9 replies to this topic

[stardude]

hiya

a few months ago with some help, i got a center exhaust fitted to my car, now i have decided i need to be able to tow a trailer as well, but keeping the central exhaust and making the tow bar removable.


i have looked at the tow bars that bolt to the rear subframe and the bottom of the seat, and designed this around that.

what do you think of these ideas then??

can you see any problems??

anyone else got around this before?



cheers

adam

[yeti21586]

i like it

dunno if it would work as ive never thought about it but imsure its possible

[Twincam]

I'm going to be facing this problem rather soon too (Central DTM)...

I think it could work but you might have an ugly bar facing the rear... Where are the brackets going to be mounted to?

[bert998]

I dont see why not. Damn ugly mind

[stardude]

the bar at the back will mount to the base of the rear seat and the 2 smaller bars will mount on the rear subframe.

yeah it will be bloomin ugly, but thats why its removable

the removable part will detatch at the back of he subframe, so that you could only see it if you were 6" tall or were looking under the car.

[lrostoke]

I was looking at this the other day, the main concern to me when I worked out where the towball would be was that it was pretty much blocking the gas flow from the exhaust.
Probably ok on the move, but not sure I'd like the possibilty of exhaust fumes building up under the car or getting in through the boot.

[Phaeton]

I would be more concerned about it's strength. you don't say what steel you will be making either the tubes (front) or rods (rear) out of. There's no dimensioning of how far the rods go into the tubes as this will determine what vertical load can be placed on it, too short & the ends of the tubes will just let go, too long & you will never get the rods in unless each tube is perfectly parallel to each other. Another factor to consider is the shearing action placed in the pins that you put through to hold the pieces together. Under acceleration then the rods will be trying to pull out of the tubes, under braking the rods will be be forced into the tubes . This constant action will need to be considered in choosing the side wall thickness of your tubes.

All in all, yes it can be done, but be careful as you don't want your Mini going in one direction & the trailer in another. This can be done, but just remember it is probably illegal to do so & will possibly invalidate your insurance as all tow-bars have to manufactured to EC94/20 legislation which I suspect this will not be.

Alan...

[stardude]

I would be more concerned about it's strength. you don't say what steel you will be making either the tubes (front) or rods (rear) out of. There's no dimensioning of how far the rods go into the tubes as this will determine what vertical load can be placed on it, too short & the ends of the tubes will just let go, too long & you will never get the rods in unless each tube is perfectly parallel to each other. Another factor to consider is the shearing action placed in the pins that you put through to hold the pieces together. Under acceleration then the rods will be trying to pull out of the tubes, under braking the rods will be be forced into the tubes . This constant action will need to be considered in choosing the side wall thickness of your tubes.

All in all, yes it can be done, but be careful as you don't want your Mini going in one direction & the trailer in another. This can be done, but just remember it is probably illegal to do so & will possibly invalidate your insurance as all tow-bars have to manufactured to EC94/20 legislation which I suspect this will not be.

Alan...

i am afraid you are wrong about the EC94/20, as that only applies to cars built fro 1998 onwards. and such will not invalidate my insurance as long as they know i am using a DIY towbar.

i see no way of this being illegal. and if it was, why would minimag print a how to build your own towbar in their magazine?

i believe practically every mini that is fitted with a tor bar, have either made it themselves, or bought it from someone that have made them themselves with no EC94/20 legislation in mind.
eBay example


in regards to the design of it, they are only quick doodles and therefor do not have proper dimensions as yet.

i would be building it out of thick box section, much like the current tow bars for sale but probably thicker.

for the bolts i will most likley be using high tensile M10 bolts, unless anyone can tell me a better bolt to use?

the bars will slide in probably about 200mm and have 2 M10 bolts going through each bar to secure it.

the flat bar with the tow hitch on it will probably be around 50mm x 10mm

i will also be getting my friend who is a commercial vehicle mechanic to weld it up with his rather big welder, to get the best penetration possible, an also to get his thoughts on it too. he can also supply me with an engineers report stating that it is a safe, bespoke towbar.

Edited by stardude, 14 May 2009 - 10:12 AM.

[998dave]

I'd think it'd be better to have two bars go just each side of the exhaust, bolted through the subframe, and bent to converge behind the exhaust for the tow ball.

Like this:



So the four black bolts hold the towbar to the subframe, and it's those that you remove.
(Possibly eight bolts, with flats welded to the tow bar, and bolted each side to the subframe.

Dave

[stardude]

I'd think it'd be better to have two bars go just each side of the exhaust, bolted through the subframe, and bent to converge behind the exhaust for the tow ball.

Like this:



So the four black bolts hold the towbar to the subframe, and it's those that you remove.
(Possibly eight bolts, with flats welded to the tow bar, and bolted each side to the subframe.

Dave

that seems alot easier!

cheers dave