Help! I broke my rotor mount bolts!

[GengeT]

Well firstly, hello all! My first post, and it's a whining one!

My R1200GS with 10K on the clock failed it's MOT a week ago. To top of the day, I dropped the bloody thing turning it on a canter when a car pulled in front on me on an incline... being a short ass my legs dangled in the air and I keeled over. Good buy magnesium heads, but oh well. Anyway; it failed the MOT because my rear brake "fluctuated" in breaking power. Breaking at low speed, you could feel a distinct "judder" as it slowed. This was the break fluctuation.

The trouble is it's ALWAYS been like that. I never thought it was a big deal, and assumed it was nothing to worry about.

From what I've read, a new rotor MIGHT fix it. I ordered one in (£70). Being strapped for cash, I removed the rear wheel at home, got a set of torx (star) sockets and began removing the existing rotor. It was just 5 bolts that looked a little awkward to get at; no problems. Without removing the rotor mount (which I'm terrified too) you only have a small arch at around 7 o'clock on the hub assembly to even reach the rotor mount bolts.

First one undid with some effort; clearly they're set to a high torque. Second one... the fricking bolt threaded. The material seems to be very weak metal (or I'm super strong) so it just gouged out the bolt. Fabulous. Next bolt; that undid OK. Next bolt; threaded.

I'm now totally fricking stuck. Is it a recipe for more DOOM to remove the whole mount for the rotor from the hub assembly? I'm hoping it would be a case of just removing the "gasket" which appears to be holding it in; but I can just imagine and explosion of barings and fluid. I'm to be honest out of my depth, out of cash and totally rodgered.

Is there any schematics available on the net of the rear hub assembly?

Tips appreciated!

 

[Pukmeister]

How to do it the easy way:

Undo and remove rear wheel.
Clean dirt out of disk bolt heads. this prevents the tool from slipping or camming out.
Ensure you have the best fitting Torx tool for the job, smaller ones can seem right but always try the next size up.
Use a blowlamp or heatgun to carefully heat the disk bolt carrier to allow the threadlocker compound to release.
Using the torx tool, undo the bolts easily.

Replacement is the reverse, but be sure to use NEW bolts, a set of 5 will cost £4 inc Vat from BMW. Also check the rear flange for cracks in the disk mounting lugs. Do a thread search on here and you'll find all about it. As you aren't a subscribed member yet you can't search.

FWIW my rear disk was worn and warped, sadly for me the flange was also cracked. Not a cheap day at the office.

EDIT: Here you go

http://www.ukgser.com/forums/showthread.php?t=181453

If you pay the annual site subscription you can search for a mine of information and help.

For schematics you'll need a copy of the BMW Reprom, available to buy on disk from your dealer.

 

[GengeT]

How to do it the easy way:

Undo and remove rear wheel.
Clean dirt out of disk bolt heads.
Ensure you have the best fitting Torx tool for the job, smaller ones can seem right but always try the next size up.
Use a blowlamp or heatgun to carefully heat the disk bolt carrier to allow the threadlocker compound to release.
Using the torx tool, undo the bolts easily.

Replacement is the reverse, but be sure to use NEW bolts, a set of 5 will cost £4 inc Vat from BMW. Also check the rear flange for cracks in the disk mounting lugs. Do a thread search on here and you'll find all about it.

FWIW my rear disk was worn and warped, sadly for me the flange was also cracked. Not a cheap day at the office.

EDIT: Here you go

http://www.ukgser.com/forums/showthread.php?t=181453

If you pay the annual site subscription you can search for a mine of information and help.

Awesome, I appreciate it. Those sneaky engineers, puting in thread locking compounds to thwart the slightly stupid!

 

[Jonnie Boy]

When you say 'threaded' do you mean stripped the thread, or stripped the torx bit out of the top of the screw?

Yes they are locktited in, and I chewed up the torx head on one of the screws. Had to use a screw extractor to remove the knackerd screw . (A bit of heat would have probably prevented this!)

