Tires/Gear Leg/Toe In
Posted: Sun Nov 19, 2023 6:00 pm
by tps8903
I burned through a set of stock tires in 70 hrs, with 2/3 of the landings being on turf. One tire blew out on me while taxiing today.
I took the opportunity to upsize to 5x5.00, because I wanted to, and also my hand was forced because that’s all the FBO had in stock.
When I got back while looking at the plane I felt like the left main gear might have a bend in it, and that might be causing alignment issues? I’m going to pull it off and check it against a straight edge this week. Does anyone have advice for straightening a main gear with a press that has done it?
Once that’s done I’m going to have another look at the toe in…The plane kit had it set when I bought it, so it was one of the tasks I didn’t have to do during the build. Advice is welcome.
I am considering using grease plates to get the toe in correct, I may have to up drill the axels to move them on the current gear. Task #1 however is making sure they are not bent.
Re: Tires/Gear Leg/Toe In
Posted: Sun Nov 19, 2023 6:14 pm
by Bryan Cotton
We are about to replace the tires for the second time at 185 hours or so. We had a blowout on the first set. I suspect alignment and plan to measure it carefully when ballasted up. I was going to put steel rods under a steel plate to let the gear spread out, same idea as a grease plate. No advice yet, it’s going to be a winter project.
Re: Tires/Gear Leg/Toe In
Posted: Sun Nov 19, 2023 8:02 pm
by tps8903
Bryan Cotton wrote:We are about to replace the tires for the second time at 185 hours or so. We had a blowout on the first set. I suspect alignment and plan to measure it carefully when ballasted up. I was going to put steel rods under a steel plate to let the gear spread out, same idea as a grease plate. No advice yet, it’s going to be a winter project.
Roger.
I’m gonna haul the legs off this week and check to see if they are bent. If they are ill bend them back, maybe a touch the opposite way with a 12 ton pipe bender.
Then I’ll throw them on grease plates and see how they look.
I suspect my high landing speed when the plane was new and resulting excessive braking didn’t help time wear. I’m gonna leave the pants off u til I figure this out
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 9:18 am
by bvolcko38
What tires are you running? What tire blew out?
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 9:30 am
by Bryan Cotton
bvolcko38 wrote:What tires are you running? What tire blew out?
Not sure if you are asking Chris, me, or both. Cheng Shin, right tire. We had let it get too worn and it failed during taxi.
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 10:00 am
by tps8903
bvolcko38 wrote:What tires are you running? What tire blew out?
Cheng Sing tires. Pilot side. Same, blew out during taxi. Both were worn equally poorly however.
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 10:53 am
by Area 51%
tps8903 wrote:When I got back while looking at the plane I felt like the left main gear might have a bend in it, and that might be causing alignment issues? I’m going to pull it off and check it against a straight edge this week. Does anyone have advice for straightening a main gear with a press that has done it?
The factory prototype Xenos had it’s gear legs bent pretty badly here in Crystal River a couple of years ago. The owner has a friend with a press and he straightened the legs with admirable results.
I can put you in touch with him if you like.
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 10:58 am
by Bryan Cotton
I’ll confess my flat was pilot induced. It’s hard to see the tires with the wheel pants. We wore a hole which exposed the tube. I was a little shocked how quickly they wore but now I know!
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 2:21 pm
by tps8903
So an update. I purchased a rolling chasis when I acquired this kit. I thought I checked everything over when I bought it. Indeed I found 3 relatively important things when I went over the airframe. It should be mentioned the previous builder was on his 4th build and was a very good builder.
I checked the gear legs today. They are NOT bent, just a little bit of an optical illusion the way the plane sits.
However, I ja ked it up and checked the wheel alignment. 3.9° toe out!!! WTF!
No wonder I shredded those tires in 9 months.
So now I have to rotate the axles and re drill. I have to move them enough, should I just drill a new hole about 1" above the current one? Or drill out the current hole large enough to see the gear leg hole and weld new pieces and back drill each side? I would prefer not to leave the plane on horses with wheels removed to do the welding and painting…
Suggestions?
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 3:02 pm
by Bryan Cotton
Chris,
I had 3 thoughts on how to do it:
- weld up the axles and then redrill.
- make a sleeve, drill to the gear leg. Slot the original. Get it lined up, mark/tack weld it, then weld for real.
- buy new weldments.
Would like to see your setup for checking alignment.
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 3:28 pm
by tps8903
Bryan Cotton wrote:Chris,
I had 3 thoughts on how to do it:
- weld up the axles and then redrill.
