revtothelimit - motorbike forum

The front brake on my Aprilia Caponord (mkII 2007/8) is very spongy despite repeated bleeds and fresh fluid, so I suspect the front master cylinder needs rebuilding. Brembo don't do a rebuild kit so it looks like I need a new one at £233 plus VAT (with no UK stock).

Before I break out the bank card from its leather prison, is it worth considering other brands? I suspect not but I've got to ask. My current lever perch/master cylinder is also the mirror perch as well as, obviously, the brake light switch.

Contact these guys. Did superb job on my Accossato

[email protected]

Maybe ask on a couple of Guzzi forums I think a lot of parts were shared across both the ranges during that time

I bought a (very) cheap one from ebay - obviously sourced from the Far East - and it worked perfectly and seemed very well made. This was on an oldish Honda 250. It did have the boss for the mirror (10mm IIRC). You just have to make sure you get the same bore as the one you have. This kind of thing although mine was much less blingy: https://www.ebay.co.uk/itm/235592197769

Yeah pretty much anything will work assuming the MC bore matches up. For the switch, if its currently a mechancial switch (and the replacement mc/perch doesn't have one) could consider a pressure switch.

iansoady wrote: Mon Jun 03, 2024 10:21 am You just have to make sure you get the same bore as the one you have. This kind of thing although mine was much less blingy: https://www.ebay.co.uk/itm/235592197769

DefTrap wrote: Mon Jun 03, 2024 10:45 am Yeah pretty much anything will work assuming the MC bore matches up. For the switch, if its currently a mechancial switch (and the replacement mc/perch doesn't have one) could consider a pressure switch.

Can I just check, when you say making sure the I get the same bore/the bore matches up, you're talking about a new master cylinder lever, not a rebuild kit?

This looks like it will fit - m/c ⌀ is 16mm, got a reservoir, mirror boss and brake light switch. Worth a punt.

https://www.ebay.co.uk/itm/164978485268

a picture usually helps!
brembos are used on many bikes, so getting a match is quite high. does yours have a lh threaded mirror mount or something stupid?

Sadlonelygit wrote: Mon Jun 03, 2024 11:45 am a picture usually helps!
brembos are used on many bikes, so getting a match is quite high. does yours have a lh threaded mirror mount or something stupid?

D'oh. I've updated the post above with the link. Nothing special about my Capo's brakes as far as I am aware.

Beancounter wrote: Mon Jun 03, 2024 10:05 am The front brake on my Aprilia Caponord (mkII 2007/8) is very spongy despite repeated bleeds and fresh fluid, so I suspect the front master cylinder needs rebuilding. Brembo don't do a rebuild kit so it looks like I need a new one at £233 plus VAT (with no UK stock).

Before I break out the bank card from its leather prison, is it worth considering other brands? I suspect not but I've got to ask. My current lever perch/master cylinder is also the mirror perch as well as, obviously, the brake light switch.

Last time I had permanently spongy brakes I changed the discs and it sorted it straight away.

Rockburner wrote: Mon Jun 03, 2024 12:02 pm

Beancounter wrote: Mon Jun 03, 2024 10:05 am The front brake on my Aprilia Caponord (mkII 2007/8) is very spongy despite repeated bleeds and fresh fluid, so I suspect the front master cylinder needs rebuilding. Brembo don't do a rebuild kit so it looks like I need a new one at £233 plus VAT (with no UK stock).

Before I break out the bank card from its leather prison, is it worth considering other brands? I suspect not but I've got to ask. My current lever perch/master cylinder is also the mirror perch as well as, obviously, the brake light switch.

Last time I had permanently spongy brakes I changed the discs and it sorted it straight away.

Were your discs past the wear limit? My front brake pads need changing and are no doubt contributing to the problem but I hadn't thought of the discs.

