Worn Cobra rear-door hinges (both pin and hole)

On Dec 19, 6:51*am, Dave Nadler wrote:
On Saturday, December 17, 2011 12:51:02 PM UTC-5, Dave Nadler wrote:
Hi Folks - Anybody else had this problem ?
http://www.nadler.com/Antares/Cobra_...orn_hinge_clos...
I've got replacement pins from Spindelberger and
replacement rear corner channels, but I'm thinking
about an insert so all the loads aren't taken in
a thin bit of channel...
Thanks,
Best Regards, Dave "YO electric"

PS: ~55k miles on the trailer.

OK, lets recap, from thread here and private emails.

As it says above: I have NEW REPLACEMENT aluminum pins
and NEW REPLACEMENT (undrilled) corner channels
from Spindelberger.

I do not want to repeat the problem by using these
as used originally.

The structure (pins/channel) is STRONG enough, but
the aluminum pin on the thin aluminum corner channel
wears excessively. Aluminum-on-aluminum is NOT GOOD.

Suggestions so far via email and in this thread:

A bushing (as suggested by T8 and others) reduces
wear with a better fit and materials that wear less;
anything is better than aluminum-on-aluminum.

A replacement pin of steel (drill stock or cut
bolt with a couple holes through it for mounting;
no complicated machining required) will not wear
out so easily.

A steel insert, block or 1/4" plate bolted to
inside of channel, will give better wear and more
surface.

A tube insert (all the way through the corner channel)
can do likewise. Add a plastic cap on the outside
to keep the dirt out. Easy to make and install
(before riveting in replacement corner channel);
no complicated machining required.

Notes on more modern Cobra trailers:

The bottom of the existing corner channel is not
open; the sidewall extrusion is cut leaving this
area blocked. You cannot just slide a reinforcement
part in from the bottom; you have to remove the
corner channel (bunch of rivets).

The skids are mounted forward of the rear corner
channel.

Further thoughts ?
Thanks in advance,
Best Regards, Dave "YO electric"

http://www.onlinecontest.org/olc-2.0....html?dsId=217....

Dave, you already have lots of good advice but here's another idea.
http://www.popsci.com/diy/gallery/20...-plans?image=4

Metal filled epoxy like this is just as strong as aluminum. It could
be used inside the frame tubes to re-size the holes. If you coated
the new pins with mold release compound and clamped the door in
perfect alignment while the epoxy set up, you'd have a tight, rattle
free fit. The fix would probably last as long as the rest of the
trailer. If it didn't, it's easy to repeat the repair.

Can't use that, product doesn't even have
the word "Miracle" in the name.
Might work for winch bearings though.

On Dec 19, 7:38*am, Steve Koerner wrote:
Dave- Removing the rivets on the corner channel and reinstalling it
with new rivets is not a big deal. *That only took a few minutes to
accomplish.

Keep in mind that aluminum and bronze aren't very compatible from a
corrosion standpoint. The aluminum is going to be sacrificial to the
bronze. Since you've got lots of aluminum and only a little bronze it
isn't horrible, but a stainless bushing is a better choice if you're
going to stay with the aluminum pins.

Cheers,
Craig

"JJ Sinclair" wrote in message
:

On Dec 18, 8:07*pm, Steve Koerner wrote:
Joe -- making some kits sounds like a great idea. *Please make one for
YO so he doesn't try to stick a bushing in that aluminum channel.

For a long time I had intended to do a write-up on this mod but I
never got to it. *I wish I had. *I didn't locate any pictures but I
did locate my dimensioned sketch that I made at the time of
fabrication. *From the date on the page,I did this in '06. *Th sketch
is crude but it should be all you need to make the block that goes
into the channel. * The block is 1.00" X .74" X 4.00". *It has 3 M8
tapped holes in the bottom and the reamed .501" hole in the side. *I
suppose there is the possibility that the skids are located at
different longitudinal locations on various trailers -- so that would
need to be checked first. *It looks like I didn't make any sketch of
the part that goes on the door -- I'm thinking it was just an obvious
duplication of the existing part there but with the .500" steel pin in
place of the aluminum metric size pin.

If anyone makes one of these, you should put some grease on the pin or
in the hole when you put it together.

I have posted the sketch hehttp://www.box.com/shared/3ul281v6y0aek31gmva5

Steve Koernerwww.wingrigger.com

Back to the 'why' is the rear door hinge getting all chewed up? I'm
thinking the culprit is the heavy ramp (with jack ('s). The rear door
locks the ramp in place with a bolt that extends into the door when it
is closed. I have found (and fixed) the hole in the door that holds
the ramp, to be severely elongated, why? The ramp & jack are bumping
up and down causing the elongation. This becomes a jack-hammer and the
destructive action doesn't stop with elongating the ramp to door lock.
I believe it is undoubtedly causing the door hinge galling. Recommend
a 1/16 wall, steel plate with bolt hole drilled in center, be pop-
riveted over the elongated hole. Set the new plate so it holds the
ramp & jack firmly against the floor. Then fix the hinge pins ala
Steve & Joe's recommendation.
A good winter project,
JJ


Hmmm? What about out-of-round or out-of-balance tires? Maybe a lot of
vibration going on back there...

Just a thought....

Zero One

Tires balanced, no visible motion in rear view mirrors...
I don't think so...
Best Regards, Dave

I'm going to use bushings in the corner channels and
a steel (ideally stainless) hinge pin. The pin won't
wear out, and if the bushings wear they're just a
few minutes to replace.

Anybody up for making replacement pin kits ?
Here's a rough (I know, very rough) sketch:
http://www.nadler.com/Antares/CobraRearDoorHinge_4.pdf

Joe ? Steve ?

Alternatively, can anyone recommend a favorite
internet machine shop ?

Happy Holidays,
Best Regards, Dave "YO electric"

PS: Wear on pins is only on one side: door moving
downwards when closed, or upwards when open. I think
most likely I've caused this by cranking trailer nose
up against door opened on ground to steady rear of
trailer(instead of using the cranky rear jack stands)...