BMW K bikes (Bricks)

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1Back to top Go down    Rear caliper on Thu May 04, 2017 4:00 pm

smoll1


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Hi all

Another problem on the k100rs.

The back brake has always been bit rubbish and found the master cylinder seized. I replaced it for new one as old one was too pitted to change the seal. 

The disc is fairly new and is straight. 

I replaced seals in caliper and no corrosion or anything which is good. 

Question is when I nip up the bolts hold caliper on it is not central with the disc. Loose off a couple turns and it central again with the disc.

It means when I do bolt up it is rubbing the right brake pad (looking from the back pad).

Here what checked. 

Caliper clean as whistle and pistons are good and seals
Brake line is fairly new
Brand new master cylinder
Brake pedal is all good and adjusted to allow some play

The only thing it looks like is caliper is bent somehow. Which seems unusual.

Any thoughts would be greatly received. 

The disc rubs and keeps heating up disc too much. But wheel moves when spun but not as I think it should be.

Help  Very Happy

    

2Back to top Go down    Re: Rear caliper on Thu May 04, 2017 4:37 pm

Laitch

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smoll1 wrote:
Help  Very Happy
Is the part #2—the wheel spacer—missing from your assembly?


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1995 K75T 60,000 miles
    

3Back to top Go down    Rear caliper on Thu May 04, 2017 4:49 pm

smoll1


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Yes spacer is there. 

The rear brake caliper bends to the left when you do mounting bolts up. It is really weird. I thought the caliper tipped to the left when looking at it from the back as I tightened up the mounting bolts. 

And because that happens the gap between the disc and caliper body is less on the right hand side, and then the pads rub on this side. 

Sounds more complicated writing this than actually what is happening.

    

4Back to top Go down    Re: Rear caliper on Thu May 04, 2017 4:53 pm

Laitch

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smoll1 wrote:
The rear brake caliper bends to the left when you do mounting bolts up. It is really weird. I thought the caliper tipped to the left when looking at it from the back as I tightened up the mounting bolts.
Do you think the difference when tightening would show up in photos that you could post here?


__________________________________________________
1995 K75T 60,000 miles
    

5Back to top Go down    Re: Rear caliper on Thu May 04, 2017 5:36 pm

92KK 84WW Olaf

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Does the caliper look like its leaning over or just offset too much to one side?

If its an 8 valve its two castings, as in the final drive unit and the caliper are both cast and there is no scope for something to be out. I don't think there is a washer/spacer between the caliper and the final drive and I should [but can't] remember as I have had mine off a few times in the last few months.


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 87,100 miles
1997 K1100LT 58,000 miles
    

6Back to top Go down    Rear caliper on Thu May 04, 2017 6:28 pm

smoll1


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I will see if I can get a picture.

It looks like leaning to the left. The offset is ok. It's weird. If it didn't need doing up it would be great. I wonder if something wrong with where it bolts to final drive. 

Again as has been said cast items both of them so should be ok. 

I will keep investigating

    

7Back to top Go down    Re: Rear caliper on Thu May 04, 2017 9:47 pm

RicK G

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The machined face of the caliper should be parallel with the disc. Make sure the disc is not dished and the tabs on the drive are not bent.


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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
    

8Back to top Go down    Rear disc on Sat May 06, 2017 8:59 am

smoll1


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Hi all

Update on caliper issue. I check machined face on final drive at it was ok.

All evidence pointed to caliper as didn't seem to be parallel to disc. 

I ordered a used disc low mileage one.

Arrived this morning and bolted it on and it was perfect. 

When looked at side by side with the old one, the old one looked slightly bent or worn at the bottom where it bolted on. 

Took for ride and decent back brake excellent.

It even rotates when on centre stand when bike is running.

Just shows you how something that looks good is ever so slightly worn. 

Thanks for all advice and help. The forum is great Very Happy

    

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