Spongy brake pedal

[FRENCHMICK]

Hi I bought my Megablade last weekend, had it in the garage on Tuesday for mot and a general check over, the brake pedal to me seems spongy, however the guy at the garage says the brakes have passed through the mot no problem. I suggested to change the brake fluid, but he said it was not necessary.

What are other people's brake pedals like ?

The brakes work ok, but the first part of the pedal travel is soft, do you have any advise ?

[XTR2Turbo]

I have always struggled with a soft pedal on my busa. Others who have tried it suggest air somewhere, probably the Sierra rear handbrake callipers

They are notoriously difficult to bleed completely

[CosKev]

The lack of servo assistance makes the brake pedal feel more 'on' or 'off' IMO.

It's probably just the fact your used to a lot of servo assistance on production cars?

As above though,the rear calipers if yours are Sierra ones can't be bled with the caliper bolted to the upright as the bleed nipple is not at the top of the caliper.

Another point which can hold some air is the brake light switch if it's using a hyd switch in the brake line

[Terryathome]

Might be other things like pads stuck, soft, bolts, flexing, discs scored etc.

[SootySport]

You're not the first to have a spongy brakes and it's usually air in the sierra rear callipers.  Raising the rear of the car and unbolting the callipers from the upright and tying them up high in the wheelarch helps bleeding.  Bleeding each side several times helps and depends how patient you are.  You'll maybe be not be able to rid all the air from the callipers but at least improve the feel of the pedal to a acceptable level. 

[Bogyoch]

Winding the pistons back in helps eliminate air pockets in the Sierra calipers.