Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Sprocket on February 20, 2019, 09:03:46 AM
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Hi. When I stripped the bike the large bolt that goes through the top of the top engine case at the front simply cheesed its way off. I was left with a little stub of thread on one side and a flush twisted off wreck the other.
So, in the few months since removal I've had plus gas dripping over it every couple of days. I've centre punched it from both sides. I've gently tapped it from both sides. I've attached a mole grip on the threaded portion and tried to wiggle it. I've put two nuts on the thread done up against each other and monkeyed on the biggest bar I've got and I've gently tapped a very lot harder.
This thing will not move.
Can anyone confirm if there's a thread in the casting?
My last two options are heat and if unsuccessful, a local engineering firm who I think will apply all the above but then some additional machines with long drill bits. :-\
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Its not threaded into the casing just badly corroded
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As Bryan says, that corrosion holding it tight. They can be very, very difficult to remove when like that. Be careful, or the engine mounts will give way and break before you get them out. 😱 Deal with them once the engine is stripped, a lot more manageable then.
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Ouch thats nasty. I would try machine shop next as risk to cases not worth it...... Good luck.
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So, is that built up aluminium fur then? :o
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Yes, aided by a good supply of salt solution from winter roads.
Pretty strong bond it makes too!
I use SDS hammer drill to get things like this to release, as Julie says though, you have to be veeeeery careful to support the cases to avoid damage to the casting.
If you used a steel pipe with a flange on it to place over the stud, then support that pipe, the loading is not taken by the cases so you can attempt to drift it out.
The advantage of a percussion hammer effect is to use much smaller but insistent blows. It usually starts with the aluminium powder coming out first, so you can see it's agitating it. It's will take time to gently persuade it to move.
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Have you tried heating and cooling it several times to see if thermal shock will loosen it, might help penetrating oil soak in as well.
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Soak in diesel for while , then give it lots of heat. it will move .
Just had the same issues with one of mine
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Had one like that on my brothers Zephyr, in the end drilled it with an extra long 6mm drill followed by an 8mm, it came out then i guess the heat from the drilling done the job.
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Well, I have no real progress to report. I've got it as hot as a butane/propane blowlamp will go and still nothing has worked.
I think I'm going to have to strip the top casing as much as I can and get it to the engineers. :(
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Last one I had like that resisted every effort, up to and including oxy acetylene torch. I think I may have burnt it out eventually, then a year later it did the exact same thing despite copper slip being used. That time I used a bit too much welly on the spanner and the some of the ally case snapped off when it turned :'( good thing I had spare cases. These days I would go streight to drilling it out, if I cannot get a standard length drilling in there I bore out a length of steel bar in the lathe, pop the drilling in the bored out hole, secure it by centre dotting around the drillbit in place of a chuck. Then carefully drill out. Start small, increase diameter of drill once a pilot hole is established. This gives a bit more leeway for correcting if your hole goes a bit off centre down the length of the hole you bore.