Fastener setting for R1200rt front discs?

[RichardSpag]

Have just replaced my standard front discs with a set of EBC frnot discs. Looking at the Haynes manual it states that the torque setting for the disc carrier bolts should be 24 Nm - however if they are tightened to this value they crush the spring washer (which I presume is there to allow a little "float" and stop the famous brake pulse problem) that sits under the main washers. I guess that

the bolts should be loctited and done up to give a consistent degree of compaction (preload) on the spring washers. Has anyone got the definitive low down on this issue?. I would think that a clearance should be specified for the distance (measureable with feeler guages)of the main washer from the surface of the disc carrier?

 

Cheers

 

Richard

[Ken H.]

Per the BMW manual - Initial torque in a diagonally opposite sequence - 15Nm, final torque - 30Nm.

 

There is no float on the R1200xx disks. The float is at the caliper.

[RichardSpag]

Thanks for the quick resonse. What I find odd about the attachment of the front discs is that as standard, when tapped the discs gave a dull sound and there was some discernable movement if I pulled the disc by hand. Torquing to a final 24N/m (Haynes) the new discs give the more usual high pitch sound when tapped (indicated that they are held hard in contact with the wheel). When torqued I got brake judder. Easing the fasteners off by about 180 degrees (such that the spring washers were not totally flattened), the judder decreased and the note when tapping the disc returned to what it was with the original set of discs!

 

As an aside isn't the only floating caliper on the rear - the front is simply opposed pistons in a rigid caliper mount?

 

Cheers

 

Richard

[T__]

Have just replaced my standard front discs with a set of EBC frnot discs. Looking at the Haynes manual it states that the torque setting for the disc carrier bolts should be 24 Nm - however if they are tightened to this value they crush the spring washer (which I presume is there to allow a little "float" and stop the famous brake pulse problem) that sits under the main washers. I guess that

the bolts should be loctited and done up to give a consistent degree of compaction (preload) on the spring washers. Has anyone got the definitive low down on this issue?. I would think that a clearance should be specified for the distance (measureable with feeler guages)of the main washer from the surface of the disc carrier?

 

Cheers

 

Richard

 

 

 

 

Richard, the 2006 & up RT use a rubberised thrust washer between the disk & wheel casting.. Those rubberised thrust washers were added to the some of the early (pre 06) bikes by some dealers to cure a brake squeal .. Does (did) your bike have those rubberised thrust washers between the original rotors & the wheel casting? Is so maybe those are causing your problem..

 

My suggestion would be to first measure (use a mic or digital caliper) the thickness or the OEM rotors & the EBC rotors at the attachment areas.. If the same thickness & you have those rubberised thrust washers maybe you are compressing those during installation & that is your initial tightness that you notice..

 

If still a mystery call the EBC tec line & talk to them about your issue..

 

No way would those rotor bolts have to be left loose with just Loc-Tite retaining them.. If the bolts can’t be torqued to the proper specs you have an issue that needs to be addressed (either thicker rotors,, or an issue with those rubberised thrust washers,, or the new rotors need special attaching bolts,, or tight is right for the new rotors,, or ????)

 

BTW my BMW RT service manual shows 12 nm initial & 24 nm final torque of rotor attachment to wheel..

 

 

Twisty

 

[Ogri]

The 2005 RT doesn't have a floating disc arrangment. Although there is a wave washer behind the retaining bolts this isnt to allow the disc to float and the disc should be bolted solid to the wheel with the washers fully compressed. 24N/M in my Haynes manual.

 

Around 2006 model year BMW changed the mounting design of the disc to include a rivetted float arrangement in the disc mounting holes which allowed the disc to float on the mounting bolts. The bolts are still bolted solid to the wheel.

 

If you have a brake judder problem my advice would be to buy replacement discs from BMW instead of EBC as I understand the modified type is all they supply now and the float was done to cure early model brake judder.

[RichardSpag]

Ogri,

 

Thanks for that information!

 

Cheers

 

Richard

[Ogri]

Richard

 

My statement above is incorrect.

 

The 05 RT DOES have a floating disc arrangement.

 

Ive had a brake judder problem with my bike since I bought it about 6 months ago but only now have I managed to get to the cause of the problem.

 

The standard disc on the bike should be 4.5mm thick. This allows the retaining bolts to be torqued correctly to the wheel and leaves a small gap for the wave washers to sit in against the disc. This gap is what allows the disc to float.

 

In my case it turns out that the dealer had fitted new discs bought from EBC before I took delivery. These were the incorrect thickness at 5.5mm instead of 4.5mm. This meant that the disc is locked solid by the retaining bolts when torqued correctly.

 

My dealer has contacted EBC and it turns out they supplied the wrong disc due to some mix up in part numbers in the catalgue.

The correct discs have now been fitted, the float is correct and the juddering problem has disappeared.

 

Just a thought but maybe you have the same, incorrect discs, from EBC. Check the disc thickness. It should be 4.5mm

[RichardSpag]

Thanks for the message. In the end I took off my EBC discs and put the old (worn) discs back on again. Instant return to judder free braking! Having read your e-mail I think I'll contact EBC and see what they say (their discs being definately thicker than standard!).

 

Regards

 

Richard

[RichardSpag]

Just measured the thickness of the EBC discs - 5.66mm!

[Ogri]

Seems like you have the same problem I had. I didnt get the full details from my dealer but he seemed to indicate they had ordered the correct discs from the supplier but the part number in the EBC catalogue was wrong. Took a phone call to EBC to sort it out then they replaced them foc.

 

If u need I can have a look at the discs now fitted and try to get u the correct part number.

[RichardSpag]

Ogri,

 

Thanks - I'd appreciate the part numbers. I have dsent EBC an e-mail, so I'll see what they have to say too!

 

Cheers

 

Richard

[Ogri]

Sorry Richard but the part number is stamped on a part of the disc that is obscurred by the retaining bolts and I dont really want to remove the bolts to get at the part number. Probably not much help but the little bit of the part number I can see ends in 03.

[RoSPA_man]

Guys

Assuming I get the correct thickness of EBC disc, do I need to get any fittings from BMW to fit EBC on an 07 RT?

Was the change based on cost only? Do you/can you contunue to use BMW pads?

[Ogri]

Once I got the correct discs from EBC it was a straight fit using the original BMW retaining bolts etc. Yours may vary as the 07 fixing will be different from mine.

In my case the original change was done by the dealer before I took delivery of the bike as he reckoned the discs were below minimum thickness, although with hindsight that may not have been the case. He went with EBC discs and pads as they are a fair bit cheaper than BMW parts.

Having said that, Im now running EBC discs (the correct ones) and pads and the brakes are superb.