919 Exhaust Support Bracket Break/Repair - Wrist Twisters
 
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post #1 of 2 Old 12-26-2016, 12:13 PM Thread Starter
Young Old Man
 
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919 Exhaust Support Bracket Break/Repair

Hey everyone,

Let me preface this with an apology if I've posted in the wrong place or there's already a topic; I couldn't find any with the search feature.

Today I was taking off my headers to polish them up real purdy like. Went to loosen the bolt that holds the rear of the headers to the frame and... SNAP Didn't put much torque on it at all, just with my 3/8" drive socket wrench. Anywho, it broke at the frame, not the exhaust, and the bolt hole is whole. Since I've seen this issue pop up on the site before, I wasn't too concerned and figured, as a welder recently certified in 2" SCH40 Pipe (6G) that I could handle the repair. It'll be a while before I can get the bike to where I have access to a machine, not to mention that it's winter and I currently have the headers off, so I figured I'd ask a few questions before I dive in.

The frame is steel, but what kind of steel? I'm guessing these high performance superbike torque monsters are rocking chromoly tubing. Or probably something simpler. Can any welders here suggest an appropriate filler metal?

Secondly, as I've never welded on an assembled vehicle, is there anything electrical I need to protect before sending some serious amperage through the frame? I saw someone advising to "unplug the black box."

Thanks for the advice! Keep the shiny side up.

Whelan

EDIT: I guess since I already have the headers off I should just swap in CBR headers and get some new cans, right? Anyone want to buy a kidney?

Ride naked.
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post #2 of 2 Old 12-27-2016, 12:57 PM
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Quote:
Originally Posted by Whelan View Post
Hey everyone,

Let me preface this with an apology if I've posted in the wrong place or there's already a topic; I couldn't find any with the search feature.

Today I was taking off my headers to polish them up real purdy like. Went to loosen the bolt that holds the rear of the headers to the frame and... SNAP Didn't put much torque on it at all, just with my 3/8" drive socket wrench. Anywho, it broke at the frame, not the exhaust, and the bolt hole is whole. Since I've seen this issue pop up on the site before, I wasn't too concerned and figured, as a welder recently certified in 2" SCH40 Pipe (6G) that I could handle the repair. It'll be a while before I can get the bike to where I have access to a machine, not to mention that it's winter and I currently have the headers off, so I figured I'd ask a few questions before I dive in.

The frame is steel, but what kind of steel? I'm guessing these high performance superbike torque monsters are rocking chromoly tubing. Or probably something simpler. Can any welders here suggest an appropriate filler metal?

Secondly, as I've never welded on an assembled vehicle, is there anything electrical I need to protect before sending some serious amperage through the frame? I saw someone advising to "unplug the black box."

Thanks for the advice! Keep the shiny side up.

Whelan

EDIT: I guess since I already have the headers off I should just swap in CBR headers and get some new cans, right? Anyone want to buy a kidney?
I think youíre travelling a new road here, certainly in some respects thatís the case.

Your frame tab busted off, as compared to the typical exhaust tab breaking off.
The metal failure will surely be rust at the weld and/or fatigue Ė more likely fatigue and my guess is that the fault line tracks the edge of the weld.
Regardless, all old weld will need to be removed from both pieces before attempting to repair.
My guess is that the fatigue is on the tab side not the frame side.
Iíd be fully descaling and depainting the broken tab, then heating it to the high end of red and into orange all through the section near the weld site, then letting it slowly air cool. Dress the weld point after cooling.

I donít think any of us know what the frame material is, but I am very certain it is nothing remotely like a chrome moly steel. Iíll bet itís nothing more exotic than plain vanilla carbon steel. I am very doubtful that itís alloyed at all.

I donít recollect hearing/reading any experience about doing such a repair with the electrics still in the bike. Theory suggests that directly grounding next to the weld zone will keep the current in that area only. IF you want to be the guinea pig on this, disconnecting the battery and totally isolating the ECU is requisite. Total isolation requires no grounding exist from fasteners or any kind of grounding connection, be it dedicated external wire or a wire within the harness. In other words, remove the ICU.
This area really needs Mr. Rob Tharlsonís input. He is the gospel on this kind of thing. Try to PM him.

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