Slide on camper design advice

Submitted: Saturday, Oct 22, 2016 at 13:27
ThreadID: 133642 Views:14548 Replies:12 FollowUps:15
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Hi All
In the process of designing a slide on camper for the back of my 2015 dual cab dmax. We did a lap over a few years a while back now and just missed to much as we were restricted by our vehicle (Mazda2000 camper).
I like the trayon and wedgetail designs not only for their functionality but also their light weights and plan on incorporating ideas from both in my own slide on.
Now onto design-
I plan on having a pop top not a flip over roof like the two mentioned above and when the roof is up I would walk in through the rear entry and have the bed slide out over the cab or off to the side (similar to say a jayco camper). Can anyone see a problem with this? as I have only found flip over and was thinking there may be a reason for this.
It would also contain all the usual's, fridge stove gas bottle, 60l water tank etc with storage available from inside and out.
I know weight and slideons are worst enemies and plan on keeping weight to a minimum. Framework would either be aluminium or fiberglass sandwich panel 30mm thick any pros or cons on either of these?
We plan on being offroad but nothing too over the top.
I have attached a rough sketch of dimensions and design so have a look and let me know what you think.
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Reply By: The Bantam - Saturday, Oct 22, 2016 at 13:56

Saturday, Oct 22, 2016 at 13:56
As you have already indicated, your single biggest problem will be weight ...... and weight distribution and centre of gravity.

I have heard some absolute horror stories direct and there have been plenty on here.

You will be wise to account for every single bit of weight before you even order materials.

There are some great composite materials out there ....... look into the marine and sail boat market.

Fiberglass its self is not very light ...... but combined with lightweight plywood core or things like foamed plastics or astroboard can be incredibly light and strong.

If you can lay your hands on 't have a read of "the Gudgeon Brothers on boat building" ...... these guys are the fathers of fiberglass/epoxy composites.

the reason for the hinged constructions is that they can be built very much lighter that full length and width pop tops that require heavier structure for stability.

It is possible to build a very strong front hinge structure with pretty much no metal above the chassis ...... or maybe only a rear frame ..... the rest fiberglass, epoxy, plywood composite.

AnswerID: 605286

Reply By: Member - wicket - Saturday, Oct 22, 2016 at 14:07

Saturday, Oct 22, 2016 at 14:07
While I don't think they make these any more the web site is still up and you might get some ideas from what was a unique slide on.
AnswerID: 605287

Reply By: Member - Jim B8 - Saturday, Oct 22, 2016 at 15:09

Saturday, Oct 22, 2016 at 15:09
Weight is an issue, but not as big an issue as is weight behind the rear axle. Specifically, you dont have much scope loading up a dual cab, without that weight being behind the rear axle. Look at all the pics of bent (mid sized) 4wd's, a very high percentage are dual cabs, and bend for the above reason, too much weight behind the rear axle. Especially if towing. There is only a foot or so of chassis between the cab and the rear axle.......

You could probably start with a single cab? Just sayin
AnswerID: 605289

Reply By: lizard - Saturday, Oct 22, 2016 at 16:09

Saturday, Oct 22, 2016 at 16:09
We had one of these on our GU ute = excellent
AnswerID: 605292

Reply By: Peter - Saturday, Oct 22, 2016 at 17:45

Saturday, Oct 22, 2016 at 17:45
Hi it may not be exactly what you want but have look at Tong's gear really well made

also if you want to build have a look at .They have doors windows also moldings to make pop tops.

AnswerID: 605302

Reply By: Hoyks - Saturday, Oct 22, 2016 at 18:58

Saturday, Oct 22, 2016 at 18:58
Not much to add, other than weight behind the axle is a killer. So with this in mind design it so that all the heavy stuff is up against the headboard and probably access via the rear. This will give a void (that therefore doesn't weigh much ) at the back.

Personally, I wouldn't think the dual cab tray will have enough of a foot print to store all your gear for an extended trip and have enough room to climb up there as well. Mine is a bit tight, but the slide on box isn't as tall and is all storage.

