Thread: Stirlsilver's Disco Ute Project

Originally Posted by dattopimp

Looks good man. Just one thing about the rear body mounts onto the chassis...I don't know. A few gussets perhaps? Just looks like alot of stress would be placed on that flat piece.

It does have a gusset, and it is all constructed from 4mm plate. you can't really get much more gusseting in there because of the rubber mount, the only way around it is if some flat bar were bent around the perimeter and welded in place, but I think that is excessive considering so much of the body has been cut away.

Another saturday in the workshop, although this time I wasn't able to spend as much time as I would have liked. Anyway, after some more convincing I finally agreed that the body mount was insufficient, so I reworked the left hand side mount (took bloody ages!)






I made a start on the right hand mount but ran out of time before I could finish it. This is as far as I got:


After I finished my assignment tonight I got back on to doing some concept work in Solidworks. First I went about figuring out where I would be trimming the chassis to, and I am pretty sure I want to trim it down to the bottom of the curve and brace the rails together by using the original beam from the very end of the chassis (cut of portion). This would end up with removing approximately 350mm from the end of the chassis.

Before:


After:


After doing that, I started to play around with some LPG cylinder configurations. Since this will be an LPG only car I want to try and squeeze in about 200L of LPG on the car, which should hopefully give me around 1,000km of range. Looking at the APA cylinder dimensions (http://www.eco-gas.com.au/wp-content...DIMENSIONS.pdf) I think the A120 cylinder is best as two of these cylinders side by side are less than the outside width of the chassis rails, although they are quite long (1.2m!). If I were to use these cylinders, I would end up with something like below:





I'm pretty sure what I have shown here won't be an acceptable configuration since the cylinders protrude beyond the chassis making them the first point of impact on a rear end collision. Is anyone able to confirm this? If it is a no-no, I wonder how I might be able to get around that and still fit 200L of LPG in there.

I then went and sketched a few things in:


I'm toying with the idea of making up a box which the LPG cylinders would sit inside of, just so that there are less areas which mud can get to, and I would have a large access hatch through the top of the tray. Also, with the shown configuration I may be able to squeeze in my Ramsay winch under the LPG tanks, but I'm not really sure there.

In this configuration the tray would be sitting somewhere around 1.4m from the ground, which is quite high, but there really isn't much that can be done about that when you have LPG tanks between it and the chassis...

As for the engineer... STILL haven't been able to get hold of one!!!

$131 later and I purchased AS 1425-2007 to answer my question on the cylinder location requirements. They were best summarised by the diagrams below.

For a vehicle of less than 4.5 t mass or having a chassis ground clearance of not more than 600 mm at the rear (see Note 1), no part of a fuel container, compartment or subcompartment that is beneath or towards the ends of the vehicle shall lie outside a zone whose boundaries are those shown in Figure 3.3:


For a vehicle of 4.5 t or more mass, or having a chassis ground clearance exceeding 600 mm at the rear (See Note 1), the zone boundaries shall be those shown in Figure 3.4:


In terms of protection in the event of an accident, all I can find in the standard is as follows:

A fuel container together with its associated attachments, shall be located and protected so
that the possibility of damage from impact, accident, or loose objects is minimized. The
following specific requirements apply:
(a) Each container shall be located in a position, or provided with protection, such that
damage in the course of normal vehicle usage is minimized. In particular—

(i) locations vulnerable to impact by objects thrown by tyres shall be avoided; and
(ii) damage due to impact by objects being handled by or carried by the vehicle
shall be prevented.

No mention of impact protection or anything. So since I think this vehicle applys to figure 3.4, it appears that I need to modify my concept to ensure the LPG cylinders are forward of the rear-most chassis cross rail.

Ok some more work done on the Solidworks model.

Since the AS1425 standard requires tanks to be forward of the rear cross brace, I decided against re-using the existing rear cross brace. So instead I plan to cut the chassis in the same place and then build a cross brace from 5mm plate, as you see below. This cross brace will also serve as a winch mount.

Also, it seems I am not going to quite get to my 200L of LPG target, they are just too long, so I've decided I will use 2 manchester tanks each 375mm dia x 1080mm long, they each hold 88L of LPG each, which should really be plenty.

I also started working on the system which the tanks would be mounted on (along with the tray). The plan is to use 40x40 SHS 4mm thick. The challenge is to make the frame stiff enough to hold the weight of the tanks full and the tray (plus anything on it). What I have shown below is still a work in progress, I need to add some more cross bracing across the top (which will need to be bolted so tanks can go in and out if necessary). So it's going to be quite fiddley!

Also at the front, I can't get any gussetting in like I have shown in the rear.







Over this weekend I'll be going in to the workshop to weld up the wall frame (it's only tack welded at the moment).

A little bit more time spent, I did some quick calculations of the cross braces which the cylinders would mount to. Turns out the 40x40 4mm SHS is more than enough to handle the weight of the cylinders, so i've removed the gussets I had placed on the rear to make my life simpler.:

Well, I put the long weekend to good use. I was in the workshop every day Friday to Monday. Tomorrow I'll be taking a break!

I continued to weld up the rear frame during this time.

I cold galvanized and welded in the top beam and gutter assembly I had made last year:




Welded in the pieces which go in on the end of the lower sills (These were a pain in the arse to weld in):




And simply carried on until the whole frame was completely welded in:




I then prepared the left door to have it fitted, I had to weld in the collars properly and also weld up all the holes that would let water in:





And that was all I got done!! It really doesn't seem like much, but doing all the chamfering of the steel, cleaning and welding takes ages. I should get quicker as I go along.

I also did some more Solidworks work. That little bolted in cross brace was removed and the whole assembly has been shifted up so the front cross brace is now above the chassis (It would have fouled with the A bracket on the rear diff).

The tray is now going to have two levels, so that way I can fit in the tanks at what ever level they end up at and keep the tray at a reasonable level for use. The spare tyre will be mounted on top of the LPG tank frame.

In going through all of this, i've decided that designing tray frames is really tricky! There is still loads more to do, and when it comes to actually building what I am designing, it's going to take AGES. If anyone thinks of a better way of doing something, please let me know.

I figured I was starting to go overboard with the amount of steel reinforcement on the tray, particularly since I will probably use aluminium which is 5mm or so thick, which is more than thick enough to be structural itself. So based on this I did some more work on the design of the tray as follows.

The final structural layout of the frame (at this stage anyway):


Starting to do some work on the alloy parts:




For the compartments, I think I will get the panels made with the doors fitted with seals, I think that the positioning of hinges, seal positioning door placement ect. Will be far too fiddley for me to do. So I think I will find a place to make me the faces with the doors fitted so all I have to do is weld them to the compartments.

I also did some thinking about the other compartments, and perhaps a soft canopy:


The spare tyre position... it's a bit bigger than I expected once I put it in position... I won't have much of a rear window with it sitting there (I guess I should blame the LPG tanks for that):

Stand the tyre up behind the driver (length alond side the gas tank cover), you could even build a depression into the tray to make it sit lower (probably restricted by the spring holder).