Outer Limits 4x4 Board

I want to mount my winch under my tray between the chassis rails but I don't know what thickness plate to use. The rough size is about 800x300 bolted to the underside of the chassis rails using crush sleeves. The winch will be bolted through this from underneath. What thickness steel will I need to resist the forces that the winch will place upon it? 16mm? 20mm? Less? I will be using 2 12mm bolts each side.

8mm plate, 4 bolts per side and cross ribs to strengthen it

What NICK said.

Sam

Strange Rover wrote:What NICK said.

Sam

What Sam said, because the PRICK is never wrong

NICK wrote:8mm plate, 4 bolts per side and cross ribs to strengthen it

What size cross ribs? Full width at full depth or tapered at ends. Why 4 bolts each side? The winch itself only uses 4 3/8' bolts to hold it down and they're fairly close unlike the plate I'll be making. Do the ribs need to be fully welded or just stitch welded?

If I understand correctly correctly you want to bolt it to the top or bottom of the rail which might not be legit ,better check with with the transport dept first.
Regards Charlie

why wouldn't it be legal? but i don't think he'd be too fussed since he's already got a defect notice for other things. he'd be more worried about the chassis bob. :wink:

beebee wrote:

NICK wrote:8mm plate, 4 bolts per side and cross ribs to strengthen it

What size cross ribs? Full width at full depth or tapered at ends. Why 4 bolts each side? The winch itself only uses 4 3/8' bolts to hold it down and they're fairly close unlike the plate I'll be making. Do the ribs need to be fully welded or just stitch welded?

as for the winch and the bolts being close together, think of it like a broom handle, hard to break the end of but easy to snap in the middle, 8mm plate might seem thick but over the distance of 800 it will bend easy, hense the need for the strenghting. I would use around about 20x20 box, 4mm thick and stitch weld it, this will allow the plate to have alittle play in it and not put all the strain on the bolts, the reason for the 4 bolts is the same as the strength ribs, to stop the plate from wrapping.

NICK

N*A*M wrote:why wouldn't it be legal? but i don't think he'd be too fussed since he's already got a defect notice for other things. he'd be more worried about the chassis bob. :wink:

Charlie could be right here as some states dont like you to weld or drill the top or bottom flange of a chassie. I know on heavy vehicles(trucks) it is illegal to weld or drill the top or bottom flanges.
But im not sure if it is illegal in QLD.

beebee wrote:What size cross ribs? Full width at full depth or tapered at ends. Why 4 bolts each side? The winch itself only uses 4 3/8' bolts to hold it down and they're fairly close unlike the plate I'll be making. Do the ribs need to be fully welded or just stitch welded?

i would possibly be thinking about a different way to mount the winch,,from what i understand you are doing is just mounting the winch so as when it gets a load on it it will be pulling from the side,,,ie,,either forward of the vehicle or behind the vehicle,,this meaning it will be putting all the weight on the bolts and relying on there "sheer" strength,,,where as when a winch is mounted behind a bullbar the bolts dont really have a lot to do with strength,,they are just there to hold it in place,,,,,think about it......
paz

paz wrote:

beebee wrote:What size cross ribs? Full width at full depth or tapered at ends. Why 4 bolts each side? The winch itself only uses 4 3/8' bolts to hold it down and they're fairly close unlike the plate I'll be making. Do the ribs need to be fully welded or just stitch welded?

i would possibly be thinking about a different way to mount the winch,,from what i understand you are doing is just mounting the winch so as when it gets a load on it it will be pulling from the side,,,ie,,either forward of the vehicle or behind the vehicle,,this meaning it will be putting all the weight on the bolts and relying on there "sheer" strength,,,where as when a winch is mounted behind a bullbar the bolts dont really have a lot to do with strength,,they are just there to hold it in place,,,,,think about it......
paz

This is the way in which the Aussie winch mounting systems work but many of the Yankie bars have the winch mounted it the way that I've suggested. It is of slight concern to me as well.

There's a diagram for a flat bed mounting plate in the WarnXD9000 installation instructions.

1/4" plate with a pressed flange front and rear. horizontal depth 172mm, height of rear flange 38mm, height of front flange 70mm.

1st row of monting holes in base are 32mm back from front flange, 114mm row centres. Cross centres for mounting holes is 254mm.

Front flange has 2 holes for mounting fairlead rollers, 35mm up from base and 254mm cross centres. Slot for rope exit is 203mm wide x 32mm high, centred from holes for fairlead.

Total width is 610mm, if you want it wider, I suggest make flanges higher or use thicker plate.

With regard to welding or drilling top/bottom flange of chassis rails. The top and bottom flanges carry most of the bending twisting loads. Drilling holes reduces the material and therfore the strength. Welds across the flanges greatly reduces the fatigue strength.

How about welding a flat vertical on both ends of the mounting plate so that it can bolt to webs of chassis rails. Idealy the bolt holes would be close to the same height as the winch rope through the fairlead.

I'll be talking to an engineer this week so I'll get his imput as well. I don't feel that the area in which it will be mounted (basically behind the rear axle and before the shackle hangers) is a high stress area. If the chassis breaks.......the tray will hold everything in place.

Thanks for the info on the mounting plate John.

Dave let us know how you go with the crossover steering as i think this will be your biggest hassel no mater which way it is done.

Yes it will be interesting. The histeer would be ok but it changes the ackerman from factory which engineers don't like. However the double arm from chaos retains the standard ackerman and has been engineered at least once (that I know of) in Brisbane using core linkages and 80 series tre. Was done on a solid axle conversion on a hilux performed by Richard at 4x4 ngineering and engineered.

Another interesting point is the steering box mount being a chassis mod and all.

RUFF wrote:Dave let us know how you go with the crossover steering as i think this will be your biggest hassel no mater which way it is done.

i engineered my X-over but I was SUA at that time.

bj on roids wrote:
i engineered my X-over but I was SUA at that time.

Bj i also know the story behind how this was done

are you criticising my work?

what part of it in your mind is not right?

What style of crossover was it?

60 series, conversion from 40 series steering

i beleive santa has one on his too.... probly approved, and it was done by a 4x4 shop. doesnt look as neat as mine either

But that is a fairly common mod. Does it involve welding chassis?

bj on roids wrote:are you criticising my work?

what part of it in your mind is not right?

I didnt say there was a prob with your work. I said i know the story behind the engineering.

beebee wrote:I want to mount my winch under my tray between the chassis rails but I don't know what thickness plate to use. The rough size is about 800x300 bolted to the underside of the chassis rails using crush sleeves. The winch will be bolted through this from underneath. What thickness steel will I need to resist the forces that the winch will place upon it? 16mm? 20mm? Less? I will be using 2 12mm bolts each side.

is the Fairlead faceing up, forwards or backward, what sort of winch? high mount or low mount? what sort of rating? 8000lbs?

the best thing to use would be parallel flange channel (PFC) fill in the ends with some 8mm plate and bolt it through the web of the chassis rail, and use some 12mm grade 8 bolts at each end.

to do this right you crush tubes nead to be welded to a plate which is 3 times the length of the end plate on the PFC, and no more than twice Chassis rail thickness so it bends and does not cut into the chassis.

pm the winch type and size or model no. and the actual distantce between the chassis rails and i will do some numbers and let you know

Sweet!

I'll be out measuring tomorrow when I've got some light.