Awning lengths

[Ingrid]

We have to replace the awning roller tube after a freak 3am downpour snapped ours. We gently removed the canopy from the awning rail and removed the two halves of the roller tube (fortunately there is only a small repairable tear in the vinyl). We found a used A&E 8500 roller tube complete with torsion springs. Only problem is it's 27' and our existing awning is only 21'. I've downloaded the Service Manual and feel confident I can handle the replacement. I only hope the hardware is compatible as I'm trying to avoid having to remove and reinstall the Arms and Brackets. Hopefully, shortening it won't be too difficult. My concern has to do with awning lengths. I read somewhere that they are actually 7" shorter than advertised (i.e. a 21' awning isn't really 21'.) Anyone with input/ advise they would like to share would be greatly appreciated.

Thanks !

[AFChap]

My goal would be to cut the "new" roller tube as close to the original length of the broken roller tube as possible by carefully measuring the broken tube pieces ...regardless of what is 21' or 27' or 7" longer or shorter or anything else...

[Ingrid]

Thanks Paul... that's pretty much what I was thinking. Just wondered if there was a science to it such as "Awning width + 7" (3.5" each side)" or some other "industry standard" the experts follow . The old roller tube was so badly mangled in the middle, I'm afraid we won't get an accurate measurement, and possibly the awning won't roll properly if the roll is a 1/4" too long, or a 1/4" too short. Will "close" be good enough?

[Route 66]

I don't know what the tolerance is, but too short or too long will cause the arms to bind and may prevent complete retraction against the side of the rig.

[AFChap]

I'm sure "pretty close" as in 1/4" or less would work ...how far apart the arms are won't affect how the tube rolls, but could cause the arms to bind if they were angled too much from bottom to top. One way to double-check your tube length measurement would be to measure the width of the cloth ...and see if you can note from marks on the old roller how much metal was exposed at each end and add that to the width of the fabric for comparison of what you get when you measure the mangled tube.

[Ingrid]

Now, why didn't I think of that? Here's hoping I'll be able to see some markings. Now all we have to do is keep our fingers crossed and hope the end caps are compatible.