- make a sleeve, drill to the gear leg. Slot the original. Get it lined up, mark/tack weld it, then weld for real.
- buy new weldments.
Would like to see your setup for checking alignment.
I took the tires off the rim. Used metal straight edges clamped to the face of the rims. Measured, did the math. Just like a car alignment. They are visibly toe out which was alarming before I even measured anything.
How would one match drill the hole with new weldments?
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 3:50 pm
by Bryan Cotton
Somebody had a picture of description. I’ll have to see if I can find the thread. Basically you make a drill jig aligned with the gear hole. It is clamped onto the gear leg above the weldment.
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 3:58 pm
by Bryan Cotton
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 4:49 pm
by tps8903
Bryan Cotton wrote:Somebody had a picture of description. I’ll have to see if I can find the thread. Basically you make a drill jig aligned with the gear hole. It is clamped onto the gear leg above the weldment.
I guess I’ll have to see how far it rotates to the new position before I decide which method to use.
From a practical stand point. What would be the problem with drilling a new hole slightly above the original?
Re: Tires/Gear Leg/Toe In
Posted: Mon Nov 20, 2023 5:25 pm
by Area 51%
I had a similar issue. I had a machine shop relocate the mounting holes at the engine mount. This involved rotating the leg the required degree, and use a 5/16 bit. Then I bushed the hole back to 1/4.
I .
Re: Tires/Gear Leg/Toe In
Posted: Tue Nov 21, 2023 1:07 pm
by jerryhain
I had the same problem. I just removed the bolt. Did the alignment, drilled a new hole about an inch above it 90° to the original hole and installed the bolt there. Then I elongated the holes in the weldment and installed second bolt in the original hole through the axle. I really should weld that back up and re-drill but I decided if one bolt was good enough to maintain the alignment. I didn’t need to do the second bolt properly.
Re: Tires/Gear Leg/Toe In
Posted: Tue Nov 21, 2023 2:17 pm
by tps8903
jerryhain wrote:I had the same problem. I just removed the bolt. Did the alignment, drilled a new hole about an inch above it 90° to the original hole and installed the bolt there. Then I elongated the holes in the weldment and installed second bolt in the original hole through the axle. I really should weld that back up and re-drill but I decided if one bolt was good enough to maintain the alignment. I didn’t need to do the second bolt properly.
Thanks,
That’s exactly what I wanted to know.
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 12:36 am
by Bryan Cotton
Started swapping my tires tonight. This is about 110 hours or so.
new vs old tire.png (473.22 KiB) Viewed 6557 times
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 4:52 am
by Skippydiesel
Wow! Fortunately I fly off grass, most of the time - I am hoping for a long tyre service life
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 12:54 pm
by GordonTurner
Wow. Are you sure you have the correct alignment? I guess you can extend that if you swap them every oil change. Any opinions if it would be ok to just swap the whole wheel, in which case the direction of rotation would be reversed? Is there a bearing problem if you do this?
Gordon
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 1:15 pm
by Bryan Cotton
GordonTurner wrote:Wow. Are you sure you have the correct alignment? I guess you can extend that if you swap them every oil change. Any opinions if it would be ok to just swap the whole wheel, in which case the direction of rotation would be reversed? Is there a bearing problem if you do this?
Gordon
Gordon,
I followed the alignment procedure in the plans but I suspect it is off. I will be measuring and correcting it at the next condition inspection. That profile is not wear, but the quality of the Cheng Shin tire showing through. Had that shape when new, but looks normal when inflated.
Swapping the wheel is not a good option, because the tires wear on the outside due to camber. The inside must become the outside to get maximum life. I also swap left and right as my right tire wears more quickly.
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 2:00 pm
by tps8903
Bryan Cotton wrote:Started swapping my tires tonight. This is about 110 hours or so.
new vs old tire.png
Is the wear on the outside or inside of the tire? Mine was the inside of the tire. The extreme toe out was dragging my gear down trying to spread the tires. I would assume you have a bit of an opposite issue with too much toe in.
I only got about 30 pavement landing on my Cheng Sing tires before one blew out. The other 40-50 landings were on turf.
I’m going to rotate the axles, see how much it takes. If I can up drill with a custom jig to cover the size of the new hole, then I’ll do that. Otherwise I’ll elongate the original weldment hole, use that to clamp the weldment in place (like a set screw) and use my drill jig to drill a second hole about 3/4" above. This should prevent the weldment from walking around when I redrill it.