Beancounter wrote: Mon Jun 03, 2024 12:05 pm

Rockburner wrote: Mon Jun 03, 2024 12:02 pm

Beancounter wrote: Mon Jun 03, 2024 10:05 am The front brake on my Aprilia Caponord (mkII 2007/8) is very spongy despite repeated bleeds and fresh fluid, so I suspect the front master cylinder needs rebuilding. Brembo don't do a rebuild kit so it looks like I need a new one at £233 plus VAT (with no UK stock).

Before I break out the bank card from its leather prison, is it worth considering other brands? I suspect not but I've got to ask. My current lever perch/master cylinder is also the mirror perch as well as, obviously, the brake light switch.

Last time I had permanently spongy brakes I changed the discs and it sorted it straight away.

Were your discs past the wear limit? My front brake pads need changing and are no doubt contributing to the problem but I hadn't thought of the discs.

IIRC they measured ok, but they were on the thin end of the tolerance.

i still have no idea what your m/c looks like!
is the mirror perch actually part of the m/c or on the clamping part. if its on the clamp, then realistically you can fit any brembo to it, like a nice R1/R6 radial jobbie, that'll sort out spongebob!

I took a punt on this one https://www.ebay.co.uk/itm/233363432935 ... BM7Nyp9ftj as a replacement for the OE Brembo on my old Laverda (in this thread viewtopic.php?p=270388#p270388 ), and I have to say, especially considering the price, have been pleased with both the performance, and apparent quality of it.

Sadlonelygit wrote: Mon Jun 03, 2024 4:55 pm i still have no idea what your m/c looks like!
is the mirror perch actually part of the m/c or on the clamping part. if its on the clamp, then realistically you can fit any brembo to it, like a nice R1/R6 radial jobbie, that'll sort out spongebob!

Oh, I didn't get that you meant a photo of my m/c. Monday's aren't my best day. Will post one later when I get home.

Have you tried the trick of putting a strong rubber band ( slice of old inner tube works well ) around the brake lever and leaving it overnight? For some reason that can sometimes work when brakes are difficult to bleed fully.

roadster wrote: Tue Jun 04, 2024 9:34 am Have you tried the trick of putting a strong rubber band ( slice of old inner tube works well ) around the brake lever and leaving it overnight? For some reason that can sometimes work when brakes are difficult to bleed fully.

I've never found that to work and cannot see any reason why it should. Perhaps you need to believe in it!

iansoady wrote: Tue Jun 04, 2024 10:10 am

roadster wrote: Tue Jun 04, 2024 9:34 am Have you tried the trick of putting a strong rubber band ( slice of old inner tube works well ) around the brake lever and leaving it overnight? For some reason that can sometimes work when brakes are difficult to bleed fully.

I've never found that to work and cannot see any reason why it should. Perhaps you need to believe in it!

Theoretically it squeezes any air out of the fluid (because the system is at sustained pressure) which can then form bubbles large enough to migrate up to the highest point of the system - which is usually the m/c - then, when you release the lever, the bubbles can exit into the reservoir through the pressure release hole on the m/c.

It helps to have the bars turned so that the m/c is as high as possible when you do this - but that detail is often overlooked. It also helps to give the pipes a few taps occasionally to encourage the air-bubbles to travel.

roadster wrote: Tue Jun 04, 2024 9:34 am Have you tried the trick of putting a strong rubber band ( slice of old inner tube works well ) around the brake lever and leaving it overnight? For some reason that can sometimes work when brakes are difficult to bleed fully.

Thanks fella, tried that a few times but no luck. The brake lever is firmer (but not firm) for the first squeeze and then reverts to spongey.

Beancounter wrote: Tue Jun 04, 2024 6:23 pm

roadster wrote: Tue Jun 04, 2024 9:34 am Have you tried the trick of putting a strong rubber band ( slice of old inner tube works well ) around the brake lever and leaving it overnight? For some reason that can sometimes work when brakes are difficult to bleed fully.

Thanks fella, tried that a few times but no luck. The brake lever is firmer (but not firm) for the first squeeze and then reverts to spongey.

tbh - that sounds like you might have a leak.

Have you serviced the calipers? If so - did you split them?

If there was a leak wouldn't we expect to see some signs of fluid escaping?