Originally Posted by D.Bachtel
Here's what I did on my Greeves.. up front sandwiching the engine plates,
Your subframe doesn't have to be one piece, you just need four good points that will enhance and strengthen the bikes frame to create a unified structure.
I did something almost exactly like that on my CB400, too, except with no welding (and a lot uglier). Hang on a sec and I'll go out and take pictures.....
Jeez, that is one dirty mowdur-sickle!!! Ignore the oil that pukes out of the valve cover; it runs just fine! >_>
My top mount there is a Velorex U-clamp. It is "stock", except that the bolt holding the clevis and eye together was replaced with a hardened bolt. I also used a flat washer on each side everywhere, and a lock washer under every nut.
The bottom front mount is two pieces of angle cut out of a worn out grain blower chute and shaped to fit the motor mount. The four (can only see one peeking out in the picture) motor mount bolts have been replaced with longer hardened bolts (so as to reach through the extra thickness of the angle. The two angle pieces are stiffened up with a piece of 3/16 sheet steel across them, which is held on with hardened 1/4" bolts.
I don't like how the clevis on the lower front has to stick out so far. It's on my list of things to change this spring, if it doesn't break first.
Both of the rear mounts are attached using short pieces of 3/16" angle iron. The lower rear bolts onto the footpeg mount, and the upper rear bolts to the fender mount. They are the threaded block and eye bolt from a couple of other velorex U-clamps, sans U-pieces. The eye bolt tightens down against the inside of the angle iron. Both of them bolted through to the angle with two high-grade bolts. These were the ones I thought were most likely to shear off, but so far they have been just fine.
This has held for me for the most part, so far, with all three wheels off the ground a few times. But I don't have any kids riding around it in, just gear, nor do I have a family to support that would be inconvenienced if I hurt myself. ;) I lost the bolt that attaches the lower rear arm to the sidecar once. I don't know if I forgot to torque it down, or if it sheared off. After that happened, I torqued the crap out of all of those 6 with an air ratchet, and haven't had any more problems (with the sidecar, anyway; the rubber parts on that 35-year old engine are another story!).
Oh, and by the way: Take up Claude on his offer and give him a call. I did the same when I was putting mine together (though all bad design decisions of my build are mine, not his!). He's a very nice guy, and happily took time out of his day to give me a ton of excellent advice on setting up the outfit, without trying to sell me a thing. Thanks, Claude! If I ever have enough extra Real Money to get a Real Outfit built, I'll be calling you again. ;P