Topic: K2 Stripped Caliper Bolt....update: out but ruined??

[jamesw]

After struggling and trying to salvage an already rounded bolt, using heat & pb blaster, didn't really help as there just wasn't enough to provide any leverage.

Is my only option to drill it out?

[drumstyx]

Drilling it out shouldn't be too bad with a vice and a pilot hole. Take your time.

[Flyin900]

Weld a smaller dia bolt onto the broken part and the heat from the weld will help loosen the broken section, then put a socket on the new bolt head and remove.

[540nova]

As an aircraft mechanic, I deal with rounded fasteners every day. I prefer EZ-outs. Just drill deep enough for it to be thoroughly inserted. I also prefer Kroil over any other penetrating fluid.


Sent from my iPhone using Tapatalk

[540nova]

As an aircraft mechanic, I deal with rounded fasteners every day. I prefer EZ-outs. Just drill deep enough for it to be thoroughly inserted. I also prefer Kroil over any other penetrating fluid.

Totally agree with Kroil, but could not disagree more with EZ Outs. Left hand drill bits are far better, less likely to shear, and in effect help turn the bolt out while making the pilot.

Can't argue with that. I'm just old school! Believe it or not, I've never tried lefty drill bits, but know they work.
Still like my EZ outs, but I should try those drill bits. I'll order some from Amazon.


Sent from my iPhone using Tapatalk

[ekpent]

 I have removed those rounded out bolts before by drilling the hole round and inserting a very LARGE easy out type of tool bit. No chance of breaking because of its extreme size, stuff to look for at estate and yard sales of old machinists. Of course you will need to rig it up in a good vice also without damaging it.

[madmtnmotors]

I would drill the head off using a left hand drill bit. It might grab and turn the bolt out before the head is drilled clear through. If the bolt holds fast until the head is drilled off then once you remove the stationary half of the caliper you will be left with a long shank of the bolt to grab ahold of.

EZPZ 

[ekpent]

 I would bet a dollar you would never break one loose with a left hand drill bit. When those are stuck its pretty extreme. Taking some precautions like a perfect fitting bit, some heat etc. when initially taking them off is a good first step when working on that component if they do not break loose easily.

[540nova]

Anti-seize is your friend upon reassembly.


Sent from my iPhone using Tapatalk

[pjlogue]

You might try a sacrificial star socket head slightly larger than the stripped hole.  Pound it in good and hard and try using it to back out the bolt.  The pounding will also help loosen the bolt.  If that doesn't work then drill the head off and use vice grips on the stud with heat.   E-Z outs don't work except for bolts that are just slightly snug in their holes.  They are little more than reams.

-P. 

[70CB750]

You might try a sacrificial star socket head slightly larger than the stripped hole.  Pound it in good and hard and try using it to back out the bolt.  The pounding will also help loosen the bolt.  If that doesn't work then drill the head off and use vice grips on the stud with heat.   E-Z outs don't work except for bolts that are just slightly snug in their holes.  They are little more than reams.

-P.

This would be my next step.  Get in a star socket and than use impact screwdriver.

[jamesw]

Thanks for the replies everyone.

I do have a set of EZ outs that I'll try, but I'll first try what pjlogue said. I dont think the EZ will grab it enough, as I'm pretty sure it's seized in the hole.

I don't have any star socket heads, but I might try the next size up from 5/16 in my set....3/8. I'll see if I can pound it in to fit.

I've never heard of lefty bits. I'll look into that if all else fails.

[540nova]

You might try a sacrificial star socket head slightly larger than the stripped hole.  Pound it in good and hard and try using it to back out the bolt.  The pounding will also help loosen the bolt.  If that doesn't work then drill the head off and use vice grips on the stud with heat.   E-Z outs don't work except for bolts that are just slightly snug in their holes.  They are little more than reams.

-P.

You need better ez-outs.


Sent from my iPhone using Tapatalk

[540nova]

I would bet a dollar you would never break one loose with a left hand drill bit.

Can I get a dollar for each and everyone I have done with LH bits? If so, I'll forward my PayPal addy to you via PM  ;)You'll likely have to liquidate your estimable collection to finance the payments 

The unique thing about LH bits is that they create unwinding friction as they drill. This very frequently works just like an EZ Out does, especially if you use a slow speed while drilling.

When drilling metal, it's always slow speed, heavy feed. Unless you like work-hardening the thing you're trying to drill into


Sent from my iPhone using Tapatalk

[540nova]

This is turning into a fun post!


Sent from my iPhone using Tapatalk

[754]

Left wont get the beat to the thread as its too far away.
Ez out are crap in sme cases..
I prefer the spline drive type sold by Rigid and Snap-on..
But i bought a cheap set of that type, and the drill that came with it were #$%*e, so i suspect he splines are too, i dont trust them
 The good spline and nut type I used many times, uses 1/8 drill , and I got manny a 6mm and bigger out with it.
 The OP need a bigger one.... But weld another bolt to yours will probably get it, if ramming a Torx in wont

[madmtnmotors]

I would bet a dollar you would never break one loose with a left hand drill bit.

Can I get a dollar for each and everyone I have done with LH bits? If so, I'll forward my PayPal addy to you via PM  ;)You'll likely have to liquidate your estimable collection to finance the payments 

The unique thing about LH bits is that they create unwinding friction as they drill. This very frequently works just like an EZ Out does, especially if you use a slow speed while drilling.

+1000

[754]

This i dont like about EZ Outs..the twisted ones.
F the hole to uuse it exceeds 75% of the broken bolt, tightening the EZ out can wedge it further.
 Spline Drive Uber Alles...

[jamesw]

No luck so far.

I've drilled it big enough for my 2nd largest EZ out, but the the drill keeps kicking back, so the bolt must be seized in the hole pretty good.

I'm going to try to more heat and try a larger hex bolt socket.

[70CB750]

Bake it in the oven for a while. 

But both parts are available and usually not very expensive, bolts too.

Just saying 

[754]

Is it drilling OK in the middle? If so drill the head off..
Gonna bea bit of GRAUNCHING getting thru the hex..Ok if you can sharpen drill or use a masonry bit.. 3/8 oughta do it.

[madmtnmotors]

More than likely, the PO used a 10mmx1.5 screw threaded into a 10mmx1.0 hole. No amount of EZ Out or LH drill is going to remove that. Nor heat. You'll have to drill the center of that bolt out completely, allow the sides to collapse internally, and then an EZ Out might persuade it out.

I would tell you to fully expect to drill out the entire screw, and re-tap the hole with new threads/pitch. I don't know of a socket head 10mm generally available in 1.0 pitch.

Nope. Gotta call ya out on this one Cal. The original bolt is indeed a socket head (allen) bolt:

http://www.cmsnl.com/honda-cb750k2-four-1972-usa_model14362/bolt-setting_90165300023/

The earlier models used these installed from the inboard side. Later models used a hex bolt installed from the outboard side.

[754]

I doubt threading wrong pitch would seize it, likely to strip it out , but not seize.

[754]

Sometimes you will get away with that..
I bought a Grimeca rear mater cylinder on here, it used a different pitch than out brake parts, I think 1.0. Any way, I carefully ran correct tap in, then tried a fitting without bottoming it, no rocking sideways, and thread looked pretty good.. Hope it holds..

[John Eberly]

An old trick that works on the caliper bleeders that are often frozen up -

Put the caliper in a small crock pot and cover it with vinegar. Turn the pot on high for 24-36 hours and keep the vinegar topped up. The acid and the heat will eat the steel part away and leave the aluminum alone.

This might wok on the mounting bolt as well, but likely to take more time.