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Axle installation


mfryer

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I am about ready to install the axles and I am getting nervous. The plans are not very detailed about this step and I want to make sure I get this right the first time.

 

That primary concern I have is the shape of the main gear strut where the axles attach. It is still somewhat airfoil shaped and I do not feel the 3 plys of bid will not even come close to producing a flat surface for the aluminum plate and axle to mate to.

 

Should I sand the area flat? Should I build with glass layups untill I have more glass to ensure a flat surface? How do I keep the aluminium plate axle and glass from moving during cure (I know that the clamps are there for that, but perhaps there is a more secure method?).

 

One thought I had was to go ahead and pre drill the bolt holes. I have a template that I can use. My thought was that I could layup the glass plys then bolt the who mess together and use the bolts to adjust tow-in. Thoughts?

 

Also the plans method for ensuring proper toe in seem to me to require at least two four armed people.

 

Any hints, tips and advise are greatly appreciated.

 

Here are a couple of photos of my gear with an axle staged. The bottom of the strut is carved out a little differently than plans because I am using Matco brakes....

 

post-2217-141090162161_thumb.jpg

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i just did all that, not to bad

just get the flat close

set up the eye jig just like the plans say to do it.

i used the eye tube held up to the leg and checked the alignment on the wall.

then i clamped the axel on and put the eye tube in the inner flange and the outer flange. the worst part for me was drilling the holes straight all the way through. the start was fine but the exit was way off.

so later I'll re drill and flox

i think the plans way is cheep and fast and free...and fun

i did mine with no help.

Steve M. Parkins

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I am about ready to install the axles and I am getting nervous. The plans are not very detailed about this step and I want to make sure I get this right the first time.

 

That primary concern I have is the shape of the main gear strut where the axles attach. It is still somewhat airfoil shaped and I do not feel the 3 plys of bid will not even come close to producing a flat surface for the aluminum plate and axle to mate to.

 

Should I sand the area flat? Should I build with glass layups untill I have more glass to ensure a flat surface? How do I keep the aluminium plate axle and glass from moving during cure (I know that the clamps are there for that, but perhaps there is a more secure method?).

 

One thought I had was to go ahead and pre drill the bolt holes. I have a template that I can use. My thought was that I could layup the glass plys then bolt the who mess together and use the bolts to adjust tow-in. Thoughts?

 

Also the plans method for ensuring proper toe in seem to me to require at least two four armed people.

 

Any hints, tips and advise are greatly appreciated.

 

Here are a couple of photos of my gear with an axle staged. The bottom of the strut is carved out a little differently than plans because I am using Matco brakes....

 

[ATTACH]1718[/ATTACH]

 

Hold on for a minute!!!

 

Before you do any drilling, you must arrange the toe in and out as well as the caster/camber/. this can be done with a bed of flox under the axle flange.

 

Then and only then drill and bolt. If you drill and bolt before this you will have little chance to adjust this-- save some shims, if you are off by just a little. The thickness of the glass on the leg is of little importance save the plans wraps since the axle is compressed to the leg via the bolts through it through the leg through a backplate and then the nuts.

 

Ain't that the nuts.:bad:

I Canardly contain myself!

Rich :D

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Hold on for a minute!!!

 

Before you do any drilling, you must arrange the toe in and out as well as the caster/camber/. this can be done with a bed of flox under the axle flange.

 

Then and only then drill and bolt. If you drill and bolt before this you will have little chance to adjust this-- save some shims, if you are off by just a little. The thickness of the glass on the leg is of little importance save the plans wraps since the axle is compressed to the leg via the bolts through it through the leg through a backplate and then the nuts.

 

Ain't that the nuts.:bad:

it said all that in the book, so i left it out.

but i think (cuz i did it) you can drill first and bed it down with flox and glass then just leave the bolts in the holes or snug them as long as you get the tubes right on the wall as-per-plans and i do have a shim ,it is 1/8 at one end and 1/32 at the other. and the shape is the same as the Axel mount.

Steve M. Parkins

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Hold on for a minute!!!

