My understanding is that the '40s frames are welded and 'rosette' welded. I doubt 'unsweating' would work. Are you using a repro neck from V-Twin?

I would suggest cutting the down tubes and backbone close to the forging followed by adding correct lengths of tubing and 'slugging' the tubes to connect to original frame tubes.

There's a tech article floating around on this or other boards re: 'slugging' techniques.

Hope this helps and good luck.

MC

 

No replacing with original neck,,thanx I'll look for that post

 

The early frames are furnace brazed, it's only the late '46-'47 frames that are electric welded, in preperation for the all electric welded '48 wishbones. But, even in the last of the knuckle frames, the neck, seat crossover tube, and the axle plates are furnace brazed on. I guess they had to ween Oly off of the brazing slowly so he wouldn't get pissed off.

Trying to sweat the neck off is tough, because it's like trying to pull the top of a Dixie cup over it's bottom. Those tubes have serrations on them to give the braze more surface area, and they go into the neck forging about 2" to boot.

If you need it for a resto, take it to somebody who can un-sweat the neck while it's jigged down and coax the tubing out, and re-braze it afterwards. That ain't cheap.

Otherwise, if it's for a stock appearance, just do the cut/splice/slug deal. But remember, any place that the brass drooled, or any unions like the lower tank support/engine mount area needs to be kept from the welding heat, because even if you're not actually welding over the brass, it can still get brittle from the welding heat, and crack in that area later on.

 

Very cool thanx,, Rich

 

I'm not sure about HD, but Indians were pinned to hold things together during the brazing process. It takes an ungodly amount of heat and time to get these things apart. The neck, with tubes coming in from two directions at once, are extra fun.

BobW