Removing large bolts

[Jules Richardson]

Hmm, maybe that's promising, then, if one end's free.

How much thread have you got to work with at the end of the bolt? I remember 'locking' two nuts together for getting out stubborn cylinder head studs (sometimes combined with penetrating fluid and/or heat).

Even if you don't have much exposed thread, maybe there's enough space to weld a nut to the end of the bolt and use the breaker bar to free up that end, then cut the nut off once the bolt is able to turn a little along the full length of the shaft? At that point, hopefully a bar on the head, or a clamp, will be able to remove the whole bolt...

No kidding :-) It was just a random thought and I wanted to conform that someone knew for sure that these bolts weren't somehow different.

Could be worth a try, although it's amazing how much force stuff like this can need - and I suppose there's a danger that the clamp might just distort the end of the bolt, rather than forcing it to slide along its axis.

cheers

Jules

[dennis]

I wouldn't bother with the jack, just make a clamp to hold a bar in alignment with the bolt and hit it with a 28 lb sledgehammer. It should keep you fit.

If enough of the thread sticks out you could turn a bar to screw onto the end and just belt it.

[Dave]

several minutes looking at that photo thinking where have I seen this before. It all came flooding back when you mentioned stress corrosion.

No help to Matty though :-(

Dave

[Dave]

It shouldn't make anything brittle. We used liquid nitrogen to fit the wing hinge pins to the swing wing aircraft.

I doubt that would be cold enough, or would penetrate enough. Liquid nitrogen would be the best route. Full face mask, leather gloves and wellingtons that start under and above the leather apron.

Dave

[js.b1]

Heat and Cold. Heat with whatever you can get into the location, need not be to a particularly high temperature. Then spray liberally with a cold release spray, they are about =A312 a can as I recall. The high temperature delta between hot and cold, combined with the rapid change in temperature, will generally break anything free very effectively.

If very severe water ingress has occurred you might have to hire a magnetic drill and drill the bolts out. You use a centre-drill and drill undersize until it basically comes out.

If space is restricted for turning a bit spanner, you can hire torque multipliers - they work on a gear-reduction and ratchet principal against a fixed object. However, like using hydraulic pullers or pushers etc you can end up doing damage.

The cold release sprays are very effective - much much more so than merely "torch and big hammer". In particular they can avoid someone ending up bending a whole assembly in a press to release a stuck fastener, CV joint from a spindle etc.

[Dave Liquorice]

Have a look at the picture of one of the other removed bolts. There is about an 1 1/2" of taper, that is nice a clean, at the threaded end of the bolt the remaining 3" or so of bolt shaft is dirty and midly corroded. The head moving under in influence of BFO breaker bar is just the shaft twisting...

[Dave]

Since the bolt is being forced into the joint by the torque it is under, would you be able to apply pressure to the threaded end with your ten ton jack and then put some permanent torque onto the bolt head and leave it? Increasing the torque each day. The theory being that the forces would pop the grip that the body has on the shank of the bolt. I have done that in the past. But the bolts were nowhere near that old.

Dave

[Matty F]

Yes, turning the head while applying force to the other end, while heating the surrounding plate and applying ice to the bolt and hitting the clamp with a sledgehammer, is bound to work! It's been decided to leave the bolts in place, while honing or re- sleeving the cylinders without removing them.