Gosh darn it!

[ShutterPilot]

Ok, not the words I've really been using...
Performed, or I should say, started, the rebuild of the 2 ATE calipers on my '81 R65. The right side, which was the side that was frozen up, came off and came apart with little resistance. After hours (literally) of scrubbing and cleaning, I had a very clean and serviceable caliper that took the rebuild bits-along with the little o-rings from Mike V-just fine. There was some pitting on the pucks, but above the seal line so I dressed 'em up and reinstalled. All's well says I.
Then came the left side. I was stymied in minutes. The 2 bolts mounting the caliper to the fork leg loosened just fine by hand, and the top 8mm hexbolt holding the caliper halves together broke loose too.
But the lower bolt was another story. I was initially being careful, as it looked a little rounded by a previous owner, but no amount of pressure using a breaker bar would pry it loose. Hours of liquid wrench, PB blaster, and heat from a propane torch only yielded a severely buggered head. As this head is the one that stands proud, I even tried locking it in a vise and rotating the caliper around it. No joy.
I'm ashamed I let it degrade this far, but it ticked me off that bolt wouldn't give up.
I really think some PO musta JB Welded that bolt in there.
Sigh.
In defeat, I'm off to Peter Bombar tomorrow to see if it can be tapped out. I need the leprechauns on my side for this one.

[steve hawkins]

I feel your pain, I really do.

Hang in there.

Rev. Light

[Luca]

I had to drill through the end of one of the bolts on the other side of the caliper and then weld a big grade 8 nut onto the buggered head.  Then I took the whole thing to my brothers and had to use the impact gun on the nut with the caliper in a vise.

Would have been impossible without the air tools, unless maybe I had tried using more heat and oil.

[ShutterPilot]

Hi all,
Bolt is out and the caliper survived in great shape. After going thru a couple bits trying to drill-press it out (some super hard steel in there), they eventually got it out using a bolt-head Grip Fastener removal socket, big enough to go over and grip into the head. After heating to about 350º, she broke loose. No locktite or glue evident - just torqued in there real good. They popped both pucks and dropped the metal bits in the parts cleaner for good measure, and provided a replacement bolt (which I'll be using anti-seize on installation, thank you)
Kudos to Bombar's Beemers for successfully helping me with this.

[Barry]

Good result !

Surprising that they should have been torqued up so much. The caliper is alloy after all, good quality no doubt but still alloy so torque should not be too high. We have a had a couple of threads over years questioning the correct torque value because it doesn't seem to be listed anywhere. What are you thinking of using at assembly ?


I just checked back and I only used 15 ftlb out of sympathy for the materials involved and it hasn't been a problem.  It might not seem much but I didn't dare exceed it as the normal value for 8.8 M8 steel threads is only 18 ftlbs. If I had to decide again I might go for a touch less.

[Luca]

It's not the initial torque that's the problem, it's the 30 years of galvanic corrosion.  I have pretty good reason to believe that my caliper bolts were never touched, but they were an absolute bear to get out because the threads were so clogged up with corrosion.

Got some good hard allen bolts from the local big box hardware store to replace the originals, but one of these days I'll go back and replace them with some SS, as the black oxide fasteners start rusting when it's raining in Cleveland.  

Maybe I'll ask Mike V to send me some replacement rubber washers while I'm at it...  Oh wait, they're not washers, they used to be round o-rings!

[Bob_Roller]

I've found that the use of an impact gun, just a short second or two burst, will get bolts free .

Seems like that shock helps break the bond between the two parts .

But not such a good idea, if the head of the bolt is already comprimised .