Author Topic: Stuck Allen head calliper bolts! (Read 1562 times)

70cbk0 · « **on:** February 13, 2013, 02:14:44 PM »

The 2 allen key bolts that hold the front calliper (disc brake) together...CB750 K0...Unbelievably stuck. I had them soaking in PB plaster for a month or 2......used a torch today to heat the body up....I have an impact wrench...got up to about a 5 pound sledge hammer today....nothing!! I haven't wrecked the head of the bolt yet....but it's getting close....Any other suggestions? Just more and more heat, I suppose. I'm afraid I might not get it apart.

Greggo · « **Reply #1 on:** February 13, 2013, 02:18:37 PM »

The only thing that will do it is extreme heat, and force. If you bugger the bolt head, weld a bigger nut on, and get leverage on it just after the torch is off.

If it's FUBAR'd, there are always other fish in the sea.

2wheels · « **Reply #2 on:** February 13, 2013, 02:59:44 PM »

Try an air tool (impact gun). It can work miracles on some screws.

MrGardman · « **Reply #3 on:** February 13, 2013, 03:39:29 PM »

And make sure a little anti-seize on the threads when you put it back together.

Prospect · « **Reply #4 on:** February 13, 2013, 04:59:19 PM »

Yup just more heat and lot's of it. You'll smell the rubber seal melting along with old brake fluid evaporating. Work the torch from front to back. A couple of whacks to the body with a rawhide hammer won't hurt but try not to destroy the allen bolts. I'm not sure about the K0 but the sandcast has different allen bolts (the head has a different texture, rough) and it's possible that your K0 might somehow has the more desirable sandcast bolts.

HondaMan · « **Reply #5 on:** February 13, 2013, 11:12:24 PM »

Those silver K0 calipers were not anodized, and corrode quite a bit on the threads, gripping those bolts like crazy. I see this also in the engine studs for the K0-K1 engines, same reason. On the engines (usually AFTER the stud breaks off), I clip a ground to the stud, then have a nut welded to it: this makes the steel grow bigger (heat) so it pushes the corrosion back against the softer aluminum. After cooling, some penetrating oil, and a couple minutes later the studs come right out.

This would be harder to do with the caliper bolts, though. One option might be to center-drill the bolts thru with first a 7/32" drill bit, then successively larger ones until most of the bolt is gone. Then some oil and/or pick away at the threads until its all out? Maybe an EZ-out could work then? New bolts should be easy to find?

754 · « **Reply #6 on:** February 13, 2013, 11:32:23 PM »

Hold the caliper between 2 strips of plywood in a stout vise. Then put a close fitting h pipe over a good quality allen wrench...have at er...wear eye protection, and keep bystanders away..

ekpent · « **Reply #7 on:** February 14, 2013, 04:50:12 AM »

I have had to deal with those too many times.When the punky allen head finally becomes rounded out in the center, I drill whats left of it with a drill bit round and then break out my HUGE easy out and go at it with that. Never been defeated yet but it is rendered unusable afterwords.

MCRider · « **Reply #8 on:** February 14, 2013, 06:07:02 AM »

Quote from: 754 on February 13, 2013, 11:32:23 PM

Hold the caliper between 2 strips of plywood in a stout vise. Then put a close fitting h pipe over a good quality allen wrench...have at er...wear eye protection, and keep bystanders away..

Agreed. A vice, good fitting ALlen, and a 3ft cheater bar will make short work of them.

70cbk0 · « **Reply #9 on:** February 14, 2013, 06:17:48 AM »

Thanks everyone...more and more heat I guess. This is a very early K0 (dec 69) so I'm trying not to bugger those heads.

754 · « **Reply #10 on:** February 14, 2013, 07:51:39 AM »

I would try cheater bar and no heat..first

70cbk0 · « **Reply #11 on:** February 15, 2013, 10:50:20 AM »

I won! Yeah guys, I scrapped the impact wrench and put a 2 foot pipe on an allen key. Oddly enough, it didn't even looked all that corroded when I got it apart. Somebody certainly tightened the daylights out of it. I'm assuming Honda. This bike has hardly any miles on it, and the pads are like new.

MCRider · « **Reply #12 on:** February 15, 2013, 11:12:39 AM »

Quote from: 70cbk0 on February 15, 2013, 10:50:20 AM

I won! Yeah guys, I scrapped the impact wrench and put a 2 foot pipe on an Allen key. Oddly enough, it didn't even looked all that corroded when I got it apart. Somebody certainly tightened the daylights out of it. I'm assuming Honda. This bike has hardly any miles on it, and the pads are like new.

It would have been even easier with the recommended 3 ft cheater bar

This was a "first hand experience" post.

