spongey brake front brake?

[CorriganJ]

(Hyosung GT125 disk brakes)

I'm a noob with bikes but recently my front brake has gone "spongey". It was a day or so after an emergency brake, so, as I say I'm a noob but I'm wondering if the heavy braking forces caused the brake line (quite old) to bubble or stretch in one area?

The brakes do still work and stop me, but less quickly than before, and there is a noticeable loss of feedback in the lever. It feels floppy instead of engaging straight away, and gives less feedback while stopping.

Does my diagnosis sound correct? Am I looking at replacing the brake cable? I took it to the garage where I bought the bike from, because I have a waranty, and they said it was fine, but I don't believe them because yes, it does still stop the bike, but there is a noticeable change in how it feels. I think they are just shrugging it off because they can't be bothered to fix it and I don't have any way to force them to honour the warranty.

Thanks in advance for any help!
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1991 RD04

[NJD]

Remove calliper from disc, clean and lube appropriately and reattach; do the same with the brake lever pivot point and report back after a ride.

Dust and road salt at this time of year will reduce efficiency in stopping power after not very many rides if regular attention is not played as the salt will just sit in every part you never want it to and corrode away at parts.

Also take into account the effect that air temperature, road temperature and tyre temperature alongside weather conditions will have on your ability to stop on the whole (any problems aside). Its not difficult to ride this time of year and think there's a problem when there's not, but as above clean calliper and report back.
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The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶

[Kawasaki Jimbo]

[Nobby the Bastard]

[Robby]

Chances are that the brakes need a good clean, and the heavy stop has got something that is meant to move around bound up on some rust.

[jeffyjeff]

Check the brake fluid level on the front brake reservoir. You might need to add fluid and bleed air out of the brake line.
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History shows again and again how nature points out the folly of men - BOC

[Pete.]

First thing to do is remove the reservoir top, and the rubber diaphragm, then re-fit and try the brakes again. As the pads wear the level drops in the reservoir and the space is supposed to be filled with air from outside, but often the little bleed hole gets clogged and it pulls a bit of a vacuum in the reservoir.
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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

[CorriganJ]

Thanks everyone for the responses! I will see what I can find.
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1991 RD04

[pepperami]

My Hyosung gt125 has hydraulic brakes ( reservoir, hose, & caliper).

Once you have cleaned up the caliper and made sure everything can move as it should .
Try replacing the hose with a braided jobby.
It worked a treat on my GT250R
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I am the sum total of my own existence, what went before makes me who I am now!

[MCN]

Sand Paper the disc/s and pads.
Brakes can get a build up of brake pad material and road crap bonded to their 'working' surfaces.
Buy a packet of wet and dry medium grit paper (600 grit).
Remove the pads.
Place a sheet of the wet and dry on a flat surface.
Put the pad on the wet and dry and make 'Figures of Eight' on the paper to rub any build up off the surface friction material of each pad.
Take the paper and rub the surfaces of the disc to remove any discoloration.
It's a simple job, creates a bit of dust and requires the el ow to be well greased.
It will help the pads grip the disc.
It's a good habit to now-and-again do a bit of heavy braking after heating up the brake disc and pads.
Do it on a clear road, fairly slow speed (until you get acquainted with the procedure, so you don't fold the front wheel under the bike. )

If it continues to worry you, then upgrade the brake hose to a HEL Stainless Steel Braided hose.
https://www.helperformance.com/hyosung-gt125r-gt250r-2006-2007-full-length-race-braided-brake-lines

Many OEM machines use rayon/fabric braid reinforced hose. (Cheaper).

Some maintain that it makes no difference to brake performance.
Those are folk who probably did not have issue prior to fitting a SS Braided hose.

I fitted to a Honda CG125 which had Rubber hose from new.
The difference was exponential.

(And it shifted the power band 25% Degree BTDC. 👍)
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[CorriganJ]