Hey all - trying to add a ham radio antenna to my 95 by drilling a hole above the dome light. But, when I get the dome light connectors out of the way, it looks like there's a lower layer of metal that's sort of corrugated; I can't imagine getting a solid NMO-mount seal with that. Anybody got any awesome ideas?



Several people have suggested drilling above the dome light for easy access without screwing up the headliner - but man, I don't think I can drill right there - is the whole roof that way?? Doesn't look like it from the pics I can find of XJs with no headliner - but if I move outside the dome light area of course I'll screw the headliner up.....nothing is easy.........

Thanks a lot!

 

That's a bracket that's welded in at the top of the B pillar above the doors. It's supposed to be a roof stiffener, but I doubt it does anything but hold the dome light!

 

You might be surprised at how effective just a tiny bit of out-of-plane material can be (it's a cubic function - more than exponential). Stiffeners aren't necessarily load path members, but they do a lot of work to prevent buckling, deformation, and improve durability. Take a look inside a sheet metal airplane sometime - you'll see plenty of little stiffeners that don't seem to be doing much. But it would be a really bad idea to mess with them. Source: have designed some of those stiffeners.

 

If I remember correctly, back in the day when everybody had CB radios, they just drilled a hole thru the bracket and roof from the inside and there was a special feed-thru that bolted in you could get at Radio Shack. Basically it had a large flange on it that overlapped the ribs on the dome light support so it didn't crush the roof metal and had an o-ring to seal it. I think it only required a 3/8" hole. Maybe it was 1/2", IDR.

Cudos to your engineering knowledge. I am a retired toolmaker with over 40 years experience in the trade. My dad was a pilot and my brother is an A&P mechanic. My other brother is a qualified Avionics Technician. I've been around aircraft all my life. I know how rugged monocoque construction can be if done right.

 

Didn't mean to suggest otherwise, and didn't intend to come off as snarky. I'm just kind of excitable about the topic, don't claim to have any reasonable insight into CB mounts on XJ roofs. Toolmaking is quite a skill, and us engineer-folk could learn a thing or three if we'd be quiet and listen to you guys more often. Aviation can be a rewarding career, and I swear monocoque construction is still a bit magical...

 

Can we all agree that something awesome just happened here.... LISTEN UP AND BE MORE LIKE THESE GUYS, REST OF THE INTERNET

 

You. my friend, are an engineer I'd enjoy working with. They are few and far between. I had the good fortune to work with a plant production engineer during my apprenticeship that held classes for us in Algebra and Trig. I worked with him designing jigs and fixtures to supplement production of our products. We built an automatic cycle paint spraying device for use inside a spray booth using moving part logic instead of electronics because he was reluctant to even have 5 volts in there. Sorry to run on, but I'm an old fart and tend to do that anyway!

TASTYCAT, go to wearecb.com and look at the first one on the page. I'm thinking this is the one my friend used long ago. 001 Wintenna.

 

Many thanks, and likewise! I'm certainly not the smartest enginerd around, but listening to those who build and operate my designs is important to me and really helps me learn. Sounds like you got to work on some pretty fun and interesting projects! Moving part logic is really fascinating, and is super rewarding when it finally does the thing it's intended to. No worries about running on, I love these kinds of stories.

 

One more thing and then I'll drop it. The problem with air powered logic systems is the requirement for pure filtered dry air and in some cases the time delay of actuation. PLUS, it cost about 4 times what a simple solid state system would have cost!