End of what little wit I had left!

For some time now I've been working on my engine tear down to clean and prep for paint. Everything has gone very smoothy and my parts are all labelled and sitting in little baggies all over my house (standard operating procedure).

UNTIL...

...a while back I had a bit of trouble removing screws that were fastening brackets surrounding the gear shift drum. One was quite easy, the others have caused me lots of stress. I was mortified to discover that Yamaha made their panhead screws not out of steel but rather a hybrid of squishy metal and cookie dough! 4/5 screws stripped.

Fast forward to me and a bolt extractor kit: 2 out of the 4 stripped screws are now extracted (screws ruined). This leaves me with 2 more to go. One of them extracts halfway before the thread unravels (it was crazy) and the head broke off. The other broke 2 extractor bits, one inside the drilled out screw and one in the head. Even my uncles industrial drill press couldn't help me, and now I have a completely pooched screw that holds a bracket.

I've tried everything I can think of and held off asking for as long as possible, but I have finally run out of ideas. What can I do? Will the brackets be fine -1 screw? Should I JB weld the tap solid and retap it?

tldr; I have an extremely messed up tap in my engine block, what should I do to fix it/do i need it?

Edit: Stripped thread is part number 19 on the OEM parts catalogue for the shift drum. I'll post up some photos after work

did you use an impact driver?

its the only way to get them bastards out (yes I'm swearing as they are very hard to get out)

The only option is to drill and use helicoil or use the other make (can't remember it ATM) its very easy to do and hard to do wrong unless you ignore the instructions

don't forget to use thread lock when assembling

drewpy said:

did you use an impact driver?

its the only way to get them bastards out (yes I'm swearing as they are very hard to get out)

Click to expand...

I did use an impact when I was initially trying to get the bolt out. I used WD40 and every other bolt loosening project I had, but I just couldn't get enough bite to rotate the whole shaft of the bolt out. Last night I tried a longer, thinner extractor and drilled out a nice deep pilot for it, but the darn thing snapped inside! I then tried to use my uncles drill press to drill it out so I could re-tap or helicoil, but instead the bit wandered and compromised the aluminum. I'll show you the horror...



The green circle-ish blob is where the initial drill happened, and the red ovalish blob is where the drillpress bit drifted to.

This is what I was using:

very easy to do and hard to do wrong unless you ignore the instructions

Click to expand...

Wasn't even following instructions so there we go!

I'm thinking of just taking this in to be drilled out by a machinist when I go to get my jugs re-did. Any thoughts on this predicament? Is the drum going to suffer if the guide (part 18: Shift Drum Catalogue) isn't fastened securely/at all?

just fill weld the area and redrill and tap. that would be the best option

the drum will move and cause bad shifting or one at all if not dealt with

drewpy said:

did you use an impact driver?

its the only way to get them bastards out (yes I'm swearing as they are very hard to get out)

The only option is to drill and use helicoil or use the other make (can't remember it ATM) its very easy to do and hard to do wrong unless you ignore the instructions

don't forget to use thread lock when assembling

Click to expand...

Good to know! Man, I owe you a couple of pints for all of the help you've chucked on my build.

Liam, I actually had the same problem. I went at it with a small small drill bit like 5/64ths. I used some drilling oil and went really slowly and really carefully with a hand drill. I think it took me at least a hour and a half. I took a break as I was feeling frustrated. I think I took five breaks.

I then had to actually chisel some of the extractor out. I also did this very slowly.

Once I was able to drill out the extractor I then carefully used the drillpress to drill out the hole.

Once it was cleared I then re-tapped it at the closest yet a fraction larger than what it was to make sure the threads were good. I then took the case into the local hardware and found a new SS screw that would fit. It was slightly loose but with some thread-lock it should hold like new.

Hope that helps!

Lone Vagabond said:

I then had to actually chisel some of the extractor out. I also did this very slowly.

Click to expand...

This is what i'm going to try before I follow Drew's advice. I think I should be able to loosen off the extractor bit and pull it out, then I can go forward from there. Thanks for the tip mate!

good luck, its all character building stuff

i ran into the same problem luckily i had an industrial drill press and new screws to use. did you drill into the screw a bit to give the easy-out something to bite onto?

Yeah you have to drill a pilot to get the extractor into the screw. Mine snapped in half and got lodged into the shaft of the screw. Is that what you mean by easy-out?

I went to a machinist (they aren't very good at attracting my business... slow to communicate, and telling me to find dimensions for boring my cylinders...) and they were planning to drill out the post and insert a heli so I am going to try to do that part at home before I spend $85/hr at a shop

http://cdn.houserepairtalk.com/attachments/f33/2979d1313072552-need-extractor-tool-help-ez-out.jpg

as long as its this, then yes. you should be able to drill through it all and try again as long as you have quality bits

or if worst comes to worst, my case was 50 bucks shipped from ebay. cheaper than 85/hr. i happen to have a 360 engine im stripping down right now and if i recall, they are interchangeable. if it comes down to it, ill sell ya that. shipping to BC might not be worth it tho. just something to think about