caliper bolts

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Hi All, I have a '96 328i. Can anyone tell me what size hex wrench is needed to remove the front brake caliper guide bolts? Also, is it the same size
wrench for the rear caliper? TIA to all!
J
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They're all the same. IIRC, it's 17mm (although I could be wrong and it's 14mm or so...)
Floyd
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Someone not used to the metric system. ;-)
17mm is *almost* 3/4" (0.67") That would be a *vast* allen head bolt.
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On Thu, 22 Sep 2005 11:14:13 +0100, "Dave Plowman (News)"

I've got a 46mm 3/4" drive socket somewhere... Maybe he'd like that. Can't remember what I bought it for, must have been a crank pulley or drive shaft nut on something.
Dodgy.
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If you don't have a 17mm Allen key, use a normal bolt with a 17mm head and lock two 17mm nuts on the other end. I used this to open the oil filler plug on our beetle's gearbox once.
MW
London SW

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Thought he was asking about the bolt holding the calipers onto the wheel assembly... Biggest socket I have is 36mm for the oil filter cap...
Floyd
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Ah - I assumed by the 'hex wrench' he meant an allen key - not a spanner. And you need an allen key for the slides on BMW brakes.

I've got larger than that. ;-)
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7mm. Best to get one to fit a 3/8" socket set. But when the discs need replacing you'll need an 8mm (IIRC) for that so get a set.

Yup.
Don't forget to buy a pad wear sensor at the same time as the pads.
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7mm Mike.
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Thanks to all who posted. Just to clear up the bolt sizes for anyone new to the thread: road wheel= 17mm; rotor to hub=6mm hex; caliper guide bolts=7mm. I removed the caliper and the bolt holding the rotor to the hub but the rotor is stuck fast to the hub. The last brake job was done by the dealer and they have usually done good work for me, so I assume it was installed correctly. I tried to loosen it with a rubber mallet to no avail. I'm hoping to tap into the collective wisdom of the group, once again, for advice! Thanks again to all!

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That's most unusual on a BMW.

Since the only reason to remove the disc is if it needs replacing, hit it with large hammer. ;-)
Make sure the mating faces of hub and new disc are spotless, and use a little copper grease to stop it seizing again.

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Jim wrote:

The disk is trapped on the hub by rust. Try to clean up as much rust along the center hub as you can with a wire brush. You can try using something like PB Blaster on the junction between the rotors and hubs and let that soak in a bit.
Assuming that you are removing the rotors to replace them, hit them harder with a bigger hammer.
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Malt_Hound wrote:

This part is almost pointless except in terms of clearing a path for the penetrant.

Fred is right. You're being much too gentle. You can shoot some penetrating oil of your choice (I tend to use WD-40 or Kroil.) into the bolt holes, too. That distributes it better in there. If you're in the mood and you have a propane torch handy, heat it up a little, but try to stay away from the hub. Heat only the disk hat. I find a sharp oblique blow from a hammer on the hat portion is often enough to break it loose. Remember: you're going to throw this part away, so any damage you do to it is OK. -- C.R. Krieger (BT, DT)
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Thanks guys. And I always thought "Use a bigger hammer" was just a joke! I'll try it tomorrow AM and report back. If it wasn't for frozen hubs this would be the easiest brake job I've ever seen. A well designed set-up I think. It's hard to understand why the dealers get $450+ for the job.
Jim

to
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Best way to mark the ball bearings ! Not a cheap part and not easy to replace ;-((
I never ever use a hammer on mechanics except for body work and for very special cases. If you use WD40 or similar, make sure you don't spray on the seals.

^^^^^^^^^^^^^^^^^^^^
this ^^^^^^^^^^^^^^^^^^
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Don't be silly.

Good for you. But how else are you going to remove a stuck disc? And it won't be stuck like some that may need an angle grinder to remove them.

Which seals?
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Not my problem if you ignore the basic rules ! However I wouldn't bring my car for a fix into your garage !

Have a look o this link http://www.sam-outillage.com/fichemere.asp?index=4&page=1&idf &recherche=m ulticriteres&sf147=on&sf146=on&sf150=on&sf149=on&sf148=on

Callipers, and every seal around, depends on the model and front/rear. Could be between the universal joint to the arm.
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Since I don't fix cars for a living, you're not likely to. But then I'd guess you don't fix them yourself anyway. ;-)

Can't be bothered.

I don't use WD40 for anything. It's just a heavily marketed 'fix all' product which does nothing as well as the correct product for the job.
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On Sun, 25 Sep 2005 22:59:08 +0100, "Dave Plowman (News)"

Oh, c'mon. Penetrating oil has its place in any toolkit. Just like an adjustable spanner does...
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wrote:

The problem with any penetrating oils, WD40, PlusGas etc, is that they are innefective at freeing badly corroded fasteners. It just doesn't penetrate to where it's needed. The Consumer Association, 'Which' carried out some tests some years ago and came to the same conclusion. I've carried out some tests myself once. I found some heavily rusted bolts with nuts screwed on in a shed at work. I left them to soak overnight in PlusGas. Next day I tried to free the nuts. One or two I did manage to free, but noticed the threads in the nuts appeared to be dry, so I washed and dried another couple, and cut the nuts off. The threads were completely dry. Evidence that the PlusGas hadn't penetrated the rusted thread in the nut at all. It may be of some benefit if a fastener has some slight movement, as it's likely that it will then be able to get to where it can provide a little lubricant, but as far as doing what they claim it does, forget it. In a few cases it might help, so maybe because of that it's worth a try, but IMO you'd do just as well with parrafin, (kerosene) or an oil thinned out with petrol. Mike.
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