Topic: Looking for Gordon frame mod equivalent 1975 CB750f

[scottly]

The weight difference is neglible, the strength is massive.

Just how much do those solid aluminum bars weigh?

[calj737]

thats a nice version of this , how do you fix the attach to the top tube bits ?

I abandoned the connection to the top tube but welded in a cross tie. The whole affair just slides in and out and is secured with a 10mm button head.

[calj737]

The weight difference is neglible, the strength is massive.

Just how much do those solid aluminum bars weigh?

Each leg weighs less than 1#. Heavier than thin steel tube, but you’d never ride the difference.

[willbird]

The weight difference is neglible, the strength is massive.

Just how much do those solid aluminum bars weigh?

Each leg weighs less than 1#. Heavier than thin steel tube, but you’d never ride the difference.

One can get super heavy wall aluminum tube intended for suspension rods too, has an ID close to the correct size and maybe the exact tap dril size for spherical rod ends. Friend used it on a Sprint Car. That would be a .578"  ID for 5/8 rod ends. of course then it cannot be milled on the ends like a solid bar. Tying the two bars together is interesting for sure, makes things simpler. Gives me something to ponder in my drive time LOL.

I had planned on milling up a solid jig out of 1" square solid steel to hold the parts getting welded into the frame in alignment...it would need an area for RH and LH side gusset fixturing to bolt on. Thinking out loud the whole bolt in portion could maybe be plasma cut out of plate as one piece with some thought. Not sure where plasma cut drops the microphone with aluminum as far as thickness goes. Just saw a guy cut some 3/16" on a youtube channel and it looked really nice as far as cut quality goes. Quick look says it takes 300 amps to plasma cut 1" aluminum :-).

[calj737]

If you used tube aluminum, you’d still need to mill and weld the lug into it so that you could connect to the steel frame. Hence, I went with solid bar and simply milled the lug end. Super simple. Chucked the rod into a collet block, milled it, spun it 180* in the vise and pushed “repeat”. Did the same collet block milling on the steel lugs after I turned a shoulder for fit into the stock tube.

Put the steel lugs into the stock frame, bolt the aluminum bar in place, align it as needed, tack the steel lugs. Weld it out, unbolt it, massage as needed. I doubt it took me a full 2 hours from raw frame to done.

I did add some shim stick between the round bar and steel lugs when welding in the cross tie to prevent it from pulling the bars too tightly and not allowing removal.

[willbird]

If you used tube aluminum, you’d still need to mill and weld the lug into it so that you could connect to the steel frame. Hence, I went with solid bar and simply milled the lug end. Super simple. Chucked the rod into a collet block, milled it, spun it 180* in the vise and pushed “repeat”. Did the same collet block milling on the steel lugs after I turned a shoulder for fit into the stock tube.

Put the steel lugs into the stock frame, bolt the aluminum bar in place, align it as needed, tack the steel lugs. Weld it out, unbolt it, massage as needed. I doubt it took me a full 2 hours from raw frame to done.

I did add some shim stick between the round bar and steel lugs when welding in the cross tie to prevent it from pulling the bars too tightly and not allowing removal.

Indeed, there are several ways to skin that cat :-).

Bill