question about drawbars
Submitted: Sunday, Feb 17, 2008 at 10:37
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rumpig
i'm putting a new chassis under my caravan over
easter and i'm trying to work out the drawbar that needs to go on it. does anyone know how you calculate a drawbar lenght, as in how far it needs to go back under the van in relation to how far it sticks out the front of the van. and does where the axel sits under the van relate to what lenght you need to make the drawbar.
any help would be much appreciated, or a good link to working this out.
cheers
RUMPIG
Reply By: Geepeem - Sunday, Feb 17, 2008 at 17:02
Sunday, Feb 17, 2008 at 17:02
HI Rumpig,
I'd also
check with your Registration department as they would probably have the specifications. I recently registered an unregistered van in Queensland and as
well as obtaining a road worthy and gas certificate I had to physically take van to the Motor Registry inspection depot where they measured all sorts of distances - front of drawbar to first axle, second axle, overhand last axle to rear of van, width etc etc. Presumably there are standards which must be complied with. If you are making it different to original design I would
check with them else you may have trouble if it wasn't compliant and had an accident etc. It seems like the simplest way is to just duplicate old drawbar.
Cheers,
Glen
AnswerID:
287968
Reply By: rumpig - Sunday, Feb 17, 2008 at 17:13
Sunday, Feb 17, 2008 at 17:13
thanks for your comments so far,
the drawbar will be connected to the chassis in 3 different
places as it goes back under the van (chassis will be a big rectangle, with a few spreaders inbetween), so connection of the 2 won't be a problem at all. as for laws relating to what i can do, i've found a couple of sites that help me out with those. just trying to research more about drawbars themselves. the comment relating to a engineer makes sense, but being a self employed tradie i find it hard to get time away from work during the week, this being the reason i'm after any good website links to help me out.
cheers.
RUMPIG
AnswerID:
287970
Reply By: Dunaruna - Sunday, Feb 17, 2008 at 18:03
Sunday, Feb 17, 2008 at 18:03
We do this kind of job regularly and for the most part we just duplicate although sometimes we add 300 or 600 mm to the overall drawbar length. A stress rail is almost a must these days, we won't do the job if the customer won't pony up for the extra cost.
As for axle positioning, you are governed by the mudguards unless you are going to do major structural and cosmetic modifications.
I suggest you get her weighed so that you can determine the ball weight ratio, don't forget to add luggage/water etc to your final figure. Also, measure from
the tip of each axle spindle to the ball coupling, this will tell you if the original chassis/axles are square and true (you would be amazed how many are not). This will give you a reference guide for the new chassis.
Finally, I see cracked and bent chassis all the time. Correct welding/gusseting is a must.
AnswerID:
287984
Follow Up By: Isuzumu - Sunday, Feb 17, 2008 at 18:27
Sunday, Feb 17, 2008 at 18:27
Hi Dunaruna,
I have been thinking of replacing the chassis on my 15 Viscount 1978 model, could you tell me what the cost would be?. It already has a
suspension up grade eye to eye leaf springs with shocks solid 2 inch round axlel and 15 inch rims.
Any info be most helpful.
Cheers Bruce
FollowupID:
553271
Follow Up By: rumpig - Sunday, Feb 17, 2008 at 21:21
Sunday, Feb 17, 2008 at 21:21
sorry if this sounds stupid but that's why i'm asking questions before i tackle the job. what's a stress bar and what's it do? my guess is a bar running lenght ways down the middle like mentioned in an earlier posting, but i've really no idea what it is and what it does.
my plan is to make a complete rectangle shape chassis out of 125mm x 75mm x 3mm RHS (prefer 150mm x 50mm, but it's to high where my step goes), about 700mm back from the front i'll have another "spreader" for the back of the storage box to sit on, aswell as another spreader near the middle of the van somewhere.
so the drawbar will have 3 points at which to attach to the chassis, (1) front cross piece (2) back of box spreader (3) lenghtwise chassis rail back near spring hanger. would i still need a stress bar that you mention?
thanks for all your help
RUMPIG
FollowupID:
553297
Reply By: Dunaruna - Sunday, Feb 17, 2008 at 20:49
Sunday, Feb 17, 2008 at 20:49
Every job is different, some need a new 'A' bar, some need the whole shooting match, some need raising. Rotted floor ply also throws a spanner in the works. We only quote after a detailed inspection but to give you a very rough ballpark - somewhere between $1000 and $4500.
BTW, I'm one of the grunts in the workshop, the blue-bloods in the office do the quoting.
AnswerID:
288011
Follow Up By: Isuzumu - Monday, Feb 18, 2008 at 07:47
Monday, Feb 18, 2008 at 07:47
Thanks for your answer.
Cheers Bruce.
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553345