BMW K bikes (Bricks)

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robmack

robmack
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Hi,

AFAIK the rotor size for the K1200LT front brakes is 320mm and uses a 5 hole attachment directly to the wheel.  The K1100 rotor is 305mm and uses a 6 hole attachment through a carrier to the wheel.  So far, so good.

This photo shows a K1200LT wheel on a K1100 yet there is no adapter fabricated for the 4-pot Brembo calipers; they bolt directly on the fork stanchions despite the 15mm rotor diameter difference.

K1200 front rotor on K1100 forks (size and bolt hole differences) K11og_k12wheelconv_03_b

There isn't a lot of headroom under the caliper even with the K1100 rotors, as this picture demonstrates:

K1200 front rotor on K1100 forks (size and bolt hole differences) Brake%25205

Is there some "trickery" to accomplish this?

My interest in getting an answer to this question is driven by the idea that I might perform this K12 wheel swap on my K75.  There is a local seller offering a K12LT wheel at a good price. The reason is partially to get access to a selection of wider radial tires and partially esthetics.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

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Interesting topic. Trouble is that there were a number of different wheels on Ks. I thing that the RS and the LT had 17" and 18" fronts with different widths.
I would like to change the rear on mine from an 18" RS wheel to a 17" wheel but the LT one is too narrow. I wonder if the 1200 has a 17" and if it would bolt onto my bike. I could try and nick the 17" from the back of the wifes F800, but she might notice.

    

K75cster

K75cster
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They may have skimmed 7mm off the rotor just to fit?????????


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

Rick G

Rick G
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I recall seeing a K1100 with K1200 wheels and the calipers needed to be spaced back to fit but I cant even remember the guys name but I do know he came from Sydney so that narrows it down to only 4 million people.
Of course the big problem is which model 1200 there are so many wheels.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1986 K75 GS.
    

Two Wheels Better

Two Wheels Better
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The only size front wheel ever put on the K1200RS/GT series is a 3.5" x 17". The K1200LT uses a different part number on the same size 3.5 x 17 wheel bit it's only down to the paint. They're the same wheel as on R1150R & R1100S but those bikes have a speedo drive gear on the LH side. All use the same bearing sizes and axle shaft. There's a caliper change with the EVO brakes about late-2001. All are Telelever front ends as well.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

robmack

robmack
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I believe early model K12LT and RS wheels will fit better than late model.  Also, K12LT front wheels are better than K12RS front wheels (suppposedly stronger, less easy to bend) and 5" K12RS rears are better fit than 5.5" K12RS rears.  The latter requires skimming the walls of the drive shaft housing and substantially modifying the centre stand.

I have a line on 2001 K12LT front wheel.  I need to find a 5x17 K12RS rear and K12 rotors.  But it sounds like I'll still have to space out the caliper from the rotor, meaning I'll need to design and have built an adapter plate.  This is a long term project for me and I'm just slowly collecting parts and planning my strategy at the moment.  I'm interested to find out if I should pull the trigger on this wheel or wait for one that is even earlier.

BTW, I have dimensioned drawings for the front axle that needs to be machined to adapt the K12LT wheel to the K1100 forks, if anyone is interested.  PM me for a copy.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Inge K.

Inge K.
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RicK G wrote:I recall seeing a K1100 with K1200 wheels and the calipers needed to be spaced back to fit but I cant even remember the guys name but I do know he came from Sydney so that narrows it down to only 4 million people.

"Ausbrick".


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

robmack

robmack
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bikerboy wrote:Interesting topic. Trouble is that there were a number of different wheels on Ks. I thing that the RS and the LT had 17" and 18" fronts with different widths.
I would like to change the rear on mine from an 18" RS wheel to a 17" wheel but the LT one is too narrow. I wonder if the 1200 has a 17" and if it would bolt onto my bike. I could try and nick the 17" from the back of the wifes F800, but she might notice.

As I mentioned, from the research I've done so far (and realize I've never even handledd a K1200 part), K12RS rear wheels come in two sizes, 5x17 and 5.5x17.  They are also available in two different rear rotor mounting configurations, the early ones being the same as the K100/K1100.

I understand that some fiddling is needed to make the rear work well but they are direct bolt-on replacements.  The wheel has to be spaced further from the final drive (use 2 shims instead of one).  The bolts need to be changed because the K100 bolts are too long.  The centre stand has to be widened or removed altogether to accommodate the wider tires available for the 5" K12 rim.  Because of the smaller rim diameter and the availability of low profile radials for such, it may be necessary to raise the length of the rear shock to restore the bike's stance ( or lower the front forks in the triple tee).

BMW may have used the same rims on different model bikes (R-bikes, K-bikes) but I've never done research into part numbers to confirm that hypothesis.  I'm sticking with what others like Beachcomber, and Ausbrick have succeeded in doing.



Last edited by robmack on Thu May 22, 2014 6:14 pm; edited 1 time in total (Reason for editing : corrected some text; spelling)


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Robert
1987 K75 @k75retro.blogspot.ca
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A 5x17 sounds like a good change then as mine is a 4.75x18 as standard. If I remember correctly our R1100S's had 5x17 and were fitted with 170 tyres, so only slightly wider than the 160 fitted as standard to my bike.
I can get 16mm lower on the front by dropping the tubes through the clamps.
Now to find a wheel! Thanks for the information.

    

Guest

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Made an offer on a 5x17 K1200 rear wheel, lets see what happens now.

