As a new member of the forum, I thought it might be good to try and bring something to the community that might be useful.
I’m part way through what’s likely to be a long restoration of a 1971 S2 0285P and one of the first jobs that needed to be tackled was the chassis. As seems to be common, the front end was badly corroded. So bad in fact that the previous owner had cut off the front part and replaced it with new parts that he had fabricated.
On close inspection, the suspension pick up points were out of position, holes were in the wrong place and the metal was far too thick.
Luckily, I still had the original rusty part, together with copies of the factory manuals (file s2a Chassis.pdf) which contain some key dimensions on page 4. I was keen to get something as close to the original as possible so an aftermarket chassis wasn’t an option.
I was able to 3D model the chassis front end and then using this data, I created dxf files that can be used to get the individual parts laser cut and pdf files which show material and bending information.
The pdf files have some dimensions marked ref, this means they are for reference, are approximate overall sizes, or sizes after folding. If the blanks are folded as indicated, the finished parts should be the ref sizes shown in the sections.
I’ve not shared the 3D model but if the parts are cut and folded as indicated, the parts will go together the same as mine which is shown in photos below. My assumption is that anyone who needs to make a new front end will probably have the old one to use as a guide to see what goes where.
No welding information is included, this will need to be done to your own specification – spot, plug or seam welded, obviously to a good standard. I used a mixture of seam welds and plug welding through holes drilled after laser cutting.
These parts produce a very good replica of my S2 chassis. They include all the original holes found in mine, including the LHD holes that I don’t need.
Check carefully before folding, otherwise you will end up with holes for steering and brakes on the wrong side of the car.
All parts are dimensioned in mm unless otherwise shown, I prefer to model in mm. Where holes were in exact imperial sizes, they still will be in laser cut parts.
I used zinc coated steel for the main parts to give better corrosion resistance.
I’ve spent a lot of time creating this data, done lots of checking and my own parts have turned out fine but I offer NO GUARANTEE that your chassis will be the same as mine. I don’t know if the TC chassis is the same as I’ve not compared it. I do have a TC chassis I could reference but it’s not on my to-do list at the moment.
I did think about manufacturing either a kit of parts or complete assemblies to sell but frankly, I don’t have the time. I rather just make the data freely available. Obviously someone else could do using my data, which I really rather they didn’t but I can’t really control that.
The laser cut parts are as follows:
Frame Upper 1.6mm thick, 1 off required. The original part has 2 large, plunged holes in it. I replicated this feature by welding a short length of tube into each of the laser cut holes to add stiffness to the parts. This part has holes in it for the suspension pick up points. These are 12.7mm diameter, smaller than the 20mm (3/4”) that will be used for the suspension pivots. These holes should be opened up to the required metric or imperial size once the complete assembly is welded together. This will ensure they are the right size and are in the correct place in the Side Reinforcement.
Frame Lower 1.6mm thick, 1 off required. As with the Frame Upper, the suspension pick up holes are undersize. This part is as the original chassis, however I was informed of the issue of chassis cracks where the frame isn’t welded to the bottom of the main chassis section. To counter this, I cut the Frame Lower after assembly to make a tab that could be bent flat against the main chassis and welded through. This can be seen in the photos. For now I’ll keep the laser blank as original and when time permits, I may provide an update with this feature.
Side Reinforcement 2mm thick, 2 off required. No suspension pick up holes in this part, drill them through after final assembly – I opened them out to 12.7mm using the Upper and Lower frame holes as a guide. Then I used a step drill to go through both parts to maintain exact centring on the original holes.
Diaphragm Plate 2mm thick, 2 off required. These need to have one end cut off at an angle – this can be seen on the original chassis. I kept things simple and just trimmed them off after folding.
The following parts need to be turned on a lathe. You can use 20mm or ¾” bar but make sure your chassis holes are opened up to the correct size to suit.
Lower Arm Shaft 2 off required.
Upper Arm Bush Long 2 off required.
Upper Arm Bush Short 2 off required.
These parts need to be welded into the main assembly. Position is critical to maintain the correct geometry so position carefully using a known good chassis for reference.
