My version of a Land Rover off road trailer

[mark2]

For a while now, I've been looking for a trailer to tow behind my Perentie which is functionally and visually compatible.
The Haulmark PT-1 was high on my wish list, but they are fairly scarce and fetch good money at the auctions plus I wasnt sure I wanted to attack one with the welder to customise it to my requirements. No. 5's dont have a tailgate and the drawbar is too short IMHO. I'm also not a fan of short leaf springs, which is a particular issue with a No. 5

After being inspired by some recent threads, I decided to do something with the old rangie chassis which was lying behind the shed. I knew roughly what I wanted - something incorporating aspects of the No. 5 trailer and the Haulmark PT-1, with the ability to be a dual use box trailer and camper. Corrosion resistance, strength and coil springs were on the list. Storage space for a spare tyre, the ability to jackknife without damage and a pintle tow ring were also there. Dimension wise, the requirements were to fit an 1100 w Spacecase across the body and to be able to sleep comfortably in it if necessary.

After attacking the rangie chassis with the grinder and oxy, it looked like this:


88283

88284

The remains of the donor, showing where the front diff pan was cut off to fill the hole left in the rear axle housing after the diff center was removed.
88285

The frame starts to take shape:
88287

The body width was constrained to about 1110 mm between the inside panels, due to the spring mounts and axle width. Any wider would have meant a risk of wheels rubbing on the body with certain wheel offsets. This met my spacecase requirements. Body length was more flexible and I settled on 2100mm. These dimensions are almost identical to a Haulmark PT-1. The tub is 450mm deep

I used a 100 x 4 SHS section for the drawbar which is fixed at the rear to the rangie suspension A frame cross member and the rangie chassis rails at the front. The chassis rails were notched, bent and plated to tie into the drawbar. I would have liked to have run the drawbar all the way through to the rear to tie into a recovery point, however it would have fouled with the suspension on full compression. It also interfered with my plan to use the rear underfloor area to store a spare tyre. By now I was also realising that weight was going to be something to keep in check. I was hoping to achieve a Tare weight of about 300 kg, with the ATM under 750 kg so as not to initially require brakes, with the plan to upgrade down the track when funds permit, to an electro/hydraulic brake system, using the standard Rangie discs and calipers.

[mark2]

The frame nearly completed:

88292

I bought a drawbar toolbox from ebay which fitted neatly accross the front of the body and still left enough drawbar length to jackknife to 90 degrees.

Rear levelling legs were also from ebay, as was the jockey wheel. I had to extend the jockey wheel and used a section of tube cut from one of the Rangie driveshafts.

At this point, the plans were evolving to incorporate a removable ladder rack type frame to which a roofrack or rooftop tent could be mounted. The frame legs would slide into the body corners and be held by a pinch bolt.

I was also planning on hot dip galvanising the entire frame. Becasue of this, I decided not to weld floor and side panels to the frame, because of the risk of the sheet warping during galvanising. The plan was to Sikaflex 3mm alloy sheet to the frame after galvanising. 3mm alloy is about the same weight as 1mm zinc anneal sheet and probably stiffer in a HT grade. Sikaflex 252 is used to bond panels to truck and coach bodies. In hindsight, I perhaps should have used less hollow sections and more open sections eg EA or PFC, as all the hollow sections had to be drilled for venting. One mistake I definitely made was to use Duragal steel sections - this was all my local steel place had in stock. While it generates a lot more weld spatter than black or primed steel, the real issue is that the galvanisers have to strip it by leaving it in the acid bath overnight. Typically this adds about $1/kg to the galvanising cost. Having said this, the rangie chassis had some fairly heavy surface rust on the inside which probably needed the same amount of time in the acid to be fully removed.

Galvanising also means that you preferably want to have all the welding done, holes drilled, brackets fitted etc that you can before hand. Its frustrating having to weld and damage the galvanising when you change your mind or realise something was forgotten.

[mark2]

Back from the galvanisers and axle/suspension bolted up:

88293
88294
88295
88296
88297


The frame without axle, suspension or wheels weighed 230 kg.
I estimate that as it stands now the Tare weight is around 350kg.

I lightened the axle by cutting off the axles from the drive flanges, there is no diff center and I removed the rotors and calipers for the time being. I'll be running oil lubed bearings and will fill the housing to the level plug - this will probably take around 5 litres as there is a lot more empty space in there now. I'll use a cheap engine oil, the wheel bearings should be fine with this.

By the time I add the alloy sheet and the roof frame it will easily be 400kg. Heavier than I'd hoped but the overall weight with a normal load of camping gear and water should still be around 750kg.
I believe a Rover axle housing is rated to 1200kg, hopefully this is an off road rating.



Still to be done:
-Wiring/fit led lights
-add sheet alloy
-fit water tank or roller drawers under the front floor (not sure which yet)
-build removable upper frame
-etch prime and paint olive drab
-registration

Registration is easy in QLD for a home built trailer - there are no inspection requirements. Its a matter of filling in 3 forms, paying the fee and engraving the issued VIN on the issued ID plate.

[tomalophicon]

Looks great mate. Really looking forward to this build.

Are you using the radius arm/panhard rod configuration for the suspension?

[tomalophicon]

Edit, sorry - looks like you used the rear setup?

[stealth]

Are you going to modify the axle to get rid of the diff housing?

[Brad110]

Hi I've built 2 similar trailers, one with an aluminium 1 tonne ute tray and the later with an 130 tub.

The only comment I'd make is that in retrospect I regret removing the sway bar as it would ride better or prevent roll.

Well done why not use the best suspension available on your trailer.

[Bundalene]

Great build !


