Warped disc(s

[Major]

Just got back from 6 days in France on 1200. Had its 600 mile service two days before I left and discs were tiptop. 2 days and 1000 miles later a front disc has warped!! . I was one up, lightly loaded and most of the pre-warp miles (600ish) were motorway so very little brake use, and very dull. Am I just unlucky or are OE discs crap?? They should be replaced under warranty but it’s a pain in the a*se none the less.


Don’t mention the war, Basil.

 

[northengit]

Just got back from 6 days in France on 1200. Had its 600 mile service two days before I left and discs were tiptop. 2 days and 1000 miles later a front disc has warped!! . I was one up, lightly loaded and most of the pre-warp miles (600ish) were motorway so very little brake use, and very dull. Am I just unlucky or are OE discs crap?? They should be replaced under warranty but it’s a pain in the a*se none the less.


Don’t mention the war, Basil.

Whats the evidence/proof that the disc's are warped' it's had a 600 mile service and since then you now have warped discs... Are you saying you have had it back to the shop and its confirmed by BMW that they're warped... if so then yes I would say it's over to them to sort it.
But are you just supposing they are warped.

 

[Major]

Under hard braking there is not much to notice other than a slight vibe, but when braking gently from say 10mph its like the brakes are being squeezed on and off. Its not the ABS, I've tried that and thats quite a different feeling.

Its not been to BM yet (its an hour away from me) but my guess is that one if the discs is slightly warped. As I say all was fine before so something is definitely up. Any suggestions for what else it could be will be gratefully recieved!


Don’t mention the war, Basil.

 

[Tarka]

There`s no need to guess or wonder if the discs are warped.

Spin the wheel while looking at the discs from the front,while sighting against a parallel surface such as the fork leg.

You`ll know then if there`s a warped disc (or two).

 

[DavidJames]

My disc warped at some point after the 600 mile service and was replaced under warranty at the 6000 mile service. I probably could of taken it back before the scheduled service, but couldn't be @rsed as it was not a big problem for me.

The dealer was Vines BTW.

 

[JoeKnow]

It's not uncommon for the disks to warp early in there life,just drop it into your dealer and they will sort it for you.
It's nothing you have done,just bad luck.

 

[GEOFFREY DEACON]

My discs seemed warped on my first service but I continued to use them untill 4000 miles and had them change under warranty, but now the back is still warped and will be change next.
And my fuel sender...

 

[(RIP) Kaister]

Theres a whole world of difference between so called 'warped discs' and unevenly worn discs and oil on the discs.

Let me explain.

The calipers have fixed bodies and fully floating pistons.

If the disc is 'warped' - ie bent then both surfaces of the disc move the same amount side to side.
This causes the pistons to follow the surface by the same amount - but the amount of fluid - or pressure - in the system WILL NOT change.
Therefore - you will not feel a warped disc at the lever.

However - if one section of the disc has worn unevenly then one piston will pulse in and out as it passes the worn section - this you will feel straight away.

Also - a drop of oil on one side of the disc will also give an impression of pulsing - but it won't be the lever - just the rate of change of slowing down.

PROOF: - i had a guzzi with a rear disc that was bent by a good 1/4" - but it had fully floating brembo's - i couldn't feel it at the pedal and i only noticed it when cleaning. You could spin the wheel and apply the brake and watch the pistons go in and out as they followed the disc with no pulsing at the pedal.

I'd be cleaning the discs and calipers with brake cleaner as the first step

 

[EURTRAF]

Hi

Would agree with Motomartin.

My 1100S supposedly had warped disks when MOT'd (Brake pressure indicater fluctuated greatly) but tester thoroughly cleaned both front disks and then re-tested and then NO fluctuation.

Steve

 

[Major]

Thanks everyone. I'll give it a bloody good clean and let you know.


Don’t mention the war, Basil

 

[Major]

Thanks Motomartin, looks like you were right. I have finally got round to cleaning the discs and all is back to normal.

That'll teach me.



Don’t mention the war, Basil

 

[Geeza]

This problem is not just BMW related.........my mates 55 plate Triumph Tiger is now on its 3rd set of front discs and the wifes 05 plate Bonney is on its 2nd.