 

Before you do any drilling, you must arrange the toe in and out as well as the caster/camber/. this can be done with a bed of flox under the axle flange.

 

Then and only then drill and bolt. If you drill and bolt before this you will have little chance to adjust this-- save some shims, if you are off by just a little. The thickness of the glass on the leg is of little importance save the plans wraps since the axle is compressed to the leg via the bolts through it through the leg through a backplate and then the nuts.

 

Ain't that the nuts.:bad:

Oh, I am in no hurry to start drilling anything, hence my questions. I am still a little unclear though. My confusion here is that I am bolting flat axle and flat aluminum plates to an oval shaped strut. Should I sand the strut to flat, or build up more glass plys. Perhaps a little of both? (I think this is what this plans are trying to indicate).

 

Am I just over thinking this a little? It seems that every time I get to a scary step, its really not that bad, rather EZ in fact. Still, I prefer to use some caution and get some advise.

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I used flox to build up a flat mounting surface and did not sand a flat on the gear strut.

 

Also, be sure you have the axle positioned correctly. The plans are not real clear on vertical postioning. This sets your 3-point takeoff pitch angle. You may have to cut a little off the gear to get the correct axle position. Also, watch for too much camber because this will cause premature tire wear on the inner edges.

 

You may have to shim the axle away from the gear leg to get enough clearance between the brake disc, heat shield, and gear strut.

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Once you drill, you won't be able to shim more than a degree or so without bending bolts. Mine are way off in camber and a little off in toe in (not built by me). Right now I am just living with it---and the only way that I can see to fix is to fill all the holes with flox and redrill----thoughts?

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I have done six of these and found that my laser torpedo level works in lieu of the sight tube. As inexpensive as they are now you can afford two of them. If you understand the geometry and theory on front end alignments, you will be well prepared to take this on. The caster is the angle that your gears legs are in relation to the fuselage. (done right :D) The camber will look a little radical to you since the axles WILL NOT be parallel to the floor. Just make sure they are at the same angle while the plane is upside down. When you hang the wings, engine and fill it with fuel, the wheels will be more vertical. The axles will want to slip and slide around when you flox them on. Be creative and build a jig to hold them. If you are not satisfied with one or both of the axles you can break the flox bond, use a hard sand block and tweak the flox pad then epoxy the axle back on. And as the plans say, drill the gear leg after the flox has cured.

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I have done six of these and found that my laser torpedo level works in lieu of the sight tube. As inexpensive as they are now you can afford two of them. If you understand the geometry and theory on front end alignments, you will be well prepared to take this on. The caster is the angle that your gears legs are in relation to the fuselage. (done right :D) The camber will look a little radical to you since the axles WILL NOT be parallel to the floor. Just make sure they are at the same angle while the plane is upside down. When you hang the wings, engine and fill it with fuel, the wheels will be more vertical. The axles will want to slip and slide around when you flox them on. Be creative and build a jig to hold them. If you are not satisfied with one or both of the axles you can break the flox bond, use a hard sand block and tweak the flox pad then epoxy the axle back on. And as the plans say, drill the gear leg after the flox has cured.

 

What I did was to use a bed of flox and bid for the bed, and orientate the axles approximately correctly. At this stage, it is somewhat like pushing a string. Use packing tape as a separator on the axle and give a little extra thickness on the pad.

 

When this is hard, using a flat sanding block, reshape the pad so that when the axle is flush to the now modified pad, the caster and camber is correct, and rock is slight. ( I also suggest the use of lasers. Keep in mind that the laser beam has to be parallel to the ground when aiming to the target or all bets are off.)

 

Now the "flat" pad that you sanded will not be completely flat unless your sanding technique is impeccable. This must be corrected.

 

Using a new thin bed of thickish flox, Smear some on the hardened, sanded pad and clamp your axle (and laser to the thick new flox with 4 clamps, two on the bottom and 2 on the top. With proper iterations of clamp tightening, you should be able to get your laser directly on the spot.

 

Of course, you have re taped the axle so you can get it off for future.

