Wanted a dirt bike nut !!

[dads tractor]

Can anyone please give me the bike and size and the weights for the front and rear axle as I have the job of making a 3 bike trailer and am working out where to put the coil independent suspension .all the bikes here are stripped getting setup for the Finke Desert Race .I need the weights to place the axle and work out a draw bar length for 10% ball weight. Your help would be greatly appreciated in suppling the info .

[nissannewby]

How accurate do you want to be? Most lengths and overall weights are on any specs sheets available on the manufacturers sites. The only thing that may be of concern is a bike setup for finke will have a different weight to a standard item that most will have in there shed. Also what size are the bikes? 240,450? 2-stroke, 4-stroke?

[Gecko17]

If you know the make and model of the bikes, the weights etc should be available on the net as part of the manual specs. let us know and will see if we can help track it down unless someone else knows without google....

[dads tractor]

Thanks nissannewby for replying I want it balanced down to the kg as at this late stage as it might have to be a 2 stage project with the shed left till after the Finke .Bikes are 2 x KTM 300 exe and a Hondog 450 crf . Looking at 2 facing forward 4stroke facing rear and am using cruisemaster 1.2 t suspension. Also water tank in front of axle and jerrys of fuel at rear of axle

[dads tractor]

Gecko you can get whole weights but not front and rear this trailer will not be towed slowly on hwy or dirt so am trying for stability plus hence the attention to weight distribution.

[Bob]

Wont the weight distribution alter as you use the Fuel and Water ???

[dads tractor]

Yes Bob but the fuel will be for bikes and go first and the water tank will still be in the 10/20% tongue weight or we can move a spares /tool box back to counter the balance .

[nissannewby]

Are you also taking into account riding gear,tooling and spares or will these be carried in the tow vehicle?

[threedogs]

there is a formula for working out draw bar lengths in relation to axle position.
Longer drawbar say 180cm will tow like a dream and allow easy reversing as well
Plus you can fit work box on the front as well
I'll see what a can dig up

EDIT put it {axle} central then its a matter of two facing forward or two facing the rear
to get some weight on the towball

[dads tractor]

Are you also taking into account riding gear,tooling and spares or will these be carried in the tow vehicle? mostly in the tow vehicle mate .

[dads tractor]

[
EDIT put it {axle} central then its a matter of two facing forward or two facing the rear
to get some weight on the towball[/QUOTE] So your for centre of load area and work draw bar length from there ?

[dads tractor]

Also what about a small amount of toe in for tracking do you feel it will have any bearing on a single axle it certainly does on a tandem car trailer with a rally car and spares towed like a dream.

[threedogs]

No if your making it from scratch you'll build it up side down and get the axle as plumb as possible.
other wise it will have a crab stance. Easy enough to flip over

[dads tractor]

3dogs the brain is going 100k/hr at the moment so everyone's input will help me over engeering it and make a nice trailer this is a project with my lads so we only want to do it once , as a dry old bloke said to me once some butchers ware a apron and some ware overalls that cracked me up .LOL

[threedogs]

heres two of three I've made, the second I still use.
one is a SR5 extra cab the other is a J deck single cab [hilux]
string line and tape is your friend.
Chassis wise I'd suggest 40x40x2mm RHS fully welded.even 50x50x2mm rhs
once the springs are on you can flip and make the front stone/wind
storage area to protect bikes in transit. Yes over engineer it
As you know triangles are your friend, cant bend a triangle
I a big believer in triple draw bars with the centre one going the full length
It can be from smaller material, notch it in then you weld a plate on top to except which ever coupling you want.
I went the O'Brien coupling Aust made and easy to use, don't forget to use rated chain and shackles
Question ::: will you be running 6 stud rims and or brakes

[dads tractor]

Sorry mate had to run down and back to Brisvages for a course today from Mackay bit how its going but to answer the ? disk bakes and 6 stud and I'm with you running a centre chassis rail then side rails is the way to go .My uninformed view is that all stress is on the centre rail and the side rails only have to cope with flex so the load is centred on the centre rail and the design is specked to that , I hope you understand that and I think you do going on your designs .

[BigRAWesty]

Your A frame draw bar is the strongest as it gets the forces of tow to drag in a straight line.
Your wheels (the drag) ain't in the middle of the trailer, and you'll have very little trailer flex as that's what the suspension and coupling control.

The central bar just aids the A frame it load bearing, but for bikes woukd be way over kill..

I would have thought a bike cog would be as central as possible, so the rider has full control and not having to out weight it.

I like the 2 forward and 1 backwards idea, but most do all 3 forward with the middle one in front a bit to allow tie downs to clear the side bikes.

Also use fold flat tie down points. You'll want 5 for the handle bars and 3 for the tails. The 2 outside bikes will tie to a central point which will be under or behind the middle bike.

Also place these tie down points next to a cross rail, adds more strength.

If your looking at a light sheet I'd also add some smaller frame work into the chassis so the tie down ain't relying on the sheet to hole em down..

I've always used the simple 10% behind cog for axle position, but being a dedicated bike trailer you'll have to work that one out..

Have you worked out water and fuel weights yet?

[dads tractor]

Westy we had a bit of a think tank and no 2 son may have come up with the fluid solution .Use jerry cans that way if a rock or stick goes into a tank u will only loose 20 lts and move them around to balance so that's where we are going .

[BigRAWesty]

I like the jerry can idea better for sure.
A few fuel a few water.