Front Brakes - lack of performance

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Graeme
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Front Brakes - lack of performance

Post by Graeme » Fri Jun 29, 2012 1:22 pm

My front brakes seem to have gone from 'stoppie-tastic' to abysmal in the last two years - not sure what cause might be but looking for some advice. It's become bad enough that I've recently had to change from 2-fingered braking to 4, as the lever is coming back far enough under heavy braking that my other two fingers get trapped. The lever is already at maxi extension, but I got a wake-up call when I almost ran into the back of a van last week because I couldn't stop quick enough :eek

The bike is a 2001 GSXR-750 (K1), 40K miles and has had HEL braided lines fitted since day one. The discs are the originals but visually in good condition, although maybe worn? The fluid was changed at the last service but didn't improve matters :x

I've that the radial master cyclinder from a K3 or K4 is compatible, and can make a big difference - I would be interested to hear if anyone tried this?
Money is an issue at the moment, so looking for the most inexpensive cure. :cheers

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CBRXX
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Re: Front Brakes - lack of performance

Post by CBRXX » Fri Jun 29, 2012 1:30 pm

If your lever is coming all the way back to the bar and you have good well bled fluid I would suspect the master cyliders had it.
Cheapest fix try bleeding it again its only a couple of quid to ensure you can rule it out.
Maybe get hold of a vacum bleeder from ebay again much cheapness, but some systems can be a bitch if not done this way failing that I'd be off to breaking point for a master cyl

Oh aye not to forget to clean the pistons in the calipers

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Graeme
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Re: Front Brakes - lack of performance

Post by Graeme » Fri Jun 29, 2012 1:47 pm

I previously bled the brakes myself, and they were just done again last week at Ecosse so I'm fairly sure fluid is not the issue.

I'll try cleaning the calipers, as described here, before splashing out on bits ;)

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steve
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Re: Front Brakes - lack of performance

Post by steve » Fri Jun 29, 2012 3:13 pm

Did you see Ecosse bleed your brakes or did you just pay for the pleasure ?

If your calipers an pads are ok just bleed them yourself. , check all the banjo fittings too

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Re: Front Brakes - lack of performance

Post by Newbus » Fri Jun 29, 2012 4:40 pm

It is also good to change brake pipes as when brake pipes start to fail when you pull the lever the pipes start to swell rather than allow all the fluid to go to the brake caliper causing lever to have excess travel.
Ask anyone that has fitted braided hoses the diffrence it makes to the feel of the brake lever .
For the price of braided pipes that would be my first port of call if still got a problem look at the master cylinder and calipers. For such a life saving part of the bike i would put on new master cylinder or calipers rather than 2nd hand ones .

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Graeme
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Re: Front Brakes - lack of performance

Post by Graeme » Fri Jun 29, 2012 9:47 pm

steve wrote:Did you see Ecosse bleed your brakes or did you just pay for the pleasure ?
Of course, doesn't everyone stand and watch every major service? :roll

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Graeme
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Re: Front Brakes - lack of performance

Post by Graeme » Fri Jun 29, 2012 10:08 pm

Newbus wrote:For the price of braided pipes that would be my first port of call if still got a problem look at the master cylinder and calipers.
Yeah, it's already got braided lines (hel). Time to clean the calipers and see if that makes any difference.

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Re: Front Brakes - lack of performance

Post by metallninja » Sat Jun 30, 2012 7:57 am

Excess travel on the lever'
1/ A sign of poor adjustment - on a bike though the lip seals on the pistons provide "auto adjustment" unless the pistons are seized.
2/ Previous experience - having owned a K2, K3, K7 & K8, If the master cyclinder is not bled correctly and BEFORE the calipers - this results in excess travel and wanky brakes.
3/ No mention of the pad condition - are they "glazed", are they worn?
4/ Are you sure the discs are original? Have you owned it from New? - replacement cast iron discs can take a lot of heating up when it's wet. unfortunately it's been wet for at least the last 2 years :(


If it were me, and the pads are ok. i'd be trying to bleed the master cylinder first. If there isn't a bleed nipple - crack the banjo bolts.
If that doesn't work - try a new (used) master cylinder.

Bon chance rodney

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Re: Front Brakes - lack of performance

Post by steve » Sat Jun 30, 2012 8:41 am

Graeme wrote:
steve wrote:Did you see Ecosse bleed your brakes or did you just pay for the pleasure ?
Of course, doesn't everyone stand and watch every major service? :roll

Yeah I do cos it's me that services my bike , I don't trust anyone to work on my bike :eek

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Re: Front Brakes - lack of performance

Post by Big Little Dave » Sat Jun 30, 2012 6:28 pm

steve wrote:Yeah I do cos it's me that services my bike , I don't trust anyone to work on my bike :eek
And I only trust Steve now I know what he can change on a bike :2up

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Re: Front Brakes - lack of performance

Post by Graeme » Sat Jun 30, 2012 9:43 pm

Yes, discs are original (and it's been owned since new). The calipers/pistons have never been cleaned, so this will be a first :log

I'll report in again and post the results :2up

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Re: Front Brakes - lack of performance

Post by steve » Sat Jun 30, 2012 10:35 pm

Big Little Dave wrote:
steve wrote:Yeah I do cos it's me that services my bike , I don't trust anyone to work on my bike :eek
And I only trust Steve now I know what he can change on a bike :2up

Thanks mate , only thing I leave to someone else is my tyres an Rob Sillet is the only person I trust with that job


If your calipers an pistons Isn't been cleaned in 11 years please expect the worst

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Re: Front Brakes - lack of performance

Post by Graeme » Mon Jul 02, 2012 9:14 am

steve wrote:If your calipers an pistons Isn't been cleaned in 11 years please expect the worst
Finally got round to it last night, calipers off, pads out - no fluid leaks. The discs are in good condition too.

Toothbrush & hot soapy water to get all the crud off, then sprayed in a healthy dose of brake cleaner. They scrubbed up like new, no sign of corrosion/pitting or sticking pistons. Obviously the layer of protective filth did its job. Replacement pads are on order - no glazing but they are due for a change. The lever feels much firmer now and doesn't squeeze anywhere near the grip any more.

Now I just need some sun so I can take it for a test spin :P

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Re: Front Brakes - lack of performance

Post by steve » Mon Jul 02, 2012 10:10 am

Flushing your brake fluid thru wouldn't hurt either dude , fresh fluid will do your brakes the world of good , I would also replace the bleed nipples for new stainless steel ones , that will prevent any corrosion forming around the bleed nipple , it's no fun tryin to get them out when they snap

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Re: Front Brakes - lack of performance

Post by al » Mon Jul 02, 2012 7:38 pm

Did you try pumping evry indivitual piston to mak sure they moved in an out freely? I clean my pads with brake fluid as that is compatible with the seals.

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Re: Front Brakes - lack of performance

Post by Graeme » Wed Jul 04, 2012 4:45 pm

Well sort of, I didn't test them individually. But they all moved out by (roughly) the same amout when I pumped the brake so I could give them a good clean, and they all pushed back in with nothing more than finger pressure.

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Re: Front Brakes - lack of performance

Post by Graeme » Fri Jul 06, 2012 11:04 am

Bike today - glad to say the brakes are back to their old selves! No more spongy lever, or getting fingers trapped behind it :worthy

Cleaning the calipers will be part of my maintenance G-spot from now on... :2up

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