Thread: Car Trailer Dolly Q's

something like these Kryn i like these trailers but with only the frame above the trailer on the front not the sides, much prefer the flat clean trailer look

i havent bought a majority of the steel but whats available is 50x50x2.5mm and 70x50x2.5mm in 6 meter lengths

Originally Posted by gazza2009au

something like these Kryn i like these trailers but with only the frame above the trailer on the front not the sides, much prefer the flat clean trailer look

i havent bought a majority of the steel but whats available is 50x50x2.5mm and 70x50x2.5mm in 6 meter lengths

Hi gazza, the reason they put the rails on the sides of the trailer like that is to give it strength, for with out it, it would bend like a banana from the weight on the rear as the drawbar would support that section, unless you made the side rails out of 150 X 50 X 4, which will make it very heavy. As you can work out, it is a compromise. I have a car trailer chassis made from 50 x 50 x 3 that has cracked, where the mudguard is attached at the front.
I'd cut your side rails 70 X 50 X 2.5 at 4m long minimum, you'll need 4 of these. Another piece at 1900 which will be your front cross member, allowing for 2 X 300 mm wide mudguards will give you a total width of 2500, the maximum allowable, if you wanted to go slightly wider you could go 2000 but your guards will come down to 250 wide each. You'll need 3 pieces of the 50 X 50 as cross members, 100 mm less than the width you choose. These will fit in between the outside rails FLUSH with the bottom, (about a 1000 centres) otherwise when you fit your suspension, they will interfere.
Cut another piece 300 longer than the width, this will be for the rear cross member, reason for the extra length is to allow for a gusset 50mm in from the rear for a place to put lights, and protect them. Turn it over weld off and fit your suspension. Make your drawbar long enough to go back to the suspension front mounting point as this will give maximum strength, butt up against the front and plate the gap. As you want to use the 65 square, I'd weld 50 X 8 flat bar on its edge to the flush outer edge of the 65, so that it looks like a 6, to give extra support.
Before you fill in any open ends pull some steel wire through for you electrics, remember you'll need clearance lights on both sides so allow for it, as it is easier to do now rather than later. don't run your electrics before welding as you could have to replace them DAMHIKT
While it is upside down put in a support system for the ramps if you are going to put them underneath. Turn it over and finish the top, with support bars, these could be 15nb pipe, 12 mm bar would be sufficient to make Ws out of for extra support.
Regards
Kryn

Originally Posted by KBs PensNmore

Hi gazza, the reason they put the rails on the sides of the trailer like that is to give it strength, for with out it, it would bend like a banana from the weight on the rear as the drawbar would support that section, unless you made the side rails out of 150 X 50 X 4, which will make it very heavy. As you can work out, it is a compromise. I have a car trailer chassis made from 50 x 50 x 3 that has cracked, where the mudguard is attached at the front.
I'd cut your side rails 70 X 50 X 2.5 at 4m long minimum, you'll need 4 of these. Another piece at 1900 which will be your front cross member, allowing for 2 X 300 mm wide mudguards will give you a total width of 2500, the maximum allowable, if you wanted to go slightly wider you could go 2000 but your guards will come down to 250 wide each. You'll need 3 pieces of the 50 X 50 as cross members, 100 mm less than the width you choose. These will fit in between the outside rails FLUSH with the bottom, (about a 1000 centres) otherwise when you fit your suspension, they will interfere.
Cut another piece 300 longer than the width, this will be for the rear cross member, reason for the extra length is to allow for a gusset 50mm in from the rear for a place to put lights, and protect them. Turn it over weld off and fit your suspension. Make your drawbar long enough to go back to the suspension front mounting point as this will give maximum strength, butt up against the front and plate the gap. As you want to use the 65 square, I'd weld 50 X 8 flat bar on its edge to the flush outer edge of the 65, so that it looks like a 6, to give extra support.
Before you fill in any open ends pull some steel wire through for you electrics, remember you'll need clearance lights on both sides so allow for it, as it is easier to do now rather than later. don't run your electrics before welding as you could have to replace them DAMHIKT
While it is upside down put in a support system for the ramps if you are going to put them underneath. Turn it over and finish the top, with support bars, these could be 15nb pipe, 12 mm bar would be sufficient to make Ws out of for extra support.
Regards
Kryn

awesome advice Kryn and easily understandable ill order the steel tomorrow, i hired a petrol stations car trailer once about a year and a half ago to tow home a ford laser i noticed with the car parked up against the front support bar there was to much weight on the front wheels so i moved the car back and had the ass end hanging over the trailers tail, what length would u recommend i make the trailer? going by my mitsubishi pajero that is 4.8m long im thinking a 5m trailer would be ideal? so all up around 6.2m with the drawbar, i think the max length of combination is from memory 12 meters long for NSW roads i will have to check that just t make sure tho

Kryn one thing im wondering from how u explained to do the trailer is the 2nd 3rd and 4th cross members do these get welded below or do i cut and welded flush into the 5 meter lengths of 70x50?

