I am looking to replace my existing crappy McCauley wheels and brakes (single puck brakes) with new ABI double puck 6" 1.5" axels. My question is 3 or 6 bolt rims? They will be installed on an experimental PA-11 (1320 lbs GW). It is a $400 difference, wondering if it is worth the savings or go with the 6 bolt for added insurance. Your thoughts???

Just go 3-bolt and save the $400. I did this 6 months ago.

My axles are held on with 4 bolts, why the hell would I need 6 bolts for wheel halves? I'm an engineer and if you look at the load path, I can't imagine a scenario where 3 extra bolts help much on my Scout.

If I had a 180 or 185, sure I'd probably go 6 but not PA11.

Was reading about field approvals for 26" goodyears and what rim they needed. Topic of strength came up between the 3 bolt and the 6 bolt. If I remember correctly the data sheets say the 6 bolt is no stronger than the 3 bolt. I would go with the 3 bolt if you can get it cheeper. I will post the data sheet if i can find them again.

Bradley

I posed this question to the people who manufacture and sell them. Their answer was a question: “How often do you check the torque on your wheel half bolts?”

Ummmm, not very often.... “Then six bolts is better for you. They’re less apt to loosen some and induce fretting of the wheel halves.”

When I disassembled my old Cleveland three bolt wheels, one of the wheels had fretting on the wheel halves.

I bought six bolts. Cessna 175.

MTV

I have been told that three bolt wheels have more tendency to break wheel bolts... 6 bolt wheels hold up better because of more even torque across the wheel haves. For guys that abuse their wheels flying in extreme off airport the 6 bolt would be the way to go...

With that said, I have 3 bolt wheels on my Cub with 10 inch Gar Aero adapters, I just make sure they are torqued to speck every annual.. have been in there since the mid 80’s with never a problem.

Brian


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I would have no issues with a 3-bolt wheel on a lighter airplane. I feel the biggest benefit of the 6-bolt is that you have 6-points of attachment for the brake rotor to the wheel. With the Helio, heavy airplane, on 29x11-10 tires I had the rotor rip from the wheel on me. This was a 10" Airframes wheel, which is a 6-bolt wheel but it only has 3-bolts holding the brake rotor on. I now have 6-bolt 6-inch wheels and am happy. I know other Helio owners (Jaars included), C-185 drivers and others with heavy planes who operate the 3-bolt wheels but they only do it with smaller tires which keeps the torque load lower.

For a lighter weight plane, I would not worry about it and I would get the 3-bolts. Airframes and I calculated the strength limits on the 3-bolt rotors and it was clearly borderline at the 3400lbs of a Helio (and probably C-185 at 3350) but plenty of margin at lower weights. So with a PA-11 get the cheap ones!

This is a timely conversation based on a recent experience I had.

I had just landed at my home base after a trip to Trigger Gap in Arkansas. Pulling into the fuel pump for gas, the right tire went flat. That would have been a bad deal at Trigger Gap.

Come to find out, the last person to assemble the wheel halves had inadvertently pinched the tube between the halves (just barely). There were multiple slits down the inside of the tube that were evidence of the pinched condition, and it took 70 flight hours for the hole to materialize.

When the mechanic went to separate the wheel halves to replace the tube, a small amount of torque on one wheel bolt (of the three) snapped the head off the bolt. A close look revealed that there was about 20% of the thickness of the bolt shank that was holding the head on the bolt. It's likely the pinched tube allowed the wheel halves to work, putting added stress on the hardware.

Naturally more fasteners allows the working load to be more distributed. However there is a possibility the assembly as a whole becomes more fault tolerant, too.

You may have an opportunity to catch a bolt failure on a preflight when you have 6 bolts in the assembly. In other words, the assembly may not fail catastrophically if one out of 6 fasteners fail in operation.

It's less likely the wheel halves will stay together if one out of 3 fasteners fail.

tbabbott wrote: Was reading about field approvals for 26" goodyears and what rim they needed. Topic of strength came up between the 3 bolt and the 6 bolt. If I remember correctly the data sheets say the 6 bolt is no stronger than the 3 bolt......

I got a field approval earlier this year for 26" GY's on my 180.
I gathered up a lot of approved 337's in the process of preparing my own--
some specified 6 bolt wheels, some didn't.
I wrote mine up for standard 40-75D 3 bolt wheels,
and it was (eventually!) approved.
Another factor besides strength--
I like to run hubcaps, and besides being more expensive,
at least some of the 6 bolt wheels are not drilled for hubcaps.

hotrod180 wrote:

tbabbott wrote: Was reading about field approvals for 26" goodyears and what rim they needed. Topic of strength came up between the 3 bolt and the 6 bolt. If I remember correctly the data sheets say the 6 bolt is no stronger than the 3 bolt......

I got a field approval earlier this year for 26" GY's on my 180.
I gathered up a lot of approved 337's in the process of preparing my own--
some specified 6 bolt wheels, some didn't.
I wrote mine up for standard 40-75D 3 bolt wheels,
and it was (eventually!) approved.
Another factor besides strength--
I like to run hubcaps, and besides being more expensive,
at least some of the 6 bolt wheels are not drilled for hubcaps.

not to hijack the conversation but have you had good luck with the 26" goodyears

bradley

tbabbott wrote:..not to hijack the conversation but have you had good luck with the 26" goodyears

That field approval took 11 months.
I was pretty disgusted shortly into the process,
By the time I actually got it approved, I'd lost the urge to put the 26's on the airplane.
I pretty much stick to airstrips, some more "improved" than others (as opposed to pioneering gravel bars & such),
so 850's work pretty good for me.
I'm kinda looking for a set of 40-75 wheels to mount the 26's on,
that way its easier to switch back & forth.

I've got a pair of used 40-75B's with discs and a spacer for the disc. I needed the spacer when mounting 26" Goodyears to keep the caliper from rubbing the tire. They're sitting on my shelf just taking up space at this point.

fredy wrote:I've got a pair of used 40-75B's with discs and a spacer for the disc. I needed the spacer when mounting 26" Goodyears to keep the caliper from rubbing the tire. They're sitting on my shelf just taking up space at this point.

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