Help - Cobra Trailer Top Lift Springs

[rec.aviation.soaring]

Installed new gas lift springs purchased from Spindelberger yesterday
afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
Installation was relatively straight forward BUT I cannot get the lid
to fully close now. I am now stuck with partially open trailer.

One side is almost latchable but the other side will not make it down
and needs to go about 2-inches farther. Has anybody had a similar
problem? Could it be a defect in the gas spring under compression?

Initially it was difficult to get the lid to within 12 inches of
closing but after working it up and down for almost an hour it reached
a point where it would go no further.

[Andy[_1_]]

On Mar 6, 7:54*am, "rec.aviation.soaring" >
wrote:
> Installed new gas lift springs purchased from Spindelberger yesterday
> afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> Installation was relatively straight forward BUT I cannot get the lid
> to fully close now. I am now stuck with partially open trailer.

If you are sure the new lift struts are no longer than the originals,
I'd suggest the following:

Pull the top down as far as it will go without excessive force
Go to the sides of the trailer and push inward on the lower edges of
the top about mid length
Try closing again
Wiggle the back end of the top sideways
Press in on the top sides again

What can happen with strong struts is that the sides of the top tend
to bow out and the side rails do not mate properly.

You may need some help if the bowing is more than slight.

I had this problem with my new Cobra at high temperatures in Arizona.

Andy

[rec.aviation.soaring]

On Mar 6, 10:39*am, Andy > wrote:
> On Mar 6, 7:54*am, "rec.aviation.soaring" >
> wrote:
>
> > Installed new gas lift springs purchased from Spindelberger yesterday
> > afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> > Installation was relatively straight forward BUT I cannot get the lid
> > to fully close now. I am now stuck with partially open trailer.
>
> If you are sure the new lift struts are no longer than the originals,
> I'd suggest the following:
>
> Pull the top down as far as it will go without excessive force
> Go to the sides of the trailer and push inward on the *lower edges of
> the top about mid length
> Try closing again
> Wiggle the back end of the top sideways
> Press in on the top sides again
>
> What can happen with strong struts is that the sides of the top tend
> to bow out and the side rails do not mate properly.
>
> You may need some help if the bowing is more than slight.
>
> I had this problem with my new Cobra at high temperatures in Arizona.
>
> Andy

Thanks - Tried It. Still will not close. Side rails seem OK. When top
is up one the side that will not close seems to be a couple of inches
higher.
Makes me think the strut is bad. Unfortunately I did not study the
labels on the struts before installing them inside the square tubing.

Any other suggestions anyone?

[Richard[_9_]]

On Mar 6, 6:54*am, "rec.aviation.soaring" >
wrote:
> Installed new gas lift springs purchased from Spindelberger yesterday
> afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> Installation was relatively straight forward BUT I cannot get the lid
> to fully close now. I am now stuck with partially open trailer.
>
> One side is almost latchable but the other side will not make it down
> and needs to go about 2-inches farther. Has anybody had a similar
> problem? Could it be a defect in the gas spring under compression?
>
> Initially it was difficult to get the lid to within 12 inches of
> closing but after working it up and down for almost an hour it reached
> a point where it would go no further.

The collapsed length of the gas spring is probably longer on the new
one.

Check if the rod ends are the same. Drill a hole in the old springs
let the gas out and measure the collapsed length.

Compare with you current spring with the shell partially closed.

If all else fails drill new hole where the spring mounts on the lower
trailer.

Richard
www.craggyaero.com

[Darryl Ramm]

On Mar 6, 1:43*pm, Richard > wrote:
> On Mar 6, 6:54*am, "rec.aviation.soaring" >
> wrote:
>
> > Installed new gas lift springs purchased from Spindelberger yesterday
> > afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> > Installation was relatively straight forward BUT I cannot get the lid
> > to fully close now. I am now stuck with partially open trailer.
>
> > One side is almost latchable but the other side will not make it down
> > and needs to go about 2-inches farther. Has anybody had a similar
> > problem? Could it be a defect in the gas spring under compression?
>
> > Initially it was difficult to get the lid to within 12 inches of
> > closing but after working it up and down for almost an hour it reached
> > a point where it would go no further.
>
> The collapsed length of the gas spring is probably longer on the new
> one.
>
> Check if the rod ends are the same. *Drill a hole in the old springs
> let the gas out and measure the collapsed length.
>
> Compare with you current spring with the shell partially closed.
>
> If all else fails drill new hole where the spring mounts on the lower
> trailer.
>
> Richardwww.craggyaero.com

Does one side almost close by itself and the other is out by several
inches? If you detach the one that is out by several inches can you
get the other one to close? I know it might be a handful with just one
gas strut and the top twisting. If so then something is wrong with the
one that does not want to close. If neither will really close and you
installed them correctly then something probably changed. Maybe drill
new holes, but I'd check with Spindelberger if that should be required
before doing that. You should find their replies to questions to be
quick.

While working on this problem, be careful thinking the gas spring
might be the only think you are pushing against. I've seen Cobra
trailer tops damaged with things like when the lever that is supposed
to engage behind the wing root dolly fouls on something and the owner
keeps pushing...

