BMW vs. Aftermarket Rotors

[gfx]

I need to replace my rear rotor on my 1988 K75S (no ABS). A new one from BMW is about $410, but I seem to have found an aftermarket company, EBC, who makes one for around $220.

See here:

http://cgi.ebay.com/ebaymotors/EBC-Pro-Lite-Brake-Rotor-84-95-BMW-K75S-_W0QQcmdZViewItemQQhashZitem4cf7f27c6eQQitemZ330577378414QQptZMotorcyclesQ5fPartsQ5fAccessories

Does anyone have any advice or experiences to offer when it comes to using aftermarket vs. BMW rotors?

Any information would be greatly appreciated!

PS: If anyone has changed their own rotors, can you tell me how much work is involved and whether or not it's worth getting someone to do it? My uncle is on the fence about helping me replace the rotor depending on how tedious BMW made the job.

[mystic red]

Why don't you check drake's used parts list? I've got both front and rear rotors from him that were in great condition.

http://www.kbikeparts.com/

They are not hard to do if you want to do them yourself.

[frankenduck]

Aside from getting the bolts that hold the rotor on out, it is very easy and straightforward.

1) Remove rear wheel.

2) Remove rear caliper. (Probably not 100% necessary.)

3) Remove rotor.

4) Put everything back on.

Chances are that you'll have to drill the heads off of the two bolts that hold the rotor in.  BMW used plenty of Loctite on them and even if you heat up the bolt with a cutting torch they will still be hard to remove.

Get the best 1/4" drill bit that you can and it will take less time.

Doesn't hurt to try to unscrew them but you'll probably strips the heads and then resort to drilling them out.

Once you've drilled the heads off there enough threads left to unscrew what's left of them with Vice Grips

You can pick up replacement bolts at Ace Hardware: Countersunk M8x20.

[mystic red]

BMW used plenty of Loctite on them and even if you heat up the bolt with a cutting torch they will still be hard to remove.

If you apply your rear brakes and drive until it catches fire it will develop enough heat to loosen that Loctite. DAMHIK ;D

[frankenduck]

That's only true for paralever bikes where there's a nice rubber boot to catch fire.  Locked brakes would get the rotor nice and toasty on a K75 though.

[HCorn]

I noticed Motobins sells Grimeca rotors, even selling one that is 1mm thicker. 

My rotors are warped and I think I'm about to bite the bullet.  The independant BMW mechanic I sometimes use says OEM ones will just warp again.  The Grimeca rotors run $125-140 which is significantly less than BMWs.  Anybody on here use them?

[HCorn]

I ended up buying the Grimeca rotors (standard ones) and Ferodo pads from Motobins.  Install went fine.  I can't say there is any noticeable difference in performance, although it does stop smoothly without the pulsing now.

I went with the standard rotors because, after researching and some observation, I don't think the rotors were actually warped.   I had read elsewhere about the BMW pads sort of "welding" material to the rotors, especially if put way wet.  I think that may have been the situation with mine.  (although the dark scuffs were 180 degrees apart which may be from warping).  It's also the reason I went with the Ferodo pads rather than OEM.

To soon to make a recommendation, but so far so good.

[Laverda]

BMW used plenty of Loctite on them and even if you heat up the bolt with a cutting torch they will still be hard to remove.

If you apply your rear brakes and drive until it catches fire it will develop enough heat to loosen that Loctite. DAMHIK ;D

Maybe that's why mine came off no problem, as my back brake caught fire. (100% true.  :-[ )

I bid on a brand new EBC one on ebay (Moto-bins or Motorworks can't remember as I use both)
& won it for £100 !!(BARGAIN) It is drilled & floating, & fits perfectly. ;D

[Rick G]

I have used two EBC rear discs and both are in my oppinion are better that the standard stainless ones but they are not stainless and do get e slight coat of rust if you dont ride regularly. Like Lav said just great Mate.

[gfx]

Just wanted to update this thread that I got a new EBC rotor and pad put on the rear. So far it works great and on metal on metal situation is no more. IMO cross-drilled rotors seem like a gimmick, but hey as long as they work...

Sorry BMW, I'm going for the $200 rotor vs. your $420 BS on this one. I tried finding OEM brembo ones but no dice...

BMW $650 parts + labor
EBC $350 parts + labor <--- Winner

[Laverda]

Just wanted to update this thread that I got a new EBC rotor and pad put on the rear. So far it works great and on metal on metal situation is no more. IMO cross-drilled rotors seem like a gimmick, but hey as long as they work...

Sorry BMW, I'm going for the $200 rotor vs. your $420 BS on this one. I tried finding OEM brembo ones but no dice...

BMW $650 parts + labor
EBC $350 parts + labor <--- Winner

IMHO you've made a good/sensible decision. :)

I had a K75 that went through discs quicker than pads.(or so it seemed !)
Fortunately the bike was still warranted & they were replaced with BM ones, but I was never that impressed tbh.

The EBC one I've fitted to my K1100LT seems to be (IMHO) an improvenment over the rear "solid" O.E one.
I will update (on the forum) any issues I have with the EBC.

[Laverda]

Here's the EBC one I bought for my K1100LT.
(The ABS ring isn't fitted on the pic but it does fit ok.)

[Rick G]

On the same line do any of you know if a rear twin spot of an R1100 will fit and work on a K1100 ABS or could it be made to fit?
I reckon it would make for a good upgrade.

[frankenduck]

What's a "rear twin spot?"

[Rick G]

Sorry talkin OZ, a twin piston brake caliper, the r1100 had them and the rear drive looks like it would fit but I don't want to spend unless I am sure it will fit.

[frankenduck]

Sorry talkin OZ, a twin piston brake caliper, the r1100 had them and the rear drive looks like it would fit but I don't want to spend unless I am sure it will fit.

Just my humble opinion but I don't see why you'd want/need more braking power in the rear.  The stock caliper can easily lock up the rear to where the ABS kicks in. With a twin piston rear I think it might be pretty touchy.

[Rick G]

I tow a camper with a fair bit of weight on the rear and find the rear single spot a bit inadequate especially when 2 up and thought it might be a fairly inexpensive way for an upgrade.

[frankenduck]

I tow a camper with a fair bit of weight on the rear and find the rear single spot a bit inadequate especially when 2 up and thought it might be a fairly inexpensive way for an upgrade.

Point taken.  Maybe installing some sintered rear pads would help. (At the expense of burning up the rear rotor a little more quickly.)