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Author Topic: Need help mounting things inside and outside my TT  (Read 1565 times)


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Need help mounting things inside and outside my TT
« on: July 25, 2010, 09:39:47 AM »
I began my first project on our new/old RV last night, it is a 1973 Layton TT.  I was replacing a brake light on the rear.  Since the old one was broken and replacement plastic was not available.  I  removed the old light and cleaned up the butyl tape as best as i could.  Any suggestions for removing the residue?  I took the old screws mounting the old light to HD and got new ones.  They matched up with 8 x 1" pan head sheet metal screws.  I aligned the new light and drilled a hole through one of the mounting holes into the trailer then installed a screw then drilled the other 3 holes.  I lined the back of the new light with butyl tape, then sunk all four screw to mount the light.

The problem is the screws did not really catch, they just seem to be spinning like i stripped the holes already.   I was using a cordless drill and had the clutch on a low setting.  I wanted the screws to bite enough to suck the light up to the trailer to seal the butyl tape, but did not appear to happen.  I will try to get some 10x1" screw to see if they will hold better.

Did I use a too big drill bit when pre-drilling, or should I not pre-drill at all?
I would appreciate suggestions on how to use the butyl tape as well.  I just put one layer around the perimeter of the light, not sure if this is thick enough to get a good seal, should I put two layer or roll the tape to make a thick layer nearer the edge of the light?

My next project is to mount the converter inside the trailer.  There is not enough room where I want to put it to lie down so I will be mounting vertically.  It will be in a bench cabinet.  I will be putting some wood below to get it off the floor to clear some water pipes running there.  I would like to mount the screws into the wall to kind of hold it into place, then add a piece of wood on the backside, so it is wedged into the cabinet and to give it support so the screws are not trying to hold all 30 lbs on their own.  What kind of screws should I use to mount things in the interior?  What kind of structure is behind the walls to support things or mount into?


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Re: Need help mounting things inside and outside my TT
« Reply #1 on: July 25, 2010, 10:40:32 AM »
I suspect you used too large a drill bit when drilling the pilot hole.  When screwing into fiberglass, you do need a pilot hole to avoid cracking, but use the right drill size.  There are charts to tell you what size drill to use for each size screw but just holding the drill bit to the screw should tell you if it's too big.

When replacing external hardware, I always spend the extra pennies and get stainless screws, nuts and bolts.  Even plated screws will eventually rust if exposed to the weather.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon


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Re: Need help mounting things inside and outside my TT
« Reply #2 on: July 25, 2010, 01:41:02 PM »
Very likely your pilot hole was too big. You did not say what the exterior material on the trailer was, but if it is aluminum like many older trailers, it is VERY thin and likely won't hold a sheet metal screw well. If it is fibreglass over a thin wood it  does not hold well either and you likely have a core of foam insulation and that does not hold screws at all.

Is it possible to reach the other side from the inside and have anything going through hidden from sight?  If so, try using a longer stainless screw, washer and nut on the inside. Take the light fixture with you and check the mounting hole size, a #10 may be too big!!!

You should only need 1 layer of butyl tape, unless the surface is not flat, you might have to add extra in the hollows.

As Ned says, stainless is the only way to go!!!
« Last Edit: July 25, 2010, 01:43:04 PM by Alfa38User »
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Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"


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Re: Need help mounting things inside and outside my TT
« Reply #3 on: July 25, 2010, 02:49:45 PM »
Thanks Guys,
I think the siding is sheet metal and very thin.  There are also tons of ridges and such as part of the paneled siding is corrugated in a way.

I am glad i asked because I was not using stainless originally, which is stupid of me as I would not think to use anything else on a boat and this will see its share of moisture as well.  Also I had purchased a bolt to mount the missing chain for towing, which was just a plain home depot bolt.  After reading this I went back and got a better grade bolt and variety of stainless screws for external usage.  Lets hope the #10 screws work.