Because the original bolt will act as a set screw, I might do the final alignment in taxi position with weight in wheels with grease plates, then I know for sure what it is once the plane is in taxi position. My assumption for why this is done in the air is because normally the weight on the axles would cause them to shift while drilling.
Re: Tires/Gear Leg/Toe In
Posted: Wed Nov 22, 2023 3:07 pm
by Bryan Cotton
tps8903 wrote:Is the wear on the outside or inside of the tire? Mine was the inside of the tire. The extreme toe out was dragging my gear down trying to spread the tires. I would assume you have a bit of an opposite issue with too much toe in.
Definitely on the outside. Regardless of toe there is a lot of camber. I would not have guessed anybody would have wear on the inside!
Re: Tires/Gear Leg/Toe In
Posted: Fri Nov 24, 2023 7:48 pm
by Skippydiesel
I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tyres still look new)
Re: Tires/Gear Leg/Toe In
Posted: Fri Nov 24, 2023 8:10 pm
by Bryan Cotton
Skippydiesel wrote:I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tres still look new)
45-55 psi.
Re: Tires/Gear Leg/Toe In
Posted: Fri Nov 24, 2023 10:07 pm
by Skippydiesel
Bryan Cotton wrote:
Skippydiesel wrote:I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tres still look new)
45-55 psi.
Thanks Bryan - that’s quit a wide pressure range for such a small tyre. My tyres are Goodyear Flight Custom III, 5.00-5, if failing memory is good Max 50 psi.
Would the tyre make/model change your recommendation?
Re: Tires/Gear Leg/Toe In
Posted: Fri Nov 24, 2023 11:27 pm
by Bryan Cotton
Skippydiesel wrote:Thanks Bryan - that’s quit a wide pressure range for such a small tyre. My tyres are Goodyear Flight Custom III, 5.00-5, if failing memory is good Max 50 psi.
Would the tyre make/model change your recommendation?
Skippydiesel,
From memory the Sonex recommendation is 50-55 psi. My Cheng Shin tyres say max 70 psi on them. The rims are cast at max PSI 30. My understanding with the stock sonex wheels and tyres is that running low pressure, like 30psi, can lead to the tyre/tube spinning on the rim. This causes a failure at the valve stem. I’ve heard a Sonex employee say he would like to grind off the 30PSI off the wheel casting, as low pressures have caused a lot of grief.
Typically when I fill mine I go right to 55 psi. They never stay there, but they don’t seem to go below 45 psi. So I fill them to 55 and leave them alone as long as they are at least 45. That is where I get my range from.
185 hours and hundreds of landings and those pressures have served me well. Now I just need to get the alignment figured out.
Re: Tires/Gear Leg/Toe In
Posted: Sat Nov 25, 2023 12:06 am
by daleandee
Bryan Cotton wrote:Typically when I fill mine I go right to 55 psi. They never stay there, but they don’t seem to go below 45 psi. So I fill them to 55 and leave them alone as long as they are at least 45.
My older rims didn’t have the 30 psi limit but the ones I have now do. I’ve always used 50 psi as my setting but even with the famous “Leakguard” tubes I still check & set the pressure about once a month. I too understand that a lower pressure can lead to tire spinning & tube failure.
One of our Sonex flyers here has said that 50 psi using the factory 11x4-5 tires is correct but that larger tires (5" or larger) would mandate using 30 psi for a limit as 50 psi with the larger tire puts too much stress on the rim.
I’ve always used the factory recommend tires on both of the Sonex aircraft I have owned (16 years total) with 50 psi as a limit and have never had a flat.
I replaced my last set of tailwheel tires at ~200 hours with many landings and my worst tire looked excellent compared to what you posted (I still had tread all the way across). 8~)
Re: Tires/Gear Leg/Toe In
Posted: Sat Nov 25, 2023 1:54 am
by Skippydiesel
The Goodyear chart would suggest Goodyear Flight Custom III, 5.00-5, Rated Pressure, range from 31 psi for the 4 ply up to 50 psi for the 6 ply (I will check what ply rating I have)
https://www.aps-aviation.com/wp-content … e-data.pdf
Re: Tires/Gear Leg/Toe In
Posted: Sat Nov 25, 2023 12:51 pm
by N190YX
Regarding the Goodyear Flight Custom III tires, while they will wear longer than just about any other tire except the Desser Monster retread*, they weigh 2 or more pounds more per tire, depending on the size. It is ~2 pounds more in the 500-5 tire size. That is four extra pounds on a tail dragger Sonex if you are using 500-5 tires! *Retread tires are commenly used in aviation with good results, the airlines and the Air Force use retreads almost exclusively.
