Restoration of Sandcast #97

[Steve Swan]

Mark, if we did not do this sort of thing, we can't profess actually working on them.

As you say, getting the hole you will drill exactly on center will be key.  Again, as you say, the best way is to make a tool that fits over the broken stud with a pilot hole to start the drill on exact center.  I'm guessing you have lathe access to make up such a tool.  Before attempting drilling, would be best if you could mark the center of the stud with a punch to prevent the drill from any possibity of wandering off center.  Perhaps, after you have your pilot tool made, you could take a piece of appropriate sized drill rod, grind a point on one end, then insert the ground end of  this made up punch in the pilot hole of your tool to mark the center.

The worst that can happen is you'll need to Time Sert the hole.  http://www.timesert.com/

I rarely use Heli Coil anymore.

[kp]

Too bad you are not in my town Mark. My good friend Mick Blake (the legend) runs a machine shop here in town and his specialty is removing broken studs fromanything. He TIG welds from the stud break and gradually builds up enough height (with weld) to clear the area and then welds a "T" handle on top of the weld. He then uses heat and "secret squirrel oil" to remove the offending slug.
On another note, Mick is a Yank (one of you lot  ) and is called the legend by me is because he was a formidable drag racer in the USA in the early 1970s. He was a Kawasaki triple rider and rode for Denko at one time. If one can get their hands on a copy of 1975 Cycle (January Edition), Mick features in a 4 way shoot-out against a modded Turbo Honda 4 and a few other 750 triples. The famous Tony Nicosia was on one of the triples but at days end it was Mick B who had the 2 best times of the day. He lived in New Zealand for a time but now resides in my town and does most of my machine work. I have never met anyone with the knowledge of metals, welding, tuning, machining and drag bike tuning he has. Yep he is indeed an assuming kind of fellow but he does know his sh*t and has a one time Ozzie drag bike record (he tuned the bike) under his belt
Anyway, thought I'd share that KP

[markb]

Thanks for the tips guys.

I’m thinking ahead here a little.  Has anyone ever removed item #6 in the drawing below?  I took off the cap (item #5) on the other side (which surprisingly came off quite easy) and it doesn’t look pretty.  I don’t know how that much dirt and sludge could get in there.  Anyway to do a proper job of cleaning out the oil path it seems like removing the plug (item #6) on the other end would be helpful.  My guess is it’s just pressed in.  Once I get the cases stripped down that will be my next job is to thoroughly clean out all off the oil passages.  Some of them are completely plugged with what looks like mud.

[hondasan]

Regarding that plug, item 6, it is only held in by the o ring in the groove around its circumference. With the cap, item 5, unscrewed, just use a long bar and push the plug out (gentle taps with hammer will do it).

Concerning your broken stud, I had a set of cases just like that. We got a piece of flat bar about a 1/4" thicker than the height of the protruding thread, and 62 long by 1" wide, drilled a hole in the middle, put it over the broken stud and welded the hole up so joining the stud to bar, and forming a "T" handle. It then screwed the piece right out (it may be that the heat during welding also broke the rust bond). Just need to make sure the flat bar is just off the crankcase face by a couple of thou or so.
Avoided the possibility of not drilling perfectly dowm the centre of the broken piece and rsiking problems with the case. You coulf of course try some gentle heat cycles, use of some pentrant or otherwise, etc before the weld job. I guess worste that happens is you break the weld joint, and if that then you can set up to drill out.
Just my thoughts - Good luck, Chris R

[hondasan]

Should of said 6" not 62 long! Could do with spell check or something given my ineptitude at typing / proof reading before posting!

Chris R.

[Riccardo]

Mark,

you could also weld over the part that remains of the stud a bolt and try to unscrew it.

It's only an idea.

In this way you should have a second chance with a drilling precision job.

[cb7504]

Mark:
       Over the years I have had more than one stud snap or twist off. A friend of mine who is a welder put an over sized nut on the sheared stud and welded the large nut (17, 19 or larger) to the stud and cooled the area with water after about 10 minutes of cooling we removed the sheared stud(s).  Marty K.

[cb7504]

Mark:
       As for the #6 plug at the end of the main oil passage I use a 3/8 inch piece of wood dowel rod approximatly 24 inches long and tap it out, it is only pressed in and when reinstalling can be done with your thumb and good lubricated o ring. Marty K.

[ashimotok0]

Hmm Mark , In an earlier post I suspected this would happen to the studs. One of mine broke off slightly below the crankcase level

I tried the 'welding a flat bar to the broken stud' method but it just kept breaking off and the amount of heat I put in MIG welding it, was really high, so I thought the steel/aluminium  'bond' would have broken. My stud was one of the short front centre ones.

