Seam welding RA28

[MWP]

MWP - you haven't driven your car yet have you? to see the effect of thewelds?

Nope.
Not that i could tell the difference anyway due to everything else thats also been done.

[Gold28]

With the stitch weld vs seam weld debate, there really is no advantage for seam welding. It isn't really any stronger and as stated above the stitching is a natural crack stopper. Having said that, it is most likely to crack adjacent to a weld than in the actual weld so that debate is fairly dependent on local geometry. Probably look to a 1in weld, 1in break and dont weld a continuous line in one sitting so you can avoid putting too much heat into one area.

I had a bit of a look at my 28 with the idea of stiffening it up a little. For me the back half seems fairly strong. A rear strut brace might help but I am not overly convinced you will notice much.

The front end in em is a like butter and everything you can do to stiffen it up there will be beneficial. Triangulating the strut tops should make a big difference, but be carefull not to introduce a loadpath into a weaker part of the plenum, otherwise you may cause problems down the track. Stitching should see some rewards too, particularly with the subframe.

For my engineers gut feeling, the weakest part is the cockpit, in particular where the windscreen is. Unfortunately this is also the most difficult part to fix. A full cage would be a perfect solution for a race car but not really appropriate in a road car. New cars have a big advantage here with bonded screens (screen is structural). With the 28, stitch welding the chassis rails and sills is probably the best you could expect short of a full cage.

Tying your front and rear sub frames together as per MWP's photo would help too. Remember that the reason why the 28 didn't get the pillarless look that the 22/23 have was because of chassis stiffness and thats about the location of the break between the front and rear subframes.

Keep us posted on your progress buddy.