roof rack

me4x4 · Mar 5, 2009

hi i have a full length roof rack for my 300 tdi auto disco if i put it on and leave it on will it make a massive difference to performance and fuel economy also want to board it out what thickness marine ply would you advise to use

Reddisco · Mar 5, 2009

I had a full length expedition rack on mine for 3 months didnt notice any difference with fuel consumption but it must make a difference due to weight and drag. The reason I removed it when not using it was due to the really LOUD whistling wind noise! and problems with height restrictions at car parks etc.

shocker · Mar 6, 2009

Thickness of ply really depends on how well supported it is,ie how many/how close are the crossmembers (?) and what you want to put on it.Marine ply is going to hit the wallet hard...how about hardwood ply,or tanalised regular ply?
I would have thought no thinner than 9mm and no thicker than 18mm,depending on above.
Once you put a board in then I reckon aerodynamics might come into play...to what end I dont know...maybe you'll have a gurt big spoiler that will give great roadholding,maybe you'll have a wing and start to fly

Pikey · Mar 6, 2009

Marine ply is also known as WBP (water/Boil Proof) Ply and is about £25 for an 8'x4' sheet of 18mm Unless you're planning on having a party on there I would have thought 12mm would be enough as long as the bars are at 400mm centres or there abouts.

Dewin · Mar 6, 2009

Reddisco said:
I had a full length expedition rack on mine for 3 months didnt notice any difference with fuel consumption but it must make a difference due to weight and drag. The reason I removed it when not using it was due to the really LOUD whistling wind noise! and problems with height restrictions at car parks etc.

rofl we had wire mesh as a base on our's and it sounded like there was a jet just above the roof drove me nuts, there is quite a bit of drag too, very noticeable on windy days, makes the disco feel like a boat

swaying from side to side.

As for height restrictions my wife "forgot" about the rack, took disco to a local carwash and promptly heard a loud thud as the brushes got stuck, Disco and rack were unscathed, not too sure about the carwash as she legged it

shocker · Mar 6, 2009

redhand said:
Marine ply is also known as WBP (water/Boil Proof) Ply and is about £25 for an 8'x4' sheet of 18mm Unless you're planning on having a party on there I would have thought 12mm would be enough as long as the bars are at 400mm centres or there abouts.

I stand corrected,and glad to be so!

Marine ply 18 mm for £25!Last time I wet for some in bristol (some years ago) it was closer to 100,I kid you not

I was in the sound industry building large loudspeaker enclosures and regularly used hardwood or preferably birch but marine was useful for outdoor stuff or high humidity enviroments....Im very glad to hear its come down.I'll be able to use 9mm marine to replace the floor rotting sponges in the back on my discos now,instead of tanalised.

Nice one,Red

Pikey · Mar 6, 2009

shocker said:
I stand corrected,and glad to be so!Marine ply 18 mm for £25!Last time I wet for some in bristol (some years ago) it was closer to 100,I kid you not

I was in the sound industry building large loudspeaker enclosures and regularly used hardwood or preferably birch but marine was useful for outdoor stuff or high humidity enviroments....Im very glad to hear its come down.I'll be able to use 9mm marine to replace the floor rotting sponges in the back on my discos now,instead of tanalised.

Nice one,Red

Here you Go though retail price has gone up a little bit. its £35 a sheet though they do half & 2/3 sheets as well. Wickes – Timber – Sheet Materials – Plywood – Exterior WBP Plywood

stu2985 · Mar 6, 2009

If you crusie motorway a lot and do big mileage then the rack and wood will hit your fuel economy. The noise is really noticable when I find when I have it on and the steering does feel more wobbly

I put a piece of harboard 10mm on my rack once so i could pop to a m8's house to pick up some stuff to sling up there (its a cage type with high sides and mesh fitted and I didnt fasten it down) I took it really easy it wasnt a windy day but when I hit 30mph I heard a big woomph and looked in the mirror in time to see the wood hitting the road behind me. Fortunately no other cars were around.

Made me realise just how much wind must be pushing up against that wood. Dread to think of effects at 70mph with that on top.

Pikey · Mar 6, 2009

haha I did that with 2 sheets of 2" Polystrene insulation. got to 25 and they broke in half had to run back and pick them up. Good thing was at least they fit in the car like that. :lol:

me4x4 · Mar 7, 2009

cheers guys think will put rack on takes up alot of room in the garden but wont board it out dont think me disco will look good with a bloody big wing on the back for downforce

roof rack

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