My Swag is a good resource, plenty of people have done it before, so it is probably worth seeing what worked and what didn't.
AnswerID: 605306

Reply By: TomH - Saturday, Oct 22, 2016 at 19:56

Saturday, Oct 22, 2016 at 19:56
Have a read here

And here with a lot of links including a thread on here
AnswerID: 605310

Follow Up By: Tomdej - Sunday, Oct 23, 2016 at 07:22

Sunday, Oct 23, 2016 at 07:22
To help avoid the bent chassis you have another option, and that is to get a chassis extension. Specialised Vehicles in Orangeville (south of Sydney), Creative Conversions in Qld, and Wide Bay Motor Bodies in Melbourne, are companies I'm aware of but I'm sure there are others.
Cost is around $5000 and for that you get the wheels placed under the load, a similar situation to a single cab, but with the extra versatility of 5 seats.
Ramp over is affected, as is the turning circle, but as a touring vehicle modification it is, in my opinion, worthwhile.
Good luck with whatever you decide.
FollowupID: 875082

Reply By: splits - Saturday, Oct 22, 2016 at 21:45

Saturday, Oct 22, 2016 at 21:45
If you are going to put a camper body that is 1992 mm long on the back of a dual cab then you had better build it with balsa wood. No matter how light you make it, it is still going to have a lot of heavy material sitting well back behind the axle.

Whatever is back there is sitting on a lever i.e. the distance from the axle back to each piece of material. The forces generated as all of this material is constantly being lifted rapidly or stopped suddenly when it falls is what bends so many ute chassis. Axle housings have also been known to break although that is not as common as chassis.

First of all do you really need a dual cab or when travelling will there be any people in the back seats? If the back seat is empty then I would fit a cargo barrier behind the front seats then remove the back seat and store as many heavy items as possible in there. It is important to remember that those five seats have been designed to carry the weight of five heavy people which means a load of over 450 kg up to about 500kg must be in the cabin before you put anything in the back if you want to take the car up to maximum weight.

The chassis damage on these cars is usually caused by a combination of too little weight up front and too much out the back with a lot of it too far back behind the axle. The car can be a few hundred kilos under GVM yet the chassis is still at risk.

Don't think this problem can be solved by installing heavier springs or air bags. They can't move heavy items further forward so the back of the car will still be thumped down at the back on rough roads and the front will still be jerked up. The end of the chassis will still be flexing up and down like the end of a diving board.

Another tip is get rid of the tray or tub and build the camper directly on the chassis. I have done that with my single cab. My homemade camper weighs 220 kg empty. The aluminium tray that I removed weighed 130 kg so after removing it and bolting the camper on, the weight of the car increased by only 90kg.

If you do occasionally use the tub or tray to carry things around town then consider getting a little box trailer. I made a trailer out of my tray in order to solve that problem.
AnswerID: 605315

Reply By: Batt's - Sunday, Oct 23, 2016 at 03:04

Sunday, Oct 23, 2016 at 03:04
You're probably not real happy with the responses at this point sorry for that but I also tend to agree with the majority do yourself a favour and don't take the risk of possibly causing unwanted damage to your vehicle. Towing a camper would be a better option for your vehicle and fitting a canopy to the tray to store lighter gear in would be safer than trying to make a slide on for it. Other than that If you're not carrying passengers and still want the room behind the seats then a space cab may be a good option still baring in mind that if you keep most of the weight around or in front of the axle it would be fine but unfortunately now were talking about selling a vehicle that you purchased for a particular reason.
The other way to be able to carry a slide on and your water tank maybe a long range fuel tank and all your gear around without the worry of possibly having a breakdown is to get the wheelbase extended more money again sorry I can't help any more than that.
AnswerID: 605320

Reply By: Member - MIKE.G - Sunday, Oct 23, 2016 at 08:08

Sunday, Oct 23, 2016 at 08:08
If you can have access from the side it will solve a few potential problems. Dust or mud on the steps as well as the possibility of seals allowing dust into the camper. Ask an Ultimate Camper owner about this nightmare. Side access eliminates this.
The fridge will need to be at the front for weight, so access from the back will mean that you need to crawl in to get to the fridge on short stops. Side access means the fridge can be within reach from outside once the steps are down.
Avoid air bags at all cost.

