BMW K bikes (Bricks)

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werewasi

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When K #2 joined the family, I swopped the wheels over to #1 so that i could could use the rubber on them.
While the wheels were off, i dissassembled the calipers and got all the grunge out of both sets, and pulled the rotors off so that I could paint the rims black. This may have set the scene for a problem.

Recently, as part of the getting #2 back on the road, and as all the rubber on it's original wheels had been used up by #1, I swopped the wheels back. But a problem!!!!!!!!. The front wheel on #2 wouldn't turn. Discs were 3.80mm thick.
Closer inspection revealed that the actual caliper body was touching the disc.

The guru (Capt Hollister) came to stay and so we spent half a day trying to figure out what was wrong. The wheel was centered correctly on the axle but with the left caliper loose, and centered on the rotor, there was a gap of 5- 7 mm between it and the fork leg. As soon as the caliper mounting bolts were tightened, it was pulled across to the the fork leg and the wheel was locked solid.
Only solution seemed to be to pack tensile washers between the caliper and fork leg.

On his way home, Nigel took photos of the bike ( when i bought it) to Smithy at Guyra who when i rang him, told me that the front discs were floating. WTF. Bike in my garage hasn't got floating discs. So I hadn't put the same rotors back on despite being sure that I had.

Pulled wheel off bike. Measured discs -about 3.8mm thick but also measured discs fr outer to outer edge -127.5mm. (not the diameter but the distance between the discs on a horizontal plane) Stamped BMW 1 454 897
So then I replaced these discs with some spares I had - 4.16 and 4.25mm so a bit thicker. Measured across discs but wait for it - 133mm!!!!!!!!!! marked GRIMECA but no part number stamped.
Put this wheel back in bike and it turned. Difference between 133 and 127.5mm took up the previous gap.

So what's going on.
Well, while the bike was at my mates place, I think there may have been some 'substitution" because I've found out that he has the floating discs. He's told me that they are stamped BMW 1 450 870 and 85 (actually the year the bike was made). I haven't measured the dics thickness yet but am told that it's about 4.8mm.
We are arranging a handover like the prisoner exchanges in wartime.

These 1 454 897 BMW carriers are obviously different from the correct ones, so what are they off?
Is there a part number stamped somewhere on the GRIMECAs?


Seems no one else has had this problem because even Rick was mystified.



Last edited by werewasi on Tue Jun 20, 2017 9:22 am; edited 1 time in total


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K100RS 1983 and 1986 (bought a 2nd and put them both together in a dark garage thinking that i would get a heap of parts from the progeny but nothing happened- think they're gay) Laughing Laughing Laughing

1985 K75, Guzzi V7 Special, 1986 GB500, 1974 T500, 1986 MB5 with the whoppa 100cc engine transplant, NC 700 SA Honda, two 1986 Kawasaki BR250s
    

RicK G

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This has now made me remember that the discs from the R100 mystic can be used on a K100 forks so the K1100 calipers can be used.
I think we figured that out one day when TWB, me and others were talking about the Suzuki discs TWB has on his Aussie K1050 RS


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

werewasi

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Rick, you've headed off in a different direction and lost me, unless you're telling me that I ended up with some Mystic discs.

Just to slop a bit more icing on the cake.
My mate (who shall remain nameless) got the 1 454 897 discs (what I'd call the problem ones) from some swap meet where the guy told him that they would fit an R. They did have the 4 hole setup but obviously the carrier is not suitable for a K. Whether they do fit an R remains to be seen.
Because he did the swithcheroo I ended up with these and he 'retained' my K floating discs. It was Smithy who alerted me to the fact that the discs looked different to the ones in the original photos.

If you suggest that he simply transfer the 1 454 897 discs on to his own R carriers, it's not quite as simple as that.
When he saw a spare front wheel off the #3 K100 that i broke up, he asked if he could have it so that he could then fit twin discs to his R65 (which came with only a single) He's only got one carrier so now could have a problem. But it aint gonna be my problem!!!!!!!!!

Maybe the lesson is - 1 keep all your K bits under your bed.
2 don't frig around with your own K. If anything needs doing, get your mum to do it.


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K100RS 1983 and 1986 (bought a 2nd and put them both together in a dark garage thinking that i would get a heap of parts from the progeny but nothing happened- think they're gay) Laughing Laughing Laughing

1985 K75, Guzzi V7 Special, 1986 GB500, 1974 T500, 1986 MB5 with the whoppa 100cc engine transplant, NC 700 SA Honda, two 1986 Kawasaki BR250s
    

RicK G

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They will be off an R100 that has a paralever rear drive from about 92 on


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

jbt

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The rotors and the brakes used on K75, K100 and R Monolevers are the same -but the offset is different.
The rotor is the same part, machined differently on the face in contact with the hub.
I re-used k75 disc brakes when I converted it to a GS version, and recently fit K75 discs on a R80 Monolever : I had to remove on a metal lathe 2.20 mm to get the correct dimension to fit on the fork.
As the front wheel is a common part on K75/100 and R Monolever, it could explain a misaffectation.

Note that on Monolevers, the thickness depends of the configuration: 1 disc 4.5mm, 2 disc 4 mm (to save weight and to cope with the quicker wear on the single disc.

    

werewasi

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jbt wrote:Tks jbt
you said

The rotors and the brakes used on K75, K100 and R Monolevers are the same -but the offset is different.
The rotor is the same part, machined differently on the face in contact with the hub.

Do you mean that the rotor is the same part BUT the CARRIER is different? i.e. K rotors can be transferrred to an R bike provided an R carrier is used.

I re-used k75 disc brakes when I converted it to a GS version, and recently fit K75 discs on a R80 Monolever : I had to remove on a metal lathe 2.20 mm to get the correct dimension to fit on the fork.

So why not use the existing R carrier and just bolt the K75 rotor to it?

I had to remove on a metal lathe 2.20 mm to get the correct dimension to fit on the fork.

Pauline : "please explain"

As the front wheel is a common part on K75/100 and R Monolever, it could explain a misaffectation.

That is a wonderful word ( like I 'misspoke')

Could be used where someone has an affair - tells wife "I had a misaffection"

As the front wheel is a common part on K75/100 and R Monolever

you mean on Monolever R80. With the R65, is it the spacers that are different or is it the hub thickness? (unlikely). If the hub on his R65 is the same, then he doesn't need that K wheel from me, can use his own R65 wheel and just get the appropriate spacers (for a conversion to 2 rotors)


Note that on Monolevers, the thickness depends of the configuration: 1 disc 4.5mm, 2 disc 4 mm (to save weight and to cope with the quicker wear on the single disc.

So if my mate wants to put two discs on his R65, then does he have to make sure that the rotors are both under 4mm, (strange because the calipers should handle a 4.5mm rotor) or are you saying that that BMW just fit 4mm rotors as OE? (on the twin rotor R80)


__________________________________________________
K100RS 1983 and 1986 (bought a 2nd and put them both together in a dark garage thinking that i would get a heap of parts from the progeny but nothing happened- think they're gay) Laughing Laughing Laughing

1985 K75, Guzzi V7 Special, 1986 GB500, 1974 T500, 1986 MB5 with the whoppa 100cc engine transplant, NC 700 SA Honda, two 1986 Kawasaki BR250s
    

92KK 84WW Olaf


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My mate told me the calipers are the exact same on quite a few of the R bikes [and Guzzis too], just reversed left to right to put them in front or behind the stanchion.....


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 84,100 miles
    

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