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

[rocket johnny]

    i was in the same boat about 2 weeks ago .   fill the recessed area with aceton/atf     give it a 4-5 day soak .  then i did the old hammer and chisel  for about 1/2 hr . then got vise grips on and it opened on first turn .  can't help it if i'm lucky   

[ekpent]

  Here is a picture of my 'little' easy out. I have removed quite a few of these bunged up caliper bolts over the years with this set up and have never been defeated yet. Drill out the allen round and deep, tap in this monster and give it a go with a 1/2" ratchet with some heat and blaster. It will succumb to my will   

[jamesw]

  Here is a picture of my 'little' easy out. I have removed quite a few of these bunged up caliper bolts over the years with this set up and have never been defeated yet. Drill out the allen round and deep, tap in this monster and give it a go with a 1/2" ratchet with some heat and blaster. It will succumb to my will   

Geez.....yea that's exactly what I need.

My easy out clearly wasn't going to help, nor did it.

I'll finish it tomorrow, but as of tonight and 6 broken bits later, the slow drilling out process is working.

[754]

Get a masonry bit, it will drill it easy..remember slower on hard stuff.
Tip for allen bolts that are loose, semi stripped, if a torx fits pretty good, it will probably work.

[scottly]

The proper hex size is 8mm, not 5/16". This is probably how you got into this mess in the first place. Is the head stripped out all the way to the bottom? If not, you might be able to drive the proper hex key down into the undamaged area. (Probably too late now)
These suckers are hard to get out! Even with the caliper arm held in a vice and the proper hex, it takes a lot of torque. Heat should only be applied on the side of the caliper body opposite the head of the bolt. The idea is to expand the aluminum so it releases it's death-grip on the threads of the bolt. BTW, the pitch of the threads is 1.25. 

[754]

I thought of that, but the difference is only a hair...a scant 2 1/2 thou...

[PeWe]

Tool and the time to get it right is not free either...
Sometimes easier to buy new and forget
https://www.davidsilverspares.co.uk/CB750K2-FOUR-1972-USA/part_223220/

[ekpent]

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.

So tell me Cal how many CB750 front caliper bolts have you removed with a left hand drill bit since this is our topic.

[ekpent]

 I 'may' owe you a dollar Cal for that one maybe  but I cannot afford the rest    I am a believer in the principle. Guess if your going to drill a hole anyways might as well have a shot at removing it also.

[jamesw]

Th bolt is out, but the pitch was all wrong. That's what you get with a hand drill and vice on a bench.

The bolt spun out fine, but as you can see the hole is oblong now.

I haven't tested a new bolt, but if it holds is it worth it? Can it be drilled out larger or just buy another one?

[ekpent]

 Drilling like you did was not needed as far as drilling that far in. I would have concentrated on just drilling off the head of the bolt, pulling the caliper apart and then removing the threaded portion of the bolt from the caliper body with a pair of vice grips. A lot of times on these calipers its more of the bolt head causing the problem then the threads but the two combined can be tough. If the threads are damaged probably best to take Cal's suggestion and replace and be done with it. Make sure if you get a used one that the bleeder screw has been loosened already so you don't have to potentially deal with another problem.

[754]

Not understanding why you drilled that far.
You could helicoil it, but should be done on. Mill or carefully set up.
 But you can probably get another caliper for under 50 bux.

[DaveBarbier]

Drilling like you did was not needed as far as drilling that far in. I would have concentrated on just drilling off the head of the bolt, pulling the caliper apart and then removing the threaded portion of the bolt from the caliper body with a pair of vice grips

+1 Or even drill the head off and weld a big nut to the shaft to be able to use a ratchet and socket.

I doubt the calipers are hard to find on eBay, though. Worst case, I got a very nice new reproduction caliper for my 550 from DSS for not too much money, I think between $50-$60.

[flybox1]

Th bolt is out, but the pitch was all wrong. That's what you get with a hand drill and vice on a bench.

The bolt spun out fine, but as you can see the hole is oblong now.

I haven't tested a new bolt, but if it holds is it worth it? Can it be drilled out larger or just buy another one?

NOTE for next time -
Drilling off the head means using a drill bit LARGER than the threaded portion of the bolt so it pops off when you get thru it. Then you stop.
The caliper half would slide off so you can vice-grip the threaded portion, and turn it out by hand.
No need for a drill press or anything fancy.  Hand drill is fine.

Contact member Godffery for a new caliper. That one's pooched.

[drumstyx]

The proper hex size is 8mm, not 5/16". This is probably how you got into this mess in the first place. Is the head stripped out all the way to the bottom? If not, you might be able to drive the proper hex key down into the undamaged area. (Probably too late now)
These suckers are hard to get out! Even with the caliper arm held in a vice and the proper hex, it takes a lot of torque. Heat should only be applied on the side of the caliper body opposite the head of the bolt. The idea is to expand the aluminum so it releases it's death-grip on the threads of the bolt. BTW, the pitch of the threads is 1.25.

+1

A great investment is a set of 1/2" metric allen sockets. Using the right tool, with a great big breaker bar or an impact wrench and you'll either remove the bolt or snap it, both of which would accomplish the job of removing the parts.

[jamesw]

Thanks for the replies guys. I didn't have a larger drill or else that would have worked.

Lesson learned.

Bill Benton has one for sale that I'll probably buy.

[70CB750]

Thanks for the replies guys. I didn't have a larger drill or else that would have worked.

Lesson learned.

Bill Benton has one for sale that I'll probably buy.

Still, good experience 

[drumstyx]

Thanks for the replies guys. I didn't have a larger drill or else that would have worked.

Lesson learned.

Bill Benton has one for sale that I'll probably buy.

Still, good experience 

Definitely...the only way to learn is to not be afraid to make mistakes.

[754]

 Actually if you had stopped at full bit size, a 1/16 of an inch past bottom of the head, a sharp rap from a punch would have taken the head right off. Then you would still have meat to grab with visegrips or weld nut on... (if it did not be ome loose once head was off ).

[DaveBarbier]

Actually if you had stopped at full bit size, a 1/16 of an inch past bottom of the head, a sharp rap from a punch would have taken the head right off. Then you would still have meat to grab with visegrips or weld nut on... (if it did not be ome loose once head was off ).

True, a lot of times it's the head that's seized. At least that's my experience with engine covers. Possibly because the head is exposed to the elements and corrosion is more likely to happen. Many times drilling the head off allows you to spin the threads out with your fingers.

[754]

Maybe not the head , rather the head putting tension on the threads. When the tension gets relaxed, the slight clearance in the threads may let it loosen its grip..
Yeah, makes it look like the head is holding it.