Snapped Rotor Bolt

[Freddy]

Hi all before I take my 1979 gs1000e to the local bike shop I would like some advice. I was tightening my starter/ rotor back onto the crank after replacing the three little bolts and I do not have a torque wrench. I have done this many times over the years and often had to get back in there and retighten the big hub night due to it slipping ( yes I should get a torque wrench ).Yesterday while tightening I thought just one more bit of a turn just to make sure it was tight and you guessed it snap :blue:. Big ride next weekend with over 600 bikes. It is a fundraiser for our local Rescue Helicopter as I am a paramedic I like attending and assisting the odd rider who has a mishap. So into it early today, it is hardened steel ,broke and wore out a couple of drill bits and an easyout. Down to the shop a couple of carbide drill tips later, broken bolt out of crank. The problem is I'm not sure about the thread left in the crank it looks dodgy and I dont know if I have all the old thread out due to loctight being applied . I had a Look at tapping a new thread but is it best now to take it to someone else and have the hole oversized and new thread tapped in. It is a very hard material to drill and difficult to stop the crank from turning if putting a new thread in. Has anyone had this happen to them? I do have another Gs to ride in the meantime

 

[chuck hahn]

Center punch the bolt and drill it to accomodate something like a 3/16 LEFT HAND THREAD bolt. Yes the tap and bolt will probably have to be got at say Fastenal. Anyway, tap it with the left handed bolt and as the bolt tightens up ( youll be turning to the left ) it will lock to the stud and back it out.

I think thats like a 12 MM bolt so as large as 1/4 inch will work ( should ). If youve loctited it throw some good heat to the bolt to soften the thread locker and ease the extraction.

 

[chuck hahn]

To hold the crank still, take and old belt an cut it so it just wraps around the rotor. Take a big C clamp and clamp it to the rotor from the front..... So the 'C" is facing to the engine. Now get a rod of some sort and jam the C clamp against the floor so the rotor is now holding the crank solid...follow me??

Idea is to use the clamp in a way that you can jam it to lock the crank down via the rotor.

 

[Freddy]

Thanks that old belt tip sounds like a good one. I already have the old bolt drilled out, but i'm not sure if the thread I see in the hole is the old thread or just some of the old thread stuck in there with the loctite. I may not have drilled out enough or I may have drilled out to much. I have another bolt to go in and it wont go in as it feels to tight and meeting alot of resistance. Is it easier to slightly oversize the hole and tap a new thread just to be safe.
Thanks.

 

[chuck hahn]

You do have a little wiggle room but not a lot. Maybe get a tap and see if it chases the threads. That way you preserve the thickness and all youd need is another bolt.

 

[Nessism]

Do NOT drill that hole oversize. Get a tap and clean up the threads. I don't know the size but you can figure it out. It's not rocket science. Needless to say, get a new OEM screw. It's a special hardened screw with a built in washer as you know. You could get away with a high strength aftermarket screw but that should be last resort.

 

[GregT]

Do NOT drill that hole oversize. Get a tap and clean up the threads. I don't know the size but you can figure it out. It's not rocket science. Needless to say, get a new OEM screw. It's a special hardened screw with a built in washer as you know. You could get away with a high strength aftermarket screw but that should be last resort.

Correct - from memory it's 12 X 1.25. If all else fails - and you can't source a new screw - sing out and I'll look through my stuff here.

 

[GSX1000E]

Is he not talking about number 13 here?: http://www.partsoutlaw.com/oemparts/a/suz/50d4028bf8700230d8b4e7db/contact-breaker
8 X 60mm bolt?

 

[Freddy]

Hi GSX1100E That is the one for the points plate I am at the other end of the crank on the starter clutch. Yes I have another hardened bolt Nessisim but I will try to insert it using chucks belt idea. On another note the picture attached is from a local drag meet I went to today a really quick GS1000 1980.

 

[chuck hahn]

Thye belt keeps the rotor from getting torn up and the clamp gives something to hold the crank still so you can have both hands to work. Just have to find a way to jam it against the floor and not have the bow of the clamp right in line with the hole. And yes, I know it is a 12 MM but dont quote me on the pitch. 1.25 sounds right though.

 

[Freddy]

Right new thread tapped all went well. Put all back together bike started then stopped suddenly, clicked only at starter solenoid. Pulled starter motor felt siezed, put spare in same thing happened ( Opened up starter motor what a mess ). Removed stator cover and a wee bit of looking discovered the rear of the rotor with the starter clutch, The big toothed wheel/ sprocket was very tight. loosened off rotor bolt put all back together and wallah it roared into life. My only concern is that I torqued the bolt up to 70 ft lbs and the whole setup just spun and did not engage starter clutch, I tightened it up to 90 ft lbs and thats when I quickly wore out two starter motors. Now it all works well but I'm afaid it will just start spinning at a startup a long way from home. I did not not do anything but re thread a hole is there a way of making the bolt tighter. P.S it has loctite on bolt.

 

[chuck hahn]

If its loctited it wont come out. And the crank turns counter clockwise and to thighten the bolt you turned clockwise..its made that way so the rotation of the crank actually sucks the bolt into the crank to some extent.Your good to go.

 

[GSX1000E]

I recently went though something very similar with a 1000 engine that I have piled on a little more than 170,000 miles on over the decades. I never had a starter motor problem in all of those miles BUT,
after rebuilding the starter clutch with all new parts, I had the same experience with tightening that bolt and not getting the S/C to cooperate all of the time and that bolt did loosen up after a period of
time even with blue loktite on the threads. I somewhat cured it by applying red loktite to the tapered end that sits inside the rotor and putting blue loktite on that bolt. My crank end taper did not show
any signs of wear yet over the years the two tapered parts must have been wearing enough to not allow that bolt to get tight enough without loosening or too tight and put too much force on the torrington
bearing making it hard for the starter to turn it. So, after that long boring stoey, I would recommend putting loktite on the tapered end also if/when that bolt comes loose again.

 

[chuck hahn]

Blue is semi permanent..use red. If the bolt needs to come out heat it so the loctite gets gummy and then it will release and not until. And , no, the engine heat wont make it weak either.