pompy's handbrake

[Big_Richard]

On this forum, theres a nice write up on the correct procedure for using easy outs

http://www.netrider.net.au/forums/showthread.php?t=81674

I'm very impressed with his ability to drill perfectly central into the old bolt, my half assed efforts are probably most of the problem everytime I've used them in the past

[s class]

Yeah, drilling centrally, plus selecting the right size hole, and right eeze-out seems critical to the likelihood of success.

[koan]

I've had two successful and two failed Ezyout attempts.

I have a Suttons brand set, looks like the set in the mentioned thread, weren't cheap. Both successes were with this set.

The failures were with non-descript hardware store bought items that snapped, might have been that I was using a size that was too small.

Using the proper size, accurate axial drilling, and soaking in penetrating oil I think have helped. Also when centre punching the remains of the bolt I "went to town" on them, hoping it might help crack them free.

Ever wondered why bolts always sheer at the surface and not some way into the thread?

Did a bit of research on how nuts and bolts work and was surprised to learn that most of the engaged treads do nothing, only the first two or three threads of the hole are doing the holding because of the way the metal stretches under the load.

koan

[Big_Richard]

Did a bit of research on how nuts and bolts work and was surprised to learn that most of the engaged treads do nothing, only the first two or three threads of the hole are doing the holding because of the way the metal stretches under the load.

koan

That sounds very logical indeed.

Ofcourse, theres the times when your changing an m100 water pump, and bolts are rusted into the block from the bottom up, and they snap half way into the hole 

[s class]

Today was a public holiday in South Africa.  I decided that if all I managed in the day was to deal with the sheared bolt, I would go to sleep a happy man.

First prize would be to do all this without removing the hub. 

Here was the starting point :



Drilling started :



Drilled right through the bolt with an intermediate size :



Hole nice and central, and enlarged to the point that it just touched the original threads in a couple of places.  I considered this ideal.



Lunch time, I was at the stage, and considered myself lucky.  I used a sharp awl to pick out the material from the first few threads in order to create a starting point for the tap.  It was surprisingly difficult actually. 

After lunch I settled in with a tap, cut shorter, to fit in behind the hub.



Progress was slow, but with good results.  I slowly advanced the tap and withdrew it multiple times to clear the debris, and continually check that things were on track.

And then the f-ing thing broke off inside.  I threw down my tools in disgust - and well - in any case I decided that any decision I made in a state of rage would be the wrong decision.  Hopefully a cool head will show the solution.

My saving grace is hopefully that I really don't think the tap is stuck in there that tight. 

[Big_Richard]

it was all going so nicely untill that tap decided to snap too.

Howcome you didnt use an easy out with that perfect hole?

[s class]

Yeah and I had got through about 70% of the distance too.  Real frustrating.

Eeze outs only really work in cases like that link you posted up. In his case, once the bolt snapped, there actually was no tension on it, so it wouldn't have been tight at all.

This bolt io had was rusted fast.  It seems the reason for the problem is that the hole for the bolt is not blind.  It goes right through, allowing water into the threads.

[Papalangi]

Patrick, the hole would have been to big for an easy out as it would have chewed up the threads.  There is a specified hole size for each size of extractor (easy out) and it's best to use the correct size and drill as deep as you can.  Sometimes, a left hand drill bit is enough to get the broken bolt out as it will sometimes grab the bolt enough to get it out.

You will break many drill bits trying to get the tap out, I've never had luck with drilling one out myself.  You could try heating the hub around the hole without heating the tap.  The hub may expand enough to let you get the tap out.  You aren't looking for red hot but about 100 C.  If the hub is made of unubtainium, you may need to find a shop with an EDM machine.  They will use an electrical discharge to remove the tap without further damage to the hole.

There is such a thing as a tap extractor, I've never used one but it could save your bacon if it works.
http://www.mcmaster.com/#tap-extractors/=4yrjoc

A Heli-Coil may or may not be be a good fix, there are other types of thread repair inserts out there,
http://www.mcmaster.com/#thread-repair-inserts/=4yrlh3

Michael

[s class]

Papalangi, thanks for the help.  And yes, you surmise correctly this component is made of unobtanium.  Its got the anti-squat linkage that was not supplied on any locally built W116's.  

A helicoil should not be required.  The original thread is in good condition, I just need to get the tap out.  

Those tap removers look like a godsend.  I will try phoning around machine supply shops here, but if I can't get, I'll order from that website.

THANKS!

edit

no susprise - the locals can't help me.  I've ordered one of those miracle devices from McMaster-Carr.  Plus a pack of 10 replacment 'fingers' for the device. 

It will probably be 2 or 3 weeks till they are here, but I'd rather wait for the right tools than make the problem worse with a home-made solution. 

[Papalangi]

You are welcome s class.

I love McMaster.  They are in California and will get stuff to me in three days or less up here in Washington.

I also tend to say if they don't have it, you didn't need it.  They used to have an air powered flashlight.  Yes, really.  And they still list an air powered router.

Michael

[s class]

This saturday past, i received my latest shipment from the States.  In it was the McMaster tap extractor 'miracle' tool.

I went out almost immediately and had a go with it.  It was tricky, because I had to disassemble the tool, and then  reassmble it in situ behind the hub flange.  It took a huge amount of torque on the tool to do the job - to the extent I was concerned I'd break the 'miracle' tool, but it did the job and got the remains of the tap out.  That extraction tool is really high quality stuff.  despite the force I put on it, it shows no sign of distress.

I then got another tap and finished the job without further event. 

Thanks Papalangi, this really saved my backside on this one. 

[Papalangi]

You sir, are welcome.

I was hoping that they would work out OK but I've never seen one other than in a catalog and to hear that a tool works as advertised is a good thing.

Michael

[s class]