A Thread thread ! (Help needed)

Im still struggling with a stripped thread in a mangled hole in a very difficult spot.Can anyone give me a depth for the hole as I really dont want to drill through the casing.
Top left;

Also,does anyone have a smart idea for getting a drill 'straight' onto the hole,I would appreciate it
Thanks
(J Model engine and damage to casing probably came from the sprocket bolt coming loose)

No eBay APP ID and/or Cert ID defined in Kunena configurationIs it a stripped thread or shorne bolt? If it's stripped, you can Heli Coil it. I can't tell which. In the 80's I broke the one on the left hand side bottom. It was so hard to get to, I just ran without it. Two broken covers later, I tackled it. You need a goo long sharp pointed punch to get the hole centered in the bolt. Use a small drill bit just to start the hole in the bolt. Use oil on all bits. Once it's centered, drill squarely little by little checking your work as you go along. I've always wanted reverce drill bits but have had to do with what was readally available. In that location I'd pull the starter to make room. I used a 1/4" drive socket on a long extention to use the tap for the coil. Don't try to use a drill. Turn it in a little, then back out pulling the shaving out with it. After a few tries your done. If the hole is too munged up, Time Certs will work. They use more meat and in some cases can't work.
I believe the threads go through the case there anyway. Closer pics would help.
Steve.

The problem he is having Steve is that on his motor that hole do NOT pass through. He is trying to get someone to measure the hole depth for him so he knows how far to drill so he can retap it. He has a "J" motor.

Davido, at this point I would go with the same depth as the one that does pass through, 16mm. Or go as far as the recess under that location. My thought on this is that there is not a lot of stress at this location. It does not require a lot of torque. All you have to hold is the new hydraulic clutch plate your building. It does not have any more pressure on it than the OEM set up, the hydraulic set up as to apply the same amount of pressure to engage the clutch as the worm gear did.
I agree with Steve that removing the starter may make it easier to tap and thread. Like Steve said, I would try just tapping it with the existing hole. Use cutting oil, make a couple of turns, back it out, blow out the hole clean the tap, repeat until its done. If you remove the starter you should have enough room to use a box end wrench on the tap.

Hope it works out for you David.

There's no oil back there. The problem with the tap is the point. It won't go deep enough. I ground off the tip of one of my #6 taps so it will cut to dead end. I was damaged anyway so now it's a specialty tool. The one I did, I had to go straight through. A little oil comes out and I seal the thread with RTV.
Steve

Thanks for the reply Steve. The hole is clear but mangled,misshaped and oversize. (The PO had the bolt fixed in with silicone.) I cleaned it out,filled it with 2xcomp liquid metal and flattened it down. I got an extra long 6,5mm drill which fitted snug in the bolt hole in the original cover. With the cover in place,I was just able to drill a slight indent in the hardened liquid metal,Just enough to center the correct sized drill.
I have taken out the starter and the genny cover but the distance is still too long for a regular drill (about 14/15mm I think) .I was able to find a ( cheap) drill with a hexagonal shank along with a long bit holder I could get the drill on, centered and parallel. For some reason (low quality drill?) I was only able to drill in about 10mm or so,then I hit something solid. I didnt want to force it,so I left it like that.I tapped it out and fitted a Helicoil with some thread lock. Next day,I put the side cover on,tightened it down a bit and the coil pulled straight out!
Looking at the tap that came with the helicoil,the cutting part dosnt really start until 7 or 8mm in so my coil had nothing to bite on.

So,plan D is to forget about liquid metal and helicoils or timeserts. I want to drill the hole very oversize maybe M8 or M10,whatever I can get away with. Tap it,thread in an alminium bolt,whack it off flush and drill/tap that.It should be a lot more secure.
I want to go in as deep as I safely can,hence the question 'How deep should this hole be?'
Im pretty sure the threads dont go right through on this (J model) engine. On earlier ones I believe it does and I really dont want to run it as is because Im fitting an hydraulic clutch shfter thing so I need all the mounts.

P.S.Any Idea how deep this hole should be?

Can you slowly drill a 1/8" dia test hole and watch the outflow debris for when you just kiss aluminum instead of filler?

Could do but it would be a lot easier if someone just measured it and said,'This hole should be xxxmm deep'

You probably have a easy out broken in there. I've been able to take a punch and tap on it enough to make it loose, then take it out with a magnet. I'm afraid you're going to get it out no matter what you do. I don't have a J motor so I can't give you the depth. A time cert might be big enough to use and just use a shorter bolt. WOW
Steve

Looking at it again, it looks like there was a locator pin there. That's why the lower one is so deep. Something's busted off in there.
Steve

I just measured two blocks- 75mm deep

To get maximum threads, use a bottoming tap. They are more of a challenge to get started perfectly straight, but they will make threads almost to the bottom of the hole. Alternately, you can start threading with a regular, pointy tap, then finish with the bottoming tap.

Aha! I did wonder about that. There is a locator on the bottom right mount,would they put 2 on one cover??
OK,Just checked the parts page and yes,it seems there are 2 locating dowels on the cover but they seem to be on the bottom 2 mounts.
Which would explain why the lower right mount looks a bit big but dosnt help with the depth measurement I need



Thanks anyway.Good to know.

davido wrote: Could do but it would be a lot easier if someone just measured it and said,'This hole should be xxxmm deep'

Guess what, I just tore my spare J (GPz 1100) engine down this weekend - went out and measured, that hole is 22 mm deep.

And yes, the two locator dowels for the sprocket cover are on the bottom bolts, none in the hole in question.