How can I attach GPS antenna to fiberglass cap?

belfert · September 09, 2009, 07:55:43 PM

Any suggestions for installing a magnetic GPS antenna on a fiberglass cap?

I think a piece of galvanized flashing would work, but how do I affix it to the roof? Also, how do I drill a hole for the cable and then seal that hole? I could rivet the flasing to the cap I suppose, but I would like to reduce opportunities for leaks.

MattC · September 09, 2009, 08:05:10 PM

If it were me, I'd stick it up there with Sikaflex 221 or something as nasty, seal the hole with the same and forget about it.

I'm a fan of Sikaflex so I'm sure there are other adhesives out there that would work that wasn't Sika, but why?

Nick Badame Refrig/ACC · September 10, 2009, 03:09:15 AM

Hi Brian,

if it's a puck type antenna, put it under the fiberglass cap!

Mine has been under the front cap for 5 years now. Works perfectly!

Nick-

Jeremy · September 10, 2009, 03:32:38 AM

Double-sided tape and a rubber grommet for the cable? Jobs on buses don't get much simpler.

(Actually, I'd be looking to try Nick's idea first - most GPS receivers are designed to be placed inside the vehicle in my experience)

Jeremy

paul102a3 · September 10, 2009, 03:34:01 AM

Brian,

I have my antenna mounted under the fiberglass cap as well and it works much better than I thought it would.

My cap and roof is painted with metallic silver paint so I was expecting little or no signal due to the metallic component of the paint. As a test, I taped the antenna up and did a 200 mile test drive. I did notice some signal drop off once and a while but the trade off was worth it to me.

The less holes in the roof, the better I like it.

After a 1000 miles or so, I am still pleased with the results.

Paul

gumpy · September 10, 2009, 04:40:04 AM

I mounted my magnetic antenna to the top of the steel frame, just under the fiberglass cap. I get around 7-9 ft accuracy with it, as opposed to 16-18 ft without it.

belfert · September 10, 2009, 04:49:53 AM

The idea of putting it under the cap is intriguing. Right now I have it velcroed to a flat part of the dash. The antenna is for my GPS speedometer and I get occasional dropouts where the speed goes to 0. I am hoping by getting the antenna up higher that it won't happen as often.

ake1994 · September 10, 2009, 09:30:05 AM

You will have more than aceptable performance with the antenna inside the cap. Just try to get it against the fiberglass with no steel between it and the satellites. Mine has worked very well for years. And as stated above no holes to worry about.

TomC · September 10, 2009, 09:46:23 AM

3M VHB two sided tape. It is strong enough to hold the panels on trucks, so I think it could hold the GPS. Good Luck, TomC

belfert · September 10, 2009, 10:55:08 AM

Quote from: TomC on September 10, 2009, 09:46:23 AM
3M VHB two sided tape. It is strong enough to hold the panels on trucks, so I think it could hold the GPS. Good Luck, TomC

Any ideas where to buy 3M VHB tape without buying a full 36 yard roll? A full roll is $50 to $60. Auto parts stores sell a tape for reattaching trim, but I'm not sure it is the same thing based on the minimal cost.

Nick Badame Refrig/ACC · September 10, 2009, 12:00:04 PM

Hi Brian,

Just set it in a wadd of silicone! When it dries, your good to go...

Down the road if you need to replace the antenna, you can just peel it away.

Nick-

gus · September 14, 2009, 12:00:46 AM

My Garmin GPS uses only the built in antenna and is mounted on the side window by the driver. Never have had a reception problem in 20,000 miles and coast to coast travels the past three years. It is the cheapest model!

Even if it should fail momentarily while running the bus would probably not break down or run off the road!!

eddieboy · September 24, 2009, 06:21:19 PM

I had to do something similar at work. Attach a mag mount gps antenna to the roof of an aluminum step van. We simply used silicone glue to hold up a 4 X 4 electrical cover plate to the inside of the van. The mag mount antenna wa able to hold very well to the plate, right through the aluminum. It might be different on fiberglass, depending on the thickness. Doesn't cost much to try it. You don't even have to attach the plate if you have domebody hold it on the bottom while you attach the antenna on top. Good luck. Ed

ruthi · September 24, 2009, 06:57:38 PM

ours uses the built in antenna as well. It is mounted on the front lower part of the window, works great.

Skykingrob · September 24, 2009, 07:13:19 PM

Brian
If you choose to go with the 3M tape, let me know. I have nearly a full roll from a door project and can certainly spare a foot of it.

Rob
91 Prevost LeMirage XL
Missouri