[Sam Simons]

Hi All,

I'm doing a clone of Hitchcock's 350/500 Scrambler, with the only change being
the use of a 18" rear rim. Tire are Conti TCK's,the rear a 140. Although the use
of the narrow 18" rim will reduce the inflated width of the tire,it's still too wide
to fit inside the swingarm  close to the pivot point.
So,my choices are- modify the OEM S/arm,find an aftermarket unit for the RE
chassis(dream on...) or adapt another S/arm from another bike.
To modify the OEM S/arm will require removal of atleast half of the tube diameter,
before re-capping the open area in flat plate(leaving a "D" cross section). This
is relatively easy to do(done it several times on other specials),but, IF there's
actually another S/arm that will solve this issue,I'd sure like to hear about it.....

Thanks,

Sam in IN

[ace.cafe]

Not sure about what other swing arm might fit, but there's really no room to go wider and still fit in the frame.

What I've heard is popular with the dirt Bullet riders is to lengthen the swing arm by 1 inch or 1.5 inches, which helps it "dig" a little better.
Since the swing arm widens a bit as it goes rearward, it may give you some extra width that way, so you might have to do a little less cutting into the diameter of the swing arm tube. It moves the whole wheel back by the amount of the extension length you pick.

The typical lengthening method is to just cut the round tube section and weld in some 1" or 1.5" extension pieces to suit the desired need.  Put it in a jig to make sure you have alignment, and give it a go.

If you plan to use the same shocks, you'll need to relocate the shock studs on the swing arm too. Or use a longer set of shocks if you don't want to move the studs. New longer chain required too, and a lengthening of the rear brake actuating rod. Also watch the fender clearance, because at some length, you'll be hitting the fender at some point in the suspension travel.

At least, that's one suggestion that might be considered.
I've heard that was the "hot set-up" back in the day.

[Sam Simons]

If the S/arm were'nt of the  angular wishbone design,in other words if it were
of a parallel tube style,the area where clearance is needed would be much larger.
Severing the arms from their original location,repositioning them out(closer to
the pivot ends) and negating the angle of the plates back to parallel
looks to be one fairly easy solution,and the most beneficial from the standpoint
of not removing any tubular material for the sake of gaining clearance. Doing
the "D" section is always a last resort to me;it's quicker to do,but results in
a weaker S/arm regarding strength......This is a 'street scrambler',so it won't
be ridden off road any.....