i snapped off the lower left caliper bolt changing the rotors on my 86 420 sel, i drilled out the bolt and then actually broke off the easy out, in the hole, not good- i have the hole cleared now but will need to tap it, -- any hints on how not to continue to mess this up? thanks, i am taking the rotors to a dealer to remove the hub- those hex bolts have disaster writen all over them.

I had the exact same problem on my 380SE. I used up a bunch of bits moving up to the final one, which was just a smit inside the diameter of the threads of original tapped bolt hole. At that point, a tap was sufficient to clear the remnants of the old bolt from the threads. I was very lucky, in that the first hole was centered and subsequent drills went in fairly straight. And, I didn't break off an easy-out either (that sucks)!
The hex bolts on the inside of the hub that hold the rotor are actually quite easy to loosen, but only with a good quality, exactly-the-right-size allen screw bit.

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1986 560SL
2002 Toyota Camry
1993 Lexus

Thanks for the reply- the local dealer wouldnt loosen the bolts for me because i didnt buy the new rotors from him- theres customer service for ya- the local auto shop did it for me for free, maybe took him 3 minutes. anyway after digging out the broken easy out, the hole is just a tad off center , i am thinking of helicoiling a slightly smaller size bolt in, the main stress should be mainly sheer resistance so i think this would work but any feedback is appreciated......thanks

There must be Locktite on the stuck caliper bolt. Did you try soaking it with a penetrating oil? I'd recommend doing whatever it takes to remove the remnants of the original bolt and replace it in kind, even if you end up replacing the caliper.

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Fred Hoelzle

Loctite usually cannot be broken using penetrating oil. Almost all Loctite products will break down if exposed to 500 degrees F for 5 minutes. Obviously, one has to be careful of surrounding components with this kind of temp.

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1995 S600, 1 of 618 (sold)

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Try using a propane torch for a couple minutes to loosen the broken bolt, then try another easy out. If you can see the back end of the bolt (take the splash shield off), give it a coule good smacks with a 5 lb hammer and a blunt punch, too.

The propane torch will get it hot enough to melt the locktite without damaging the knuckle -- acetylene torch is way too hot.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

all good advise and much appreciated, i am new to the mercedes world- its a bit more complex than my volvo and way beyond my suburban- Thanks!

pcmaher, thanks for clarifying that penetrating oil has no effect on Locktite. I wasn't sure, but I thought that it might help the stuck caliper bolt situation.

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Fred Hoelzle