Got new disc fixings when I got new disc so replaced them all with new


All do-able with the final drive unit in place and intact

 

[ianboydsnr]

try heating up with a hot air gun, then tap the head round using a center punch

 

[GengeT]

Hmm, heating the bolt area (ok, the flang itself) didn't seem to help at all. I don't want to risk further damage to the bolts.

I'm ashamed to say I have to admit defeat and I'll need to take it in for some expensive work.

 

[ianboydsnr]

Hmm, heating the bolt area (ok, the flang itself) didn't seem to help at all. I don't want to risk further damage to the bolts.

I'm ashamed to say I have to admit defeat and I'll need to take it in for some expensive work.

it takes a while, heat the bolt head, dont hang around as it soon cools

 

[GengeT]

When you say 'threaded' do you mean stripped the thread, or stripped the torx bit out of the top of the screw?

It's just the torx bit out of the top.

One of the problems I've got is I'm using a 3/8" torx socket, so it has to be a few degrees out to fit in the service arch. Consequently it's not getting the correct bite. I'd prefer some sort of longer tool but with the torque of a wrench... anyone got any nice links to something else?

I know I admited defeat, but I think my old dad would have been ashamed too! So... maybe there is more I can do.

Re : Heating, where should I be directing the heat? At the bolt head, at the flang or at the disk? Is a blow torch too much for this? Is the aim to get it warm only, or hotttt? I'm conscious too much heat could warp or fracture the assembly.

Re: methods to remove the bolts; can someone post a link to one of these screw extractors?

Man. I hate note knowing wtf I'm doing

 

[GengeT]

it takes a while, heat the bolt head, dont hang around as it soon cools

Ah cool ok, that answers the heating question. I would have thought heating the bolt head would expand the bolt, making it sit even tighter. I guess that's counterd by the locktight stuff melting and acting as a lubricant.

 

[Pukmeister]

Don't heat the steel bolt, heat the alloy flange. The release temperature of the loctite is 100 Centigrade so don't nuke it, just gentle warming briefly with a low flame should do it and also be careful to avoid melting the rear ABS sensor wiring.

For Torx sockets, get a set of decent Torx tools if you intend to continue working on your bike, you're gonna need a decent set. My old Draper Expert set have seen sterling service for many years, Machine mart sells an identical set for a mere £26.44, see link below for details:

http://www.machinemart.co.uk/shop/p...older-s/path/screwdrivers-bits-hex-key-sets-2

With any Torx fastener, be sure that when you think you have the right sized tool bit, try the next bigger size before you use it just in case. You'll be amazed at how many times the item you thought was the correct size was actually a little too small and the next size up is the proper item to use.

 

[Big Nick]

Just had a similar problem with a torx bolt head stripping whilst fitting a Touratwat instrument surround, the buggers are loctited in and a bastard to get out even using the right size socket

Couldn't use heat as it was in a painted section of the screen crossbar

Ended up using a drill, screw extractor with tap wrench to shift the thing

A 1 hour job ended up taking 3!!

 

[Magwych]

Couldn't use heat as it was in a painted section of the screen crossbar

When faced with needing heat but not able to use a flame, try boiling water. I use this for most areas that require heat to loosen the loctite. Fill a flask from a boiling kettle and slowly pour over the area to be heated.

 

[GengeT]

Thanks for all the help guys. New set of torx sockets ordered, along with a screw extractor set. I know what I'm going to be doing once I get this sorted; finding somewhere to put all these new shiny tools!

 

[Paul90]

Hi GengeT,
Just my 2p.

If you don't have much experience with these things then I'd would not try using the screw extractors.

Unless you dissmantle the final drive these bolts are not easy to get to. This means it will be hard to avoid some unintended bending force on the extractor. Cheap extractors (like machine mart) snap very easily. They are also very hard to drill out once that happens.

You might find that with a properly fitting Torx and some heat to soften the locktite it will shift. If not try to find someone with some experience to help you out. I'd be happy to help but you are a long way away.

I'd probably be drilling / grinding the head off rather than using an extractor. One of my favourites is to just tack weld a nut onto the head. Takes a few seconds, gives a good hex to drive on and the heat loosens any rust / locktite.