Darryl

[rec.aviation.soaring]

On Mar 6, 5:14*pm, Darryl Ramm > wrote:
> On Mar 6, 1:43*pm, Richard > wrote:
>
>
>
> > On Mar 6, 6:54*am, "rec.aviation.soaring" >
> > wrote:
>
> > > Installed new gas lift springs purchased from Spindelberger yesterday
> > > afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> > > Installation was relatively straight forward BUT I cannot get the lid
> > > to fully close now. I am now stuck with partially open trailer.
>
> > > One side is almost latchable but the other side will not make it down
> > > and needs to go about 2-inches farther. Has anybody had a similar
> > > problem? Could it be a defect in the gas spring under compression?
>
> > > Initially it was difficult to get the lid to within 12 inches of
> > > closing but after working it up and down for almost an hour it reached
> > > a point where it would go no further.
>
> > The collapsed length of the gas spring is probably longer on the new
> > one.
>
> > Check if the rod ends are the same. *Drill a hole in the old springs
> > let the gas out and measure the collapsed length.
>
> > Compare with you current spring with the shell partially closed.
>
> > If all else fails drill new hole where the spring mounts on the lower
> > trailer.
>
> > Richardwww.craggyaero.com
>
> Does one side almost close by itself and the other is out by several
> inches? If you detach the one that is out by several inches can you
> get the other one to close? I know it might be a handful with just one
> gas strut and the top twisting. If so then something is wrong with the
> one that does not want to close. If neither will really close and you
> installed them correctly then something probably changed. Maybe drill
> new holes, but I'd check with Spindelberger if that should be required
> before doing that. You should find their replies to questions to be
> quick.
>
> While working on this problem, be careful thinking the gas spring
> might be the only think you are pushing against. I've seen Cobra
> trailer tops damaged with things like when the lever that is supposed
> to engage behind the wing root dolly fouls on something and the owner
> keeps pushing...
>
> Darryl

Checked again. Now seems pretty certain that the compressed length of
one of the gas springs is not quite right. They came to me fully
extended strapped to a board. Takes about 190 pounds to compress them
- which I didn't try. I just istalled them exactly like the old ones.
One side of the trailer does latch. The front hinges and all the side
channels are clear. Looking forward the left side is slightly higher
when fully open and does not compress enough to fully close. BTW the
old springs were Hahn 10-23-500-1-1146-AU19-AU19-850N. I believe these
are specially made for Spindelberger and they are definitely not a
stock item. Hope to get Spindelberger to send another spring to swap
out.

Stuart

[rec.aviation.soaring]

On Mar 6, 6:30*pm, "rec.aviation.soaring" >
wrote:
> On Mar 6, 5:14*pm, Darryl Ramm > wrote:
>
>
>
> > On Mar 6, 1:43*pm, Richard > wrote:
>
> > > On Mar 6, 6:54*am, "rec.aviation.soaring" >
> > > wrote:
>
> > > > Installed new gas lift springs purchased from Spindelberger yesterday
> > > > afternoon. Trailer is early 1990's aluminum top Cobra for a Discus.
> > > > Installation was relatively straight forward BUT I cannot get the lid
> > > > to fully close now. I am now stuck with partially open trailer.
>
> > > > One side is almost latchable but the other side will not make it down
> > > > and needs to go about 2-inches farther. Has anybody had a similar
> > > > problem? Could it be a defect in the gas spring under compression?
>
> > > > Initially it was difficult to get the lid to within 12 inches of
> > > > closing but after working it up and down for almost an hour it reached
> > > > a point where it would go no further.
>
> > > The collapsed length of the gas spring is probably longer on the new
> > > one.
>
> > > Check if the rod ends are the same. *Drill a hole in the old springs
> > > let the gas out and measure the collapsed length.
>
> > > Compare with you current spring with the shell partially closed.
>
> > > If all else fails drill new hole where the spring mounts on the lower
> > > trailer.
>
> > > Richardwww.craggyaero.com
>
> > Does one side almost close by itself and the other is out by several
> > inches? If you detach the one that is out by several inches can you
> > get the other one to close? I know it might be a handful with just one
> > gas strut and the top twisting. If so then something is wrong with the
> > one that does not want to close. If neither will really close and you
> > installed them correctly then something probably changed. Maybe drill
> > new holes, but I'd check with Spindelberger if that should be required
> > before doing that. You should find their replies to questions to be
> > quick.
>
> > While working on this problem, be careful thinking the gas spring
> > might be the only think you are pushing against. I've seen Cobra
> > trailer tops damaged with things like when the lever that is supposed
> > to engage behind the wing root dolly fouls on something and the owner
> > keeps pushing...
>
> > Darryl
>
> Checked again. Now seems pretty certain that the compressed length of
> one of the gas springs is not quite right. They came to me fully
> extended strapped to a board. Takes about 190 pounds to compress them
> - which I didn't try. I just installed them exactly like the old ones.
> One side of the trailer does latch. The front hinges and all the side
> channels are clear. Looking forward the left side is slightly higher
> when fully open and does not compress enough to fully close. BTW the
> old springs were Hahn 10-23-500-1-1146-AU19-AU19-850N. I believe these
> are specially made for Spindelberger and they are definitely not a
> stock item. Hope to get Spindelberger to send another spring to swap
> out.
>
> Stuart

With guidance from Spindelberger, who analyzed the problem carefully,
it was determined that the bottom bolt missed the gas spring eye
during my installation. One bolt diameter was enough to prevent lid
closure.
I highly recommend getting the correct length and force gas springs
from Spindelberger as this way things will work exactly as they are
supposed to.