homemade spring gear

[1avidflyer 1983]

Hi all, within the last week or so, I read a post about someone who built their own spring gear. They made a small trailer frame, welded tabs on the frame to match the landing gear tabs on their fusaloge, and then built the landing gear mounted to the trailer tabs. After it was done, they pulled the trailer up and down a field with about 1000 lbs on the trailer to test the gear. Now I can't find the post as I'm thinking about doing the same thing. I'm on several different Kitfox/Avid sites, so it might have not been on this forum either. Does anyone remember this topic and where I can find it? The topic may have been posted a while back, I don't remember the date on it, but I just ran accross it looking at older threads. Thanks, Jim Chuk

[1avidflyer 1983]

I did some more searching after I made the first post, and found what I was looking for in the Yahoo groups Avid Flyer group's files. Avid Spring Gear Doc. was the file. Take care, Jim Chuk

[EDMO 1078]

I did some more searching after I made the first post, and found what I was looking for in the Yahoo groups Avid Flyer group's files. Avid Spring Gear Doc. was the file. Take care, Jim Chuk

There were several guys who modified the steel Cessna spring gear to fit their homebuilts - Others use leaf springs from cars/trucks - Robby Grove was the first, and I guess only, one to make a commercial business by going with the lighter aluminum. He started with 2024, but switched to 7075 for the later gears.

ED in MO

[1avidflyer 1983]

I guess I may be using the wrong name for it, I was referring to the bush gear that everyone seems to want for their Avids and Kitfoxes these days. I did get a laugh at myself after I reread my post when I made the first reply to it. The title should have been homemade gear, not homade gear. LOL Take care, Jim Chuk

There were several guys who modified the steel Cessna spring gear to fit their homebuilts - Others use leaf springs from cars/trucks - Robby Grove was the first, and I guess only, one to make a commercial business by going with the lighter aluminum. He started with 2024, but switched to 7075 for the later gears.

ED in MO

[akflyer 1427]

I guess I may be using the wrong name for it, I was referring to the bush gear that everyone seems to want for their Avids and Kitfoxes these days. I did get a laugh at myself after I reread my post when I made the first reply to it. The title should have been homemade gear, not homade gear. LOL Take care, Jim Chuk

Jim,

I fixed the title for ya, but I though the same thing when I read it the first time Gotta love a good laugh in the morning! Maybe that is what happened to Joey's gear and someone needs to pimp slap and crap outta someone.... Larry, take care of our light work for us

I have that downloaded someplace around here I think. If not on this site, it is on my laptop I think. I dont remember, but did he actually put down the part number he used for the spring or where he got it? As I recall, it was not that expensive and more time than anything to make it. I am pretty sure I can modify my wide gear pretty easy to the spring set up, I just need to find that darn spring somewhere.

[1avidflyer 1983]

Hi Leni, the spings came from McMaster Carr. Part # is 9584K98 They are $47.04 each. Sizes are 2" hole (OD), 1"rod (ID), 6" long, .225X.437 wire. They are a medium to heavy duty load spring. Probably could build this gear for $200. I'm going to price the tubeing next. Wish I was a better welder with this light stuff. Take care, Jim Chuk

Jim,

I fixed the title for ya, but I though the same thing when I read it the first time :lol:/> Gotta love a good laugh in the morning! Maybe that is what happened to Joey's gear and someone needs to pimp slap and crap outta someone.... Larry, take care of our light work for us :lmao:/>

I have that downloaded someplace around here I think. If not on this site, it is on my laptop I think. I dont remember, but did he actually put down the part number he used for the spring or where he got it? As I recall, it was not that expensive and more time than anything to make it. I am pretty sure I can modify my wide gear pretty easy to the spring set up, I just need to find that darn spring somewhere.

[1avidflyer 1983]

Just ran through the tubeing sizes and lengths, and according to the prices in my 2008 Aircraft Spruce catalog, 4130 tubeing would cost about $100. Not sure how much prices went up since 2008. Take care, Jim Chuk

[Russ. 7]

Jim,

I fixed the title for ya, but I though the same thing when I read it the first time Gotta love a good laugh in the morning! Maybe that is what happened to Joey's gear and someone needs to pimp slap and crap outta someone.... Larry, take care of our light work for us

I have that downloaded someplace around here I think. If not on this site, it is on my laptop I think. I dont remember, but did he actually put down the part number he used for the spring or where he got it? As I recall, it was not that expensive and more time than anything to make it. I am pretty sure I can modify my wide gear pretty easy to the spring set up, I just need to find that darn spring somewhere.

