me a suggestion that seems to have merit when doing the gear alignment.

The suggestion was to use two one foot square pieces of greased aluminum plate under each wheel when making the alignment measurements. The idea being, the wheels will be able to "slide" to their natural position based on the amount of weight applied to the gear.

I have not personally tried this method yet .... but the logic seems sound, so plan to give it a go when I get around to tweaking the gear.
 
John-G said:
Hi Tom,

While building my RV-12 the EAA tech councilors consulted to do periodic inspections during the build gave me a suggestion that seems to have merit when doing the gear alignment.

The suggestion was to use two one foot square pieces of greased aluminum plate under each wheel when making the alignment measurements. The idea being, the wheels will be able to "slide" to their natural position based on the amount of weight applied to the gear.

I have not personally tried this method yet .... but the logic seems sound, so plan to give it a go when I get around to tweaking the gear.
Click to expand...

This is a fantastic idea. Thanks for passing it on. I will definetly follow through with it before making any changes. ..... Tom
 
Instead of greased aluminum plate, how about wood sitting on 2 or 3 short lengths of 1/2" or 3/4" pipe?
 
Yeah, I think the wood and pipe would work well also, with less cleanup. It may be a bit more challenging to get the mains up, and in place though
 
Actual hole pattern

The hole pattern is actually 1.370 center to center. Not 1.375. If you are going to be having the shims made at a shop that can measure that close it will make a big difference.
 
Richard@Langair said:
The hole pattern is actually 1.370 center to center. Not 1.375. If you are going to be having the shims made at a shop that can measure that close it will make a big difference.
Click to expand...

Thanks Richard. I would not have expected the 1.370" measurement. I recall an earlier post about someone who had shims made and stated that the hole pattern was a bit off. My guess is that they used 1.375. I won't make that mistake............Tom
 
Definitely keep us posted on this. It would be nice not to wear the tires so uneven.

Are you flying on pavement or grass?
 
All hard surface. Got 250 hrs on the first set, with lots of short flights, but with very little braking. The brake pads look like new. I just bought a couple of recaps from Desser. They look fantastic, and tough. Hope they hold up better than the originals............Tom
 
I went with these - Dresser 500-5 6 PLY AWBS RETREAD, ELITE PREMIUM 2 GROOVE. Needed to open wheel fairings for slightly oversize tire. Now have 20 hours of mixed grass and hard surface. I like them.
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I'm trying the same Dessers now. They are wearing significantly better than the original tires but the wear pattern seems to be a bit more even across the width of the tire than it was with the originals. Not sure it'll be worth flipping the tire on the wheel after the outer side is worn. Too early tell for sure though. Time will tell ...
 
John-G said:
Hi Tom,

While building my RV-12 the EAA tech councilors consulted to do periodic inspections during the build gave me a suggestion that seems to have merit when doing the gear alignment.

The suggestion was to use two one foot square pieces of greased aluminum plate under each wheel when making the alignment measurements. The idea being, the wheels will be able to "slide" to their natural position based on the amount of weight applied to the gear.

I have not personally tried this method yet .... but the logic seems sound, so plan to give it a go when I get around to tweaking the gear.
Click to expand...

HD trash bags folded over a few times will give you all the slippery you need and no mess. :D
 
That trash bag idea sounds like the best yet.

Wow! I never would have considered a need for a weight & Balance calculation after replacing tires. So, I guess all 5:00 X 5 tires aren't created equal. Bummer............. Maybe Mel will chime in here..........Tom
 
rvbuilder2002 said:
And calculate a new Weight & Balance ;)
Click to expand...

Yes, actually I completed installation of Dynon D100 EFIS Dual Display, fuel tank attach modification, center section and side skin modifications, over size tires, and oil tank bracket. When finished, it was easier to re-weigh the airplane and calculate CG rather than add individual moment arms.
 
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