Good luck.
AnswerID: 605323

Reply By: The Bantam - Sunday, Oct 23, 2016 at 12:46

Sunday, Oct 23, 2016 at 12:46
More bad news.......

As many others have said, dual cab utes and slide on campers are just dissapointment traps.

Let's start at the very beginning, because its a very nice place to start.

ALL the dual cab utes are a bad compromise from the very start ...... none of them are from the ground up designs ...... all of them are a single cab design that has a dual cab and a stumpy tray fitted as an after thaught with pretty much no further engineering.

Pretty much all the single cab utes are designed to carry the tray borne payload centrally over the axle ..... with a 8 foot tray that puts the axle pretty much in the centre of the tray ... so it's no major problem.

BUT even with a single cab and an 8 foot tray, it is wise to load the heavier things toward the front of the tray and realy heavy things either directly above or just infront of the axle.

If there is significant mass behind the axle and worse the further back it gets ...... even though it may be balanced and the rear axle is well within its ratings ..... it presents a stability problem.

Large masses at the extremities of vehicles act as pendulums .... significantly exagerating oversteer on flat ground and tending to make the front lift and the tail wag in off road conditions ..... this is why rear wheel carriers are a very bad idea on utes.

all this is before you attach a trailer and all this is before you have a short stumpy tray on a dual cab that stops just in front of the rear wheels.

I have a pair of single cab utes, I drive them every day, often by the time they get tools, materials and ladders loaded they are pretty close to the money .... I also drive them far and fast doing country work, sometimes towing a trailer.

Pretty much every day I see dual cab utes, dragging their @$$#$ around town .... it's not that they are carrying a lot it is because it is all in the tray and mostly behind the axle.

When I have the 4wd loaded not for work but for travel ...... its is much lighter loaded, probably carrying about half a tonne all up ..... with the heavy items all low and in front of the axle it balances up pretty well 50/50 front and rear.
I travel light, my kitchen is a butane stove & a plastic bowl and I sleep in a swag.

IF I was to put the same fairly modest amount of gear in the tray of a dual cab I'd be A/ crammed tight and B/ running pretty close to the money on the rear axle rating ......... AND I'd have this half tonne pendulum outside the wheelbase.

ALL this is without a camper body, big water tanks and heavy built in kitchens.

I have no doubt that it would be possible to build a workable on tray camper for a dualcab ....... but hell you would be punching the maths and using very clever construction methods ....... AND traveling very light.

Remember too that any slide on camper you still have the extra weight of the tray.

The other thing that terrifies me is how unstable slide on campers look on 4wds ...... I've seen em around town and they look bad enough leaning and body rolling on the corners ..... I would not want to drive one off road. ...... the high centre of gravity is a real issue.

the slide on camper was probably a great idea back in the 70's and 80's when they where carried mostly on road and mostly on full length utes and light trucks.

I think they are pretty much a bad idea on 4wds and a realy bad idea on 4wd dual cab utes.

AnswerID: 605331

Follow Up By: LAZYLUX16 - Sunday, Oct 23, 2016 at 15:50

Sunday, Oct 23, 2016 at 15:50
I agree with what you have said. But have seen a couple of dual cab Landruisers and Landrovers odf road with Trayon Slide ons and they both looked quite stable and owners were very happy with them. I liked the concept off not towing and can still go.offroad.The Trayons are not that high really. I considered buying a Trayon But cost involved to convert my dual cab was bit high.My fully loaded (perhaps too much weight )Dual cab Hilux including full spare on steel roofrack handled like a dream offroad and surprised me how capable it was. I had always owned Landcruisers so was a bit concerned about toughness of Hiluxs.Cheers P.S tent camping great but not in crap wet windy weather so my wife would like a camper van with shower and toilet but hard to find compact offroad one ..
FollowupID: 875093

Follow Up By: splits - Sunday, Oct 23, 2016 at 16:53

Sunday, Oct 23, 2016 at 16:53
ALL the dual cab utes are a bad compromise from the very start ...... none of them are from the ground up designs ...... all of them are a single cab design that has a dual cab and a stumpy tray fitted as an after thaught with pretty much no further engineering.

