Author Topic: K100 Aftermarket Rotors  (Read 6989 times)

Offline 1991K100RS

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K100 Aftermarket Rotors
« on: July 12, 2014, 08:28:57 PM »
Hey all,

The front rotors on my 1991 K100RS are wearing thin and need to be replaced. I pulled up the BMW microfiche for 1991 K100RS and I find that there are part numbers for ABS rotor and one that doesn't show ABS.

My bike is ABS. I am interested in buying aftermarket - EBC Brake Rotors - because they are significantly cheaper. I'm looking at these;

MD607RS Rotor
http://www.amazon.com/EBC-Brakes-MD607RS-Brake-Rotor/dp/B006B29IRM/ref=sr_1_2?ie=UTF8&qid=1405211191&sr=8-2&keywords=MD607RS

MD611 Rotor
http://www.amazon.com/EBC-Brakes-MD611-Brake-Rotor/dp/B006B25Q1O/ref=sr_1_2?ie=UTF8&qid=1405211245&sr=8-2&keywords=1991+k100+rs+brakes

Are the right and left rotors different? I see these 2 listed as fitting my bike... but not sure if I need 1 of each, or 2 of the ABS type rotor. Any insight on these is appreciated :)


Offline kioolt

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Re: K100 Aftermarket Rotors
« Reply #1 on: July 12, 2014, 09:05:13 PM »
By looking up the oem brake disc numbers for a 90-92 K100RS with and without ABS at Max BMW, I see that the right hand disc has the same part number for non-ABS and ABS.  I would get from this that you should order one of each.  Take a look here to decide for yourself.  The left hand side where the ABS ring is are different.
2018 R1200RT 8,000 miles,2004 R1150RT 189,000 miles
1991 K100LT 128,700 miles,1982 R100RT 106,900 miles
The cheapest thing on a BMW is the nut that connects the seat to the handlebars.

Offline johnny

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Re: K100 Aftermarket Rotors
« Reply #2 on: July 12, 2014, 09:07:24 PM »
rs = right side

ls = left side

md611 = back side

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Offline kioolt

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Re: K100 Aftermarket Rotors
« Reply #3 on: July 12, 2014, 09:24:18 PM »
I took a look at the EBC catalog online.  http://www.ebcbrakes.com/Assets/ecatalogues/2014-US-MC-Catalog/2014-us-mc-catalog.html#p=78

It confirms the above post about RS = right side and LS = left side.
2018 R1200RT 8,000 miles,2004 R1150RT 189,000 miles
1991 K100LT 128,700 miles,1982 R100RT 106,900 miles
The cheapest thing on a BMW is the nut that connects the seat to the handlebars.

Offline Scott_

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Re: K100 Aftermarket Rotors
« Reply #4 on: July 12, 2014, 10:00:07 PM »
Adding to the notes in the catalog page, you will have to re-fit your ABS rings to the new rotor carriers.
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Offline 1991K100RS

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Re: K100 Aftermarket Rotors
« Reply #5 on: July 13, 2014, 12:54:38 PM »
Makes sense - RS and LS for right side and left side

MD607RS / MD607LS to change front rotors. I'm going to buy a set on amazon for $400. Significantly cheaper than OEM (but still not cheap....)

Thanks guys! Cheers

Offline wmax351

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Re: K100 Aftermarket Rotors
« Reply #6 on: July 13, 2014, 01:12:34 PM »
I've got a set of used rotors that still have some meat on them, if you're interested. If you use organic pads, they should be good for a long time.
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1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
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Offline 1991K100RS

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Re: K100 Aftermarket Rotors
« Reply #7 on: July 13, 2014, 03:35:15 PM »
Im using OEM BMW brake pads for the front, just bought a new set. I'll message you about the rotors

Offline Inge K.

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Re: K100 Aftermarket Rotors
« Reply #8 on: July 13, 2014, 03:51:38 PM »
If the brake discs Vmax have is from a K75, they won't fit a -91 K100RS.
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Offline wmax351

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Re: K100 Aftermarket Rotors
« Reply #9 on: July 13, 2014, 05:54:41 PM »
If the brake discs Vmax have is from a K75, they won't fit a -91 K100RS.


