Manufacturing a body lift kit - part three

20th May 2010

My welding mask arrived quite quickly along with some rods that I had purchased from eBay . I decided to start welding up the back section first as this seemed the simplest. The three pieces were cramped to the chassis and butted up i ground a V in all the joints so that I could get more weld in them and therefore get a stronger joint. These were soon to run out but luckily Lidl was selling a welder and welding rods I bought 4 boxes on chance for £3.95 they are superb and I am very surprised.

Front and back sections.
I started with the curve in the back section I made very small triangle pieces out of the box section to fill the area between the slits this held the position of the curve and allowed the weld to maintain it self . This was repeated until the whole curve was welded up. You can see from the picture the inner face was smooth as it required no welding whilst the outer surfaces would require grinding. the rear diagonals were all then fitted to the donor chassis and cramped in position so that the rear section could be welded. This proved quite successful I had cut a section out of each side to fit snugly into the rear chassis section. This was all tacked and welded. The middle curve section was then dropped in and the whole section was tacked and then welded up. I was very pleased with the result of this as this was a technically challenging part to make up as it had a lot of curves and bends in its construction. The rear section was then fully welded up and the whole rear section was retried on the rear of the chassis cross member. The next sections would again require cramping the new frame to the chassis. I welded up the curve of each of the front section so that it could check it on the chassis I used thin slivers of cut tubing in a wedge shape so as to not have to infill with so much weld. It was a pretty good fit. The front two halves could then be welded together whist cramped to the chassis. Once the two halves was welded together it was noticeable that one of the lower leg angles had moved due to the heat of the welding this angle was cut back out by using an angle grinder and the new angle was welded together again to make a good fit. The finished version was obviously incorrect as the top curve was totally wrong. I new this would not fit the chassis. I drew an initial template from the bottom of the section. When I superimposed it on the top It was noticeable that the curve needed to be at least another 1/2" higher. I stated fabricating a new top by making a new curve section that would fit the bottom. I made this extend further into the bend so that It would clear the existing welding. This was then welded up to make a solid curve. I was able to then position this on the top of the curve to allow me to mark the union of the two pieces this was quite complicated but surprisingly went very easy. You can see in the diagram left I have cut the two sections so that they mated seamlessly into the curve of the welded front section. The difference in the previous and the new curve is immediately noticeable. I tested this design on the body and chassis of a donor vehicle to my horror the whole top section was still wrong. Further analysis proved that there was a strange phenomenon happening. It appeared as if the sloping sections of the front section had to be thinner than the 80mm box to keep the same shape and profile as the bottom of the front piece. It looked on paper that these needed to be 12.3mm thinner. This was completely unbelievable. But yet with the top lowered 12.3mm the top would again fit the bottom of the section like it should. After a while scratching my head I decided the only reason for this had to be that the slopes vertical diagonal component had to be 80mm and this was the reason the width had to be reduced by 12.3mm. This was a very iimportant discovery as it meant the rear section may not be correct either. The math for this was also simpler than I thought it was basic trigonometry a jotting pad soon came up with the mathematics needed to find the new height required on the diagonal components based on the angle that the diagonal was leaving the vertical. Looking at the rear section this was also wrong and needed changing as clearly the end sections was wrong and not following the contour of the top either.

Front section finalized.
I new that I would have to lower the peek of the front section by 12.3 mm. To achieve this I would need to cut out this new section from the front all the way down to the flat ends. I would then have to remove 12.3mm and re weld the whole assembly back up . The picture right shows the top half lowered by 12.3 mm . This gives a vertical height in the middle of 80mm. Which is correct and now fits the body work perfectly. This would also need to be done for the rear section which is a much more complicated section. I would have to work again from the angle to the horizontal and use a trigonometry tan function to work out the new height. One really interesting thing about all of this is that the number of people that told me to get the tubing bent to make this would have all been wrong as this would not allow the body work to fit in the same way as my previous methods had not.

Rear Section finalized.
The rear section was with the new mathematical information also wrong the angle it raised from the horizontal was 20 degrees . Using trigonometry (80 mm/(cos 20) = 85.1 mm ) - 80 mm = 5.1mm shorter in the diagonal heights. It can bee seen from the photo left that the original rear section I had made fitted the bottom beautifully but the ends of the section where wrong and too short on the top section. This meant also the height of the tubing needed shortening by 5 mm. I started by marking out the cuts to each side diagonal and the increase in end required. With this I was able to cut the top of the diagonals and shorten the box tubing by 5mm. This also gave enough distance for the end pieces to be extended.

Two opposing side sections.
The side sections were much easier to fabricate to shape I cramped the side sections to the chassis and ensured they matched the curves in the chassis. I ensured that the lengths where longer than I required so that they could be trim to size. I cramped the rear section first and then moved forward placing new cramps to ensure the shape was correctly held in place. Some gaps where to large to weld so I used the cut out triangles from the rear section that I cut out and welded them into the larger gaps. This process yielded a much cleaner weld and it can be seen that it held the section together better. With this repeated for both sides the design was starting to come to shape. I tacked both sides so that they could be transported and welded up in a warmer environment. You can see with both sides cramped in situe the strength of this new section was already stiffening up the chassis. The picture left shows the two side sections tacked together before they were removed to be fully welded.

This was becoming a lot more complicated structure to build than I had figured I would need to cut the sections to shape and weld them up to make a complete chassis. This will be continued in the next episode.