Brakes still soft after rebuild

Hopefully someone can help my extremely frustrating situation.

I've been dealing with soft front brakes for months and tried everything to rectify the problem. Bled and bled them, tried removing calipers and bleeding them with the nipple at the highest point of the system. Still no luck..

Bought braided lines, new pads, new caliper seal kit, new pistons (as old seals had persished and pistons were pitted) and cleaned out all the salt and grime from the caliper.

Built the calipers back up, bled the lines and still the brakes are rubbish. I don't even have to apply much pressure to the lever and its touching the handlebar..

Is there anything else i can try without a caliper upgrade?

Thanks a lot

[R1ffR4ff]

Have you tried a new Master Cylinder or Master cylinder rebuild kit?

What year and model?

[glang]

And how did this come about? Did the lever slowly get softer, was it overnight, after you'd done some work on the system?

The bike is an sv650s k7. Haven't touched the master cylinder yet but i don't want to keep pumping money into it and get nowhere, are there any common problems that occur with the master cylinders?

The brakes have always been quite soft, they stop the bike but i did a track day a few weeks back and under hard braking the lever was all the way back to the handlebars.. Which wasn't ideal.

Cheers for the replies guys

[NTECUK]

Clapping the lever back over night might be a help.
Bunggie or something ekestical

[aesmith]

Something wrong with the master cylinder would be my guess. The SV brakes are quite straightforward to bleed with no special tricks needed, so if you've had a couple of goes then it's unlikely that you haven't got that part sorted.

New pads can give increased travel when they bed in, but not that much. When I've changed the pads I've just set the lever further out, and it sorts itself out after a couple of hundred miles.

[maviczap]

Originally Posted by Bartonam88

The bike is an sv650s k7. Haven't touched the master cylinder yet but i don't want to keep pumping money into it and get nowhere, are there any common problems that occur with the master cylinders?

The brakes have always been quite soft, they stop the bike but i did a track day a few weeks back and under hard braking the lever was all the way back to the handlebars.. Which wasn't ideal.

No point going for a calliper upgrade, even if it was easy or straight forward, as there are no straight swaps without a new calliper bracket.

Sv brakes are perfectly good enough for SV racers when in good order.

As you said, yours have always been soft, so that's maybe a clue, even after changing most of the major parts.

Agree with the others, master cylinder seal would be the likely culprit, and cheaper to replace than the callipers. Service kits are available, although the circlip is a pig to remove.

Ok brilliant, cheers for all the info!

Will post back if i get anywhere with them

[Bibio]

check you have the brake pad rattle springs the right way round, the large leafs go to the piston.

if you over fill the blind holes for the sliding pins on the carrier/calliper it will cause suction which will also give spongy brakes.

what did you use to put the piston/seals back in with. RRG?

[embee]

Do you use a vac bleeder system? If not, get one.


Various makes available, I use a Mityvac which is good quality, I can't vouch for other makes. A mityvac is somewhere in the £30 bracket but will save you all this hassle, I changed the brake fluid on the ABS combined brakes on my NC Honda a few days ago, took around 20mins total. One go, done.


purely as examples
https://www.amazon.co.uk/Mityvac-MV8...ustomerReviews


https://www.amazon.co.uk/d/Car-Brake...DJ4K7MHKBWV2X6