Disaster! Tap snapped - exhaust stud. - SV650.org

DaveW_42 · 26-04-11, 09:41 AM

Hey everyone,

Snapped both bolts off on the front downpipe where they go into the casing. Drilled and tapped one side perfectly fine, drilled the other and got to within about 4mm of finishing the tap, when the damn thing snapped on me!
No matter what I do, I can't get it to twist at all with needlenose pliers, there's nothing left outside the hole to grip with molegrips and I spent ages trying to drill it out to no avail. Eventually decided to stop before I made it any worse...
Any suggestions?

D

dizzyblonde · 26-04-11, 09:45 AM

weld a nut to it? or is there not enough left?

DaveW_42 · 26-04-11, 09:45 AM

nothing left - it's flush to the casing. Everything crumbled when I got the grips on it

26-04-11, 10:05 AM

Hi,
I have drilled taps out with a cobolt drill bit with plenty of suds but i normally mount in my milling machine as i can control the pressure and speed alot better than a hand drill.

Gaz

26-04-11, 10:21 AM

I have done this twice on older bikes - And yes you are correct it is a disaster.

Both times I have enlisted professional help in the form of a proper local engineering firm.

DaveW_42 · 26-04-11, 10:22 AM

Hmmmmm... Everyone is saying the same thing too. Looks like I might just get a replacement head, drop the engine out and swap over...
Lucky there's another 4 day weekend coming up!

DaveW_42 · 26-04-11, 10:30 AM

.

timwilky · 26-04-11, 10:55 AM

spark erosion. You need to find a man that can.

DaveW_42 · 26-04-11, 11:00 AM

Cheers Tim. Looked at that too. Would prob have to drop engine out anyway, then (the place I found) it costs anything up to £100. If I'm paying that out anyway and dropping the engine, I may aswell try and find a replacement head for less and just swap it over myself.

One of those times, you get a nice weekend and start your job list, then by the end of it, have a completely new jobs list to tackle too.

30-04-11, 03:17 PM

just checked mine out and the thread is 25mm deep ,as the hole is in a raised area of casting you could easily afford to cut the alloy back by 5mm exposing the tap sufficient to get some grips on it ,if your tap extractor doesn't work.
You would still have a good 15mm of thread allowing for the fact that the last couple of mm of any blind hole can't be tapped.

26-04-11, 09:41 AM	#1
DaveW_42 Member Join Date: May 2006 Location: Biggleswade, Beds Posts: 301	Disaster! Tap snapped - exhaust stud. Hey everyone, Snapped both bolts off on the front downpipe where they go into the casing. Drilled and tapped one side perfectly fine, drilled the other and got to within about 4mm of finishing the tap, when the damn thing snapped on me! No matter what I do, I can't get it to twist at all with needlenose pliers, there's nothing left outside the hole to grip with molegrips and I spent ages trying to drill it out to no avail. Eventually decided to stop before I made it any worse... Any suggestions? D __________________ K4 trackbike, a black K8 S loaded with my spares and a 1989 CBR 400 TriArm with all the trimmings.

26-04-11, 09:45 AM	#2
dizzyblonde Da Cake Boss Mega Poster Join Date: May 2007 Location: On a flying Horse Posts: 9,992	Re: Disaster! Tap snapped weld a nut to it? or is there not enough left? __________________ Suzy, yellow 2001 SVS. Kitty, V-Raptor 1000, ZZR1400<<its my bike now Pegasus! Hovis 13.8.75-3.10.09 Reeder 20.7.88-21.3.12

26-04-11, 09:45 AM	#3
DaveW_42 Member Join Date: May 2006 Location: Biggleswade, Beds Posts: 301	Re: Disaster! Tap snapped nothing left - it's flush to the casing. Everything crumbled when I got the grips on it __________________ K4 trackbike, a black K8 S loaded with my spares and a 1989 CBR 400 TriArm with all the trimmings.

26-04-11, 10:05 AM	#4
Gazzaleachie Guest Posts: n/a	Re: Disaster! Tap snapped Hi, I have drilled taps out with a cobolt drill bit with plenty of suds but i normally mount in my milling machine as i can control the pressure and speed alot better than a hand drill. Gaz Last edited by Gazzaleachie; 26-04-11 at 10:07 AM.

26-04-11, 10:21 AM	#5
danf1234 Guest Posts: n/a	Re: Disaster! Tap snapped I have done this twice on older bikes - And yes you are correct it is a disaster. Both times I have enlisted professional help in the form of a proper local engineering firm.

26-04-11, 10:22 AM	#6
DaveW_42 Member Join Date: May 2006 Location: Biggleswade, Beds Posts: 301	Re: Disaster! Tap snapped Hmmmmm... Everyone is saying the same thing too. Looks like I might just get a replacement head, drop the engine out and swap over... Lucky there's another 4 day weekend coming up! __________________ K4 trackbike, a black K8 S loaded with my spares and a 1989 CBR 400 TriArm with all the trimmings.

26-04-11, 10:30 AM	#7
DaveW_42 Member Join Date: May 2006 Location: Biggleswade, Beds Posts: 301	Re: Disaster! Tap snapped . __________________ K4 trackbike, a black K8 S loaded with my spares and a 1989 CBR 400 TriArm with all the trimmings. Last edited by DaveW_42; 26-04-11 at 10:35 AM. Reason: d'oh found own answer!

26-04-11, 10:55 AM	#8
timwilky Member Mega Poster Join Date: Mar 2004 Location: Not in Yorkshire. (Thank God) Posts: 4,116	Re: Disaster! Tap snapped - exhaust stud. spark erosion. You need to find a man that can. __________________ Not Grumpy, opinionated.

26-04-11, 11:00 AM	#9
DaveW_42 Member Join Date: May 2006 Location: Biggleswade, Beds Posts: 301	Re: Disaster! Tap snapped - exhaust stud. Cheers Tim. Looked at that too. Would prob have to drop engine out anyway, then (the place I found) it costs anything up to £100. If I'm paying that out anyway and dropping the engine, I may aswell try and find a replacement head for less and just swap it over myself. One of those times, you get a nice weekend and start your job list, then by the end of it, have a completely new jobs list to tackle too. __________________ K4 trackbike, a black K8 S loaded with my spares and a 1989 CBR 400 TriArm with all the trimmings.

30-04-11, 03:17 PM	#10
all the gear Guest Posts: n/a	Re: Disaster! Tap snapped - exhaust stud. just checked mine out and the thread is 25mm deep ,as the hole is in a raised area of casting you could easily afford to cut the alloy back by 5mm exposing the tap sufficient to get some grips on it ,if your tap extractor doesn't work. You would still have a good 15mm of thread allowing for the fact that the last couple of mm of any blind hole can't be tapped.

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