Warped front discs - advice sought

Marty

Marty

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roundabouts!
definately not been caused by riding 'metal to metal' but more likely by sticking callipers allow some heat build up and mild warping.

Anyway have replaced the front pads - they've bedded in but the problem remains (as it would) and gives rise to a juddering through the front lever..that is most noticeable as you pull the bike up to a stationary.

Now I can live with this..however would anybody suggesta that replacing the discs was a priority (i.e safety) and if so do you know where I might pick up a used pair or good quality pattern set?

Haven't looked into BM prices for OE replacements but I would reckon on £2-300 the pair.:confused:


Cheers for any input
 
BMW only

Frist step i would try your local BMW garage to see if you can
get a waranty claim on the old discs.
If that fails i would then purchase a set of BMW discs.
O.E. equipment designed for the bike.
 
Have you checked the pistons? I had a similar problem on my 2000 GS. changed the discs, problem was still there. Suggest getting the discs checked before shelling out loads a money.....:mad: only to find the problem remains.
Also, if you do replace discs and you ride in all weathers, don't be tempted by the cast discs you see advertised. They may be a lot cheaper than OE ones, but you will have permanentlt red wheels....not a pretty sight:D
 
No you don't

i had the same probs on my 97 1100, disks were buggered, looked into replacements and the BMW OE kit is hellish expensive and if they wear out that quickly, crap as well. I opted for the cast disks option as manufaturers gave been using cast disks for years with good results. I experienced better and more positive braking and have had not issues with rust marks on the wheels, the disks do tarnisha and not lookas good as the SS originals but other than that they are half the price and better performing.

Don't get the EBC HH pads though, they last well but the rattle will drive you mad.

Check out the calipers though, that cab cause the probs you have described. pump out the istons one at a time, hold ing the others in with wood and or calmp. The pistons ought to return with heavy finger pressure.

If not then thereis a problem.
 
Gecko knows somewhere in Germany that does replacements - i've lost the info but i'll alert him to this thread.
 
Not usually on the road but sometimes at track days when the disks are well hot glowing, the pads can burn onto the disk. This may happen on the road if your brakes are binding and getting hot.
An imprint of the pad burns onto the disk, this is only a few thou' thick but can cause the brakes to pulse giving a similar feel as warped disks. I think you can remove the burn with the white lubricant stuff used to put tyres on. If you get new disks put them in the oven on full heat for 1/2 hour this burns off any manufacturing oil. Beware of smell in kitchen this can result in death threats from people who normally have charge of the oven.
 
Not usually on the road but sometimes at track days when the disks are well hot glowing, the pads can burn onto the disk. This may happen on the road if your brakes are binding and getting hot.
An imprint of the pad burns onto the disk, this is only a few thou' thick but can cause the brakes to pulse giving a similar feel as warped disks. I think you can remove the burn with the white lubricant stuff used to put tyres on. If you get new disks put them in the oven on full heat for 1/2 hour this burns off any manufacturing oil.

sorry - but all of that is complete and utter bollox - mostly talked up by no-knowers in a pub for long enough and loud enough till it becomes 'fact'

what actually happens is that a hot, thin disc which when clamped pretty bloody tightly by a relatively cold pair of disc pads - say at a pair of lights - will immediately try and transfer all of its heat through said pads into the relatively large lump of metal called a 'brake caliper'.
Now seeing as 3/4 of the disc is still hot and 1/4 is cooling down - guess what happens - the disc distorts ever so slightly. ( very common on rally cars end of stage )

As for burning off oil in an oven - then you'd better get it exactly right and cool it down exactly uniformly - otherwise the above will happen before it gets on the bike.

Much better to empty 1/2 can of brake cleaner on each disc and pads and clean it off with an airline - the clue is in the name on the tin !!
 
what actually happens is that a hot, thin disc which when clamped pretty bloody tightly by a relatively cold pair of disc pads - say at a pair of lights - will immediately try and transfer all of its heat through said pads into the relatively large lump of metal called a 'brake caliper'.
Now seeing as 3/4 of the disc is still hot and 1/4 is cooling down - guess what happens - the disc distorts ever so slightly. ( very common on rally cars end of stage )

[/B]
Click to expand...



thats why you don't use your handbrake on the car when you park up at track days :D :D
 
so sitting at the traffic lights with the brake on can warp your discs?

interesting.
 
If the pads are capable of absorbing enough heat to allow disc distortion,surely enough heat would then be transmitted from the pad,(it's got to go somewhere),to the brake piston,heat the brake fluid and hence render the brakes useless.
 
Le singe said:
If the pads are capable of absorbing enough heat to allow disc distortion,surely enough heat would then be transmitted from the pad,(it's got to go somewhere),to the brake piston,heat the brake fluid and hence render the brakes useless.
Click to expand...


when on track days in my car, flat out racing and stopping on a race track - the brakes get used to excess i.e. hotter than you'd ever get on the road -

when you park up in the pits, if you put your handbrake on, the heat gets drawn throught the pads into the caliper - the area of disc in contact with the pads cools down a lot faster than the rest of the disc - which causes the disc to warp -

:rolleyes:
 
Steptoe said:
when you park up in the pits, if you put your handbrake on, the heat gets drawn throught the pads into the caliper - the area of disc in contact with the pads cools down a lot faster than the rest of the disc - which causes the disc to warp -

:rolleyes:
Click to expand...

Concise explanation of differential cooling, Steptoe. Believe it.
 
motobins...

just looked at their webiste..not having any joy locating parts for an 1150 GS on it though. Am I to assume the 1150RS discs are identical?
 
On this issue - I figured that my discs were slightly warped, until I got a new set of tyres - once in the balancing machine, the tyre guy pointed at my rim with these, like, HUGE eyes, and said "Monsieur, your rim is bent!" :eek:

True enough, it wobbled considerably more than the 1.3 mm that BMW has as a limit.

Given the complexity in trueing these wheels, I suppose that I'll just have to live with it. :mad: No offroad, no major bumps - but there you are. I'm out of warranty...

On the positive side, I only ever notice anything when I brake.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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