Hi gazza, everything is welded so it is flush on the bottom, inside the 70 X 50. The reason I suggested 4m length was that your lengths were 6m, and the off cuts were able to be used elsewhere, my trailer is 4m long for the moment, and I used that as a general starting point.
Kryn

ok thanks ill go with a 4 meter deck i just measured my car and if i have a small frame on the front of the deck i could roll the bumper bar over this if needed and i'd have up to 600mm to roll the car backwards to get the right balance on the suspension and tow ball weight

its early planning stages but i will also build the frame around the top of the deck for structure as u mentioned, i will need to look at some ideas

Kryn your field makeshift level surface works well i give u credit i made the bed 4x1.9m and im thinking about leaving 150mm over hang on the sides to tie into the mud guards do u think im wasting time doing this? it started raining so i packed up for today, tomorrow ill grind the paint and gal off than square up ready for tacking than cut the other middle sections

since i cant see anything mig welding im actually now thinking of tig welding it i will give it a shot and see how my welds turn out

anyone got advice on which disposable mask to wear welding the gal steel? all welding is outdoors and will be ground off just worried about the gal on the inside creeping out as i tig it

Hi Gazza, leaving the 150mm overhang on the corners is a great idea, certainly will keep the guards from getting crumpled, if your mates borrow it, would be the last time, if it was mine. Also a good tie down point, use a decent size pipe, I'd go minimum 20mm NB., make sure you go to the outer edges of the guards and the front/rear cross member.
Glad the levelling suggestion worked for you, it takes a while to set up, but is worth it in the end.
Kryn

i will extend the front and rear cross members out a little more than 150mm ill actually go with the full width of the mudguards so i can tie it all in

i have on had a pile of scrap 8mm plywood so i just snapped pieces off for the leveling out took around 20mins and i used plastic milk crates to raise the frame works good although its only good for taking otherwise the plastic will melt

heres some pics, ill cut the front and rear cross members to length tomorrow as we are copping a floggin with the rain in sydney

had a nap this afternoon after cutting two lengths of the gal steel and woke up with a head ache so ill goto bunnings and buy these mask

im probably building it the wrong way but seeing im building the trailer on grass and a sloping yard each milk crates are not level across the top so im tacking the trailer together all level and with the 50x50 to 70x50 at the top so the trailer is getting taked the right way up ill flip it over once tacked than tack and weld on the draw barsounds complicated but each joint sits nice and flush with each other

http://www.bunnings.com.au/3m-tekk-p...-pack_p5820589

http://www.bunnings.com.au/3m-tekk-p...-pack_p5820588

Hi gazza, weld the drawbar on as it is, as all the flush joints will be on the bottom, it will also help to keep it square before fully welding.
The actual floor will be down 25mm from the top leaving you a lip on the side to weld against. When the centre rails are welded in, they will be 75mm above the floor, helps prevent wheels dropping off the centre on a small vehicle. 600 mm wide should be OK for your floor panels, as that is a 1200 wide sheet cut in half, saving on waste.
Kryn

i think that may be a problem Kryn as my middle cross members and inner rails will be 70x50, only the front and rear are 50x50

i thought of making the top all flush and welding the sheets from below and around the sides to lock it all in place

doing this i would have a 20mm difference for the drawbar as the front rail is 50x50 and second cross member is 70x50 than the side rails are 70x50 so if i done this i think i would need to add a couple pieces of solid 20x50mm flat bar

If you've enough material, I'd put the front and 2nd cross members as 70mm as it will make for a stronger joint, 1 less joint to worry about also.
Kryn

i may pick up another length of 70x50 and just build the whole frame from this and use the 50x50 later on for the railing that u mentioned supports the whole deck, this idea should work better

im still up in the air weather to MIG or TIG, im not all that confident in MIG but its the much cheaper and faster process where as i think i have better penetration with the TIG

i ran the TIG today on some scrap check out the pics below, i think my welds look better than the MIG as the weld is more of a "u" shape than the MIG "n" shape only down side is i only have a D size cylinder and $95 a refill it could become costly

the impurity in my TIG welds would be from the rusty TIG rods if i do go TIG i will get new rods

forgot to ask, seeing as im welding outdoors say if i was the sand off all surfaces ready for welding and i cant weld that day or for another week because of any general reason do i just wire brush the joint to re prep it again and remove any rust? or is there a product i can prep the surface and paint or brush on a product that will stop any rust forming and i will be able to weld over this product?