Author Topic: Cracked Case (see pic) - recommendations.. (Read 6492 times)

mrhoades · « **on:** April 20, 2009, 10:29:58 AM »

Well I got the cases apart on my 74 CB750 rebuild only to find that the upper case is cracked , right behind the drive sprocket... probably from a chain failure or somethin gettin kicked up/wedged real good in that little nook of the case. Appears the PO used a bit of JB Weld as a fix .... but I would like to investigate a more permanent & reliable fix... Last nite I dreamt I was on a nice 100 mile ride, when all of sudden the fix failed...spewing hot oil up my wifes leg.

http://i681.photobucket.com/albums/vv176/rhoades999/cc1.jpg
http://i681.photobucket.com/albums/vv176/rhoades999/cc2.jpg
http://i681.photobucket.com/albums/vv176/rhoades999/cc3.jpg
http://i681.photobucket.com/albums/vv176/rhoades999/cc1.jpg

You can see from the pics the crack is almost rectangle in shape..where one side and bottom is a hairline fracture and the side opposite is where JB was used...since this side was pushed in a bit and the crack gap is about 3 MM's wide.

Anyone have experince welding a fix like this

Anyone know a good welder who has experience with welding 35 yr old M/C cases ??
Any input on some of the brazing fixes I have come across like Lumiweld or DuraFix???

Any and all input much appreciated... THANKS .. MIKE

kghost · « **Reply #1 on:** April 20, 2009, 10:48:48 AM »

Think I'd TIG weld that crack up.

Chamfer down into the crack...grinding a V then weld it back up.

MRieck · « **Reply #2 on:** April 20, 2009, 11:42:33 AM »

Quote from: kghost on April 20, 2009, 10:48:48 AM

Think I'd TIG weld that crack up.

Chamfer down into the crack...grinding a V then weld it back up.

I agree

cleveland · « **Reply #3 on:** April 20, 2009, 11:48:31 AM »

You could likely pick up a replacement case pretty cheap.

hopefuldave · « **Reply #4 on:** May 05, 2009, 07:33:30 AM »

Trouble with a replacement case is that they're line-bored in pairs for the bearings, could find the crank nipping up or worse...

A (matched) pair of cases would work, but that means a new engine number (as does a new upper case), some places that means changing paperwork and some owners clubs count that as a black mark against "originality"

TIG welder time!

Dave H.
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" - Douglas Bader

nokrome · « **Reply #5 on:** May 05, 2009, 01:00:47 PM »

looks like a nice clean crack....very weldable

nice clean crack

Scrubs · « **Reply #6 on:** May 05, 2009, 01:18:33 PM »

the low temp solder rods are good but work best on flat surfaces and that case is pretty thick for the money it would cost you
to invest in the rods I would get a tig welder just to run a bead down it. Peace of mind.

RRRToolSolutions · « **Reply #7 on:** May 05, 2009, 01:40:05 PM »

Now here is what might have been a crack, but then completely broken away.

Without question, a good welder can turn that case to like new. Here is a 1974 GT750 case that suffeed a chain break some time in it's previous life...

mystic_1 · « **Reply #8 on:** May 05, 2009, 02:15:19 PM »

So, anyone have a good resource for TIG weldors in the Chicago area who are able AND willing to do this kind of work? I have a couple of sets of cases that might be salvagable in the right hands, but don't want o pay a fortune for someone why may turn out to be a hack.

mystic_1

B.O.X.N.I.F.E. · « **Reply #9 on:** May 05, 2009, 02:19:41 PM »

You could always put an ad up on craigslist, lots of guys who could do this work cheaper on the side from home.

mystic_1 · « **Reply #10 on:** May 05, 2009, 02:20:55 PM »

True, but I'd prefer to find a weldor who has worked on small air-cooled engine blocks before, rather than someone who's certified to build bridges, if you know what I mean

Plus a recommendation from a site member carries quite a bit of weight I think.

mystic_1

B.O.X.N.I.F.E. · « **Reply #11 on:** May 05, 2009, 03:31:18 PM »

You could always check with the VW guys

Kevin D · « **Reply #12 on:** May 05, 2009, 04:39:40 PM »

Don't forget to get a new drive sprocket:

http://i681.photobucket.com/albums/vv176/rhoades999/cc2.jpg

XN · « **Reply #13 on:** May 05, 2009, 11:04:57 PM »

Go to your local airport and ask a mechanic where to find a certified welder. Company's that are certified to do aircraft welding know their stuff. You may pay a little extra, but you know it will be done right

johnny_from_bel · « **Reply #14 on:** May 06, 2009, 01:20:13 AM »

Quote from: mrhoades on April 20, 2009, 10:29:58 AM

Any input on some of the brazing fixes I have come across like Lumiweld or DuraFix???