And before people say the aluminium will melt I suggest you try it, not with a gas torch but a MIG welder, amps up high and just a quick burst in the centre of the nut.

Paul

 

[MattW]

Hi GengeT,
Just my 2p.

If you don't have much experience with these things then I'd would not try using the screw extractors.

Unless you dissmantle the final drive these bolts are not easy to get to. This means it will be hard to avoid some unintended bending force on the extractor. Cheap extractors (like machine mart) snap very easily. They are also very hard to drill out once that happens.

You might find that with a properly fitting Torx and some heat to soften the locktite it will shift. If not try to find someone with some experience to help you out. I'd be happy to help but you are a long way away.

I'd probably be drilling / grinding the head off rather than using an extractor. One of my favourites is to just tack weld a nut onto the head. Takes a few seconds, gives a good hex to drive on and the heat loosens any rust / locktite.

And before people say the aluminium will melt I suggest you try it, not with a gas torch but a MIG welder, amps up high and just a quick burst in the centre of the nut.

Paul

Wot Paul says! - I would exhaust every other avenue before I resorted to screw extractors. They once cost me a lot of time and money getting the remains of one spark eroded out of a Honda cylinder head

I've had good success hitting either a hex bit or the next size up torx into a mangled head - not subtle, but can be effective. As others have said, heat is your friend with loctite - I've got one of those little pencil butane torches which is very useful in situation like this.

good luck
M

 

[Phil Clarke]

+3 against screw extractors! everyone I know has snapped one in a bolt. Instead (and if you can) a way better way to remove a stripped bolt (assuming heat and a good fittng torx don't shift the bolts) is to drill a 3mm hole down the bolt (aim to get it as in line as possible - take time over this) and then hammer in another torx bit which is just slightly bigger than the hole. I've removed some seriously siezed studs using this method.

 

[gavin@iow]

Do a thread search on here and you'll find all about it. As you aren't a subscribed member yet you can't search.



If you pay the annual site subscription you can search for a mine of information and help.

Don't need to suscribe to 'search'.

 

[Pukmeister]

I stand corrected, confusing this site with another.

 

[GengeT]

Hi GengeT,
Just my 2p.

If you don't have much experience with these things then I'd would not try using the screw extractors.

Unless you dissmantle the final drive these bolts are not easy to get to. This means it will be hard to avoid some unintended bending force on the extractor. Cheap extractors (like machine mart) snap very easily. They are also very hard to drill out once that happens.

You might find that with a properly fitting Torx and some heat to soften the locktite it will shift. If not try to find someone with some experience to help you out. I'd be happy to help but you are a long way away.

I'd probably be drilling / grinding the head off rather than using an extractor. One of my favourites is to just tack weld a nut onto the head. Takes a few seconds, gives a good hex to drive on and the heat loosens any rust / locktite.

And before people say the aluminium will melt I suggest you try it, not with a gas torch but a MIG welder, amps up high and just a quick burst in the centre of the nut.

Paul

Thanks Paul, and the rest of you for your comments. As it turned out, I clearly wouldn't be able to get access to the bolts with the tools I had. Without removing the rear hub (impossible at home!) I'd need 4" clearance on a 3mm drill bit (good luck finding one, at least where I looked) and a screw extractor of the same length; and that's sure to snap.

So, I admitted defeat; re-assembled, put back in the good bolts and rode it to my local BMW shop (Bath Road). The extracted the bolts within 30 mins, fixed my aftermarket rotor and voila, it passed the MOT. All for (what I thought was good) £120 incl.

I'd still like to improve my mechanical skills; this little adventure has improved my toolset! I also noticed that Nippy's does a Hans manual for the GS.

I think I can feel my GS shuddering at the thought of me doing "things" to it.

Lessons learnt:
1) Always invest in the right tools.
2) Always try the next size up Torx socket.
3) Always heat anything marked as "micro-filament" (i.e. loctite) to 100 degrees before undoing.