BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down   Brake Disk Runout  Empty Brake Disk Runout on Thu Oct 03, 2013 4:09 am

Guest

avatar
Guest
I got a RWC/Rego on the blue bike today. This was the first time I've ridden it any distance after pulling it to bits and I notice a plulsing from the front brakes when they are heavily applied. A friend of mine runs the workshop at Springwood Suzuki and he did the Road Worthy Certificate for me. He also noticed it and told me it's runout on the disks. He measured the run out and said it's within spec but half way to being out of spec. I did a lap over Mt Cotton and back up the Freeway and it's manageable but very annoying.

Apart from swapping the disks, is there anyway to remove the run out problem. Both front disks are 4.64mm and the service limit is 4.5mm so there's not a lot of spare meat on them. I searched for this and read a thread where someone used an oil stone on a rear disk to flatten it by running the engine, in gear and grinding the disk with the stone. I'm wondering if that's a can do for the front somehow as well? Obviously I don't want to spend another razoo on this bike Smile

Any ideas?

    

2Back to top Go down   Brake Disk Runout  Empty Re: Brake Disk Runout on Thu Oct 03, 2013 4:20 am

RicK G

RicK G
admin
admin
To be quite honest I would seriously doubt a story like that.
I used to reco discs at one place and that sounds like a fairy story.
Find out which one is bad and replace it because to take enough of a disc to get rid of a pulsation like you describe would take it way under spec.
You may even be able to get rid of a lot of the pulsation by turning one of the discs 180° on the wheel, it could compensate for the other if both are out a bit and in the same place. Its worth a try and you dont even have to remove the 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 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

3Back to top Go down   Brake Disk Runout  Empty Re: Brake Disk Runout on Thu Oct 03, 2013 4:29 am

Guest

avatar
Guest
The floating discs (I have them too) seem to be very thing and easily bent. I would suspect that a PO had been a bit rough with them when removing the callipers to take the front wheel off at some stage. At that measurement do what I did and order a new set of EBC discs online direct from EBC UK.

    

4Back to top Go down   Brake Disk Runout  Empty Re: Brake Disk Runout on Thu Oct 03, 2013 4:37 am

Guest

avatar
Guest
It was CF. I re read it and he ground a grooved K1100 disk for a K100 bike. 

He told me this morning both disks showed run out and I think he said they measured .08 and spec is .2  I'll try rotating one disk to see what happens. If I have to I can put the used disks off the RT onto this RS and buy new disks for the RT. Cheers.

    

5Back to top Go down   Brake Disk Runout  Empty Re: Brake Disk Runout on Thu Oct 03, 2013 4:59 am

RicK G

RicK G
admin
admin
To grind back thickness maybe but you would need to be lucky to get a run out or a high spot out


__________________________________________________
"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 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

6Back to top Go down   Brake Disk Runout  Empty Re: Brake Disk Runout on Thu Oct 03, 2013 5:17 am

Guest

avatar
Guest
Cheers Bikerboy, I think you got it in one. The PO has twisted the disks.

I slipped out to the garage while there was a bit of daylight left and rotated one disk 180 degrees. It hasn't fixed it but that change improved it a lot. I'll see if I can get away with it like that for the sale.

A couple of pair of brake pad mounts with oil stones instead of pads would do the job Smile
Even if they are wafer thin, doesn't that just mean you need more brake fluid Twisted Evil

    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum