Cobra Trailer Spare Tire mount failure

Just a warning to check your trailer spare before a trip and along the
way at gas stops. My 1998 trailer spare tire mount broke on a highway
trip. The wheel is mounted on the frame that holds the glider nose in
place. Two 8mm bolts welded to the nose cone frame hold the wheel to
the frame. One bolt sheared and the other broke away at one of the
welds. I was extremely lucky that the wheel didn't go through the
canopy or damage a wing. The wheel was dangling on the remaining bolt
with the broken weld, the tire tread was 5mm from the wing. It didn't
touch the wing or canopy, so I was "spared" a horrific tragedy.
I had a small shop weld two new 8mm bolts in place. I then added a
third mount to the Cobra design to keep the wheel from rocking on the
existing mount. I suspect the wheel weight rocking caused the
failure. The third leg is very easy to make and install yourself.
Use a small metal bar from a home improvement store, two bolts,
washers and nuts. Photos of the broken mount and new third leg can be
seen he
http://www.flickr.com/photos/brucebarnard/

Mine failed in the same way. It seems to be a design feature of the
Cobra, like the hydraulic ramp jack.

Mike

On Sep 20, 11:43*am, Mike the Strike wrote:
Mine failed in the same way. *It seems to be a design feature of the
Cobra, like the hydraulic ramp jack.

Mike

I never did like suspending all that weight with no part of the tire
resting on the floor, ala Komet.
JJ

On Sep 20, 12:37*pm, JJ Sinclair wrote:
On Sep 20, 11:43*am, Mike the Strike wrote:

Mine failed in the same way. *It seems to be a design feature of the
Cobra, like the hydraulic ramp jack.

Mike

I never did like suspending all that weight with no part of the tire
resting on the floor, ala Komet.
JJ

My fix was to mount the spare flat on the floor under the fuselage
nose. This means I would have to remove the fuselage to get the spare
out, but I have only had to change one tire in 35 years. Now, watch me
blow a tire next week on my way to Williams!
JJ

Anyone have any experience with the option offered by Cobra of mounting the spare under the trailer behind the axial?


On Sunday, September 20, 2009 at 3:44:45 PM UTC-7, JJ Sinclair wrote:

I never did like suspending all that weight with no part of the tire
resting on the floor, ala Komet.
JJ

On Friday, July 17, 2015 at 8:43:15 PM UTC+1, Jonathan St. Cloud wrote:
Anyone have any experience with the option offered by Cobra of mounting the spare under the trailer behind the axial?



I don't have experience of that Cobra option and don't know how it is designed. I have, however, been under a trailer that needed to be jacked up by the roadside to unbolt an under-mounted spare and it was a very worrying experience as passing vehicles blew the trailer about. I would only have an under trailer spare if the the design is such that the spare is in a cradle so that, no matter how flat the tyre, the wheel could be slid out from the side without any need to go or reach underneath.

John Galloway

I have that option, I put a plate on the inside of the trailer to help carry the load. The real problem with the initial installment is the bolts are too short and it is a real tussle to get the wheel off the bolts because as soon as one or two are loose the tire shifts against the remaining bolt and this can cause the threads to be damaged. Additionally, it is almost impossible to get the flat tire back on the bolts because of weight and short bolts. BUT, better than having the tire break off the original mount and fall on the nose of the glider.
Boise, ID

The tire is in front of the axle not behind in that option.

"Barny" wrote in message
:

Just a warning to check your trailer spare before a trip and along the
way at gas stops. My 1998 trailer spare tire mount broke on a highway
trip. The wheel is mounted on the frame that holds the glider nose in
place. Two 8mm bolts welded to the nose cone frame hold the wheel to
the frame. One bolt sheared and the other broke away at one of the
welds. I was extremely lucky that the wheel didn't go through the
canopy or damage a wing. The wheel was dangling on the remaining bolt
with the broken weld, the tire tread was 5mm from the wing. It didn't
touch the wing or canopy, so I was "spared" a horrific tragedy.
I had a small shop weld two new 8mm bolts in place. I then added a
third mount to the Cobra design to keep the wheel from rocking on the
existing mount. I suspect the wheel weight rocking caused the
failure. The third leg is very easy to make and install yourself.
Use a small metal bar from a home improvement store, two bolts,
washers and nuts. Photos of the broken mount and new third leg can be
seen he
http://www.flickr.com/photos/brucebarnard/



Do you ever use a motorhome to pull the trailer? I have known of
another one that failed which had been pulled almost exclusively by a
motorhome with its significantly greater tossing about of the trailer.


Larry

There have been a couple of other versions of the Cobra spare tire
mount.
Under the nose on the floor works if there is room (vintage 1988) If
the tire is too large you'll need a towel over it so the glider belly
doesn't turn black. As JJ mentions, the fuselage comes out to get to
the spare, but not a headache the one time I used it.
Bolted (upright, across the trailer) to the front of the vertical
tube holding the nose cone (vintage 1999) works too, if there is room
behind the storage bin.
Jim