    

robmack

robmack
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I remember now.  There are rear wheel designs on the early models where the rear rotor and caliper fastened to the final drive, just like the predecessor K's.  Workable wheels look like this:
K1200 front rotor on K1100 forks (size and bolt hole differences) Good%2520wheel

Later designs had the rotor mounted to the wheel and caliper to the final drive. These wheel designs won't work and look like this:
K1200 front rotor on K1100 forks (size and bolt hole differences) Bad%2520wheel


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

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That's lucky then, the one that I have made an offer on is the first one.

    

Rick G

Rick G
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Inge K. wrote:
RicK G wrote:I recall seeing a K1100 with K1200 wheels and the calipers needed to be spaced back to fit but I cant even remember the guys name but I do know he came from Sydney so that narrows it down to only 4 million people.

"Ausbrick".
No it wasn't Austbrick but now you say that I do also recall looking at his front end at Tottenham last year.
The one I am thinking of was a K1100RS but Dark Green and I think it was at a Rally on the Sunshine Coast just North of Brisbane.

I have been keeping an eye out for the 5 x 17" rear so I can get a better selection of tyres for the K75.
I have even thought about getting a billet and making a hub for a spoked wheel.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1986 K75 GS.
    

robmack

robmack
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I engaged in a discussion on the K11OG forum about this topic and this caused me to do some more searching.  I found  Anton Largiader's page on BMW wheel swapping with loads of information on wheel combinations and brakes.  I was correct in that my K11 rotors will not fit directly onto K12LT wheels.  In addition, the K12LT rotors are for EVO brakes and too large at 320mm diameter.  I'll have to search for  5-bolt 305mm diameter, 40mm wide rotors (used on Oilhead wire spoke wheels or pre-EVO K1200 or R1100S for example).  These rotors will provide the correct 5-bolt hole mounting pattern and the correct diameter at 305mm and thickness at 4.9mm.  Luckily, I'm not running ABS so I'm saved the problems of fitting the ABS ring and sensor.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

15Back to top Go down   K1200 front rotor on K1100 forks (size and bolt hole differences) Empty k1200 front modifacation Wed Jun 04, 2014 3:13 am

ausbrick

ausbrick
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Hi , I have fitted a 1150 rs front wheel on to my café , it required using the bearings and axle from the k1100 into the 1150rs wheel and turning up spacers on the lathe to centre  the wheel in the forks also had to make up the mount for the calipers which needed to move out for the bigger disc . Awesome brakes . The bike at Tottenham was me tourer with standard brakes but wavey discs. Heres a shot of the front of the café.K1200 front rotor on K1100 forks (size and bolt hole differences) P8040107 K1200 front rotor on K1100 forks (size and bolt hole differences) 2014-01-19111234_zpsb95d4b8e Cheers ausbrick

    

Ringfad

Ringfad
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On my K100 16v I now have both  5 spoke wheel's  fitted (I have a 5.0 17" rim with a 160 on the back).

On the  front I have used  the earlier 305mm 5 hole discs (The same size as the original 6 hole discs).

This means no modifications are required for the callipers , I also used the slotted ABS ring and it appears to work fine, I will check the ABS signals later.

I used the standard 25mm wheel spindle and replaced the 20mm bearings in the 1200 wheel with 25mm ones and a friend turned up the spacers.


K1200 front rotor on K1100 forks (size and bolt hole differences) Dscf5010


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K1200 front rotor on K1100 forks (size and bolt hole differences) Ir-log10

   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 60K Km     ;BMW;  K1100RS Black 1996       ;BMW; K1 Blue 1990 25K Miles
    

robmack

robmack
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Ringfad wrote:... replaced the 20mm bearings in the 1200 wheel with 25mm ones ...
Do you have the manufacturer and part number for the bearing you used??


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Ringfad

Ringfad
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I used the standard
K1100LT bearings - RS are different

BMW Part No.
36 31 2 311 030

 25x47x16 ( also requires a 4.6mm spacer) as original 20 mm bearing was 20.6mm

My engineer friend helped with the machining but it was fairly straight forward.

BMW Part No.
36 31 1 450 859

25x47x12


__________________________________________________
K1200 front rotor on K1100 forks (size and bolt hole differences) Ir-log10

   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 60K Km     ;BMW;  K1100RS Black 1996       ;BMW; K1 Blue 1990 25K Miles
    

haig1968

haig1968
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Hi, great info. Can I just check that the 4.6mm spacer is placed between the bearing and the fork?

Cheers

    

Ringfad

Ringfad
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Life time member
Can you PM me your email address and I will send some pictures ?


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K1200 front rotor on K1100 forks (size and bolt hole differences) Ir-log10

   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 60K Km     ;BMW;  K1100RS Black 1996       ;BMW; K1 Blue 1990 25K Miles
    

Two Wheels Better

Two Wheels Better
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For those wondering, any 5 screw 305mm brake disc from an F800GS, early or non-Boxer Cup spec R1100S, R1200GS, etc., will slot right on, just use a low-profile screw head from a later model to clear the inside of a 16V's Marzocchi forks. I happened to use some R1100GS calipers which are virtually identical to a K1100/K100-16V. 

Since I have a mate who's handy with a lathe (nuclear sub/aerospace level) we chucked up an axle to suit the OEM bearings for less than $50, instead of the bearing and make a spacer swap.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

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