Diahatsu Dnepr build

johnfireball · Post by **johnfireball** » Fri Oct 10, 2008 7:19 pm

Hi all,
a little more progress made with my build. Engine and gearbox now mated with a heavy duty bmw clutch. Starter motor fitted but requires spacing. Have now cut the frame and am getting everything alligned trying bits on to ensure nothing fouls it, it needs a 110mm stretch. I am getting it welded professionally and will only tackle the smaller welding jobs myself (brackets etc). I am trying to source some quality frame steel tube 48mm with 4mm wall thickness for the upper frame piece and 34mm with 4mm wall thickness for the lower joins anyone any helpful contacts?
John from Dublin.

johnfireball · Post by **johnfireball** » Fri Oct 10, 2008 8:29 pm

Sorry tube sizes 48mm o/d 4mm wall and 42mm o/d with 4mm wall.
John.

Post by **Fiddler** » Sat Oct 11, 2008 9:54 am

Have you tried asking Sumo for contacts? He was doing a similar build with a frame stretch,. Might be a good place to start.

oldbmw · Post by **oldbmw** » Sat Oct 11, 2008 8:14 pm

if you cant locate tube, these relatively short pieces can be machined from solid, if you do, leave a step inside to make sure the tubes seat the same all round. I like to drill through the outer pieces and weld there as well. then even if teh weld lets go, the tube will stay connected because the weld wont pass out of teh tube.

johnfireball · Post by **johnfireball** » Sat Oct 11, 2008 10:24 pm

Hi Larry,
in the pics you can see a 25mm bar inserted into the frame tubes, my intention is to weld this bar to one side of the frame then slot a tube that fits over the frame tubes onto the frame then join the frame with the 25mm bar .Weld up the bar and then slide the tube over the welded bar and weld this over the whole join. This way the frame is double joined and I think will be immensly stronger.
John.

oilburner · Post by **oilburner** » Mon Oct 13, 2008 12:07 am

I just measured my Dnepr frame and it's 32mm or about 1 1/4 inches. For your extension pieces you can get 1 1/4 inch DOM (drawn over mandrel, seamless) tubing at any decent metal supplier. This is what I used for my frame (1/1/4 X .125 wall)

Due to the difficult bends in my frame, I built it in sections and grafted the pieces together. Below is a sketch showing how I did it.

I made dowels from DOM tubing. I turned them on the lathe to make them a tap-in fit. In your case each half of the dowel would be a slightly different diameter due to the slightly different inside diameters of the original and extension tubing pieces. I drilled holes every 90 degrees in the ends of the frame tubing and the extension piece for plug welds. I ground the ends of the tubing 45 degrees which left a "V" between the ends of the pipes.

I assembled everything, then cranked up the welder to high and did the plug welds. I then welded around the "V".

I think this is the technique oldbmw was describing. The splices are as strong as the rest of the frame.

You can grind everything smooth and the splice will be undetectable.

My $.02

oldbmw · Post by **oldbmw** » Mon Oct 13, 2008 6:54 pm

Well put oilburner. pretty much what i had in mind. I am not sure a solid bar inside would be helpfull. Creating a rigid point in a frame that flexes might cause metal fatigue. My idea was to use bar the same outside diametre as the original tubes, then drill and step it to make the internal bushings. Then lock them with the V weld and peg welds ( or as oilburner suggests) use dowels.

johnfireball · Post by **johnfireball** » Mon Oct 13, 2008 8:48 pm

Hi,
Thanks guys for the helpful advice, I will follow the oilburner plan as I like the idea of keeping the frame original looking. I have found a steel supplier in Dublin who may have the correct steel sizes. My frame tube is 33.3 mm diameter with 25mm bore, so I'll get something pretty close.Again all help appreciated.
Regards John.