Stuck Fillster Head Alternator Head Screw Screw

b25bsaboy · Dec 13, 2013

Stuck Fillister Head Alternator Head Screw

Good afternoon,

Just in from the shop and have taken everything apart in the timing and alternator chest. The Fillster Head Screw part # 12 31 8 002 348 which comes part way and that is as far as it wants to go. I don't want to start forcing it out for fear of damaging something internally. Is there something I am missing in removing this, as I have the Jacking Screw ready to go in to remove the rotor.

b25bsaboy · Dec 13, 2013

b25bsaboy said:
Good afternoon,

Just in from the shop and have taken everything apart in the timing and alternator chest. The Fillster Head Screw part # 12 31 8 002 348 which comes part way and that is as far as it wants to go. I don't want to start forcing it out for fear of damaging something internally. Is there something I am missing in removing this, as I have the Jacking Screw ready to go in to remove the rotor.

Just went back into the shop, had two mouthfuls of coffe and wondered out loud, in that maybe it screws all the way out. Sure enough it is now out and the rotor is free.

Guess there are some days, you wonder why you even get out of bed! :banghead

20774 · Dec 13, 2013

Rick -

I'm not sure, but I'm thinking that the bolt has turned out past the threads in the nose of the crank and has entered the internal threads of the rotor itself. I don't have a good visual right now...someone on the Airheads site had a real great "cartoon" of this operation. But if the bolt has gone far enough, the only thing holding the rotor on is the compression of the taper fit. If you had a way of getting it pushed off, you could then deal with the backside of the rotor and hopefully fix things. You could force some penetrant down the shaft of the bolt...that should get to the threads on the outboard side...maybe soak enough to help out. You might want to protect the rotor from flying off on its own. I might put my hands on the rotor and see if a little wiggling action might free it up...I wouldn't go at it very hard, though.

If someone had a rotor bolt out of their bike, they could measure the grip length and you could use that to see where the threads were in relation to the crank nose and the end of the rotor.

Edit...never mind...all's well!!

kwb210 · Dec 14, 2013

Anything else we can do for you!

b25bsaboy · Dec 15, 2013

kwb210 said:
Anything else we can do for you!

Have patience towards a newby!

lmo1131 · Dec 15, 2013

Rick, not to put too fine of an academic point on it ( I could have said "spin" but that would have been a pun too ), but the "screw" in your post is, or appears to be what is left of a Phillips fillister head screw. Kind of hard to tell for certain.

Virtually all of the online microfiche identify #12 as a fillister head, but it isn't... "fillister" denotes the shape of the head; cylindrical with a slight dome on top. Phillips is of course the type of recess, as does Slot (fillister head screws can be either).

Phillips Fillister head

If the screw in your engine actually is a Philiips Fillister head screw it should be replaced with a socket head cap screw (aka Allen head) for two reasons: 1) it can not be properly torqued to design specs with a Phillips recess, and 2) with the spark plugs removed, the crank shaft can be easily rotated (to set valves and timing) using a standard Allen wrench found in the tool roll.

Socket Head Cap Screw

To remove the rotor you would want use a jacking bolt; either buy, or modify, a socket head Allen bolt as shown below.

EDIT - the image of the Northwood tool I posted yesterday didn't fly this morning, don't know what's up with that. But here's the same thing, basically, with an alternate method as well.

Source: need you ask.... http://bmwmotorcycletech.info/tools.htm

20774 · Dec 15, 2013

Lew -

It looks like an Allen head bolt that has been beat up a bit.

pglaves · Dec 15, 2013

A fully threaded capscrew at that location will beget trouble. I wouldn't use anything there other than an OEM fastener. The OEM fastener has threads for a while at the tip end, then a smaller diameter smooth shank, then the head. As noted by the problem in the original post, the threads screw first through the rotor, and then the fastener slides a ways and engages the threads in the crankshaft. If the fastener is threaded full length it will interfere with obtaining the proper clamping force on the taper on the shaft since threads will be engaged in both the rotor body and the shaft.

krpntr · Dec 15, 2013

The exact same thing happened to me the first time I ventured into the internals on my bike.

But that was a time in the distant past before the internet. After frantically searching for information, thinking I striped the bolt, I lost about an hour of work time scratching my head before I proceeded to continue turning the "striped" bolt figuring I might catch enough thread to back out the bolt and, whatever I broke, I could somehow fix. When the bolt came out it was like a fog lifted, the sun was out and the birds were singing sweet songs of spring when I saw what was going on. To get the rotor off, I took a $.50 1 1/2" X 1/4" hardened concrete nail I had laying about and cut it to about an inch long, cleaned off the burrs, shoved it into the hole and re-inserted the original bolt and screwed it in till the part came off. That nail travels in the tool kit.

b25bsaboy · Dec 15, 2013

Krpntr said:
The exact same thing happened to me the first time I ventured into the internals on my bike. But that was a time in the distant past before the internet. After frantically searching for information, thinking I striped the bolt, I lost about an hour of work time scratching my head before I proceeded to continue turning the "striped" bolt figuring I might catch enough thread to back out the bolt and, whatever I broke, I could somehow fix. When the bolt came out it was like a fog lifted, the sun was out and the birds were singing sweet songs of spring when I saw what was going on. To get the rotor off, I took a $.50 1 1/2" X 1/4" hardened concrete nail I had laying about and cut it to about an inch long, cleaned off the burrs, shoved it into the hole and re-inserted the original bolt and screwed it in till the part came off. That nail travels in the tool kit.

