Front rotor play?

[Stresspuppy]

When I took my wheels off to get new tires put on, I noticed that the rotors had an ever-so-slight bit of play to them. You can wiggle them a little. I would think they should be solidly mounted with no play. Is the slight play normal or do I have a problem?

[Oldrider51]

Is the play is where the rotors mount to the wheels where the buttons are that allow the rotors to float a little then I think that a little movement is ok. My RS at 19000 miles has no play at this point.

[Geekmaster]

That is correct.  The front rotors are floating and hence that bit of play is vital and correct, while the front calipers are fixed.  The back rotor is fixed, while the caliper is "floating".

[Krid]

They are "floating" rotors and are supposed to have a wee bit of play... I would say not to worry! Plus if you're going to be at Start we'll all have a look- see and make sure all is well

 

[Stresspuppy]

Whew! Thought I had a possible issue. And the description of floating front vs rear helps. 
 

Yep, gonna be at START. BoxFlyer gave the bike his thorough once over when I first bought it but extra eyes and input from all the pros will never be turned away. 
 

Thanks for the quick responses and helping me sleep tonight. 😜

[Paul De]

Floating discs, not floating calipers.  It will be one or the other, rotors float in this case.  If they get real sloppy you will likely hear the bobbins/buttons rattling just pushing the bike around the garage and driveway, but unless your 2018 RT was ridden hard as a track bike that is not likely. Maybe a load mule in the mountains could make the bobbins sloppy so early, but doubtful as well. As with any brakes, rattles, pulsing, fading under braking should get a closer look. 

[Stresspuppy]

Does anyone know the torque spec for the bolts/buttons that hold the rotor on the front? I'll check just to make sure all is well.

 

Found that is is 19 Nm so nevermind.

[MikeB60]

I would leave them alone. The bolts have locktite and need to be heated to remove. Without heat you can pull out the threads. I'll be happy to take a look at START but if the rotors are moving that's a good thing.  

[Indy Dave]

18 hours ago, Geekmaster said:

That is correct.  The front rotors are floating and hence that bit of play is vital and correct, while the front calipers are fixed.  The back rotor is fixed, while the caliper is "floating".

This.

[Stresspuppy]

20 minutes ago, MikeB60 said:

I would leave them alone. The bolts have locktite and need to be heated to remove. Without heat you can pull out the threads. I'll be happy to take a look at START but if the rotors are moving that's a good thing.  

 

Well..... in my OCD, since I had the wheels off for the new tires, I wanted to clean up the rims to get all the road grim and caked on stuff off. (Not washing the whole bike, I don't want to jinx the weather for START). Rotors are in the way so I took one side off to be able to get to all the nooks and crannies. Bolts were tight but not too bad, no heat needed. I plan on putting locktite back on when I re-install. I just want to make sure they are torqued properly as one of them coming loose would definitely be a bad thing. 

 

Based on them being floating, I am comfortable with the tiny play that is there when torqued down so I'm not going to worry about them (once I re-locktite them of course).

 

[92Merc]

I've been using these cloths to clean my rims.  Takes any asphalt splatter, bugs, and brake dust off with ease. 

 

https://www.menards.com/main/grocery-home/cleaners-household-essentials/cleaning-supplies/cleaning-wipes/zep-reg-industrial-purple-degreasing-wipes-65-count/zuindprpl65/p-1542007745308-c-1529931701748.htm?exp=false

[MikeB60]

22 minutes ago, Stresspuppy said:

. I plan on putting locktite back on when I re-install

Make sure you get the old locktite off. I start with a thread chaser followed by a wire brush. According to BMW they are onetime use but I doubt they are stretch bolts and have reused them after a good cleaning. Make sure to use red locktite. 

[Stresspuppy]

27 minutes ago, MikeB60 said:

Make sure you get the old locktite off. I start with a thread chaser followed by a wire brush. According to BMW they are onetime use but I doubt they are stretch bolts and have reused them after a good cleaning. Make sure to use red locktite. 

 

I noticed in the manual that they are supposed to be one time use but I'm with you, a good cleaning and re-locktite should suffice. And thanks for clarifying red. 

[dirtrider]

19 minutes ago, Stresspuppy said:

 

I noticed in the manual that they are supposed to be one time use but I'm with you, a good cleaning and re-locktite should suffice. And thanks for clarifying red. 

Evening Stresspuppy

 

Just remember that red locktite (262 or 263) is quite a bit stronger than the micro-encapsulation used on the OEM BMW bolts. 

 

It will hold just fine but if you intend to remove those bolts in the future it will take upwards of 500° F to break them free without pulling the soft alloy threads out of the wheel.  In most cases the  500°f -550°f  heat required for bolt removal will discolor or even ruin the paint on the wheels in the bolt boss area. 