Any and all input much appreciated... THANKS .. MIKE

I use lumiweld. Its easy and strong if you take your time and do it properly.

jtb · « **Reply #15 on:** May 06, 2009, 05:57:58 AM »

Quote from: mystic_1 on May 05, 2009, 02:15:19 PM

So, anyone have a good resource for TIG weldors in the Chicago area who are able AND willing to do this kind of work? I have a couple of sets of cases that might be salvagable in the right hands, but don't want o pay a fortune for someone why may turn out to be a hack.

mystic_1

If you don't mind shipping them to GA, Big Jay on this forum can handle it. He welded a tab back on a carb for me, reasonable, and good work.

MCRider · « **Reply #16 on:** May 06, 2009, 06:12:45 AM »

Quote from: jtb on May 06, 2009, 05:57:58 AM

Quote from: mystic_1 on May 05, 2009, 02:15:19 PM
So, anyone have a good resource for TIG weldors in the Chicago area who are able AND willing to do this kind of work? I have a couple of sets of cases that might be salvagable in the right hands, but don't want o pay a fortune for someone why may turn out to be a hack.

mystic_1
If you don't mind shipping them to GA, Big Jay on this forum can handle it. He welded a tab back on a carb for me, reasonable, and good work.

Did you mean CA rather than GA?

MCRider · « **Reply #17 on:** May 06, 2009, 06:20:15 AM »

To OP MRHOADES and any interested party:
I have a set of cases that have been stripped, blasted with plastic media and the studs are removed. (More work than expected, one broke and I'll have to remove the stub yet.) I'm hoping for $100. High I know, but they are ready for paint and HD studs. I have to finance my budget overruns by selling excess parts.

To MYSTIC et al: Also, I have one set that has a crack in the motor mount. It was in an accident. I'll be taking it to Saldana Racing Products in Brownsburg IN to be welded up and line drilled. The machinist spends his days TIG welding aluminum radiators and oil tanks for sprint cars, stock cars etc. He is very good. I'll explain the problems of cracked cases from chain failure to confirm he is comfortable doing that work, and report back, if anyone can use them.

Sometimes shipping from Chi to Indy (B Burg) not much more than time and effort to drive across town.

mystic_1 · « **Reply #18 on:** May 06, 2009, 09:32:37 AM »

Excellent Ron, sure appreciate that. I have one motor with chain damage, another with a pinhole leak in the oil feed from the main gallery to the right-most crankshaft bearing, it leaks into the points cover area. Probably have several other parts that could be salvaged if I knew a good weldor, I just hate to throw any of these things sway, ya know?

Do let us know what you find out.

mystic_1

mystic_1 · « **Reply #19 on:** May 06, 2009, 10:50:45 AM »

Quote from: jtb on May 06, 2009, 05:57:58 AM

If you don't mind shipping them to GA, Big Jay on this forum can handle it. He welded a tab back on a carb for me, reasonable, and good work.

Thanks for the referral, will definitely keep it on file, but I figure that for something like a crankcase, shipping charges both ways would probably be prohibitive.

mystic_1

jtb · « **Reply #20 on:** May 06, 2009, 04:29:20 PM »

Quote from: jtb on May 06, 2009, 05:57:58 AM

Quote from: mystic_1 on May 05, 2009, 02:15:19 PM
So, anyone have a good resource for TIG weldors in the Chicago area who are able AND willing to do this kind of work? I have a couple of sets of cases that might be salvagable in the right hands, but don't want o pay a fortune for someone why may turn out to be a hack.

mystic_1
If you don't mind shipping them to GA, Big Jay on this forum can handle it. He welded a tab back on a carb for me, reasonable, and good work.

Sorry, Big Jim.

mystic_1 · « **Reply #21 on:** May 06, 2009, 04:43:46 PM »

Heh, so Big Jim in CA, not Big Jay in GA.

Got it!

I think

mystic_1

Jim F · « **Reply #22 on:** May 06, 2009, 05:00:40 PM »

No there talking about me

I am BIG-JIM in Georgia

If you would like to send your case to me I will see what I can do

Here is my web site

Ive done some work for some of the guys on the forum and its all turned out nice

www.jmfmicroweld.com

RRRToolSolutions · « **Reply #23 on:** May 06, 2009, 06:56:58 PM »

Yes, I will give Jim a big thumbs-up. He did me proud on a special bracket for a remote idle adjuster. Awesome beads, the man knows his stuff.

Best Regards,
Gordon

jtb · « **Reply #24 on:** May 07, 2009, 05:49:14 AM »

Quote from: Ilbikes on May 06, 2009, 06:56:58 PM

Yes, I will give Jim a big thumbs-up. He did me proud on a special bracket for a remote idle adjuster. Awesome beads, the man knows his stuff.

Best Regards,
Gordon

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Author Topic: Cracked Case (see pic) - recommendations.. (Read 6492 times)

hopefuldave