I also have the WIB gear using the bungees. If you find a way of modifying to the spring type keep a good record for the rest of us. Thanks Russ. N844RS

[1avidflyer 1983]

Just looking at the pictures of the 'home' made gear again, and I can see how you could probably convert the bungee gear. Cut the three tubes off each gear leg that go to the bungee area, weld tabs on the gear legs just above the axles, and now all you have to build is the carbane parts. Hope I'm saying that right. I think if you can see the pics of the home made gear, it might be apparent how to do it. You might save half the work and loose a good set of gear someone else might buy. Jim Chuk

I also have the WIB gear using the bungees. If you find a way of modifying to the spring type keep a good record for the rest of us. Thanks Russ. N844RS

[Av8r3400 1179]

I think your cost factor for the tubing at $100 is WAY low. $250 would be closer. What wall thickness tubing were you using? 4130? What about the plate/sheet that is needed? That crap is really spendy compared to the tubing.

The prefabricated spring conversion for a (experimental) Cub is available from Wag-Aero, p/n M-222-101, $555.00

You will be hard pressed to fabricate the landing gear with all of the spring mechanism for less than $500.00. It does require machine work to do the spring mechanism and if you have machine equipment at your disposal that will be the cost, but if you have to sub that out, double the price.

Do you have a welder? Are you skilled at welding sufficiently to trust your life with it? Do you have the tools, equipment to jig the whole thing? That's not an option, either. This is not a small shade-tree project.

Being part of the R&D I know that the Medium/Heavy springs are too stiff. I don't remember what Brett finally went with, but they were a much lighter rate die spring.

Anyone can build anything. Nothing is impossible. I just want to point out some items maybe not thought of.

Factoring in labor the $1200-1500 that is the going rate for this gear is not out of line. I don't know if Brett is still in business or not. (He won't return my calls either...) Lowell Fitt at Highwing LLC is making cabine style gear. I think they are getting in the $1500 range for theirs.

[FoxDB 17]

I think your cost factor for the tubing at $100 is WAY low. $250 would be closer. What wall thickness tubing were you using? 4130? What about the plate/sheet that is needed? That crap is really spendy compared to the tubing.

The prefabricated spring conversion for a (experimental) Cub is available from Wag-Aero, p/n M-222-101, $555.00

You will be hard pressed to fabricate the landing gear with all of the spring mechanism for less than $500.00. It does require machine work to do the spring mechanism and if you have machine equipment at your disposal that will be the cost, but if you have to sub that out, double the price.

Do you have a welder? Are you skilled at welding sufficiently to trust your life with it? Do you have the tools, equipment to jig the whole thing? That's not an option, either. This is not a small shade-tree project.

Being part of the R&D I know that the Medium/Heavy springs are too stiff. I don't remember what Brett finally went with, but they were a much lighter rate die spring.

Anyone can build anything. Nothing is impossible. I just want to point out some items maybe not thought of.

Factoring in labor the $1200-1500 that is the going rate for this gear is not out of line. I don't know if Brett is still in business or not. (He won't return my calls either...) Lowell Fitt at Highwing LLC is making cabine style gear. I think they are getting in the $1500 range for theirs.

Jim, I built my Bush Gear for my KF1 but used the air frame as the jig. I Also built a trailer for testing and performed a 2000 Lb. static test, a 1000 Lb dynamic test and a 1000 Lb drop test using the trailer. In the fall I botched a landing on a steep grade. The gear held up fine but fuselage failed. Mainly due to the tab location allowing a torsion on the longeron.

Dave

[1avidflyer 1983]

Not trying to argue with you in the least, I did mention that the tubeing prices were from my 2008 catalog. Not my design either. I did price the springs mentioned and they were 47 each. This all started by me running accross this file and looking at it a while back and then I couldn't find it the other day. Well I did find it, in the files of the Avid flyer Yahoo group. For lenghts of 4130 tubes ect, I used what the guy said or estimated rough lengths. Wall thickness was mostly .058 with some .049. The guy said his gear weighed 17 lbs. I think that's heavier than Brett's if I remember right. Maybe way heavier. All your points about welding are correct. Not sure I would trust my welding skills either. Take care, Jim Chuk

I think your cost factor for the tubing at $100 is WAY low. $250 would be closer. What wall thickness tubing were you using? 4130? What about the plate/sheet that is needed? That crap is really spendy compared to the tubing.