[Indy Dave]

@dirtrider

 

I've never used it, but apparently there's now a yellow locktite, which has the holding properties of red without having to heat up to remove, similar to the blue.

 

@Stresspuppy Just my two cents sir, but don't overthink or complicate. You're just cleaning your wheel, and they're going to be dirty after your next ride whether it's raining or not. So in the end, removing mission critical things like brake rotors - which are generally intended to be mounted only once before being replaced due to wear- isn't really worth the effort in my opinion. There's no reason to introduce potential issues down the road for that 5% extra cleaning, and 20% less effort.

 

 

[Stresspuppy]

4 minutes ago, dirtrider said:

Evening Stresspuppy

 

Just remember that red locktite (262 or 263) is quite a bit stronger than the micro-encapsulation used on the OEM BMW bolts. 

 

It will hold just fine but if you intend to remove those bolts in the future it will take upwards of 500° F to break them free without pulling the soft alloy threads out of the wheel.  In most cases the  500°f -550°f  heat required for bolt removal will discolor or even ruin the paint on the wheels in the bolt boss area. 

 

Thanks @dirtrider. Good info. Should I ever have to replace a rotor I'd prefer not to mess with that much heat or possibly damaging things. Can I get away with Blue?

[dirtrider]

11 minutes ago, Stresspuppy said:

 

Thanks @dirtrider. Good info. Should I ever have to replace a rotor I'd prefer not to mess with that much heat or possibly damaging things. Can I get away with Blue?

Evening Stresspuppy

 

I have been using blue 242 for years & never had one come loose. There is a 246 High Temperature blue Locktite (about the same holding strength as 242) it can be broken free at a little over 400°.

 

The stock micro-encapsulation usually breaks free at just under 200°f. 

 

 

[Stresspuppy]

Just now, Indy Dave said:

@dirtrider

 

I've never used it, but apparently there's now a yellow locktite, which has the holding properties of red without having to heat up to remove, similar to the blue.

 

@Stresspuppy Just my two cents sir, but don't overthink or complicate. You were just cleaning your, and they're going to be dirty after your next ride whether it's raining or not. So in the end, removing mission critical things like brake rotors - which are generally intended to be mounted only once before being replaced due to wear- isn't really worth the effort in my opinion. There's no reason to introduce potential issues down the road for that 5% extra cleaning, and 20% less effort.

 

 

 

This stuff I am trying to clean up is stuck in corners and seams and is almost baked on there. Here is the rear wheel before I started and once I was done:

 

The front has the same stuff and I'm just trying to get that out and put a good ceramic coating on them. They will definitely get dirty again, but should be easier to just hose off and wipe down. 

 

OCD....

 

[Dave_in_TX]

2 hours ago, Indy Dave said:

@dirtrider

 

I've never used it, but apparently there's now a yellow locktite, which has the holding properties of red without having to heat up to remove, similar to the blue.

 

 

The new locktite is orange, not yellow. I have some in my garage.

[Indy Dave]

Yes I meant to say orange! Thanks Dave

[Geekmaster]

@Stresspuppy, just for your information, when reinstalling the front rotors, the BMW service manual says to tighten to 19nm, and specifically says to "tighten by stages in diagonally opposite sequence."

 

Not sure if you already had this info, but wanted to share, just in case.

[Paul De]

FWIW, here is my 2 cents.   I’ve learned the hard way that if it isn’t broke, don’t fix it.  So many times I’ve dug into something that was functioning fine and not requiring service “just to be sure” it was in perfect form, only to mess it up in some way leaving said thing in worse shape than if I had left well enough alone.  YRMV

[Stresspuppy]

1 hour ago, Geekmaster said:

@Stresspuppy, just for your information, when reinstalling the front rotors, the BMW service manual says to tighten to 19nm, and specifically says to "tighten by stages in diagonally opposite sequence."

 

Not sure if you already had this info, but wanted to share, just in case.

 

Thanks for passing along. It’s just habit for me to do things star/diagonally pattern and usually I go through and tighten in stages so I should be good. 
 

49 minutes ago, Paul De said:

FWIW, here is my 2 cents.   I’ve learned the hard way that if it isn’t broke, don’t fix it.  So many times I’ve dug into something that was functioning fine and not requiring service “just to be sure” it was in perfect form, only to mess it up in some way leaving said thing in worse shape than if I had left well enough alone.  YRMV

 

Yeah, I’ve been hit by that 2x4 before myself. I ended up leaving the one side on and then putting back the one I took off. All should be good now, so I just need to get the wheel on the bike and go for a ride with the new shoes! (which is the reason the wheels were off in the first place)

 

I appreciate all the input. I have a tendency to let my OCD leanings take me down some deep rabbit holes at times. Fun going down them, not so fun trying to get back out of them.