Here is what I did. I got a piece of stainless steel tube off Ebay, which was a tight clearance fit in the stud hole of a scrap set of barrels. I found that a 6mm long series drill was also a clearance fit on the tube ID. Using a Dremel with  conical stone I ground the top of the broken stud concave. I then used the dowels to locate the barrels on the crankcases and the SS tube as a long guide for the drill bit. The hole produced was perfectly concentric with the hole thread. That's as far as I have got but I also had a piece of the tube bored out to the M8 tapping size of 6.8mm but I have not yet drilled because a few  SOHC4 members site tell me that I will never get a tap to clear out the hole because Honda used 'unobtainable' machine taps with a special profile. I hate the word 'unobtainable' - surely if it is a special thread - a tap could be made to match the original thread profile. So any advice on the thread profile would be helpful. Once you have drilled though the broken stud you can inject release agent of your choice down the hole and it then can penetrate upwards on the reamining thread as well as downwards. I am also told that if I drill to 6.8mm, I may we able to pick out or 'winkle' out the remainder of the stud threads after a long soak in penetrating fluid.

Perhaps if I had 'TIG' welded the 'welding a bar' method, I may have been more successfull but I feared melting or overheating the crankcases, particularly as I would have had to trust someone else to do it.

Cheers for now,

AshD

[markb]

Some good news.  My studs are out!  I’m afraid I wussed out on you guys though.  After much good advice I had a shop EDM (Electrical Discharge Machining) them out.  I mentioned my problem to one of the guys in my shop and he suggested I just do that.  Doh!  We occasionally have a tap broke off in an expensive part and we just send it out.  I felt the odds of maintaining the threads was better that way too.  The threads look good and I did a test torque and they went to 8 lb.-ft. no problem.


Now I can move on to this mess.

[markb]

Wayne’s request for a piece of fin was pretty timely.  Last weekend I was looking at my cylinders and I saw I had a broken fin too.  Ash offered to send me a piece too but after reading some of the responses about fin repair I think I’ll opt for building it up layer by layer and shaping after welding.  Either that or “borrow” the jugs from 1553 and repair it later.
I can’t believe I missed it before.  But looking at it at this angle I guess it’s not totally obvious.


But you can see it on the right side from straight on.


Here’s another closer shot.


I don’t know how it can be broken off that far in.

[ashimotok0]

Got your PM Mark - I agree - I think,that, looking at your barrels, building up on your fin would be the best option. You missed out on the two free large oil pump 'O' rings though!! I included them with Wayne's packet!

Cheers

Ash

[Steve Swan]

given the location of the missing fin BETWEEN fins, seems best to have a welder build it up.  Scavenging 1553 might let you stay a smaller o.s. as well as deal with the broken fin issue.  i guess the only other factor would be E100's cyl being identical or not to the cyl from 1553

[markb]

I tried to pull out the gearshift fork shaft but it wouldn’t budge.  The end of the shaft is tapped with an 8mm thread so I threaded in one of my studs to try to pull it out.  The forks moved freely so I figured the shaft was stuck in the case.  So I drilled a hole in a piece of bar stock and made a slide hammer.  Then it came out easily with a few light taps.


Then I decided to tackle the pin the holds the kick start spindle.  Normally I use a side cutter to pinch on the pin and a thin piece of sheet metal to protect the machined surface on the case and pinch and pivot until it comes out.  Of course the pin gets damaged but I just replace it.  No luck this time.  I’ve been soaking it but being a press fit I’m not sure how much good that does.  I don’t want to try to rotate it because being a spring pin I’m afraid it will damage the hole and I think it’s too hard to try to drill out.  Any ideas besides burning it out?

[Wayne]

Mark I know Aerocroil is a good product but it looks like you are in a pinch here with that split pin. I never swore by a product before until I tried Liquid Wrench. I was changing a ball joint in the driveway for a guy and there was no way the nut was coming off without heat in my opinion. He comes out with this Liquid Wrench. I kind of laughed, put it on, waited a few seconds and gave it a try. Nut still frozen. He reads the instructions and says "you have to tap on the nut a couple of times to loosen it".  I chuckle, give the nut a couple of taps, put the wrench on and the darn nut spun without effort! I have had a bottle on my shelf ever since. So far only one broken bolt on my sandy and that was an exhaust spigot bolt I'll bet someone tightened the hell out of when they put the headers on. It broke way to easy.

If you try it, let it soak, some tapping helps with a small hammer.  It stinks, it burns my skin and it melts rust. I have literally had fasteners go from frozen to spinning them off with my fingers. Don't forget to tap the case and even lightly on the pin with a small hammer. It really is the shock that helps this stuff work. I will have to give this Aerocroil a try sometime though if I get stuck. I'm sure it's everything Steve says it is. Good luck!