The sticktion can occur from various points. First I don;t think the factory torque was really anything more than one might expect on an 8mm critical duty bolt. 10 to 18 ft/lbs. I mean, if they really wanted to crank down on it would they have used allens?

Certainly we think the threads bind together. I think the majority of the stick comes from the bottom of the Allen head sticking to the caliper surface. (I think this is also true of the oil filter bolt, and the engine case screws. The proof being that if you drill the heads off, the rest of the screw threads out easily.) This will occur from moisture (condensation cycles) wicking underneath the head and causing a chem reaction.

This could happen regardless of mileage, more a function of how it was stored.

Believing this then makes me doubt the efficacy of using anti seize on the threads. Rather put a thin coat on the bottom of the Allen head.

Just my 2¢. HAsten to add I defer to those with more experience.

754 · « **Reply #13 on:** February 15, 2013, 11:35:35 AM »

Not the head holding it, it is the steady pressure of the threads against one side of the female thread. Oncehead is removed the threads can maybe have clearance and can be moved around, so then .. They come out easily..

Vinhead1957 · « **Reply #14 on:** February 15, 2013, 12:56:34 PM »

Gotta love a happy ending!

HondaMan · « **Reply #15 on:** February 16, 2013, 09:51:42 PM »

There's 2 things that improve the situation "next time", in my experience: 1. A touch of anti-seize on both the threads and the face of those bolts, and/or 2. A small stainless washer (AN type, which has a small OD, found at Ace Hardware) installed with the rounded side toward the aluminum. This prevents the face of those bolts from digging into the aluminum over time. I've also used thin shim washers, which don't make the heads stick out as far, if cosmetics are a concern.

70cbk0 · « **Reply #16 on:** February 17, 2013, 01:51:22 PM »

Thanks everyone.....now I still can't get the cylinder out of the calliper!! it sure is an annoying damn thing!!! Tried hooking up the air compressor to the calliper, no luck.....I hooked the calliper back up and tried just moving it with the front brake/master cylinder, but it hasn't moved yet. Next I guess I'll try the grease gun method.....grrrrrrrr!!!!

754 · « **Reply #17 on:** February 17, 2013, 02:05:35 PM »

Grease wins every time..

Rigid · « **Reply #18 on:** February 17, 2013, 02:16:04 PM »

Pb residue on the threads after it came out? I didn't think so. I have never personally had a fastener loosen from any length of time soaking in any so called penetrating oil. I will also reaffirm what 754 has said, the head corrosion doesn't hold anything. Part of the posters comment was true, it is galvanic corrosion.
As far as the grease gun goes, it will work, be careful, that puck can shoot out with extreme force when it gives way. Best to have it contained in some way.

MCRider · « **Reply #19 on:** February 17, 2013, 03:36:16 PM »

Quote from: Rigid on February 17, 2013, 02:16:04 PM

Pb residue on the threads after it came out? I didn't think so. I have never personally had a fastener loosen from any length of time soaking in any so called penetrating oil. I will also reaffirm what 754 has said, the head corrosion doesn't hold anything. Part of the posters comment was true, it is galvanic corrosion.
As far as the grease gun goes, it will work, be careful, that puck can shoot out with extreme force when it gives way. Best to have it contained in some way.

The grease gun method works for sure. There is no danger either as with air. The piston wil only travel as far as a pump of grease will push it, 1/8" or so. Once it has budged it stops and waits for the next pump.

bjbuchanan · « **Reply #20 on:** February 17, 2013, 08:40:43 PM »

Grease gun is easy and super effective. Its a 5 minute cleanup afterwards, go for it

wvshooter · « **Reply #21 on:** February 17, 2013, 09:01:04 PM »

Quote

I have never personally had a fastener loosen from any length of time soaking in any so called penetrating oil.

Same here with one exception... I've had success heating a stuck fastener with a handheld MAPP torch or an oxy acetylene torch, (gotta be careful with OA not to melt the item being worked on) and then squirting with PB Blaster.

Beyond a certain temperature the PB Blaster will ignite into flame when it hits the item being worked on, so be ready if that happens. The flames aren't too big if you don't shoot too much PBB at one time. Once the temperature of the work gets "right" the PBB will just smoke and evaporate and can be applied several times as the work cools. This method has worked a few times for me.

70cbk0 · « **Reply #22 on:** February 18, 2013, 10:26:38 AM »

Got it out this morning with the grease gun method! Thanks for all your help. It's kinda amazing after all these years the seal inside looks perfect. I had ordered a new one, so I used it, but I wouldn't have been too worried about using the old one again. John.

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Author Topic: Stuck Allen head calliper bolts! (Read 1562 times)