I just realized that too. The 91 k100 is a 4v
  • Ann Arbor, MI
  • 1991 BMW K75 Standard, Refreshed '94 engine
Bikes:
Current:
1991 BMW K75 Standard, Refreshed '94 engine


Past:
'83 BMW R65LS (An R65 with a prototype K Bike Front End)
'75 Honda CB550F
'69 Honda CB175
1999 Royal Enfield Bullet 500 (Last month of the original '55 model)
1973 Triumph Tiger TR7V (5 speed, Right Shift, Disc Brake)
1971 BMW R75/5 in Toaster outfit
1979 Harley Davidson XLS-1000 Sportster Roadster

Offline jacksdad1963

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Re: K100 Aftermarket Rotors
« Reply #10 on: July 14, 2014, 06:25:12 PM »
From what I can see, both front brake discs/rotors are basically the same: the LH one has predrilled holes for the ABS ring, but would work as a RH disc...are the non ABS discs the same size as ABS? if they are you could swap them about a bit, depending on your bike spec, and what parts are on reduced price offers!
Can you get just the brake disc part that the pads bite on? no need to replace the carrier parts on floating brakes, or all the fixing bobbins, washers and circlips!
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Offline tg4360

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Re: K100 Aftermarket Rotors
« Reply #11 on: July 20, 2014, 10:57:27 AM »
What's different is the drill pattern.

Other than that, you could actually use two lefts or rights and it'd not be a big deal........ except.......

I found (before I GS'ed my bike) that the brakes pulsed slightly while coming to almost a complete stop.  The lever didn't pulse but the apparent friction did.

I thought about it after reinstalling the rotors on my new spoked rim (Lucky me I could re-use them) and when looking at it, you can index the drill pattern so that they are "in phase" or "out of phase" it seems.  In other words, looking ACROSS the disks at each other, the holes are either lined up or not.

I think that they were in phase so the friction changes between drilled and undrilled were passing both pads at the same time.  Now they are out of phase and it doesn't "pulse".

Bottom line, if you got a really good deal on two lefts or rights, I wouldn't turn it down.

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Offline jacksdad1963

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Re: K100 Aftermarket Rotors
« Reply #12 on: July 20, 2014, 01:58:55 PM »
Interesting theory....
My K1100 had a bad judder when coming to a stop: nothing wrong with the brakes tho...apart from the RH pads being full of fork oil!
I replaced the fork seals when I bought the bike, didn't realise the leaking oil had got down to the the pads on the RHside  :2thumbup:
New EBC HH pads have cured the problem, along with de-greasing the rotor: this took longer than expected as every hole was full of grease-like crap! In the end I stripped the wheel, removed the disc from the mount and washed out in boiling water...didn't want to ruin expensive new pads, but now its stunning! New HH pads on grease free discs are amazing....
K1100LT 1995 mystic red
Yamaha XS650 1976 fully restored
a few cars and 4x4's

Offline Scott_

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Re: K100 Aftermarket Rotors
« Reply #13 on: July 20, 2014, 06:36:33 PM »
....... New HH pads on grease free discs are amazing....

Just some food for thought for you, using the HH sintered pads will wear the disk's faster than the original organics. Yes you will have much better stopping power, but shorter disk life.....YMMV
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1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline johnny

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Re: K100 Aftermarket Rotors
« Reply #14 on: July 20, 2014, 06:43:29 PM »
im getting 40 thou mileage outta ebc organic brakes pads... aints never changed a disk cause it was thinn...

fa18 rears...

fa407 fronts...

j o
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Offline 1991K100RS

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Re: K100 Aftermarket Rotors
« Reply #15 on: July 22, 2014, 01:58:24 PM »
I ended up buying the EBC right and leftfront  rotors from amazon for $200 a piece and OEM front brake pads for both front calipers.

Had to use a torch on the bolts to remove rotors from wheel, and ABS disc from left rotor... but otherwise, didn't take too much persuasion. Worked well. Thanks for sharing your thoughts guys!

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