BMW K bikes (Bricks)

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1Back to top Go down   Rear brake disk removal? Empty Rear brake disk removal? Mon Nov 15, 2021 4:12 am

ouafnico

ouafnico
active member
active member
HI everyone,

I'm actually working on my K100, and I saw the 2 screws holding the rear brake disk are completely destroyed...

Rear brake disk removal? 1920-1080-max

It seems my rear disk is around 0,39mm, I guess it's good to be replaced?

But with this destroyed screws, any idea how I can remove them?


Thanks,

    

2Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 5:28 am

Dai

Dai
Life time member
Life time member
A lot of heat to start with as the bloody things are held in with Loctite (stupid idea on BMW's part). Then try the following:

1. Get a 1/4" Allen bit and slightly chamfer the leading edges so that you can feel the head of the bolt when you put the two together. Hammer it in and don't be gentle. This should reshape the head of the allen bolt and get a good grip at the same time as 1/4" is 0.25mm bigger than the 6mm head.

2. Drill the head off. Start with a 6mm drill because you just want to remove the head. The drill should self-centre. Once the heads are off, knock the disc off and file small flats on either side of the bolt to take a 4.5mm or 5mm spanner. Apply a lot more heat to the remains of the allen bolts, then try the spanner. If they still won't come out (unlikely at this point), grip them with a pair of good quality mole (vise) grips.

I've had success with both methods. Do not Loctite the new bolts in. You'll need to order them from a BMW dealer as the head is a non-standard size but clean the blue Loctite off first and apply Copaslip or similar before putting them in. Their only function is to hold the disc in place when you take the wheel off - it's the four big bolts that do the job of keeping everything together when you hit the brake.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

3Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 6:21 am

ouafnico

ouafnico
active member
active member
Many thanks for your feedback !

I'm hesitating actually to remove the disk, I'm still searching if I have to change it, I don't find the good value of the thickness.

On the disk is written 0,18", but in millimeters it's 4,5mm, but even at the edge of the disk where it's thicker, it's not that tick... so I don't understand what is the correct value.

    

4Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 9:05 am

Dai

Dai
Life time member
Life time member
If I recall correctly, BMW say that it's worn out at 4.0mm. Many of us have run discs that are a lot thinner than that without any problem - Charlie99 (I think???) was running one at 3.0mm. As you have the wheel off and are looking at the problem, I'd attend to it now instead of leaving it until later.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

5Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 9:14 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
If you have it, you can hammer a 3/8" drive Torx bit into the screws after heating them(a lot).  Torx bits are very hard and seem to have a geometry that bites into the stripped out sides of the Allen hole.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

6Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 9:47 am

ouafnico

ouafnico
active member
active member
Thanks you Smile

Do you know some replacement part for this disk?

    

7Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 4:46 pm

Laitch

Laitch
Life time member
Life time member
@ouafnico wrote:Do you know some replacement part for this disk?
Look down this list at tills.de


__________________________________________________
1995 K75 81,000 miles
Rear brake disk removal? Usa-lo10
    

8Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Mon Nov 15, 2021 5:30 pm

Dai

Dai
Life time member
Life time member
I just checked ebay.fr. Some of those sellers are taking the piss - asking almost the same price for a secondhand hand disc as the cost of a new disc.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

9Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Tue Nov 16, 2021 3:46 am

ouafnico

ouafnico
active member
active member
Prices seems good on tills !

On ebay I checked too, and some are awful...

    

10Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Tue Nov 16, 2021 4:17 am

Pete Riley

Pete Riley
active member
active member
There is a firm in Greece called tsuboss. they might be worth a look. Sorry no link but a google search will bring them up.

    

11Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Tue Nov 16, 2021 10:16 am

92KK 84WW Olaf

avatar
Life time member
Life time member
I have never bought a used disc. New EBC discs are good enough price.

I had to change the rear disc on the RS as it escaped the recall for the early slotted rear disc. I used lots of heat before trouching the disc bolts as they were original and in the 35 years. They cam out first shot but the replacements are only hand tight.  They only stop the disc falling off if the wheel is removed.

My K1100LT needs new front discs.........


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 40,490 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

12Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Wed Nov 24, 2021 7:20 am

playlikewedream

playlikewedream
Silver member
Silver member
You could try Thom Hellebreakers in the Netherlands, he's on Facebook,Twitter,Instagram and messenger,


__________________________________________________
Rear brake disk removal? Ir-log10Rear brake disk removal? Ir-log10
;BMW; K1 1990 Laguna Blue and Yellow ;BMW;
;BMW; K1100RS 1997 Sedien Blue.;BMW;

Its not about the journey or the destination, it's about the friends you make on the way.
    

13Back to top Go down   Rear brake disk removal? Empty Re: Rear brake disk removal? Sat Nov 27, 2021 12:09 am

Gaz

Gaz
Life time member
Life time member
Another variation of the methods above if you are unfortunate enough to round out the shallow hex in the countersunk screws holding the disk, you can safely drill out the centre of the screw as the depth of the threaded hole in the hub is greater than the length of screw. Then apply heat and a screw removal tool.

Note that this advice is based on my experience when replacing the rear disk on my K1100LT where I was lucky enough to get one out and then was able to measure hole depth versus screw length before attacking the other with the drill. I assume the K100/75 set up is the same.


The common theme is heat.


I was able to buy replacement screws of the right length in stainless at my local bolt shop. As others have noted I then installed them with anti seize and just nipped up by hand.


__________________________________________________
Gaz
1990 K75 6427509; 1987 R80G/S PD 6292136; 2010 G650GS ZW13381; 95 K1100LT 0232224
    

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