Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board OIF cracked frame fix

my pal calvin's 72 A65T frame leaks like a sieve.....it has for a long time he patched crack with JB but that's kaput...here are a couple of questions....how much of bike needs to be taken apart to fix? crack seems to be on timing side at top engine mount bracket....can it be brazed? if has to be welded how much electrical stuff needs to be unhooked if any?
thanks in advance for any help in this oily situation

. Any electronic ignition components especially the control box. The regulator regulator.
Brazing requires that the surfaces to be welded absolutely from from any paint or oil!!!!![/quote]

We ran a short story in Vintage Bike that came from one of the road testors that tested bikes when the factory was having frame problems with the oil in frame models. He claimed that he could break a frame in the swing arm area at will. They did get it better, but as you see the cure was not perfect

The best repair I have seen is the one that Keith Martin (Big D Cycles, Dallas TX) did to all of his oil in frame race bikes. You should ask him if he brazed or welded the added triangulated support tubing.
John

Once you have put any goo on the surface you severly reduce the cance of any real metal fix taking
You usually get a etter repair with oxy ecause the oxy can burn off all of the trash which floats to the top of the weld puddle
Down side is the relatively large HAZ will cause a change in the physical strength of the welded region and can cause the site to warp or bend during the repair or latter on in use .
Even with a good weld you have to remember that it is in effect a casting between two pieces of wrought metal thus will have a substantially lower tensile strength so will need to be thicker by at least a factor of 2 plus it will be less flexiable than the surrounding tube

the hard part is cleaning the oil out of the cracks

sometimes it is better to weld or braze a plate over the crack. that moves the repair away from the original damage. it is best to fit the contours pretty close to be effective. that repair might even work with epoxy. or... 3M 5400 poly glue. its made to glue sailboats together... amazing stuff.

remove the elix if you like. I have welded many vehicles without removing anything. just keep the ground lead on bare metal close to the work. leave the battery in too

My 71 had a crack in the exact same place, it was fixed by removing the rear engine plates, draining the oil, Veeing out the crack and welding, . I firmly beleive this crack is created by un lubed swing arm bearings, at least mine had suffered this, I had to replace the bushes, bobbins and spindle and fit grease nipples which were missing. Do not braze, and remember glue doesnt work, welding does work.

Hi there,

on my 71 Firebird I doubt the frame was oiltight right from the start/the assembly line. I had bought the good looking bike and it was always leaky.

When looking at the issue I am inclined to think the bracket was not welded properly and the weld seam was never fully fused. A kind of cosmetic weld seam.







Welding did the trick.

Cheers!

Phil

I would kind of like to see some pics of the bit the OP is talking about ... otherwise what do we have to go on ?

DEPENDING on where it is it is going to be either more or less difficult. as others have said oil residue must be removed ... prefreably with a grinder .

but how are you going to remove the oil inside the tube ?

a MIG welder would be the best

but as i said all speculation without seeing the problem area

I am confused ! ( not unusual ) but are the pics Phil posted the same frame that raf90 seeks advice on ?

My '72 Bonnie had the same issue, a leak from just above the swingarm mount.
I trailered the bike over to my favorite welder. I took the bike off the trailer and removed the rear wheel on the sidewalk in front of his shop. He was able to weld it well enough to stop the leak.
However, five years later I'm beginning to see a bit of oil on the back of the frame, might be time to fix again.
I'm afraid that the only permanent repair is to take the bare frame to a radiator shop for cleaning so the weld can penetrate properly.

I suppose, yes. The bike is a Firebird Scrambler oif, the frame-# indicates a manufacturing date in July 1971 so raf940's pal Calvin 72 frame very likely will look the same. When re-reading raf940's post, he is talking about the oil seeping around the bracket area, so Calvin's situation could be similar.

Given, I am not sure whether or not the bracket with the incomplete weld fusion has been a standard feature or something that has been introduced into manufacturing after some time.

Coming back to raf's original questions:

The battery was taken out, Podtronics unit was disconnected, the engine could stay in, of course the r/h engine plate and the swing arm went out for the welding, see attached pic.



All the best

Phil

phil's pic above is exactly the situation.....

ok.... like i said i recon a MIG welder is the tool for the job ... clean it up as best you can and weld it up ... diconnect all the things others have said to and

Robert is your mothers brother .

The migs the tool, but all traces of oil must be removed to get a clean strong weld. Also, oil can ignite.