The prefabricated spring conversion for a (experimental) Cub is available from Wag-Aero, p/n M-222-101, $555.00

You will be hard pressed to fabricate the landing gear with all of the spring mechanism for less than $500.00. It does require machine work to do the spring mechanism and if you have machine equipment at your disposal that will be the cost, but if you have to sub that out, double the price.

Do you have a welder? Are you skilled at welding sufficiently to trust your life with it? Do you have the tools, equipment to jig the whole thing? That's not an option, either. This is not a small shade-tree project.

Being part of the R&D I know that the Medium/Heavy springs are too stiff. I don't remember what Brett finally went with, but they were a much lighter rate die spring.

Anyone can build anything. Nothing is impossible. I just want to point out some items maybe not thought of.

Factoring in labor the $1200-1500 that is the going rate for this gear is not out of line. I don't know if Brett is still in business or not. (He won't return my calls either...) Lowell Fitt at Highwing LLC is making cabine style gear. I think they are getting in the $1500 range for theirs.

[SuberAvid 617]

I "built" the gear for my Avid+, 5.5 " taller (vertical height) and upsized all the tubing one dia from the Airdale wide bungee gear. Overall, with the longer and larger tubing lengths and 3 connection points to the fuselage, it is probably a notable increase in materials over the Airdale wide bungee gear. I ended up with about $600 in just materials, but that included the jig I built first out of 1.5" sq. tube mild steel. The 4130 I ordered from AC Spruce so that included the outrageous shipping cost.

I say "built" because I only did the design, built the jig, and cut and fit all the tubing. I had the advantage of a friend who is a good TIG welder who did all the 4130 welding.

[akflyer 1427]

Jim, I built my Bush Gear for my KF1 but used the air frame as the jig. I Also built a trailer for testing and performed a 2000 Lb. static test, a 1000 Lb dynamic test and a 1000 Lb drop test using the trailer. In the fall I botched a landing on a steep grade. The gear held up fine but fuselage failed. Mainly due to the tab location allowing a torsion on the longeron.

Dave

Dave,

Was the file posted on the yahoo groups done by you? If so, I would like to post it here also. I looked at the gear many times in the past and was ready to build it based off that design, but time and other projects stopped me from doing it. I know the reason I was able to buy a wrecked Avid was do to the gear failures (twice) so I beefed up the fuse. If my fuse fails at the truss or longerons, I wont be around to worry about it. After seeing Joeys gear and his failure, I would want to play with lighter springs for sure!

Jim,

I was thinking the same thing you are. Cut the tubes across the top and then make the cabane strut system. I am also thinking of using a snowmobile shock on them like the guy is going for the RANS S-7 I just happen to have a pile of shocks from old race sleds that I could use and I have a good buddy who can actually get them tuned and valved right so the rebound and compression is perfect. Not to take anything away from the guy that is building them for the Rans, but the FOX floats that he is using SUCK! We tried for years to get them dialed in on my Cross Fire and the Mountain sled and they just dont work very well as there is not enough volume in them to really dial in the spring rate using air. The newer EVOLS work good, but I am not going to drop 2000 on shocks

[FoxDB 17]

Dave,

Was the file posted on the yahoo groups done by you? If so, I would like to post it here also. I looked at the gear many times in the past and was ready to build it based off that design, but time and other projects stopped me from doing it. I know the reason I was able to buy a wrecked Avid was do to the gear failures (twice) so I beefed up the fuse. If my fuse fails at the truss or longerons, I wont be around to worry about it. After seeing Joeys gear and his failure, I would want to play with lighter springs for sure!

Jim,

I was thinking the same thing you are. Cut the tubes across the top and then make the cabane strut system. I am also thinking of using a snowmobile shock on them like the guy is going for the RANS S-7 I just happen to have a pile of shocks from old race sleds that I could use and I have a good buddy who can actually get them tuned and valved right so the rebound and compression is perfect. Not to take anything away from the guy that is building them for the Rans, but the FOX floats that he is using SUCK! We tried for years to get them dialed in on my Cross Fire and the Mountain sled and they just dont work very well as there is not enough volume in them to really dial in the spring rate using air. The newer EVOLS work good, but I am not going to drop 2000 on shocks

Leni,

I am not the guy who posted on yahoo. My strut is a down sized version of the Bearhawk strut. I have not seen the John Roberts Rage Gear just a picture but it is evident the Fox Shock is paired with a Bungie.

