Onex main gear
Posted: Mon Sep 11, 2023 10:43 pm
by rpf
Hi Guys,
My landing gear, when I taxi (or just pull my plane forward 10-20feet), spreads outward quite a bit. Like there’s too much toe out. This is an older kit(2014) that I purchased a few years ago. I read some old posts that there might have been a bad batch of onex gear??? Because, per onex plans, the axles are press fit into the gear so there doesn’t appear to a way to adjust toe in or out. Does anyone else have this issue with their gear? Or is there way to adjust toe out? I’ll try and attach a couple pictures. One showing the gear normal and one showing it spread out after pulling the plane forward about 20 feet.
Thanks
Re: Onex main gear
Posted: Tue Sep 12, 2023 12:01 pm
by Onex107
I received my Onex kit 107 in late 2012 and finished it in early 2014. But when I attached the main gear, put the wheels on and rolled it out of the garage the right wheel stuttered as it rolled. It was a nose dragger but that shouldn’t matter. I didn’t have the skins on the stub wings yet so I could site down past the spar and see the angle of the toe out. Roughly measured it was 7 degrees. I took the gear off and checked the gear for square and found that the last section where the axle goes is supposed to be bent from the straight side of the gear leg and the right one was bent from the tapered side of the leg causing it to toe out. Sonex didn’t believe me on the phone but after shipping it back they found the same thing and sent a new gear. Big pain re-drilling the same bolt holes. Yours is possibly the same but on both sides. You can do a standard wheel alignment, like spelled out in the Cessna parts manual, by putting center lines on the hangar floor and mounting straight edges to the wheels and measuring for parallel.
Re: Onex main gear
Posted: Tue Sep 12, 2023 8:43 pm
by rpf
Onex107, thanks for responding. You mention doing a wheel alignment but I don’t see how I could adjust the toe in/out with the sonex gear? If the axle’s were bolted on they could easily be shimmed.
Re: Onex main gear
Posted: Wed Sep 13, 2023 12:36 am
by N190YX
My Cessna 170 (tail dragger) did the same thing, as I found out due to toe out. As I recall it was fixed with shims to the correct wheel alignment.
Re: Onex main gear
Posted: Wed Sep 13, 2023 12:05 pm
by Onex107
The Sonex alum gear cannot be adjusted for toe in without bending which I don’t advise. I suggested checking the alinement to provide you with the info you need to talk to Sonex.
Re: Onex main gear
Posted: Wed Sep 13, 2023 1:01 pm
by Bryan Cotton
Cessnas use tapered shims for alignment. Seems like that could be an option for the Onex. I can understand wanting Sonex to make it right also, if they had a bad batch of gear.
Re: Onex main gear
Posted: Wed Sep 13, 2023 2:38 pm
by rpf
Hi Brian, I don’t think you can shim or adjust the axles on a Onex. They’re press fit into the axles.
Re: Onex main gear
Posted: Wed Sep 13, 2023 3:06 pm
by Bryan Cotton
rpf wrote:Hi Brian, I don’t think you can shim or adjust the axles on a Onex. They’re press fit into the axles.
My misunderstanding, thanks.
Re: Onex main gear
Posted: Wed Sep 13, 2023 6:58 pm
by 13brv3
I haven’t noticed any toe in/out issues, but dragged mine straight out of the hangar today and took a look at the gear. I didn’t notice anything different. With around 200 landings, they do appear to be sagging a bit, but that’s gravity for you 
I’d like to have a little taller gear for prop clearance (Rotax) and also for the stall attitude. The plane hits decidedly tail first if you try to full stall it. O’Keefe used to make a special order gear, but they appear to have retired.
Rusty
Re: Onex main gear
Posted: Thu Sep 14, 2023 2:44 pm
by Onex107
An easy way to check your toe out is to remove the wheel on one side, place a board across the bottom of the gear, and check to see if the axle is parallel to the board and if the gear leg is square with the board. If it isn’t Sonex owes you a new gear.
Re: Onex main gear
Posted: Thu Sep 14, 2023 4:58 pm
by rpf
Hi Rusty, I’d like a little taller gear as well. I went to Groves website to design custom gear but, because of production issues, they are not taking any orders for new gear. When I called they said they don’t see doing so in the foreseeable future. I wonder where sonex gets their gear and what alloy they’re made from?
Sonex onex gear is made from 2024. According to Grove, landing gear should be made from 7075.
