What the feck are my front brakes doing?!

Slipperyeel

Slipperyeel

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Hello folks

I posted recently asking about my front brakes which have been clicking immediately after applying them. Well, i am now getting the kind of feedback from the brakes suggesting the discs are warped, a sort of slow pulsing of braking effect (i've experienced this years ago and it feels the much the same).

I had a quick look at the discs this evening and the left disc seems to have more play in it than the right. I can see there are some sprung wave washers between the discs bolts, which presumably allows them to 'float' a little?? I've no idea how much play is normal. Thought the bolts might just need a tighten, but nothing is budging! So it will need my full attention later, in the daylight!

Before i start pulling all this apart, has anyone got any ideas or experience of this? Any previous posts i should read?

Cheers
 
Sounds like the discs need replacing to me.


Take the disc and move it back and forth as opposed to side to side, does it rattle in that direction, cause if it does you need to get ya wallet out:thumb
 
Flipfly said:
Sounds like the discs need replacing to me.


Take the disc and move it back and forth as opposed to side to side, does it rattle in that direction, cause if it does you need to get ya wallet out:thumb
Click to expand...


He's probably right, but before you splurge out, spray the discs with brake cleaner and run the bike round the block :thumb2
 
Thanks for the feedback gents. I fear you might be right and i'll have to part with some dosh to fix this one.

Weather is rubbish today so tomorrow i will make a proper check. The left disc seems to have more play than the right, but that was side to side (rather than front to back, which i will now try).

I have read of people having trouble with the mounting points for discs, where the wheel has worn away. I never really understood this but now i understand that the disc is given some free play, i can see how that might happen...:eek

Any tips for unscrewing the disc bolts? should i heat them? Presumably i need to use a threadlock when re-fitting. I always have in the past, presumb BMW is the same?

Thanks again
 
Thanks for the tip Smudger. I'm looking through past posts right at this moment.

At this moment i am beginning to think the route cause may be the pistons in the left caliper. When i cleaned them a couple of months ago, the pistons on this side needed a lot more force to move them (the RH side were smooth as silk, as were the rear caliper pistons).

I may have a warped disc...but looks like i should also service the LH caliper with service kit as well as replace the disc, if it needs it...

I will try and gather as much info today and then tomorrow i will give the front a thorough check (run out on the discs, caliper pistons, pads etc). I will post what i find here
 
Take the disc off and check the bobbins they wear over time and ovalise which gives the same effect as as a warped disc, new bobbins and wave washers often cures it and is a lot cheaper than a new disc. It's quite a common prblem and easily solved.
 
Go down the gears? Not sure i can handle any more weird noises these bikes make :D.

But yes, i do this anyway as it happens. Actually, the effect is only noticed in the once the speed has dropped to roughly below 10mph...

Thanks for the tip to check the bobbins. Checked the cost a full set from MWs and bobbins, washers and new bolts (for both discs) is already 67 quid so i'm gonna make real sure what the issue is before the wallet is released! Here's hoping this is all it is.

Thanks for all the comments. Back tomorrow with some news of what i find!
 
Smudger: I checked out your link (thanks). I'm pleased to say my GS is in very good nick. But if i end up getting anything from MWs then i'll be adding those shims to the shopping list. Good idea.

Cheers!
 
Ok. I have had the front wheel off and the discs too today (A brief space between the rain!). I have attached some pictures which show what i found.

Basically, the LH disc which had a lot of play has 3 broken wave washers and one which is completely flat. Only one washer is 'ok'. RH disc seems all good to me and it had no play.


Some pictures (i think - haven't uploaded any before, so this might not work...)

No.1 LH disc with bolts removed
No. 2 Disc seats
No. 3 Disc seat detail
No. 4 Versions of wave washers (left = flat, middle = broken, right = ok but worn)
No. 5 Detail of broken wave washer.

My question is, will a load of faulty wave washers cause the pulsing , like a warped disc? Oh, the discs are just fine, in all respects.

In my own mind i think i should just replace the wave washers, fit the BMW shims Smudger recommends (albeit for worn disc seats but i'm thinking to prevent the wear happening!). I also intend to replace the hoses, they're well out of date and probably the cause of problems not much further ahead...

Any thoughts on the duff wave washers?

Cheers
 

Attachments

  • Front disc off - disc seats.jpg
    Front disc off - disc seats.jpg
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  • Disc seat - detail.jpg
    Disc seat - detail.jpg
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  • Disc edge - like new.jpg
    Disc edge - like new.jpg
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  • Wave washers - 3 versions.jpg
    Wave washers - 3 versions.jpg
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  • Broken wave washer.jpg
    Broken wave washer.jpg
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Those discs look knackered to me, I think you should buy new ones, oh, and give me the old ones:augie:augie

I'd just renew the wave washers, fit a set of those shims as a preventative measure, and new hoses, job done.
 
Previous owner put new discs on. I think at about 37-38k so they;re in good nick. All yours for an extortionate fee :D

Thanks for confirming my thoughts. A big help. Will order the parts this week and fit next weekend (weather permitting!). Will report back with the results!
 
Oh, Smudger. For those shims, does MWs sell them or is it a part i have to get from a dealer?

Cheers
 
F** sake Lads (n lasses) I checked a few times and I haven;t found that "yet" But then again that's maybe just my local dealer

Main example being the large rear bearing seals and o ring for the oilhead FD

10 washers are £9.10 plus post WTF !!!! Get real How much is a New front wheel going to cost you ??? :blast
 
Have you tried ebay item 370585251678?
Is this close enough in size?
£5.60 for 100 inc. p&p.
 
Last edited:
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