BMW K bikes (Bricks)

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1Back to top Go down   Reducing diameter of brake rotor Empty Reducing diameter of brake rotor on Sun Jul 19, 2015 5:58 am

Packo

Packo
Silver member
Silver member
I am in the process of changing my rear brake  caliper and have adapted a R 1150 single sided caliper to fit the existing k100 FD. The only problem I have is the brake rotor just rubs on the top of the gap in the caliper. I would like to reduce the diam of the rotor by 5mm to allow clearance. Does anybody for see any dramas in doing this. To fill in the gaps the rear wheel is now a BMW hub laced to a 15 inch rim and the conventional caliper will not clear the spokes. Would I need any special tooling to trim the rotor down being stainless.


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83 K100 HRD outfit
77 R100RS
2008 K1200S
1983 K100
    

2Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Sun Jul 19, 2015 7:44 am

Dai

Dai
Life time member
Life time member
Provided the brakepads don't end up trying to grip either mid-air or the rotor centre, I don't see any problems with removing that much metal. You'll need a lathe and the proper cutting tools, but I'm assuming you already have those?


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

3Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Mon Jul 20, 2015 8:46 am

indian036

indian036
Life time member
Life time member
No kind of expert, but from my limited knowledge of machining, stainless is problematic. Someone will be sure to correct me if necessary, and I can ask an expert on Wednesday Oz time, but a sharp cutting tool and constant lubrication/cooling will be necessary, I think.

Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Newest toy, slightly non-original
    

4Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Mon Jul 20, 2015 9:23 am

Holister

Holister
Life time member
Life time member
I'd agree with that Bill. I've drilled thru quite a bit of stainlees steel... very difficult. Need to use tungston carbide lathe bits at a slower speed. Spinning a disc with that diameter you'd need to calculate the required rpm.


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1988 K100RT     VIN No.  0094680
1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
 Reducing diameter of brake rotor Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

5Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Mon Jul 20, 2015 6:10 pm

Dai

Dai
Life time member
Life time member
And don't forget the earplugs. It's gonna ring like crazy! Very Happy


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

6Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Mon Jul 20, 2015 8:52 pm

Packo

Packo
Silver member
Silver member
Thanks for the input guys.
Have now done the job, slow speed with carbide tip tool and very light cut. Took a while but got there and the noise was not too bad, only occasionally did it squeal a bit. Interesting point, as we know the disc is sort of bright silver in colour (stainless) but as I took a cut the swarf came off as a golden colour,  thought originally it might have been a combination of the light cut and heat discolouring it but it did not seem to have that blue tinge to it that you get with
overheating.
Anyway the disc is now 5mm smaller and the caliper fits and does the job perfectly. Good result


__________________________________________________
______________
 
83 K100 HRD outfit
77 R100RS
2008 K1200S
1983 K100
    

7Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Mon Jul 20, 2015 8:58 pm

RicK G

RicK G
VIP
VIP
Gold means low quality stainless it is the high chromium content that goes blue and nickel makes it gold then if hotter almost black


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"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats."  from Mencken's 1919 Prejudices

Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

8Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Tue Jul 21, 2015 7:11 am

Dai

Dai
Life time member
Life time member
Ahhhh...... that might explain why every stainless brick rotor I have ever seen has brake pad grooves in it? I'm running cast iron rotors all round; I got incredibly lucky last week and got a second front pair off a breakers on ebay who were selling them cheap (£40) because 'they were covered in rust'. I said nothing and just hit the BIN button. Not a mark on them.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

9Back to top Go down   Reducing diameter of brake rotor Empty Re: Reducing diameter of brake rotor on Wed Jul 22, 2015 10:15 am

indian036

indian036
Life time member
Life time member
Glad it all worked out, Packo.

Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Newest toy, slightly non-original
    

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