Re: Onex main gear
Posted: Fri Sep 29, 2023 12:04 pm
by 13brv3
Greetings,
After a couple hundred landings, I can see that my main gear is starting to bend a bit. I’ve definitely made a few landings that were harder than intended, but they weren’t hard enough I’d ever worry about bending anything. Mine isn’t bad enough to need replacement right now, but it will eventually get that way. This seems to be an ongoing issue for Onex owners, and there’s more info in this older thread- viewtopic.php?f=5&t=5536
As others have done, I asked Sonex about re-bending the gear, and they said it’s not recommended. They verified that the gear is still 1/2" thick, so it hasn’t been strengthened since my kit was made. They didn’t answer the question about the specific alloy or tempering, but in the other thread it was reported to be 2024-T351. The only recommendation from Sonex is to replace the main gear with the identical gear they sell. I’m guessing that would be around $750 with shipping.
From 100 hour of flying the plane, I’d have to say the main gear is the weakest link, though not my least favorite design decision. I really wish they’d offer a 5/8" gear, or maybe one that uses a stronger alloy, because main gear shouldn’t really be a routine replacement item.
O’Keefe used to make Onex gear, even custom taller gear using 5/8" aluminum, but they appear to be retired and out of business now. It sounds like Groves isn’t offering anything now, and I’d be afraid to ask the price if they did. What other option is there for a stronger, and possibly taller replacement?
Another thought is some sort of reinforcing plate that fits on top of the main gear, and extends maybe a foot or so down the legs to add support for the main bend at the fuselage. I’m not sure how well that would work, but it would be easier to fabricate than making the whole gear. Any other ideas?
Re: Onex main gear
Posted: Fri Oct 06, 2023 9:28 am
by rpf
H Rusty,
I’ve decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I’m going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.
Re: Onex main gear
Posted: Fri Oct 06, 2023 11:10 am
by BRS
rpf wrote:H Rusty,
I’ve decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I’m going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.
I like to see some pictures on how those bends are done.
Are you going to build it so that you can use bolt-on axles? Gives you more options if you need to later add shims.
Re: Onex main gear
Posted: Fri Oct 06, 2023 6:04 pm
by 13brv3
rpf wrote:H Rusty,
I’ve decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I’m going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.
That sounds like a definite improvement. Where did you get that 7075? I’m afraid to ask the price… I just got the Sonex replacement gear today. I figured with the way the industry is going, I’d better at least have a spare stock gear just in case they become unavailable like Grove and O’Keefe.
I started a thread on the homebuilt airplanes forum, and there has been a lot of discussion. I think it’s safe to say the design could be improved, though I’m not sure Sonex has any motivation to make changes.
https://www.homebuiltairplanes.com/foru … nex.48216/
Re: Onex main gear
Posted: Fri Oct 06, 2023 7:53 pm
by peter anson
rpf wrote:I’ve decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I’m going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.
I don’t know how sharp the bends in the Onex gear are but the best method for making these would be to bend them with the metal in a soft condition and then have them age hardened. To do that you need to get the material solution treated - heated to about 500°C for a time and then quenched. After quenching the metal will be soft but returns to a fairly hard condition within a couple of hours at room temperature but you can delay it by keeping it cold, like packed in dry ice cold, until you are able to form it to the shape you want. The final step is age hardening, heating the formed parts to around 180°C for around 12 hours. All those temperatures and times are just guesses but the information is available in spec sheets. You should end up with parts that are high strength without inbuilt stresses. I know that may seem like a lot of trouble but I would guess that’s how the original parts are made. It would probably be best to get the parts anodized too because 7075 is not corrosion resistant.
Peter
Re: Onex main gear
Posted: Fri Oct 06, 2023 10:33 pm
by tps8903
peter anson wrote:
rpf wrote:I’ve decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I’m going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.
I don’t know how sharp the bends in the Onex gear are but the best method for making these would be to bend them with the metal in a soft condition and then have them age hardened. To do that you need to get the material solution treated - heated to about 500°C for a time and then quenched. After quenching the metal will be soft but returns to a fairly hard condition within a couple of hours at room temperature but you can delay it by keeping it cold, like packed in dry ice cold, until you are able to form it to the shape you want. The final step is age hardening, heating the formed parts to around 180°C for around 12 hours. All those temperatures and times are just guesses but the information is available in spec sheets. You should end up with parts that are high strength without inbuilt stresses. I know that may seem like a lot of trouble but I would guess that’s how the original parts are made. It would probably be best to get the parts anodized too because 7075 is not corrosion resistant.
Peter
Would it be easier to buy the bar stock annealed as 7075-0 and then bend and heat treat to T6?