 

Let this harden and you now have maximum contact between the axle flange and pad. Drilling now becomes easy (remove one clamp at a time, drill, bolt then do the next) and your gear will be SPOT (laser) On!

I Canardly contain myself!

Rich :D

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When you initially install the axels, you want to get the toe-in (the front of the wheels pointing at each other ) and camber (The top to bottom tilt of the wheel) as close as you can to the specs. If you do a good job here, you won't need to shim or adjust later, and the mount holes will be perfect. You can't do anything about caster, this is set by the forward angle of the gear bow.

 

The Plans tell you how to measure and install the axels to give you the toe-in and camber, but leave out one very important step;

 

The gear bow must spread apart and angled forward as if you were Taxiing or taking off.

 

I spread mine so that the flats of the bow (the portion where the axel mount) was almost vertical. In this position, the flats on both side of the bow will be almost vertical, and the camber will be strainght up and down

 

( If you set the Toe-in and camber with the bow unsprung, these numbers will be WAY OFF when you jump in your plane and start to taxi.)

 

The fuselage needs to be level, AND the gear bow needs to be spread apart.

 

I used a come-a-long to spread the bow, then cut a 4x4 and wedged it between the two legs to hold the bow spread apart. Reverify the fuselage is level front-to-back and side-to-side. ( Put blocks under the 4x4 to hold it in place, probably wouldn't hurt to put a couple blobs of Bondo on the blocks and 4x4 to keep them from getting bumped.)

 

Build up the axel mount areas with FLOX and small squares of BID, use small "C" clamps. If you use three clamps per axel, you can make adjustments to the toe in amd camber by systematically adjusting the clamps. With the wet FLOX you'll have a couple hours to play with these and get them as close as you can.

 

Two additional comments regarding these measurements:

 

1) Don't forget that the axels need to be level in relation to the fuselage, otherwise your plane will taxi lopsided. Cut two wooden block and allow the axels to rest on these. This will hold the heights of the axels constant as your adjusting the clamps for toe-in and camber.

 

2) When measuring Toe-In, there are two measurements you need to be aware of; The each wheel in relation to the other wheel, AND, each wheel in relation to the centerline of the aircraft. If your not careful with the centerline measurement, your toe-in could be correct in relation to the other wheel, BUT, your plane will dog-leg (taxi sideways) when you taxi.

 

 

When the FLOX cures, Reverify the fuselage level and the Toe-in and camber measurements.

 

If you carefully remove the clamps, the axels will stay on the bow. If you need to make another adjustment, you can lay up a couple squares of BID and reclamp the axels to the corrected position.

 

OR, you can use a block sander and sand off a little of the FLOXed pad to make the adjustment.

 

The axel holes can then be marked and drilled.

 

I mounted a heat shield plate between the axel and the bow. The heat shield plate doubles as my wheel pant mount.

 

http://www.iflyez.com/Wheel_Pants.shtml

 

Waiter

F16 performance on a Piper Cub budget

LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract

visit: www.iflyez.com

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I mounted a heat shield plate between the axel and the bow. The heat shield plate doubles as my wheel pant mount.

 

http://www.iflyez.com/Wheel_Pants.shtml

 

Waiter

What gauge/thickness aluminum is good for this heat shield plate? I want to mount my pants this way as well.

Self confessed Wingnut.

Now think about it...wouldn't you rather LIVE your life, rather than watch someone else's, on Reality T.V.?

Get up off that couch!!! =)

 

Progress; Fuselage on all three, with outside and inside nearly complete. 8 inch extended nose. FHC done. Canard finished. ERacer wings done with blended winglets. IO540 starting rebuild. Mounting Spar. Starting strake ribs.

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I used .125. Make it about 1/2 inch larger in diameter than the brake disk. Then cut out for about 1/4 clearance for the brake caliper assembly.

 

Waiter

F16 performance on a Piper Cub budget

LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract

visit: www.iflyez.com

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Gracias. Then drill holes as required and fuss and fume over fitting the wheelpants- first together- then onto the mounts- or so I hear.=/

Self confessed Wingnut.

Now think about it...wouldn't you rather LIVE your life, rather than watch someone else's, on Reality T.V.?

