Thread: Roof rigidity, roof racks and tropical roofs

Originally Posted by THE BOOGER

As for your question the body is isolated from most of the chassis flex so I dont think a rigid roof rack or tropical roof would be a problem.

The roof maybe bolted to the chassis via body panels but 110 roofs flex plenty!

With my current 110 if I fully cross axle it I cant open the doors due to roof flex / twist.

Many people complain about the gunk cracking between roof panel and windscreen frame, I believe this is due largely to roofracks "fixing" the roof panel and that gunk is the weakest / most flexible bit left when the rest of the vehicle tries to flex.

My rack is a Patriot rack and is of bolted construction rather than welded... It is designed to flex a bit across the fixings for this very reason.

Having said all that Mark, I suspect if you only put 3 or 4 riv-nuts down the outer most ribs you would be fine. The alternative it to use rubber mounted riv-nuts. You install them just the same but the insert is in a rubber mounting and therefore allows a degree of movement between the fixing surface and object. These kind of fixings would better as you could secure your ally plate with more fixings and thus avoid the resonating sheet effect when moving!

J

If you do that use a larger hole so that if it does move the bolt is not acting directly against the edge of the hole. Maybe use a rubber grommet to dampen it.

The series vehicles, the bolt holes vs the bolts are slightly larger plus there's the rubber seal under the roof along the windscreen line and the sides are bolted together under the roof edge.

How does this compare to the counties?

I think on defenders, that the front of the roof is attached to the windscreen frame via three self tapper screws, in each corner. The frame in the roof that these tappers hold via is just an aluminium bracket that is spot welded to the roof. I think any roof rack or wieght on the roof is likely to break or pull out the spot welds, or the screws to pull through. You then end up with a very creaky and leaky roof. My TD5 roof broke and I don't have a roof rack, just from vibrations in the road.

I reckon the Defender roofs - whilst with luck are OK - they are not capable of taking a roof rack without long term damage.

Thanks for all of your advice and experience.
I think a somewhat flexible mount might be best, rather than risking flogging holes in the roof ribs and popping off the windscreen. It already rattles itself apart without any further help...

So i'm thinking of using a multitude of rivnuts in the ribs with a bit of mastic or sikaflex on the outside of the shaft, then foam rubber ala Series truck cab mounting, oversize holes in the tropical roof and then the bolts (+washers), through grommets, done up tight enough to compress the foam a bit less than halfway.
I want the tropical roof to be removable in case it all goes to buggery.

Originally Posted by inside

The Perentie wagons have a fibreglass tropical roof that is mounted to the three ribs down the roof and it has no flex at all so I think mounting aluminium there wouldn't be too much of an issue. Mounting a RTT to it though without support from the gutters may be an issue though. It's a lot of weight directly on the roof.

The RTT weighs around 17kg, it isn't the normal canvas style as Geoff and Mark's remarks may indicate... I have spare ribs from another roof to brace the underside of the tropical roof and spread the load better too.

Look up the Mackay rubber products catalogues, vibration isolators catalogue. Page 14 has some that have a threaded hole for a stud fixing.

I think you're making mountains out of molehills. I put a very solid roof rack, all gal steel, 4 'legs' each side joined by a 6mm x 50mm bar, that sits in the side gutter, AND a OEM 'Tropical Roof' onto my 1985 110 County when I bought it in 1986. 270 th Klms and 27 years later and I cant see any roof flexing, w'screen putty falling out &c, &c, I also carry one of my spares fitted to the Trop Roof above the front cab. After all, it is the grown mans meccano set!

Hi Mark, Just stumbled across this, i am looking doing a similar thing to my county too, but adding some extra ribbing to the outside of the roof for some 3mm checker plate to sit on, also adding some additional bracing to the under side of the roof supported off the gal roof base/gutter. I also plan to follow the slope in the front of the roof similar to the perentie style roof platform. For tie down points i will probobly use some small diameter ally or steel tube following the roof line also acting as a roof slider if i lean it into a tree, i also plan on making a basic roll cage up around the windscreen so the sliders will likely mount to this and act as support back to a rear hoop behind the rear doors and again at the very rear of the vehicle.

My plan is a little more involved then what you have described but should give me a very solid roof rack adding only 5mm to the roof height also doubling as a safari roof.

Have you got anywhere with yours yet?

Watching a Swedish show called Real Humans on SBS. One of the characters drives a series 3 with a tropical roof, which begs the question, why would you need a tropical roof in Sweden?