Re: Onex main gear
Posted: Sat Oct 07, 2023 5:05 am
by peter anson
tps8903 wrote:
Would it be easier to buy the bar stock annealed as 7075-0 and then bend and heat treat to T6?
Definitely yes but I don’t know what is available. My local supplier (in Melbourne, Australia) can only supply thick plate in T651. Sheet and thin plate up to 0.25" thick is available in T0. You might have more options in the US.
Peter
Re: Onex main gear
Posted: Sat Oct 07, 2023 8:50 am
by Bryan Cotton
With some proper engineering, I wonder how Ti would trade.
Re: Onex main gear
Posted: Sat Oct 07, 2023 10:42 am
by LarryEWaiex121
I can definitely see some squat in my gear I just installed 12 flight hrs ago. I can also say that I have not had any questionable “arrivals” that would explain this. The gear is just very minimal in its nature and clearly built out of a poor choice of material. This is consistent though with the Sonex “kiss” mantra.
Don’t make it necessarily good but make it cheap.
Replacing gear like its a consumable isn’t really very cost effective for the owner. My unit was the price of whatever Sonex was asking and $300 shipping on Old Dominion. A freaking staggering amount of money for something that had a 14lb shipping weight. Why it couldn’t go FED EX Ground for a fair price I’m not certain?
Seems like everyone in the freight business agrees; if its an airplane part, that’s license to steal.
I purchased my Onex as a retirement project for something I enjoy doing. It has surpassed my expectations for an enjoyable project. I did a ton more work than I expected and found a laundry list of things that clearly were not done satisfactory from day one. This little sweetie is really starting to shape up and I’ve just about got it to the place I can call it a “rock solid flyer”.
A bit more adjusting and tinkering and I’ll call it a successful rebuilding of a cute little plane.
My Waiex is getting jealous of all the attention to this Onex but its all going to work out.
Larry
Waiex 121YX, 1028 hrs
Onex 752MR, 82 hrs.
Re: Onex main gear
Posted: Sat Oct 07, 2023 11:13 am
by 13brv3
My new gear showed up yesterday via UPS ground. The box isn’t all that big, and certainly not that heavy, but it was still $120 shipping.
Would other Onex owners take a look at the gear and see how much the center horz section is bowed? Since it’s bolted through to the angle that’s inside the floor, when the center of the gear bends, it also bends the floor. On mine, I’d estimate the center of the gear is 3/16" to 1/4" lower than the left and right ends, and I can only imagine what happens with any landing force. It really seems wrong to me to have your landing gear constantly flexing the floor of the fuselage.
Most gear like this is mounted only at the left and right ends, and with a clamping type radiused block. The way this is mounted, the main landing force probably exists on those two washers that are between the outer bolts and the fuselage. When I remove mine, I fully expect to find significant dents in the skin where those two washers are being smashed into the aluminum. At the very least, I’ll make a full length plate for those outer bolt locations to spread the load, and I’d highly recommend anyone who’s still building one to do that as well.
Re: Onex main gear
Posted: Sun Oct 15, 2023 11:04 am
by 13brv3
How did others handle the brake lines along the rear of the gear legs? My original gear already had holes drilled like the plans show, but 2 instead of 3. As suck, I needed to use tie wraps between the two to keep the line from flailing around. With the new gear, I don’t really want to drill holes, though I’ve seen that it doesn’t become the weakest portion of the gear leg.
I’d really like to just wrap the gear in something to hold the line, but anything you put there seems like it would be a problem later. On an RV-3B, I temporarily used tape of various types, and it was never good once the sun and age got to it. How about some sort of vinyl wrap like they put on cars?
If I can’t find something long lasting and not super ugly, I’ll end up going with holes and clamps. I’d probably opt for using round head screws rather than countersinking the gear leg to preserve some strength. I even thought of using smaller holes, and small tie wraps rather than screws and clamps.
Rusty
Re: Onex main gear
Posted: Sun Oct 15, 2023 11:32 am
by XenosN42
I drilled three countersunk holes in each side of the gear, as shown in the plans. Then used clamps. Worked out well.
I don’t think vinyl wrap would work well for this application. The wrap gets much of it’s adhesion from being stuck flat on a flat surface. If the wrap had to hold down a round tube it would quickly lift off.
The small holes and small tie wraps sounds like the best alternative to the Sonex plans method. But, when I replace my OneX gear I’d just go with the Sonex way. It works.
Re: Onex main gear
Posted: Sun Oct 15, 2023 8:08 pm
by 13brv3
I don’t have any experience with vinyl wrap, but I would have thought it would work well for this. The gear leg is mostly flat, and it would wrap around onto itself for good adhesion. If you keep the top edge pointing aft, the airflow wouldn’t tend to get under it, and it should have a good chance of success.
