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rotor removal


RPG

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Since I'm changing the front tire on my '04 RT, now is possibly the time to re-paint the scratched up rim. does anyone know if the brake rotor fasteners (Torx bolts) are loc-tited, requiring heat before removal?

 

thanks much,

 

RPG

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Straight from the BMW repair manual

 

X Tightening torque:

Brake disc to front wheel

[RS/RT]........................................................ 21 Nm

[GS] (clean thread + Loctite 243).................. 24 Nm

[R] Cast alloy front wheel ............................. 21 Nm

® Spoked front wheel (clean thread + Loctite 243).......................... 24 Nm

 

So it looks like loctite is required for the GS and for spoked wheels, but not the RT. That being said......I think I would at least heat the first one to be on the safe side.

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Afternoon Rick

 

From my latest BMW 1150RT service & repair manual.

 

Front Brake Rotor removal---

L Note:

Retaining screws (1) are secured with thread-locking

compound and should be heated if necessary

before removal.

 

They will usually come out without heating (BUT) the wheels are alloy so without heating the bolts there is always a chance the bolts will pull the threads out of the wheel upon removal.

 

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thanks guys. Tested one fastener last night and it felt like loc-tite had been used so will do the heat routine.

 

Looking forward to new painted wheels and Dunlop RoadSmart II's. (loved the original Roadsmart's).

 

RPG

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Loctite 243 is the blue loctite for removable threads.

If the bolts are large enough (which they are), it can have considerable holding power.

Into alloy with larger size bolts, I would agree to use heat for removable.

The problem is that it requires a bit of heat, where at some stage it will turn into a gooey type substance. Take it too far and it reverts to the opposite again i.e, it starts to carbonize and now locks even worse then it did originally.

Using this stuff for 20 years now in another hobby, I suggest to heat one bolt at a time with a paint stripper gun and after minute try to undo the bolt...if not ready yet, heat it for another 30 seconds..try again...etc.

After the 1st bolt you should have a feel for the bolts.

 

Myself being a over the top for accuracy, would handle the re-mounting in the following way.

 

Clean all the threads and bolts carefully using a mechanical device. (Never found any chemical that would truly remove Loctite..even Acetone doesn't do the job).

Personally for this I use an engineering scribe, where the 90 degree end is perfect for those internal threads.

Finish by cleaning both, bolt and internal thread with a Wax and Grease Remover.

Now re-mount the disks "without" any type of loctite to the correct torque (on both sides of the wheel).

Re-install the wheel on the bike, including the brakes, key on the ignition (if yours has servo brakes) and use the front brake lever a few times to settle the pads onto the disks.

With the front raised, now rotate the wheel and make sure that the disks are spinning evenly between the pads.

If all is well, you can now remove one bolt at the time (with the wheel mounted..no reason to take things apart again) and apply loctite.

Do one bolt at a time and tighten each one straight away back to the required torque.

 

Over-complicated and time consuming???...maybe.

But if you do find an issue, i.e one disk running crook due to warped disk, mating surfaces not 100% clean..etc, you would be really unhappy, having to go through the whole procedure of applying heat..cleaning all the threads again.....

 

 

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Afternoon Rick

 

Remember those are blind holes in the wheel so put just a little LocTite on the bolt threads then use a tooth pick & put a couple of LocTite drops in the wheel holes on the internal threads.

 

What happens with blind holes & LocTite is when you screw the bolt in it pressurizes the hole under the bolt & that escaping pressure forces the LocTite back up the bolt threads so you never know if you retain enough LocTite in the holes to effect proper bolt retention.

 

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  • 4 months later...

At 103,000 miles, the front rotors on my 1999 RT are below minimum thickness, and I have purchased a set of EBC rotors from Beemer Boneyard. The came with new screws for the ABS ring. I'm planning to re-use (with blue Loctite) the existing machine screws that attach the rotors to the wheel, but, with a strong enough recommendation, I could be convinced to replace them with new screws.

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Evening Selden

 

Nothing wrong with re-using the old bolts as long as they are in good shape & the threads are fully cleaned of old encapsulation.

 

Personally I use Red LocTite High Temp 272 (good to 450°f). If you use Blue try to find some 246 (also good to 450°f). The standard Blue 242 found at most hardware stores & auto parts stores is only good to just under 300°f. (brake rotors run HOT)

 

Because the holes in the wheels are blind you need to put some LocTite inside the holes on the internal threads as well as just a bit on the bolt threads. If only on the bolt threads most will just push out as the bolts are screwed in & pressurize the holes. Don't overdue the LocTite, if the bottom of the holes fill the bolts will hydro-lock before reaching proper torque.

 

 

Added: when removing the original bolts use some heat. The original encapsulation is pretty robust & can easily pull the threads out of the wheel if not heated first.

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I thought I would report back on the rotor replacement which, on difficulty scale from 1-10, might be a 2 or 3. Getting the wheel off the bike and past the calipers is far more difficult than replacing the rotors.

 

Tools you need:

  • Heat gun
  • T40 torx bit
  • 3mm hex bit
  • Loctite 237 or Permatex Red

Tools you will want

  • Torque wrench appropriate for 25Nm.
  • M8 x 1.25 tap and die

Use the heat gun on the small screws on the ABS ring first. (Tip: While removing one 3mm hex head screw, hold the heat gun over the screw on the opposite side; by the time you get the first one out, the next will be hot enough to remove.)

 

Same procedure with the T40 bit.

 

Clean both the bolt threads and the threads in the wheel. I used a tap and die to clean the threads; I am not aware of any solvent for Loctite. If you don't have a tap and die, clean the threads as well as you can. NB: If you choose to chase the threads in the wheel with a tap, be very careful not to cross thread; for fine control, I used the naked tap in my fingers.

 

Put a drop of Loctite in each threaded hole, put the new rotor in place (observing that the holes are in the proper direction), and tighten in opposite pairs to 21 Nm. Similar procedure for the ABS ring.

 

Even for a slow-as-molasses shade tree mechanic like me, this is at most a 1-hour job.

 

I bought EBC floating rotors from Beemer Boneyard; they come with one set of new screws for the ABS ring, and the bobbins are pre-installed. The larger bolts that hold the rotors to the wheel can be re-used.

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Nice write up, thank you.

 

Acetone is a solvent for Loctite. I use a thread chaser rather than a tap&die as this avoids the (slight) risk of increasing thread clearance.

 

Andy

 

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Both good points.

 

Acetone was my first thought, but the Loctite site said there was no solvent that would penetrate. I suspect this was a misreading on my part; they meant that you must use heat, rather than a solvent to break threads loose. Once the parts are separated, acetone is probably a safer approach to remove the old Loctite.

 

Thread chasers are difficult to find, although I have read that it's fairly easy to make one from an old machine screw: cut 3 or 4 vertical slots equidistant from each other on the length of the bolt threads, clean up the threads with a die, and voila! The much softer metal of the bolt should pose less of a threat to the aluminum in the wheel (or any other place).

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Afternoon Kent

 

Unfortunately 2701 is about impossible to find in the United States. It is mainly a European offering.

 

2701 claim to fame is it's hot oil resistance. That is not needed in brake rotor attachment retention (that is unless a person rides through boiling hot oil). BMW specifies that 2701 for other engine & drive train locking/retaining tasks so (some) dealers have it handy through BMW stock (that is mostly why they (BMW) specifies it for most high retention thread locking duties. My local dealer doesn't even stock it as they buy most of their shop supplies locally.

 

 

Added: even if your BMW dealer carries the 2701 it is about $18.00 for a small (10ml) bottle.

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