Time for a new front rotor, what about the rivets?

[lukemike]

I'm getting my feet wet by jumping all the way in the ocean here... starting to do a little bit of a rebuild on my 81 R65... first things first, ticking off some of the necessary items, ie. new brakes.

To start with, I removed the front wheel and the disc/hub assembly (single disc system).  What I knew before I started is that there are rivets holding the disc to the hub.  I have searched Google far and wide and cannot for the life of me figure out if I can remove these rivets or not.

Here in Sydney, the front disc from BMW is noticeably more expensive than say, an alternative, like one manufactured from NG. However, from what I can gather from BMW fiche, a replacement includes the hub assembly as a unit... vs NG only sells the disc. (forgive the image quality, slightly blurry)

This bike has the Brembo calliper.

Thoughts from all you experts out there?  :-/

[Bob_Roller]

You can drill the heads off of the rivets and then use a punch to remove the remaining rivet shank .
But I don't know what your replacement rotors will require to get them mounted to the old hub .

[montmil]

There are replacement discs available from several vendors. Some require that you ship the disc and hub to them. others provide proper nut n' bolt replacements for the rivets. EBC is one source that comes to mind.

To answer your rivet removal concern, the rivet heads are ground off and a punch is used to drive out the shank; being cautious to care for the carrier component. As you are replacing a well worn brake rotor, any nicks from the grinder are of no consequence.

I've not done a disc replacement on either of my R65s but did find a like-new, sans grooves disc-hub that I installed. Hopefully, a couple members will respond with additional help.

[Bob_Roller]

I had two old rotors modified by this company in the US .
The hub was machjned and then a semi-floating disc was added to it .


http://spieglerusa.com/brakes/bmw-rotor-conversions.html

I also have a set of EBC steel rotors on my '81 R65 along with a their graphite pads ,
Have not noticed any increase in dry baraking capability with this setup, but wet braking is greatly increased .

[lukemike]

Thanks for the feedback guys.

Glad to learn I wasn't crazy looking at the replacement options - knowing I'd have to grind off rivets is helpful.

I'll look at some local shops here in Sydney, perhaps I can drop it buy a shop and they can fit a semi-floating setup with appropriate hardware and get matching pads.

I'll post an updated photo once complete. Cheers

[Bob_Roller]

If by chance you go with new rotors, there are two different rotors for the R65, the ' snowflake ' wheels take a deeper hub or carrier, than the ' composite ' wheels of the LS model bikes .

[Burt]

An option is this mob in Brisbane.  

http://metalgear.com.au/view_model_details.php?model_id=1456

I have not used them but others have.  

Cheers, Dave.  

[Kookaburra]

Other alternative is to buy the whole rotor assembly (which is what i did, an after market part). Then it is only a matter of dealing with the five bolts. More expensive of course but then there is no stuffing around with rivets, either getting them out or getting new ones in! I am now running with EBC brake pads.

Check out Munich Motorcycles and/or Motobins for these parts by mail order.  

[Julio A.]

When I was in Australia back in December, I was introduced to a BMW specialist shop in Rydalmere called Motohansa. They sell brand new and 2nd hand parts. When I was looking for parts for my brakes, he told me he could replace the Brake rotors with the original spec or convert them to semi-floating. But it would take them at least a week to do it since they ship it elsewhere to be done.

And just like Dave said, there's this company there called Metalgear in which you pay them the money, send your whole rotor assembly to them, then they they send it back to your refurbished.

[montmil]

Do be advised that the stainless front rotor may be ground to remove the ridges only if the re-worked disc is still greater than the BMW specified minimum thickness. The danger is having cracks form between the drilled holes and the rotor breaking -not braking- during operations.

[lukemike]

Late reply to close out and update... I went through ProCycles in St Peters and they shipped off - now semi floating front disc.  Fantastic - and well worth not grinding off rivets.

Cheers

[Tony Smith]

An option is this mob in Brisbane.  

http://metalgear.com.au/view_model_details.php?model_id=1456

I have not used them but others have.  

Cheers, Dave.  

Absurdly expensive!

Motobins will sell and ship complete Grimeca disc assembleys for less than you can buy a new disc alone from Metalgear.


I especially feel the loss of Don Wilson in Sydney, the guy had a seemingly endless supply of ex-council manhole covers that once you removed the bits that didn't look like disc rotors, give long and brilliant service. I have three of his discs and whilst occasionally I do wish that cast iron didn't rust so fast, the braking performance reminds me why i bought them.

[mrclubike]

Motobins has been out of the Deep Grimeca disc  for a while
I need a rotor also and wondering how long it will be be for they get them in again  

[Tony Smith]

Motobins has been out of the Deep Grimeca disc  for a while
I need a rotor also and wondering how long it will be be for they get them in again  

Hmmm. You are correct.

I would go to your local metal recycler and buy a cast iron manhole cover and then take it to the engineering firm of your choice and have them make you one or two discs. The actual machine time is not excessive, if they have a blanchard grinder they can finish them to a high standard, but if not a belt sander such as is used for cylinder head re-facing will produce a perfectly useable item.

[Tony Smith]

I know that others have responded to this, but here is my two bob's worth having done a number of these.

Firstly, do not touch the heads of the rivets, you don't need to and you run the risk of either slipping onto the alloy casting or worse, expanding the rivet head makign them difficult to get out.

If you are changing rotors then your existing rotor is sacrificial - use an angle grinder to grind off the base of the rivets to a point that is below the surface of the disc as a whole.

Next find a lump of timber that, once you have drilled a hole bigger than the rivet head in it, fits nicely under the carrier and supports it to a certain extent either side of your target rivet.

Using a hardened pin punch and light ball-pein hammer (or better a light "dead-blow" hammer if you have one) gently tap the rivet base, slowly escalating the force involved - the object being to use no more force than is absolutely necessary to drive the rivet out - my experience is that only very light taps are required and that some of the rivets will kind of fall out once you get them started.

replace the rivets with correctly sized high tensile steel bolts and use locktite green.