Most likely, I’ll just hit the gear with some rattle can paint, and add 3 bolts and clamps on each side. I’m still working on the best way to support the fuselage while I have the gear off. I have a metal sawhorse but it’s a bit higher than I’d like, so I’ll probably pick up a couple tall jack stands tomorrow then use whatever seems to work best. Pity hydraulic hoists (jacks, or anything else) don’t stay up reliably.
Rusty
Re: Onex main gear
Posted: Wed Oct 18, 2023 8:57 am
by rpf
Hi Rusty,
This is how I supported my plane when i removed the gear to upgrade to 5/8 thick 7075 aluminum.
Randy
Re: Onex main gear
Posted: Wed Oct 18, 2023 9:47 am
by 13brv3
rpf wrote:Hi Rusty,
This is how I supported my plane when i removed the gear to upgrade to 5/8 thick 7075 aluminum.
Randy
You sure didn’t waste any time making that gear! BTW, what engine mount is that?
I removed the gear yesterday, and match drilled the holes for the new gear. I tried to take pictures of the bend amount for each side as well. Just measuring the angle, the new gear is 51.5 deg, and the old is now 47 and 48 deg.
Rusty
Re: Onex main gear
Posted: Thu Oct 19, 2023 8:54 am
by rpf
Yeah, I still have to match drill mine. I’m also waiting for new axles that I ordered. That mount is for an aeromomentum am13 engine.
Re: Onex main gear
Posted: Thu Oct 19, 2023 5:15 pm
by sonex892.
13brv3 wrote:How did others handle the brake lines along the rear of the gear legs?
Rusty
The Sonerai project I’m working on came with grooves cut into the rear edge of the gear legs. I intend use thinwall aluminium as a conduit, glued to the gear with proseal.
Re: Onex main gear
Posted: Thu Oct 19, 2023 7:04 pm
by 13brv3
sonex892. wrote:
The Sonerai project I’m working on came with grooves cut into the rear edge of the gear legs. I intend use thinwall aluminium as a conduit, glued to the gear with proseal.
I don’t think I’ve seen the rear groove option before. I now Grove used to offer a gun-drilled brake passage in the gear leg.
I ended up drilling the normal 3 holes, but I didn’t countersink them, and used tie wraps instead of clamps.
Re: Onex main gear
Posted: Thu Oct 19, 2023 7:21 pm
by 13brv3
I finished installing everything today. I decided that the tires and discs were fine for now, and the pucks were OK to use for a limited time. The new pucks will be easy to install, and I’ll do that in the near future.
Once the plane was back on the gear, there was some good news. First, the tires are at about 0.5 deg positive camber (0.6 R, 0.4 L). This is a promising start, since the original gear was measured at 1.2 deg negative for the left, and 2.7 deg negative for the right before the plane was even taxied. It’s always possible that the early kits (SN-085) had gear that wasn’t bent correctly, and they fixed that later. I’m also hopeful that they improved the heat treatment, or changed alloys. I’ve never seen any comment that suggest Sonex ever made a change to the gear, and I can imagine reasons why they wouldn’t make that information public if they did.
I also measured 6.25” of prop clearance in level attitude, compared to 4.5” with the old gear. This is a very nice change if it stays that way.
Naturally it’s going to be raining all day tomorrow, and I work the weekend, so maybe Monday it will fly again. I’m thinking I might go back to flying the plane on at 3-pt attitude, rather than trying to land slow. Landing slow tends to be harder on the gear since the tail will always hit first. We have 6500 ft or runway, so I’ve got just a little extra room
Attached is a before and after picture of the right wheel, and I’m guessing you can tell which is which The left wheel was similar, but not quite as bad.
Re: Onex main gear
Posted: Mon Feb 05, 2024 10:19 pm
by rpf
Hey Rusty your new gear looks nice. I hope it works as good as it looks. I’m very happy with my new gear and the 3 extra inches in height is a plus. Like you I’m using a longer prop than stock and the extra ground clearance helps.
Re: Onex main gear
Posted: Mon Feb 05, 2024 10:23 pm
by 13brv3
I’m haven’t noticed any change in camber, so I’m happy about that. The original gear had negative camber from before the first flight, so maybe they have improved the bending over the past decade. I’m also hopeful that maybe those early gear just weren’t heat treated properly either, and with any luck they are now. Time will tell. I really do wish I had more prop clearance, because I’m giving up a lot of performance with that 60" prop.