300SE 126

while removing the front brake caliper the upper retaining bolt snapped .Need advise on a replacement bolt and removing the broken stub in the carrier .the stub is flush ,no protusion to get a grip.
Thanks
mak

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mark

There are several ways you might rescue this. For all, suggest using lots of PB-Blaster or Kroil to chemically allow some loosening. Also, some heat on the carrier may be helpful. Note that, not being immediately familiar with your exact solution, my suggestions are somewhat generic and apply to any bolt that has broken off inside something.

First, drill it and use an easy-out. Be very careful about the easy-out, they are extremely hard but also very brittle. You have to have a straight shot at the easy-out, or it may bust off in the bolt and they yer screwed 2x.

Second, it's a through hole, drill the bolt and the heat and vibration may be enough to loosen the grip and it will spin right through with the drill bit.

Third, and if the hole isn't through, many of us nowadays have reversing drills. If not, a cheapo at WalMart may be enough... _IF_ you can find a reverse drill bit. The bit should be a little less than the diameter of the bolt so you don't cut the threads, but often if you can find such a thing, the heat and vibration of drilling will be sufficient to back out the busted bolt.

Once in a while you can weld "something" to the bolt that will be sufficient to turn it out.

There is also, rarely, a machine shop service that uses some kind of high voltage magic to remove bolts frozen in. You'd have to contact a machine shop for this to see if they have it, and take the part to them. The likely means disabling your car for a while, but you're at that place already.

As for another bolt, the dealer is the place to go for mission-critical parts. You may be able to read the hash marks on the bolt head and determine the grade of the bolt and get it at a hardware store, but BE SURE that you get at least the same grade. DO NOT substitute any common galvanized or coated bolt simply because "it fits". DO NOT use anti-sieze upon reinstallation unless MBz does it that way.

Mark, best to buy a replacement bolt at your local MB dealer. Call ahead so you're sure they have that specific caliper bolt in stock. You want to use only high grade parts in the braking system.

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Fred Hoelzle

Thanks most helpful advise . now to get all the required items for the operation and have a go at it.
Regards
mak

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mark

took quite a effort and eventually it came out.replacement installed.
mak

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mark

You're supposed to replace them all EVERY time you remove them. Just check WIS.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles