Roof rack load capacity

[reciprovac]

NW roof rack supports

Has any one thought of fitting a rack to the roof rails and reinforcing the rails by dropping a couple of brackets down into the roof tracks ?
I did this on my 2014 Challenger and carried a 10 ft boat on the roof with no problems.
I am about to make up the same now for the Pajero.
By placing the brackets between the points where the roof rails are attached,and insulating the roof with a rubber spacer the roof rails do not bend at all.
Regards

[grhyso]

When my rhinorack rails were fitted I had planned to bolt them on, however I was short of time and paid for a store to fit them. They come pre drilled from rhino to fit in the factory roof "track" and are attached with 9x 5-6mm rivets each. The track may also not allow a bolt head in as it us specially designed to fit in the pajero roof track.

The track comes with a sticky back foam already attached which is more for sealing than adding any strength. Also it must be noted they are pop rivets therefore need the centre sealed or else it will fill with water and rust out.

Alternatively to bolts you could try source some cherry rivets or hylocs however both are probably more expensive than the trouble is worth.

[insect_eater]

Thanks for the details, Rhys. From subsequently looking at images of the tracks, I had seen that they were pre-drilled, with cutouts for rivet gun access. I also wondered about clearance between screw heads and track accessories (though countersinking may be an option).

Maybe having a series of new holes in addition to the pre drilled holes and clearance cutouts somewhat defeats the purpose of the exercise. I wonder if rhino sell a version of the track that is just plain undrilled rail, so that you can custom fit.

EDIT: I've a mate who'd building a plane, so I'll see what fasteners he has.

[grhyso]

The height of a bolt head or screw will have no impact on fitting the rhino feet. On the rhino site there'll be a front on picture of the track and the attachment for the feet stay within the confines of the top section, the extended lower is purely to suit the pajero roof profile.

Your mate might very well have a cherry gun and some cherry too, just be careful, it's been a while since I did my trade school so I can't remember if cherrys come in only steel or not. You don't want aluminium or else you may induce dissimilar metal corrosion.

[insect_eater]

Thanks, good to hear about the clearance - I can recall the cross-section image, but didn't realise the feet stayed high and clear. Nylock-nutted screws in exisitng holes with large washers may be a realistic compromise.

So if the track is aluminium, and the roof is steel, won't I have dissimilar metals corrosion potential whatever I use?

[old Jack]

Thanks, good to hear about the clearance - I can recall the cross-section image, but didn't realise the feet stayed high and clear. Nylock-nutted screws in exisitng holes with large washers may be a realistic compromise.

So if the track is aluminium, and the roof is steel, won't I have dissimilar metals corrosion potential whatever I use?

It is important to prime and paint the holes in the roof. If the foam tape supplied is porous then do not use it! Use a non porous seal or sikaflex. Attaching Aluminium to Steel use compatiable fastners be it rivets or bolts. Goggle "Galvanic Corrosion" and pick a fastner material half way between the 2 metals. Also to be extra sure dip rivets or coat bolts in WET zinc chromate primer and make a "wet joint". If riveting you will need a power riveter to pull up 5-6 mm rivets correctly

OJ.

[grhyso]

Thanks, good to hear about the clearance - I can recall the cross-section image, but didn't realise the feet stayed high and clear. Nylock-nutted screws in exisitng holes with large washers may be a realistic compromise.

So if the track is aluminium, and the roof is steel, won't I have dissimilar metals corrosion potential whatever I use?

After re-thinking it, Hyloc's aren't really worth the effort, you may as well just use a bolt or screw. If you ever have an issue they can be an absolute PITA to remove.

I'd follow OJ's advice, he's more up to speed on this sort of stuff, I haven't done any study or training on it in about 7 or 8 years and haven't had hands on experience in nearly as long.

[insect_eater]

galvanic corrosion factors

Firstly, I remain remain in awe of the depth of expertise and willingness to share the knowledge forum members offer. Thank you.

That all makes sense to me, and I can easily do most of this (stripping the foam might be not so easy.....) although I need to refresh my chemistry of galvanic corrosion (my training is also rusty* on this topic), and try to get a handle on risk management options and whether exclusion of an electrolyte through good sealing does some of the job, and what my readily accessible fastener material options are.

(* nominee for worst pun of forum in 2016)

[damienpajero]

Might i add if you drop your lining itwould be a good idea to customise the lining you can pick up material from $6 a meter that shows less marks is tougher and looks better the whole job including glue costs around 80 - 100 and is super simple

[discodave555]

Has any one thought of fitting a rack to the roof rails and reinforcing the rails by dropping a couple of brackets down into the roof tracks ?
I did this on my 2014 Challenger and carried a 10 ft boat on the roof with no problems.
I am about to make up the same now for the Pajero.
By placing the brackets between the points where the roof rails are attached,and insulating the roof with a rubber spacer the roof rails do not bend at all.
Regards

Damien, did this work?
If so where did you get the brackets/ rubber from?

Thanks
Dave

[signo1985]

Reviving an old post.....if the recent pajero have a roof load limit of 100kg, how can the backbone system take 120 on the same vehicle?
cheers

[toddy99]

its a good question, I just did the Gibb river road with a wheel and an Oztent on the roof with a flat rack bolted to the crossbars. I had to take the fuel off the roof as the rails were bending.
The standard racks just aren't up to it, so I'll have to fit a "tradie rack" or something along those lines

[nj swb]

Reviving an old post.....if the recent pajero have a roof load limit of 100kg, how can the backbone system take 120 on the same vehicle?
cheers

Weight distribution over the mounting points.

The factory system has three mounting points per rail, effectively concentrating loads on the sheet metal of the roof. A well designed backbone system will distribute the load better.

[cruisn06]

Weight distribution over the mounting points.

The factory system has three mounting points per rail, effectively concentrating loads on the sheet metal of the roof. A well designed backbone system will distribute the load better.

Spot on, will back that up 100%

Depending on how remote we go, I carry a RTT, 2 x 5kg LPG bottles, 1 tool box (20kgs), 3 x 20L jerry cans and normally about 30kg of wood.

Never had a crack or any faults.

[old Jack]

Weight distribution over the mounting points.

The factory system has three mounting points per rail, effectively concentrating loads on the sheet metal of the roof. A well designed backbone system will distribute the load better.

Not all backbone systems are the same, some look the part but only use the factory anchor point to attach the backbone to the roof. To fit a good backbone system it really needs to be through bolted, with reinforcing and bonded doubler plates on the nut side that are the same size and shape as the contact point or at least large mudguard washers fitted under the nuts. Extra attention is required to paint exposed metal in any new hole drilled and to seal the attachment areas so water does not leak or accumulate, particularly if you are going to carry heavy loads over rough roads and off road. Some installations just use pop rivets for the extra attachment points and these are prone to failure and cracking the roof structure over time. Most manufacturers of vehicle and rack systems down grade the allowable weight to 50% or 60% of the maximum roof load when driving off road.

OJ.