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Re: Cbr600fx
Posted: Mon Apr 20, 2026 5:48 am
by Ssray
I realised that one of the discs was a bit warped quite early, I've planned to replace it .
Yesterday morning as I've been off work I hadn't used the bike for ova week.
Off the stand and tried to ride off, the front brake felt like it was stuck on, as I didn't have time I jumped in the car.
Got home and loosened the calipers, the one on the warped disc slid off but the other side was stuck, I attempted to clean the caliper but it looks like it needs new seals and a strip down.
Seal kit ordered, I'm going to remove the pistons and put them in vinegar, as the pad end has got some rust on it.
Hopefully the seals will be here Thursday ish
Re: Cbr600fx
Posted: Mon Apr 20, 2026 8:56 am
by A_morti
While you're opening it anyway: if you can find some CBR 929/954/600rr4 calipers in good condition, they fit 1:1 and have teflon-coated aluminium pistons which seem to be basically impervious to corrosion. And they're a fancy gold colour.
Nissin seem to have been playing with finding the best piston sizes around then, so they may not be the same as the seals you've bought already. But still, if you get in there and the pistons are rotten, this could be your fix.
Re: Cbr600fx
Posted: Mon Apr 20, 2026 10:16 am
by Supermofo
A_morti wrote: Mon Apr 20, 2026 8:56 am
CBR 929/954/600rr4 calipers
They are considered an upgrade for loads of Honda's. I fitted a pair to my Firestorm years ago.
Re: Cbr600fx
Posted: Mon Apr 20, 2026 10:32 am
by Druid
Supermofo wrote: Mon Apr 20, 2026 10:16 am
A_morti wrote: Mon Apr 20, 2026 8:56 am
CBR 929/954/600rr4 calipers
They are considered an upgrade for loads of Honda's. I fitted a pair to my Firestorm years ago.
and I fitted Firestorm calipers to my VFR750
Re: Cbr600fx
Posted: Mon Apr 20, 2026 10:41 am
by Supermofo
Druid wrote: Mon Apr 20, 2026 10:32 am
Supermofo wrote: Mon Apr 20, 2026 10:16 am
A_morti wrote: Mon Apr 20, 2026 8:56 am
CBR 929/954/600rr4 calipers
They are considered an upgrade for loads of Honda's. I fitted a pair to my Firestorm years ago.
and I fitted Firestorm calipers to my VFR750
I've still got my Firestorm calipers, MC, hoses and lever in the garage somewhere I think. Meant to sell them, but I never get round to it! I ended up skipping a set of OE Firestorm cans and an OE 2004 Z750 end can last year as they took up loads of room and looking on Ebay were only worth about 20 quid so didn't bother.
Re: Cbr600fx
Posted: Tue Apr 21, 2026 7:57 pm
by Ssray
Supermofo wrote: Mon Apr 20, 2026 10:41 am
Druid wrote: Mon Apr 20, 2026 10:32 am
Supermofo wrote: Mon Apr 20, 2026 10:16 am
They are considered an upgrade for loads of Honda's. I fitted a pair to my Firestorm years ago.
and I fitted Firestorm calipers to my VFR750
I've still got my Firestorm calipers, MC, hoses and lever in the garage somewhere I think. Meant to sell them, but I never get round to it! I ended up skipping a set of OE Firestorm cans and an OE 2004 Z750 end can last year as they took up loads of room and looking on Ebay were only worth about 20 quid so didn't bother.
I didn't realise there was an upgrade, I'll have a look on the bay
I've bought the seals so.could rebuild them and sell them on
Thanks
Re: Cbr600fx
Posted: Tue Apr 21, 2026 8:03 pm
by Ssray
I've found two for £50 but I've also possibly got the chance of getting a 1998ish fireblade.
I'll try the rebuild, it may be easier to sell with oe calipers that work correctly
Re: Cbr600fx
Posted: Tue Apr 21, 2026 8:41 pm
by A_morti
The same gold calipers also fit a '98 fireblade.
They're an upgrade to all those bikes, but for road use that's mainly just in terms of corrosion resistance. So realistically it's only worth doing if the calipers you have aren't worth saving.
Re: Cbr600fx
Posted: Sat Apr 25, 2026 5:02 pm
by Ssray
Calipers rebuilt, they work well but even riding to the end of the road the lever was coming back to the bars, pump it a few times and it goes hard, the warped disc is pushing the piston too far back.
I thought it wasn't really a big deal but I assuming the calipers were quite well seized and the pistons weren't moving back at all when the warped bit went by
I've ordered some vfr800 discs from evilbay, hopefully back in the road next weekend
Re: Cbr600fx
Posted: Sat Apr 25, 2026 9:05 pm
by A_morti
Runout spec is usually 0.2mm, if it's more than that there's no ignoring it.
That being said - is it definitely that? If the square seals are lower quality, the groove still has corrosion in it, or etc , then it could be the pistons are being pulled back in by other means.
Can also be that when you bled the brakes, the master cylinder piston touched parts of the bore it doesn't usually reach, hit a burr or piece of dirt it usually misses, and damaged it. Then you'd be losing pressure and pumping it up would regain that.
So... Unless you're getting a decent bit of pulsing through the lever and/or have measured out of spec runout, it might not be the problem.
Re: Cbr600fx
Posted: Tue Apr 28, 2026 5:16 am
by Ssray
A_morti wrote: Sat Apr 25, 2026 9:05 pm
Runout spec is usually 0.2mm, if it's more than that there's no ignoring it.
That being said - is it definitely that? If the square seals are lower quality, the groove still has corrosion in it, or etc , then it could be the pistons are being pulled back in by other means.
Can also be that when you bled the brakes, the master cylinder piston touched parts of the bore it doesn't usually reach, hit a burr or piece of dirt it usually misses, and damaged it. Then you'd be losing pressure and pumping it up would regain that.
So... Unless you're getting a decent bit of pulsing through the lever and/or have measured out of spec runout, it might not be the problem.
I can see a dark area on the disc where it's not swept by the pads, also the spider/carrier is obviously bent either through a disc lock incident or someone trying to remove it.
The lever is very firm but if I push it 10 feet then the lever comes back to the bar before building pressure
Re: Cbr600fx
Posted: Tue Apr 28, 2026 8:28 am
by Rockburner
New disc time.
Re: Cbr600fx
Posted: Tue Apr 28, 2026 9:51 am
by Ssray
Rockburner wrote: Tue Apr 28, 2026 8:28 am
New disc time.
Hopefully Wednesday or Thursday
Re: Cbr600fx
Posted: Tue Apr 28, 2026 10:17 am
by Rockburner
Ssray wrote: Tue Apr 28, 2026 9:51 am
Rockburner wrote: Tue Apr 28, 2026 8:28 am
New disc time.
Hopefully Wednesday or Thursday
Brakes are the one thing I won't skimp on. When push comes to shove they're the thing that can save your life.