Brake rotor allen retainer bolt head stripped
 

Good Afternoon,
Since it's above 40 degrees fahrenheit, I decided to check the back sides of the rotors on one of my BMWs. On the passenger side, the inside facets of he allen bolt are rounded enough so the bolt won't unscrew. Do I go for the drill and drill it out and then hope to grab the remainder with a vice grips once the rotor is off or do I tack weld a bolt on and anticipate I will be able to remove it with a socket. I've drilled them off before but as I recall, it was a wonderful warm Spring day and it took a bit of effort to drill it off. Anyone been there done that lately? I need to get the rotors turned as part of a brake job.

I would tack-weld

You can also drill a hole in the outer shoulder of the screw and use a punch to tap it loose counter-clockwise.

I've drilled off the head. Remove the rotor. Use a vice grip or bolt extractor to get it off. I've found that after drilling off the head and removing the rotor, most of them screw off by hand afterwards.

Or first use some heat and knock a suitable size Torx bit on the rounded allen.

your best bet is to break the rotor off the hub, chisel the remains off the hub and heat the retaining bolt up and use a vice grip to remove it.

"break the rotor off the hub"??? As in smash it off? I hope not because that is the most ridiculous suggestion. Just do as others have suggested. I just did this a couple weeks ago, drilled the head off, rotor came right off than unscrewed the bolt by hand. SMH....

Tack weld a nut to it would be my method. The head is big enough fortunately

your obviously not a mechanic or have any real world knowledge working on BMW's as this is a very common thing we do in the real world. maybe you got lucky no rust of the thread of your locator bolt. what i'm suggesting will work for everyone without drilling, welding or lost time. a new rotor is cheap to replace vs the time needed to drill the bolt out.

with a pry bar you can break the rotor off the hub with a little bit of effort behind the backing plate.
the hat of the brake rotor is the weakest part of the brake rotor so you'll get 99% of the brake rotor off and then you can remove remains with ease.

Ok - that seems like a brutal but solution of last resort. OP - drill he head off - you can use the rotor again, if you have enough meat on it. I’d rather not hit the rotor that hard, and have any collateral damage. In the end, the anchoring screw is not such a key item - the rotor gets sandwiched by the lug bolts between the wheel and the hub. If none of the other suggestions work, then get out your frustration on the rotor.

I think you have proven who is a "mechanic" and who isn't. Anyone that will take a sledge hammer to something and smash it off, putting extreme, not designed loads on bearings, emergency brake system, fasteners, suspension, has no idea what they are doing. Of course it can be done, but is it correct? Absolutely not. Not going to get in a pissing match with you and give examples of the work I have done on my numerous BMWs, Italian, Japanese cars. Just stay the f$%* away from anything I have or will potentially buy! The OP has received all good advice here on a simple problem. Just don't take this donkeys advice!

Can I ask that we give Killcrap a pass on this and move on?

I have scanned a couple of the 20+ pages of his posts on this forum. He is a Tech with a lot of knowledge and like most of us, appears to give more than he takes from this forum.

I didn't like (nor agree with) his smash and break response, nor his "obviously not a mechanic" comment, but I suggest we give him the benefit of the doubt, and a pass, given his long and positive history here.

It is the Holidays after all..

I don't know Killcrap from Jesus, just call me a pacifist.

Happy New Year everybody....

No one wants to sledgehammer a rotor off. But it’s sometimes necessary. Also, techs are generally paid flat rate, so they aren’t going to dick around with a rotor for a couple hours when there’s a fast solution.

Finally, wheel bearings and hubs take much greater loads than that sledge hammer is going to deliver. Smashing the rotor off largely works because they have very little ability to take side loads.

Net-net, the answer is:
1) drill the head out
2) hope that you can get the remainder of the screw out (easiest if you have a welder)
3) hope that the rotor isn’t rust welded on - it happens.

In the dozens, if not hundreds of rotors that I’ve done, i’ve only had to take one off in pieces. But it happens.

I will say, it’s hard for me to imagine turning an X5 rotor. They’re so cheap to buy new, and then you don’t have to worry about how well calibrated the rotor lathe is. (Not to mention the cost of turning, gas to get there, etc.

E53 rotors are at 2x the price of any brake rotors I've ever purchased before. What kinds of cars do you have that E53 rotors are cheap in comparison to? I spent $160 on two third-party front rotors for my 3.0 and am putting them on tomorrow. The last time I bought rotors it was something like $25 a corner for non-OEM parts.



I will admit that local machine shops can't fix a warp in a rotor, and in my experience won't even check for warp before they turn it. But if your rotors are not warped them it saves you at least 50% over the price of a new rotors for an E53.

You can buy a rotor for a good bit less than $80 from a solid brand. Although at least the $80 gets you a lifetime warranty at FCP.

I looked all over (including ebay) and couldn't find anything for much less than about $75 for a front rotor. (I didn't replace the rears because they were barely in spec)

maybe the online translation service you are using is inaccurate. not once did I mention the word sledge, hammer or smashing. maybe in your native language it means something else. nothing wrong if you identify as "The HULK" i like him very much, but maybe lets improve our vocabulary after SMASH! either way I accept your apology and your welcome!

Rockauto. I generally like to pay a few bucks extra for the coated rotors.

Follow up. You guys are most entertaining.
I welded on a bolt after sort of countersinking the heads of the screws.
It was quicker than drilling off the heads.
Additional information for clarification. The were two piece StopTech rotors as part of a gonzo expensive big brake upgrade on my 335i. My favorite machine shop charged $26 each to turn the rotors. Last time I did this I drilled the bolt. Both good options.