[Av8r3400 1179]

I tell you what, if I were going as far as my own gear design, I'd copy the new Highlander super-stol design and to hell with the cabine style.

[akflyer 1427]

I tell you what, if I were going as far as my own gear design, I'd copy the new Highlander super-stol design and to hell with the cabine style.

The only issue with the highlander super stol gear is the wing mods that need to be done to. That is a 15000.00 upgrade on the highlander to retrofit the gear and the wing. YIKES!

I saw the RAGE gear and see the use of the bungee still but that still leaves a shock that could perform better.

The issue with the fox float may be OK to soak up that one good hit, but in stutter bumps (big rocks) it will pack and cant transfer fast enough so we can never get the rebound dampening to work right. You can make it better by adding an air expansion chamber, but they still don't work as they should.

On the other hand, the airplane is traveling at lower speeds than we do on sleds and you probly dont need as cushy of a ride as we like for the 100+ MPH stutter bump stuff. Our golden rule is that if you cant take one hand off the handle bars at 100+ in 2' high bumps then your not valved right

[Av8r3400 1179]

Why would you need to do the Zennair wanna-be slotted wing?

I'm just saying if I was going to clean sheet a landing gear design, it would follow the patter of the long travel super-stol design, or maybe the Wilga trailing link (also a long travel).

Personally, I like my Grove aluminum spring gear. I'm going to use the same on my project and highly recommend it...

[1avidflyer 1983]

Leni,

I am not the guy who posted on yahoo. My strut is a down sized version of the Bearhawk strut. I have not seen the John Roberts Rage Gear just a picture but it is evident the Fox Shock is paired with a Bungie.

The guy who put the file in the Yahoo group used the name whizzer something. Looked at his profile and all it said was Mac. Jim Chuk

[BryceKat 125]

That's Bob Mc Dunna

[C5Engineer 1170]

I am doing some research to see if Avweld has any plans to do a system for the Kitfox cabane style gear. My biggest complaint I had with my "Bush Gear" was the springs that didn't flex.

If your not familiar with the RAGE gear you can check it out here http://www.backcountrypilot.org/forum/viewtopic.php?f=13&t=11744&p=156699&hilit=Rebound#p156699

[Av8r3400 1179]

The "bush gear" style cabine gear is design-limited on it's travel, regardless of what kind of spring/shock arrangement is used. The wheels spread out too dramatically for it to work efficiently.

This is one of the reasons Troy & the boys did a clean sheet design on the "Super STOL" gear. That gear design is amazing if you haven't seen it work. Watch closely in this video, you see the wheels spread, but not much. This is why it works so well...

[akflyer 1427]

No doubt about it Larry, that is ONE BAD ASS bump soaking gear system! It is a little more than I think I need I learned how to land so I dont gotta test it with the 10' drop every time

Here is the file from the Yahoo group that shows roughly how to build the gear. I noticed that his pull is straight across on the cabane vee, where the super cub and other gear like it are not a straight pull. I will talk to my engineer buddy today and see how or why/if it transfers the loads differently. At any rate, using this document, I dont see any tough road blocks for a do it yourself guy to modify the existing wide gear to the spring gear. I may change out the tubes at the top of the gear legs to use 5/16" or 3/8" bolts instead of the 1/4" .

Avid Spring Gear.doc

[FoxDB 17]

No doubt about it Larry, that is ONE BAD ASS bump soaking gear system! It is a little more than I think I need I learned how to land so I dont gotta test it with the 10' drop every time :stirthepot:/>

Here is the file from the Yahoo group that shows roughly how to build the gear. I noticed that his pull is straight across on the cabane vee, where the super cub and other gear like it are not a straight pull. I will talk to my engineer buddy today and see how or why/if it transfers the loads differently. At any rate, using this document, I dont see any tough road blocks for a do it yourself guy to modify the existing wide gear to the spring gear. I may change out the tubes at the top of the gear legs to use 5/16" or 3/8" bolts instead of the 1/4" .

I would like to see the design of the Bungie Strut gear as in the Standard Highlander or the John Roberts gear without the Fox Float. I used a down sized version of the Bearhawk Gear struts but it is not easily tuneable. I believe the bungies could provide more travel and be easier to tune. If anyone has pictures of the strut parts without the bungie installed I would like to see it.

Thanks Dave

[C5Engineer 1170]

I am not sure why everyone opted to go with the metal springs over a cub style bungee gear.