I don't agree that they are a bad compromise. Both single and dual cabs started many years ago as commercial vehicles with the same chassis and suspension. One carried two workers and a large load. The other carried five workers and a smaller load. There was a need for both and both did an excellent job.

Things started going pear shaped years later when they became popular for recreational duties. That is when many owners started loading them up with half or less of the manufacturers intended maximum load in the cabin and far too much out the back. The aftermarket industry did not help by making products that had owners thinking they could load the car anyway they liked and these products would fix everything.

All these springs and air bags did nothing more than lift an correctly loaded and sagging rear end. They were nothing more than a cosmetic solution. Had they worked we would not have an endless number of broken cars all over the bush.

There is nothing wrong with the design which is why the manufacturers have not changed it. How could you change it anyway? They would need a truck like chassis with rear springs more suited to a train carriage to take what so many people load into the back of them.

If manufactures set them up to survive treatment like that, they would be very tail heavy. They would not break anymore but how on earth would they make them handle properly?
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Follow Up By: The Bantam - Sunday, Oct 23, 2016 at 16:59

Sunday, Oct 23, 2016 at 16:59
Plenty of people are oblivious to their stability problems .... many people would be greatly surprised how capable their 4wds are if they where not dissadvantaged by how much they carry the way they are loaded.

there is no question that slide on campers significantly raise the centre of gravity of the vehicle, some to a dangerous extent.

FollowupID: 875095

Follow Up By: The Bantam - Sunday, Oct 23, 2016 at 17:29

Sunday, Oct 23, 2016 at 17:29
Splits, mate dual cabs are a pretty recent thing ....... they pretty much did not exist before the 80's...... and they are a horror ...... they will not carry 5 "workers" in comfort, unless three of them are dwarfs or short skinny apprentices. .... no way I want to travel far in the back of any dual cab utility.

AND ya cant even lay a long handled shovel straight in most of the trays

There have been some instances including a recent issue with the SES, where once fitted out they are pretty much useless, because they are easily overloaded on one or the other axle.

the one tonne ute format, that comfortably carries average 2 adults and 1 tonne in the tray ...... with the tray payload centred over the rear axle works very well.
It performs very well off road with 2 in the cab and 500KG in the tray

But as soon as you try carrying 5 adults and a payload behind the rear axle, the whole format goes pear shaped. ...... ya simply cant put 5 x 90KG average workers, their lunch and their toolboxes in a vehicle that size without risk of overloaded one or the other axles ..... particularly when you fit a steel tray and a bullbar ....... this is why pretty much all the mine spec dual cabs have upgraded suspension or GVM upgrades.

It would not take a truck chassis and a rediculously stiff suspension to to solve the problem ......... the solution is a longer chassis and a longer wheel base

BUT wait ... the Hilux extracab has a longer chassis and a longer wheel base..... but the dual cab does not ... figure that ...... I could never understand whay the hilux dualcab is not on the longer extracab chassis ...... though being longer again would be better

A dual cab format could be made to work far far better than it does if it was simply on a longer chassis

A far far better option is to move up into a small 4wd truck .... then you will get 5 in the cab in comfort and a tonne in the tray happily.
Yeh and ya probably get a whole pile of others things standard that people pay to modify in a light commercial ...... like bigger wheels, difflocks and no need for GVM upgrades

FollowupID: 875096

Follow Up By: splits - Sunday, Oct 23, 2016 at 18:19

Sunday, Oct 23, 2016 at 18:19
You can say what you like about them but they are currently selling like hot cakes and the manufactures have no intention of altering the design.

They will work perfectly for any owner who keeps them within their design limits. That applies to all cars, not just dual cabs.

