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  #1  
Old 02-16-2019, 07:43 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
Posts: 381
Default Homemade jack pads

Howdy,

Inspired by the cool jackpads from Winter, I made my own out of 1" X 1 1/4" 6061 T6. I did the whole deed with out much more than a drill press, carbide burr, and a miter saw. The mounting holes are 15/16" OC and I used AN4-21A bolts. I had to make one spacer at about 17/64". The AN4-31A bolt only has about a half inch of threads so I reamed the hole halfway and tapped the rest. That way the shank of the bolt is in shear. I made a sleeve out of 3/8" OD 4130 reamed 1/4" ID to take advantage of more bending resistance and so I could torque the bolt into place for jacking. The pad weighs less than 2 oz. and fits under the wheel pant with the jack bolt removed. I bought an aluminum Porsche jack on Ebay which weighs less than 3 lb. I'm gonna throw that in a bag for the baggage compartment on cross countries. With a spare tube and a CO2 inflator, I'm ready for tire trouble.

Ed Holyoke





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  #2  
Old 02-16-2019, 08:47 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default

Thanks for sharing this! It's a good idea and definitely feasible without a machine shop.

Nicely done.

Dave
RV-3B, still on the fuselage
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  #3  
Old 02-16-2019, 09:26 PM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,765
Default Jack point

Love it. Brilliant.
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Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 01/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
Empennage, wings, fuse, finishing kit, now FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #4  
Old 02-17-2019, 02:08 AM
rvdave rvdave is offline
 
Join Date: Jun 2005
Posts: 459
Default

Looks like that may easily break off?
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  #5  
Old 02-17-2019, 11:05 AM
David Paule David Paule is offline
 
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Location: Boulder, CO
Posts: 5,063
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Can you get the jack under the flat bottom of the mount without using that bolt?

Dave
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  #6  
Old 02-17-2019, 12:11 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
Posts: 381
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Quote:
Originally Posted by David Paule View Post
Can you get the jack under the flat bottom of the mount without using that bolt?

Dave
Not happily. The base of the jack would be right up against the tire and I only have an inch of block to work with. I wanted to have full registration on the jack to reduce the chance of slipping off. The bolt through the slot seemed to me to be the best/easiest way to accomplish that. If I had made the block thick enough to put the jack on, the wheel pant wouldn't fit over it.

Hmmmm..... I could, I suppose, make a block that bolts on instead of the bolt sticking out with the bottom flush to the one on the axle. I do like the way the bolt in the slot of the jack keeps it from moving fore or aft, tho.

/Looks like that may easily break off? /

I hope not. I've got a lot of meat where the bolt is. With a half inch of shank in a snug fitting (reamed) socket, I'm trying to prevent the bolt from bending at the end of the threads. I think that also reduces the stress on the bottom of the threaded area. If the bolt were to pivot on the fulcrum of the edge of the hole, it would try and blow out the bottom of the threads.

I jacked the tire right off the ground using this setup and nothing bent. We'll see how it holds up to continued usage, but so far I think it works as intended.

Ed

Last edited by Bicyclops : 02-17-2019 at 12:14 PM.
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  #7  
Old 02-17-2019, 12:23 PM
Mike S's Avatar
Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,096
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If you are really worried about the strength of the bolt, widen the slot in the jack, and up size the bolt.

The reamed hole bearing on the shank is a good idea, puts the stress where it belongs, not on the threaded area.

I may have to steal this idea............
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Rv-10, N210LM.

Flying as of 12/4/2010

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  #8  
Old 02-17-2019, 12:42 PM
David Lewis David Lewis is offline
 
Join Date: Feb 2011
Location: Burbank, CA
Posts: 131
Default Nice Job

Quote:
Originally Posted by Mike S View Post
I may have to steal this idea............
A lot of us will be doing that.
Nice job Ed.
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  #9  
Old 02-17-2019, 01:08 PM
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Aviaman Aviaman is offline
 
Join Date: Feb 2018
Location: Louisville KY
Posts: 96
Default Homemade jack pads

Are the 2 bolts (heads flush with the aluminum bracket) replacing the lower 2 bolts holding the axle to the gear? If so, it looks like much longer bolts with the head on the opposite side than before the mod. On my RV9A, all 4 bolt heads are on the outboard side. Are there any issues with clamping force (axle to gear) being reduced due to softness of aluminum? I.e., aluminum yielding over time?
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Cessna 170B-sold
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  #10  
Old 02-17-2019, 03:00 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
Posts: 381
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Quote:
Originally Posted by Aviaman View Post
Are the 2 bolts (heads flush with the aluminum bracket) replacing the lower 2 bolts holding the axle to the gear? If so, it looks like much longer bolts with the head on the opposite side than before the mod. On my RV9A, all 4 bolt heads are on the outboard side. Are there any issues with clamping force (axle to gear) being reduced due to softness of aluminum? I.e., aluminum yielding over time?
Yeah, I used the two lower bolts on the axle to brake stay. They have been increased in length to account for the 1" thick jack pad. I turned the bolts around so I could get the jack closer to the axle. One of the bolts required a longer spacer to get it out flush with the wheel pant bracket. I was a bit concerned about the nut and washer being on the wheel side of the brake stay, but it clears everything just fine. I don't think I'll be able to significantly crush the 1" thick block of aluminum, and I will inspect for tightness every time I remove the wheel pant. The nut side of the bolt is on the steel brake stay, so no problem there.

Hmmmm..... Flush with the jack pad. 'Nother idea. I could counterbore the jack pad for the bolt heads and install shorter bolts. That would allow me to get the jack that much closer to the action and I could use a shorter bolt and spacer for the jack. I don't have a piloted counterbore to make a nice flat bottom hole, so I probably won't bother.

Ed
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