Not enough space between brake pads to get caliper back on..

[Kaph]

Turning into a bit of a saga this.

Have changed the front brake pads on my CB-1, and now I can't get a gap wide enough to get them back on either side of the disk with the new pads.

The pistons won't go in any further, have tried many different approaches and they wont budge, but will come out somewhat when front brake is pressed.

Now, the issue I have is the reservoir screws have rusted in and the heads are a pathetic sized hex, and are just rounding off when I try and get the screws undone.


Is the issue with not enough space between the pads likely to be the result of too much fluid in the reservoir?

Many thanks!

[CaNsA]

[Kaph]

Roger. Any suggestions on loosening the rusted bolts? Not drilled anything out before, shall Google.

[Pete.]

Are the screws countersunk hex? If so, take a small hammer and strike them flat on the top. This will close up the hex holes, upset the hold on the countersink taper and shock the threads, making removal much more likely.

If all else fails and you absolutely need to get the pads in without opening the reservoir so that you can use the bike, you can crack one of the unions and let oil seep out there whilst pressing back the pistons but this is a last resort and carries the risk of introducing air, plus having an over-filled reservoir. If you have any problems you still have to tackle the reservoir screws, and you'll have to anyway sooner or later.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Kaph]

Removed some fluid via the bleed nipple through a one-way, but still no luck with getting the pistons to push back any further.

Shall try the above tomorrow and see if I get anywhere!

Cheers.

[Turkish]

For the hex screws, find a torx bit that is one size too big, line the points up with the corners of the hex and hammer it in. This should bite enough to undo the screw. Don't try and reuse it obviously.

To drill out the screws, get a sharp bit about 2mm to start with and drill centrally about 5mm into the head of the screw. Increase the bit size 0.5mm at a time (same drill depth) until the head drops off. With the cap off, you can remove the thread remnants with mole grips.

The pistons are probably not going back far enough due to corrosion or crap on the pistons. You should be able to get them flush to the caliper. You might want to try scraping the crap off them and giving them a good clean with brake cleaner.

Worst comes to worst, strip the caliper down, removing the seals very carefully. If your trying to avoid spending money, clean off all corrosion from piston and bores then reassemble with the same seals - lube with red rubber grease or brake fluid only.
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ZX-6R G2
CBR125R RW6

[Robby]

I have come across this problem when the caliper has rebuilt with pattern piston(s) that are slightly higher than the originals. Combine this with (often cheap) pattern pads that are thicker than the originals, and it just won't go together.

You need to get the top of the resevoir open regardless. If the screws has rusted up, then there is a fair chance that the brake fluid is more than two years old and needs replacing.

It is quite possible that even when you get the top open, the pads are just too thick and you won't get them to fit.

[Kaph]

Thanks for the explanations guys, that's this afternoon sorted.

Shall clean up the pistons and see if that gets me anywhere - but like you say the reservoir is going to need to be sorted anyway.

I've got some red rubber grease and shall order some new seals if necessary, after 24 years I think it deserves a little bit of love!

Just desperate to get back out on it, have been faffing with the forks for weeks.

[Vincent]

You may end up having to drill those screws out......esp if they're stainless.

I've got a few CB-1 caliper spares if you get stuck.
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Space Is Deep

[Kaph]

Woo! The one-size-too-big torx bit and hammer tip worked! Turned out it wasn't overfull, but am very relieved that I now have access to the reservoir. Anyone know where to source replacements? There's some on Wemoto, only 28p but £3.00 for delivery. It's the principle.

Pumped out the pistons and cleaned them up as suggested, before red rubber greasing. Managed to get them to push back in! Pads on, caliper is now back on the bike!

Very satisfying! Shall bleed it and replace with new fluid as the stuff in there was a disturbing colour.

What spares have you got Vincent? May well be interested.

[Aff]

PM me the specs of the screws and I'll see if I can get you a few.
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Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[Vincent]

[Kaph]

Unfortunately I've also misplaced two of the fork axle pinch bolts. Shall definitely be organising things better in future! Any ideas on where to source those? Wemoto/DavidSilver/eBay reveal nada.

[Vincent]

I can give you the bolts out of a used leg if you like.....but the post may cost more than getting some from your local blacksmith.

I bought my first CB-1 after years of litre-plus bikes and realised how much more fun a smaller bike was around town.

Don't be tempted into changing the cams or sticking a different swingarm in with a fatter tyre - it's a great bike as it is IMO. It feels like it needs an extra gear on longer runs but the engine can withstand plenty of punishment The bars are a bit low for me, the MKll had higher ones....oh...and the rear shock can be improved upon...no biggie tho. As with a lot of Hondas of that period, the original reg/rec was next to useless. If for any reason, the bike won't start, don't spend ages fruitlessly turning the starter as the starter clutch may pack up. Mine has a certain starting procedure - tiny amount of throttle and no choke unless feezing.
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Space Is Deep