GS500E stripped / damaged crank threads -----I FIXED IT :)

[fireyphoenix1989]

Hi all
Bit complicated so a quick explanation whats cause this issue
My GS500E locked up and it turned out to be the generator rotor ha disintegrated. I bought a very cheap broken bike to use as a donor.

Following the Haynes manual instructions i made a 36 mm spacer out of a bolt, put this inside the crank and wound my crank puller in ...rotor popped off with no issues at all.


Did the same with my bike .....
And the fecking bolt bent and jammed itself in the crank....
Three days a lot of swearing and enough use of needle nose pliers that i never want to see another pair in my life and i got it out ...






Made another spaced from a cut up allan key as its hardened steel and fitted that in the crank shaft ...





Popped the extractor on and after a day of tightening, heat and turning the air blue i have managed to get it off .



Now we get to my new problem .....

The bolt knackered up the internal threads when it got twisted up :/.
This is the best pic i could take .. the first 5/10 mm of thread is knackered cant even get the bolt started ...


Ideas on how i can repair this... ?




Gutted only done 51 miles on this bike FFS

[Courtice_GS500]

Not sure what the thread size is but it's the first 5-10mm of the thread you can find a tap and chase the threads out. That will reshape the start of the threads for you and the bolt will go in. As long as you have enough good threads left you should be good to go. For steel you need 1.5 times the diameter of thread and aluminum you need 2-2.5 times the diameter of the thread.

The trickiest part will be getting the tap to start straight so that you don't cross thread the remaining threads.

Not sure if you know any machinists or millwrights who could give you a hand.

Just a note: buy a good quality tap like Sowa or Clarkson Osborn, don't buy some piece of crap Chinese tap, it will give you nothing but grief.

[Janx101]

Just a note: buy a good quality tap like Sowa or Clarkson Osborn, don't buy some piece of crap Chinese tap, it will give you nothing but grief.

+ like a bazillion!!!

.. edit... just in case .. by the look of that last photo ... tweezer or otherwise remove as much loose detritus (those metal shavings?) and bits out of the hole before tapping again... lube the tap appropriately! ... probably superfluous info seeing as your gear puller thingy looks like good gear and you otherwise have enough good skills to get this far!! ..

i wouldnt have probably attempted the fix myself... not enough of the right tools... but my grandad was a fierce teacher on the tap and die thing! .. he would come back and haunt me if i muffed one up now or omitted any info i could offer!! .. 

[The Buddha]

You also need something called a bottoming tap ... you dont quite need a starter tap.
Cool.
Buddha.

[Blueknyt]

When it comes to cranks i tend to let a machine shop chase threads for me, they more then likely have the tools needed as well as plenty of experience doing just that.   i dont think i have ever paid more then 20$ for their work and often they knock it out in 10 mins or less.  very few shops will turn down some fast beer money.

[fireyphoenix1989]

unfortunately i live in Blackpool UK which is a tourism town ....very little in the way machine shops here meaning i have had to become a proficient mechanic to make running bikes economical.

Is there any method i can use to get the threads to match up ?
Or would it be simpler to drill out the first 5/10 mm and retap the known good threads ?

[piresito]

Your generator desintegrated?! Check for "Goats Syndrome".
There might be magnet pieces chewed all over the engine. If that's the case, you might want to change the whole enigne, and forget about that thread.

[Courtice_GS500]

No need to drill the threads out. Just find the right tap and chase the threads out.
It's not overly difficult you just have to take your time and use lots of tapping fluid.
You should be able to measure the old bolt to get the diameter then use a pitch gauge or another bolt to get the thread pitch.

Use that info to get a good tap and you are on your way.

[fireyphoenix1989]

This was my thread where goats was believed to be the cause .

http://gstwins.com/gsboard/index.php?topic=65005.msg776432#msg776432

Created this separate thread for neatness as its two separate issues

[piresito]

Oh...my bad! Sorry!
Nice you did that, much better for furture searches! 

[sledge]

I agree with previous comments in that the only realistic option is to try and clean the threads up with a tap and hope they hold out.

There are dozens of machine shops in NW England who can do this but if you want someone local try Encee Engineering, nothing to lose in giving them a call and ask if they can help you out. If the threads are too far gone it might be possible to build them up with Belzona 1111 or something similar prior to retapping.......if they cant help you out ask them if they know someone local who can.

Thread is an M14 fine, either x1 or x1.25......cant remember which 

http://www.qimtek.co.uk/profile/encee_engineering_ltd-48SLX21147.html

http://www.belzona.com/en/products/1000/1111.aspx

[fireyphoenix1989]

Its defo an M12 x 1.25 not an M14  the rotor is a 14mm thread tho pal.
Local engineers all wanted the crank stripped out before they would look at it 


Well after searching net for hours i managed to find a local place that could supply a M12 X 1.25 Fine pitch thread cutter.
I also bought a can of cutting fluid as any little helps right ?


Anyway starting with a taper type tap i cut the first ten mm as i have read its easier to get the cut straight with a taper.
I got about 10 mm in then switched to a plug tap as it cut cleaner.



20 nerve wracking mins later the tap was able to spin freely all the way in and out.

Then i oiled the bolt and ran it in and out fully a few times to make sure the threads were good


I cleaned all the parts with some fuel and clean paper towels the used some 150 grit wet and dry to rough up the surface of the crank slightly as it had some residue on it.
Threadlocked the bolt and put some on the threads inside the crank.
Then installed the good parts off my donor bike and tightened the bolt to 92 ft /ibs   



Just letting the thread lock set before i  fit the new left side cover and stator, then oil and battery.
Should be up and running in a few hours .

[Courtice_GS500]

 

Great news and I'm glad to hear that you did it yourself.
Nothing better than fixing it yourself then taking her for a spin afterwards.

[adidasguy]

[rharding91]

Your a man after my heart! Always love to see people who are able to DIY and overcome challenges. Congrats and cool thread. Just a word to anyone else doing this work. I had the same situation having to change the generator rotor and I found that autozone sells a bolt with the proper thread pattern but its actually a lug bolt for a ford truck like on the tires. It worked perfect and cost only a few dollars. Used that and a strap wrench. Also make sure you beat that sucker on, I had to go reset mine because I was too gentle the first go round.

[fireyphoenix1989]

Did 100 miles on it tonight lol first proper bit of riding since i bought it .
Really weird after riding my GSX750F for over 2 years haha.

[fireyphoenix1989]

Just wanted to update this, the bike is with its new owner and has done 5000 trouble free miles since the repairs were done.

I would have been stuck with a broken bike if not for this forum so thank you .

I now have an RF600 i am doing up as my winter project.