Chapter 9 – Mounting Gear Axles

I started out today by applying orange Torque Seal to all the gear mounting bolts in the hell hole.

Gear mount extrusions torque seal

I then mounted a 1×2 vertically on the firewall, offset 3/8″ so that I could then mount a horizontal 3/4″ wide board down the CL of the fuselage.  I originally was going to use my German aluminum long boards for the alignment board, but it wasn’t as straight as the 1×4 pine board I had on hand.

Mounting CL alignment board

Here’s a shot of the 1×4 CL alignment board.  As you can see, completing Chapter 13, the nose gear, allowed me to set the nose gear at just the right height & use it as a mount. Pretty darn handy!

Mounting CL alignment board

I set & verified the CL alignment board with a plumb bob at a few spots along the length of the board.

Mounting CL alignment board

Mounting CL alignment board

Here’s a shot of the installed CL alignment board.

CL alignment board mounted

I then clamped my own version of the “Straight Tower of Pisa,” somewhat like my buddy Marco did.

Mini "Straight Tower of Pisa" erected

A shot of the left axle clamped in place, with a square it.

Configuring Toe-In

Another selfie for the FAA, right before I started in on all the major sanding of the gear bow.

Selfie for you FAA!

I sanded the left gear leg down to set the toe-in.

Gear leg sanded for proper Toe-In

Then, when I started checking the toe-in on the right gear, my measurement at the gear strut came out right about 0.12″ farther outboard than the left side.  I strung up my plumb bob over the center mark on the gear bow & confirmed that the gear was set about 0.12″ off center to the right.  Not sure how this happened since I had it dialed in while in Germany, but it was definitely an issue that I felt I should deal with.

After some thought, I decided to simply add 6 plies of BID on the exterior side of the left gear to move the wheel out about 0.1″.  Really, I don’t think being an 1/8″ off would cause any noticeable issues, but I want to keep the wheels difference from CL under 0.07″ or smaller.

Gear offset to right about 0.12"

After getting the initial toe-in set for the axles, I sanded down the entire gear legs for both the axle mounting BID gear pads, and the eventual installing of the gear fairing.

Final sanding of Gear Legs

Final sanding of Gear Legs

Here’s a shot of the right gear leg after final sanding.

Final sanding of Gear Legs

I then double-checked the lower gear leg markings . . .

Final markup of left gear leg

. . . and then initially trimmed the end of the gear legs.

Trimmed lower right gear leg

Here’s another shot of the trimmed gear legs.

Trimmed lower gear legs

Here’s the specialized gear trimming tool . . .  ok, it’s a jig saw!

Lower gear trimming tool

I then test fitted the wheel assembly onto the end of the gear leg.

Initial check of wheel/brake assembly

Another shot of the wheel assembly test fit.  I still have some lower gear glass to trim, but this is a good start.

Initial check of wheel/brake assembly

Here’s a wide angle shot of the whole axle install effort.

Wide angle shot of axle install structure

I cut the 3″x 3″ square BID plies for mounting the axles.  I cut 2 sets of 3 plies of BID for the right side, and then 1 set of 3 plies and another set of 9 plies for the left side.

3" x 3" inner & outer BID gear pads

I then prepregged the BID pads in sets of 3 plies,

Prepregged lower gear leg BID pads

and wetted them out.

Wetted out lower gear leg prepreg BID pads

I then laid up the BID onto the lower gear legs.

Lower gear leg BID layups

Lower gear legs 3-plies BID (outboard right side)

Lower gear leg BID layups

Lower gear legs 3-plies BID (inboard right side)

Lower gear leg BID layups

Lower gear legs 9-plies BID (outboard left side)

Lower gear leg BID layups

Ok, I then let the epoxy cure for over an hour to set up to just tacky before mounting the axles to minimize the slipperiness & sloppiness of the wet BID. Well, it didn’t make any difference really.

To be honest, I’ve never been more pissed off during this build than this step right here.  If ever I should have followed my buddy Marco’s lead & taken a page out of his book and pre-drilled the axle bolt mounting holes it is here.  Trying to mount multiple components to a surface with multiple curves on BOTH sides with clamps is, to put it politely, stupid at best.  Hats off to other builders that have done it, but as I said it was truly the most infuriating thing I’ve tried to do on this build.  It also may be that the Matco axle base is narrower than the other brands, not sure, but it was about impossible (at least for me) to keep so many variables in check.

With the nearly cured glassed getting tweaked by the constant re-clamping of the axles, I eventually chucked them and simply used the face of the heat shields to determine toe-in. For any builders reading this, I would highly recommend this route.  That combined with just laying up the BID one side of the gear leg at a time to minimize variables and slop.

Setting toe-in left gearSetting toe-in left gear

I say this because after the sheer ass-pain with the left gear, then of course I spent well under 10 minutes on the right gear side mounting the heat shield and back axle plate.

Setting toe-in right gear

Setting toe-in right gear

As for the toe-in figures, my goal was to keep the difference between the 0″ measurement and the 24″ measurement between 0.1″ and 0.15″ to ensure that there is some toe-in, but not too much.  I hate to say it, but this is one of those layups that I’m crossing my fingers and hoping on, since it looked good after I was done clamping it all together, and 10-15 minutes later… but it’s late, I’m turning it and who knows what will greet me in the morning.

Setting toe-in for right & left gear

Tomorrow, I plan on pulling off the tape backed heat shields that are certainly in the slightly wrong position, finalize the clean up the bottom gear leg profile, and then mount the axles & wheels.


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