Get up off that couch!!! =)

 

Progress; Fuselage on all three, with outside and inside nearly complete. 8 inch extended nose. FHC done. Canard finished. ERacer wings done with blended winglets. IO540 starting rebuild. Mounting Spar. Starting strake ribs.

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The Plans tell you how to measure and install the axels to give you the toe-in and camber, but leave out one very important step;

 

The gear bow must spread apart and angled forward as if you were Taxiing or taking off.

 

I spread mine so that the flats of the bow (the portion where the axel mount) was almost vertical. In this position, the flats on both side of the bow will be almost vertical, and the camber will be strainght up and down

 

( If you set the Toe-in and camber with the bow unsprung, these numbers will be WAY OFF when you jump in your plane and start to taxi.)

 

The fuselage needs to be level, AND the gear bow needs to be spread apart.

I do not see anything in the plans about camber.

 

If I spread the bow apart untill the flats are vertical and set the axles to level, will not the natural angle of the flat still determine the camber? (I suppose we are ensuring here that they are both equal.)

 

Is all this work done with the bow installed on the fuse?

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I set the camber to vertical (match the flats of the bow when its spread) double check that both wheels match.

 

The bow needs to be on the fuselage to do this.

 

Waiter

F16 performance on a Piper Cub budget

LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract

visit: www.iflyez.com

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I set the camber to vertical (match the flats of the bow when its spread) double check that both wheels match.

 

The bow needs to be on the fuselage to do this.

 

Waiter

Thanks for the advise. You now have made this step far more involved than I was anticipating. However I will forgive you as you probably have saved some future headaches.

:)

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While we are on the subject of axles I would like to mention my Grove brake system. They are definitely worth considering. Although they look very similar to Clevelands, they are very high quality and have tremendous stopping power. My Cozy had the recommended Super Heavy Duty Cleveland system. I can't say enough about how much better the Grove brakes are. Not that you want to but I can lock the wheels up if I get on them too aggressively.

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The heat shield is meant to reflect radiant heat therefore thickness is not important.

In my case, the heat shield was also used to mount the wheel pants,

 

OR

 

The wheel pant mount plate also acted a s heat shield for the disk brake.

 

:D

 

Waiter

F16 performance on a Piper Cub budget

LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract

visit: www.iflyez.com

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  • 2 weeks later...

I am resurrecting an abandoned LE project, the previous builder(s) have carefully annotated the plans and I have all the CP issues. I’ ve removed the main gear to do various mods and I'm checking the main gear geometry.

 

The plans state on p9-1 that the axle centre line should be 15inches forward of the aft face of the centre section spar (at BL 26.75) at FS110.5 . I’ve measured using the plans method, and double checked by measuring forward from FS125 but I keep arriving at the same figure of 16 inches (FS109.50).

 

There isn’t any annotation on the plans (indicating plan changes) and I’m unable to find anything in the CP’s. relating to it.

 

Question: Does anybody know of any plan changes that I’m missing? If this is a mistake by the previous builder, what would the implications be if I left it as it is?

 

MikeD (U.K.)

Tell me and I forget.

Show me and I remember.

Involve me and I understand.

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I'm not aware of any plans change that relocated the mains.

 

According the the Pilots Operating Handbook. the main gear needs to be at 110.5 +/- one inch. So, your measurements are in tolorance.

 

Moving the mains forward will allow the nose to be rotated ealier during the takeoff. It will also allow you to tip the plane over backwards a lot eaasier.

 

Waiter

F16 performance on a Piper Cub budget

LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract

visit: www.iflyez.com

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Thanks Waiter, I presume the original builder was thinking about the earlier rotation during take off bit, long runways are ‘far and few between’ in the U.K.

 

I’m fitting a O-320 and have extended the nose so I will need to pay attention to getting the CG in the correct place.

 

There’s lots of very useful information in this thread, this forum has become a very important part of my project, a great big ‘thank you’ to all contributing members.

 

MikeD (U.K.)

Tell me and I forget.

Show me and I remember.

Involve me and I understand.

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