Are you going to re-install the shocks. Makes a huge difference. We have a similar set up on our boat trailer. using the rear of a Series 1 Disco.
The biggest issue we had was to get the weight on the drawer bar correct,


Can post a pic if you want.





Erich

[mark2]

Yes, the shocks have been reinstalled on the original mounts, I would say these are mandatory as without them its like a soft pogo stick.
With the shocks, the ride quality is superb, I towed my son in it around the paddock and he reckoned it was more comfortable in the trailer than the 110. This is relevant for protecting gear in the trailer, reducing overall stress on the structure and should make it tow better on rough roads - the wheels are more likely to stay in contact with the ground.

Regarding drawbar weight, the plan is to tune it with jerry can placement and whether or not I fit the spare tyre under the rear floor. At the moment there is about 40 kg on the ring, this will change when the tool box is loaded and if I end up fitting a water tank under the front floor. The water tank has to be custom made as I cant find an off the shelf one with the height I need. The quote for a custom 80 llitre tank was $300 so that will have to wait till after Christmas.

I've been quoted $450 for the 5 sheets of 3mm HT Alum body sheeting cut to size.

In regard to the question about the diff housing, I've welded a front pan to cover where the diff center was removed, and will fill that with oil for the wheel bearings. I thought about modifying it to get rid of the lower part of the housing for more clearance, but came to the conclusion that its not worth it - I'm not sure how to do it without either warping the housing or weakening it and the clearance is no worse than the vehicles anyway - if the tow vehicle gets through, so will the trailer. The top part of the housing ties into the A frame ball joint mount so that really needs to stay. It probably looks a bit funny having a diff housing under a trailer, but I can live with it....

[mark2]

Edit, sorry - looks like you used the rear setup?

Yes, its the full rear setup with original mounts.

There was no sway bar on the donor vehicle when I got it, but I can see that it would probably benefit from one.

[mark2]

Time for an update - finally got around to fitting the body panels and painting etc.
The panels are 3mm HT marine alloy plate, sikaflexed to the frame. This should the skin to contribute to the overall strength, but still permit flex without fatigue if necessary. I then etch primed it and hit it with a couple of coats of Protec Enamel.
90581905829058390584


Since painting it, I've done a couple of off-road trips and am very happy with the way it handles corrugations and rough roads. I think the soft, long travel suspension takes a lot of stress off the trailer structure itself and also the tow vehicle and coupling. There is nothing like the clunking and skipping I used to experience with the old No. 5 trailer. The fact that its a pintle coupling is virtually un-noticable, although this may due to a good fit between the ring and pintle.

I now have lots of stone chips in the new paint due to rocks thrown up by the tow vehicle, might need some better mud flaps...At least the camoflage enamel is easy to touch up. I also need to fit some mud flaps to the rear of the trailer guards to be fully legal. Its heavier than I planned, I estimate it to be around 400kg in box trailer form.

Almost finished the drop in ladder/boat rack which will also be designed to take a roof top tent. Deciding on the height of the upper frame rails was a challenge - I wanted it high enough to mount an awning and give good access underneath. However I soon realised it was potentially going to look a bit ungainly, especially once the roof top tent goes up there.
I understand why Drifta decided to use linear motors to raise the frame on their camper. I also thought about using sliding SHS tubes with locating pins for simplicity, however I think this would end being a multi person job to raise the frame.
I think I will also need stiffer coils once the roof top tent goes on, it currently has body roll like an early RRC which will only get worse once the COG gets higher.

[mark2]

Ok, an update for anyone who's interested.

After much deliberation, I decided to go with a lift up frame. I could not find a compromise between a raised COG I was happy with (once the RTT goes on) and a lowered height which was also useful in terms of awning heights and access to gear in the tub.

I looked at electric linear actuators - the chinese versions were fairly affordable but decided against due to complexity and doubts over reliability.

Gas springs (struts) were the next option - there is a huge range of lengths and strengths available. They are rated in Newtons (N) - 10N being close enough to 1 kg. I chose 700N/310mm stroke versions - probably overkill but it needs to overcome the weight of the frame, basket and a RTT, plus friction in the sliding tubes. This also allows some weakening over time. About $35 each. They contain some sort of internal damper which means they extend at a controlled speed.

Next issue was a way to raise and lower the frame. Electric ATV winches winches with remote controls can be had on ebay for around $100 and these were tempting. I ended up going with simpler and much cheaper geared hand winches. The front one is mounted permanently and the rear winch slots into the rear 2" receiver when required. Raising and lowering with the winches is easy, best with two people, but doable with one as long as the differential lift at each end is kept to a about 3" to prevent jamming in the tubes. Initially I had issues with jamming at very small amounts of differential lift, but some spray lube sorted that out.
I'm currently using 10mm pinch bolts to lock the frame legs in position, not sure how these will hold on rough roads and may incorporate some spring bolt latches which will lock into holes drilled in the frame legs.

In conjunction with the gas lift and the landing legs, I have around 450-500mm of total lift, which allows plenty of headroom under the awning and will keep the top of the RTT below tow vehicle height for aerodynamics and low COG. This will also allow setup of the RTT at an easy working height before the frame is raised on the struts.

I also built a basic kitchen bench, which drops down from the rear tailgate when required. This will suit my needs and does not take up space in the rear tub. The RTT will fold over the rear and provide shelter for the 'kitchen' at the rear of the tub .

The frame is removable in about 5 mins, which converts it all back to a basic box trailer.

I'm currently looking at either a Safari RTT or a Gordigear RTT, which seem to be the best value within my price range.

Lowered (travel position)
91972

Rear winch
91973

Raised position, awning extended
91974

Rear 'kitchen'
91975

[The Beast]

very impressive. looks factory built.