Brilliant!

20774 · Dec 16, 2013

Just be sure that the shank you put in there is well hardened. If the piece bends under load, you won't be having a nice day. You can use a piece of an old drill bit cut down to size. For the garage maintenance, I bought something like what Lew showed from Cycleworks.

SCBuckeye · Dec 16, 2013

lmo1131 said:
Rick, not to put too fine of an academic point on it ( I could have said "spin" but that would have been a pun too ), but the "screw" in your post is, or appears to be what is left of a Phillips fillister head screw. Kind of hard to tell for certain.

Virtually all of the online microfiche identify #12 as a fillister head, but it isn't... "fillister" denotes the shape of the head; cylindrical with a slight dome on top. Phillips is of course the type of recess, as does Slot (fillister head screws can be either).

Phillips Fillister head

If the screw in your engine actually is a Philiips Fillister head screw it should be replaced with a socket head cap screw (aka Allen head) for two reasons: 1) it can not be properly torqued to design specs with a Phillips recess, and 2) with the spark plugs removed, the crank shaft can be easily rotated (to set valves and timing) using a standard Allen wrench found in the tool roll.

Socket Head Cap Screw

To remove the rotor you would want use a jacking bolt; either buy, or modify, a socket head Allen bolt as shown below.

Be sure if you do it yourself, by buying a bolt and grinding off the threads as shown, purchase a bolt that is a higher grade than soft as explained by Kurt. You don't want that end to mushroom or bend in the process. Most bolts in general, purchased at the hardware store are as soft as butter. Ask for harder bolts or a higher grade.

b25bsaboy · Dec 16, 2013

lmo1131 said:
Rick, not to put too fine of an academic point on it ( I could have said "spin" but that would have been a pun too ), but the "screw" in your post is, or appears to be what is left of a Phillips fillister head screw. Kind of hard to tell for certain.

Virtually all of the online microfiche identify #12 as a fillister head, but it isn't... "fillister" denotes the shape of the head; cylindrical with a slight dome on top. Phillips is of course the type of recess, as does Slot (fillister head screws can be either).

Phillips Fillister head

If the screw in your engine actually is a Philiips Fillister head screw it should be replaced with a socket head cap screw (aka Allen head) for two reasons: 1) it can not be properly torqued to design specs with a Phillips recess, and 2) with the spark plugs removed, the crank shaft can be easily rotated (to set valves and timing) using a standard Allen wrench found in the tool roll.

Socket Head Cap Screw

To remove the rotor you would want use a jacking bolt; either buy, or modify, a socket head Allen bolt as shown below.

Morning Lew,

Trust you had a good weekend and not covered in too much white stuff.

Thank you for the lesson in English grammar, however according to the MAX BMW Web Site fiche the term is Item #07 12 31 8 002 348 FILLISTER-HEAD SCREW 0.04 1 $14.75ADD TO CART. I agree that it should be called an Socket Head Cap Screw/Hardened Steel, but I didn't write the parts description. :blah

b25bsaboy · Dec 16, 2013

jimmylee said:
Be sure if you do it yourself, by buying a bolt and grinding off the threads as shown, purchase a bolt that is a higher grade than soft as explained by Kurt. You don't want that end to mushroom or bend in the process. Most bolts in general, purchased at the hardware store are as soft as butter. Ask for harder bolts or a higher grade.

JimmyLee, Totally agree and I will only buy OEM BMW Parts for this particular application.

SCBuckeye · Dec 16, 2013

b25bsaboy said:
JimmyLee, Totally agree and I will only buy OEM BMW Parts for this particular application.

I also agree to use OEM on the assembly SHCS, but I was referring to the "jack" bolt being purchased locally.

lmo1131 · Dec 16, 2013

I agree that it should be called an Socket Head Cap Screw/Hardened Steel, but I didn't write the parts description.

I noted that.

Virtually all of the online microfiche identify #12 as a fillister head, but it isn't...

It looks like an Allen head bolt that has been beat up a bit. .

and...

the "screw" in your post is, or appears to be what is left of a Phillips fillister head screw. Kind of hard to tell for certain.

just so we're clear

pglaves · Dec 16, 2013

I have figured out precisely what that fastener is. It is one that ought to be replaced.

SCBuckeye · Dec 16, 2013

PGlaves said:
I have figured out precisely what that fastener is. It is one that ought to be replaced.

Do ya think?

That is definitely one you want to be like new - the allen socket, that is. It would be a horrible bolt to have to drill out if the allen wrench wouldn't grab it!

Jeff488 · Dec 16, 2013

Paul always cuts right to the heart of things.

b25bsaboy · Dec 16, 2013

lmo1131 said:
I noted that.

and...

View attachment 42790

just so we're clear

Hay Lew,

Here are some better pictures of the infamous bolt that we are discussing. Was looking at a BMW workshop manual from the factory and they are calling it a cheese head hex. So for now I will just say I agree with all who have commented and a new one is on order from by local BMW dealer.

This one is a side shot.

Shot of the top of the bolt and this may explain why all the confusion is the PO didn't have the correct tool back in the day! I am surpassed it even came out.

Lew, Paul and the rest, Thank you for your input!

Stuck Fillster Head Alternator Head Screw Screw

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