TOPIC:

Hi all,
Didn't want to hijack the cam caps stripped threads, er... thread, so here we are.

We've acquired a set of cases in which the M6 bolt for electrical ground is broken off just below the surface. Don't know the history.
Our plan is:
Repeated application of MMF* for a few weeks prior to using a heat gun and drilling the broken bolt with a left-hand flute drill, to prep for using an extractor. We might luck out & see the broken bolt spin out while drilling. If not, application of the extractor along with more MMF* and heat is next.

If the extractor is unsuccessful, the next step is to use progressively larger left-flute drill bits. If necessary, we may have to drill the threads out of the cases.

The ground bolt does not carry any real load aside from just the torque needed to secure the ground ring terminals.

We're unfamiliar with the selection & use of thread repair schemes in aluminum. What say the forum on the advantages/disadvantages of Time-sert vs Heliciol? Which to use on this particular application and why?

Thanks all.

Good Ridin'
slmjim & Z1BEBE

" MMF = Magical Mystery Fluid. A 50/50 mix of acetone and ATF. From an article published in Machinist Workshop Magazine circa. 2007.
"Recently “Machinist Workshop Magazine” did a test on penetrating oils. Using nuts and
bolts that they ‘scientifically rusted’ to a uniform degree by soaking in salt water, they then
tested the break-out torque required to loosen the nuts. They treated the nuts with a variety
of penetrants and measured the torque required to loosen them.
This is what they came up with:
Nothing: 516 lbs
WD-40: 238 lbs;
PB Blaster: 214 lbs;
Liquid Wrench: 127 lbs,
Kano Kroil: 106 lbs
(ATF)/Acetone mix (50/50): 50 lbs.

This last “shop brew” of 50% automatic transmission fluid and 50% acetone appears to beat
out the commercially prepared products costing far more."

Extractors are spaun of the devil. They love to break off inside the old bolt and greatly increase the bolt removal task effort. Unless you are highly experienced in their usage, and you wouldn't be posting this thread if you were, I'd stay clear. Just use the left hand bits and stay centered in the hole. Work up slowly through the sizes and the old bolt will likely spin out as you get near full size. Worst case, use a tap to clean up the hole but most of the time that is not needed.

Nessism wrote: Extractors are spaun of the devil. They love to break off inside the old bolt and greatly increase the bolt removal task effort. Unless you are highly experienced in their usage, and you wouldn't be posting this thread if you were, I'd stay clear. Just use the left hand bits and stay centered in the hole. Work up slowly through the sizes and the old bolt will likely spin out as you get near full size. Worst case, use a tap to clean up the hole but most of the time that is not needed.

Not disagreeing about extractors being a potential problem. It would be nice if extractors were supplied with any sort of spec on maximum torque recommendations. We've used them successfully many times on threaded fasteners of known history. We just don't know if this particular bolt had thread locker applied, or is just frozen due to time or moisture.

Any advice on the pertinent inquiry re: Time-sert vs Helicoil?

Go9od Ridin'
slmjim & Z1BEBE

I prefer the helicoils over timeserts, proper installation is key with either one.
Now, for the broken bolt, weld a nut on top of it, this has been the best method for even bolts below the surface, the heat shocks the threads and they almost always come right out.

Les Holt

Probably just time and moisture coupled with an over zealous tightening by a previous owner, forget the easi outs just go for the left handed drill bits, if you drill the bolt right through just fill up the hole with diesel and warm through then fill up again capillary action will occur and as you increase drill size it should wind out, chase thread and use a new bolt smear thread with copper grease.
With regards to inserts, its time-serts all the way for me, far more substantial but more expensive too, which ever way you go get an insert that will go the full depth of the hole and follow the instructions to the letter

Unless the owner is obsessive about originality, it might be far easier to tap the buggered hole out to the next bolt size and put an appropriately sized bolt in there and get on with life. The wire terminals may need a little persuading, but that is easier than any of the coilsert doodads .

If you are really worried about keeping the originality of the cases. There is a procedure called "metal disintegration" that can remove that bolt without hurting the treads of that bolt hole!!! Any real good machine shop should have access to that type of machine.

I saved a set of Z1 cases with a broken off cylinder stud on the oil galley stud hole. Didn't even hurt the treads in that hole at all!!! Its a amazing process. They use an electrode placed near the broken bolt, and uses voltage to blast out the metal of the broken stud.

I'd use helicoils for that application. As long as the cams are clamped down into the head using vicegrips before installing the caps the stress on the threads isn't too bad.

Dr. Gamma wrote: If you are really worried about keeping the originality of the cases. There is a procedure called "metal disintegration" that can remove that bolt without hurting the treads of that bolt hole!!! Any real good machine shop should have access to that type of machine.

I saved a set of Z1 cases with a broken off cylinder stud on the oil galley stud hole. Didn't even hurt the treads in that hole at all!!! Its a amazing process. They use an electrode placed near the broken bolt, and uses voltage to blast out the metal of the broken stud.

Electro Discharge Machining (EDM).

If this was an irreplaceable item, something really mission critical as to bolt size, or cosmetically critical, we'd do so without a second thought.

Good Ridin'
slmjim & Z1BEBE

Try to do heli coil first, it need less metal removal on the cam cap threats.
Worked like a charm on my ported Z1000J head on Z1B 900 engine.
Time sert need more metal removal.

BTW: my CAM CHAIN IDLER ADAPTER

Scirocco wrote: Try to do heli coil first, it need less metal removal on the cam cap threats.
Worked like a charm on my ported Z1000J head on Z1B 900 engine.
Time sert need more metal removal.

Time sert and helicoil M6 size have the same external thread, it's only the lip at the top of the time sert that has to be taken into account and a this is taken care of by using the correct tool for the job.

Scirocco wrote: Try to do heli coil first, it need less metal removal on the cam cap threats.

This isn't on cam caps. It's for the ground bolt above the kickstart shaft.

Duly noted about need for additional material removal.


Good Ridin'
slmjim & Z1BEBE