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Topic: Gas spring (strut) replacement for my 93 U300 bay doors (Read 932 times) previous topic - next topic

Gas spring (strut) replacement for my 93 U300 bay doors

I just bought 20 new gas struts to replace all those in my bay doors since a lot of the old ones were fading.  I looked at the part number of the originals and all 20 of them were marked SL-34-20 (12-20" long, 20lbs, 10mm ball)

I bought 20 of the equivalent Columbia Strut model CS2000-20 off of eBay.  When I received them I started on the the little bay door next to my step and replacing them improved the performance greatly.  Then I replaced the big bay door over my joey bed and the door just fell like it didn't have any support at all.  Obviously the big door is much heavier than the small one, but why would the old struts mostly hold it up and the new ones would not?  These are supposed to be the same struts!

So I got the bathroom scale out and and pressed on the new Columbia ones and they all held at about 25lbs - it seems like they are just fine.  I then removed the two that were actually holding up the big door and both of them were holding a whopping 55 lbs!  And these are supposed to be 20 lb struts according to the mfr PN.

Has anyone else seen this kind of problem?  Could the gas struts have been custom charged with higher pressure than the PN would indicate?  Does anyone have any idea what the right struts should be for this application?  And of course, anyone interested in buying some new 20lb struts?  :)

Thanks in advance

Dave & Judy
'93 U300 40'
6V92
Dave and Judy
1993 U300 Grand Villa 40ft AKA 'Las Vegas Betty'
Calistoga, CA

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #1 –
Quote from: Aeres707 –
I just bought 20 new gas struts to replace all those in my bay doors since a lot of the old ones were fading.  I looked at the part number of the originals and all 20 of them were marked SL-34-20 (12-20" long, 20lbs, 10mm ball)

I'm somewhat surprised by that OE p/n.  Our bus-style pantograph ones are SL-34-100 and our top-hinged, lift-up are SL-34-70's.  100 lbs or 70 lbs.  That's why an Irwin Quik-Grip clamp is needed to compress them.

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #2 –
It was not that uncommon for struts to have different force than their label would indicate.

If the strut maker had a huge number of 20 pound struts and got an order for a bunch of 30's, they may have redone the 20 into 30's. 

You might take the strongest of the original "20's" and use the scales to see what it tests out at.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #3 –
Thanks.  Yes, as I mentioned before I measured the force of the strongest I found and they were at 55lbs.  The problem now is that these likely have faded some so I'd like to know what the right ones should be.  Otherwise I am going to have to reverse engineer each door by weighing it open, calculating the lever arm, and then make my best guess as to the right amount of excess force to hold it up solidly while also making sure my dainty wife is not swinging from it while trying to close it. 

Is there a resource to find what was originally spec'd by FT?

BTW, thanks for the tip on the Irwin clamps.  Looks like I'll need them...
Dave and Judy
1993 U300 Grand Villa 40ft AKA 'Las Vegas Betty'
Calistoga, CA

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #4 –
I've seen stickers placed over the original numbers.  The stickers on yours may have fallen off.
Here's what I remember about the forces for each door:
6 ft long doors = 120 lbs strut
4 ft long doors = 60 lbs. struts
2 ft long doors = 20 lbs. struts

As they get weaker (loose pressure) I migrate them down to the next smaller door so I typically just buy the 120 or 60 lbs struts.  You will notice in very cold weather the force drops off quite a bit, so in the heat of summer you want to make sure force isn't marginal.

I buy mine from Foretravel and find their price is very reasonalble for these - about $15/ea.  Mine have a different style end:  no ball - I think they call them eyelet style.  Has a flat "blade" end with a 3/8" hole in it.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #5 –
That's great info JohnFitz!  Thanks!  Those force numbers seem like they will work well.  I'll buy two sets of 120 lb units as you suggest and then play musical struts with the rest of them.  Great idea...
Dave and Judy
1993 U300 Grand Villa 40ft AKA 'Las Vegas Betty'
Calistoga, CA

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #6 –
Dave, I had exactly the same experience. Mine all said 20 lbs but the 20's barely held up the small rear battery and air filter doors. Please post the source if you find a good one for the stronger struts. So far I only had to replace one set on the little rear battery door.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #8 –
Thanks Kent.  Glad I'm not alone with this issue.  When I bought the 20 pound struts I bought 20 each (doh!) for about $13 ea. plus shipping on eBay.  The user name for the guy was "strut-your-stuff-here". They were name-brand Columbia Struts and apparently great quality.  Now I'm going to go back to see if they guy will exchange some of them for the right ones...
Dave and Judy
1993 U300 Grand Villa 40ft AKA 'Las Vegas Betty'
Calistoga, CA

Re: Gas spring (strut) replacement for my 93 U300 bay doors

Reply #9 –
And a word of warning, new struts will place a lot of stress on the hinged connection when you close the door if you're not careful.
1996 U270
Build #4846