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Follow Up By: The Bantam - Monday, Oct 24, 2016 at 00:00

Monday, Oct 24, 2016 at 00:00
They are selling like hotcakes, because there are tax advantages over a station wagon.
FollowupID: 875104

Follow Up By: Tomdej - Monday, Oct 24, 2016 at 07:55

Monday, Oct 24, 2016 at 07:55
The extra cabs have the same wheelbase as the single cabs and dual cabs. The problem with dual cabs is the fact that the rear wheels are not under the load of the tray. See my post further up regarding a chassis extension and you will see that a modified dual cab can carry a slide on camper.
FollowupID: 875106

Follow Up By: Baz - The Landy - Tuesday, Oct 25, 2016 at 07:52

Tuesday, Oct 25, 2016 at 07:52
Perhaps there are dual cabs, and there are dual cabs, but I have had no problems with ours...

Cheers, Baz - The Landy
FollowupID: 875134

Follow Up By: The Bantam - Wednesday, Oct 26, 2016 at 21:34

Wednesday, Oct 26, 2016 at 21:34
In the pre 05 hiluxes the single cab and the dual cab had a wheelbase of 2850, the extracab was 3085 .... 235 mm or 10 inches longer.

In the post 05 hiluxes they are all 3085 wheelbase.

lengthening the wheel base another 350 ish mm or 14 inches and reducing the rear overhang would make a great deal of difference to many of the dual cab problems.

FollowupID: 875189

Reply By: Geckoz - Tuesday, Oct 25, 2016 at 06:58

Tuesday, Oct 25, 2016 at 06:58

This is how we do the rear step.
And kitchen
Feel free to contact me if you need some advice on vehicle or camper.
AnswerID: 605386

Follow Up By: Batt's - Friday, Oct 28, 2016 at 13:27

Friday, Oct 28, 2016 at 13:27
It's a nice looking slide on. I'm not being rude but looking at the first pic it doesn't look good the chassis seems to be flexing and the front of the tray is a fair bit higher than the rear disregarding suspension sag it looks like the tray may be out of line with the rest of the body now. I would be checking it out more thoroughly with and without the slide on for any noticeable differences. Measuring the gap between the tray and body on either side of the vehicle also the gap between the body and roll bar in a few spots on either side and at the top with a ladder to see if there is a noticeable difference. Maybe checking and measuring gaps at the top and bottom of the doors. Also I'm sure there would be an instrument that can be placed on the chassis to measure flex or movement. Hey I could be wrong about all of it though.
FollowupID: 875243

Follow Up By: Geckoz - Friday, Oct 28, 2016 at 17:43

Friday, Oct 28, 2016 at 17:43
its just an illusion the campers centre of gravity is exactly between the spring mounts.
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Follow Up By: Batt's - Sunday, Oct 30, 2016 at 02:16

Sunday, Oct 30, 2016 at 02:16
That's the slide on in the 1st pic the rear entry version which is longer and has part of it overhanging the tray which is different to your latest pic. I don't think it's centre of wouldn't be that far forward just an observation.
FollowupID: 875262

Follow Up By: Geckoz - Sunday, Oct 30, 2016 at 04:37

Sunday, Oct 30, 2016 at 04:37
Yeh it's the same car and camper in all photos
The water tank,battery,hot water service,fridge etc are all on the front wall putting the centre of weight over the axle !
There is no disputing Dualcab Utes are pushing the boundaries of having a Slideon but it can be done. If the vehicles have suitable suspension are not overloaded and drive to the conditions it's all good.
There not for everyone but I like the mix of freedom, comfort and access to remote areas they give. Along with the ability to tow a boat or your companions out of trouble.
FollowupID: 875263

Follow Up By: Batt's - Monday, Oct 31, 2016 at 13:48

Monday, Oct 31, 2016 at 13:48
Ok it looked square at first but had another look can see the angled section. So if you able to design it so that the majority of the weight is at the front then yeah it should help any 4WD a fair bit no worries.
FollowupID: 875298

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