brakes Rotor Hex Bit Size Question

[Napes]

Don't want to wait until everything is apart to find I don't have the right size hex bit to remove the rotors, so, I thought I'd ask what size I need.  The Fillister head screws are M10 x 25.

 

Thanks,

 

Bob Napier

[Hans]

Can't give you the number, but it was a common size since I had it in my set.

[Napes]

Maybe I'll be alright, then.  I have 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, and 10mm in my set.

 

Bob Napier

[roadhog0]

I think you're good. I wanna say it's an 8mm...

[Mike Self]

8mm seems to ring a bell with me too...I know that's what E30s use to hold their rotors in place, and it would make sense that BMW would have used the same size screws for a similar job.

 

mike

[Preyupy]

8MM

[Hans]

there you go! I trust you have the PB Blaster at hand. Go slow.

[mike472]

The best thing is to use an 3/8 drive impact driver (the kind you hit with a hammer) with your 8mm Allen bit to loosen them instead of taking a chance on stripping them with a regular Allen key. Clean the holes out good with a little oil and make sure your Allen bit is firmly seated before you try to loosen. I like to tap mine in with a hammer to make sure I have a good bite.

[Napes]

Thx for the tips, Guys.  For Hans:  I use either Wurth Rost Off or Kano Laboratories AeroKroil, both of which have been shown in tests to be far superior to PB Blaster.  I will clean out the holes real well (as I do with the Fillister heads on the half-shafts) and might try easy hits with the air impact wrench.

 

Bob Napier

[Hans]

We just recently got PB Blaster in Canada. Apparently no rusty bits here. I seem to recall using the air gun to get started, then the old out a bit, back in a bit, out a bit more, by hand.

[ray_]

Thx for the tips, Guys.  For Hans:  I use either Wurth Rost Off or Kano Laboratories AeroKroil, both of which have been shown in tests to be far superior to PB Blaster.  I will clean out the holes real well (as I do with the Fillister heads on the half-shafts) and might try easy hits with the air impact wrench.

 

Bob Napier

 

This is always interesting:  http://www.garagejournal.com/forum/archive/index.php/t-200247.html

 

Cheers,

[mike472]

I wouldn't use an air impact wrench.  It might be too powerful and it isn't the same as the hammer driven one.  With every hit of the hammer you are driving the bit in and turning it at the same time. It won't slip.   An air impact gun is only twisting it and if it isn't seated properly or straight you will strip it real quick.  

[Hans]

Good points Mike 472. I use it with trepidation, more to just crack the bolt a bit. Then move to hand tools for more "feel". But yes, important to get bit firmly seated.

[TobyB]

I rattle- gun the suckers all the time.  But I DO tap in the bit with a hammer, and sit on it to get it to break loose.

 

While wearing safety glasses, of course.

 

The real stinkers are the 6mm rear CV bolts- those really want to strip out...

 

t

[ray_]

The real stinkers are the 6mm rear CV bolts- those really want to strip out...

 

t

Yeah, but aren't those not recessed? So you could, perhaps, grab them with vise grips as required?

 

They are indeed tougher than the front CV bolts.