2007 C70 Spongy brakes after front pad replacement

[PaulR]

Hi All,
Hope someone can help. Have just changed the front pads on my 2007 C70. Slowly compressed the pistons back with the reservoir cap off as I have always done. Everthing went fine and the brake pedal was solid initially but as soon as I started the engine, creating vaccum assist, the pedal went soft and I had to pump it. After doing this a number of times there was a small loss of brake fluid from the reservoir. When leaving the car for a while, allowing the vaccum to dissipate, the brake pedal returned to normal again, solid. Starting the engine made it spongy again. Tried the brakes on gravel and the ABS kicked in fine.
Have already done some research and aware that some people recommend opening the bleed valve when retracting the piston to avoid flipping the seal on the MS. Other people seem to regard this as an 'urban myth'.
I intend bleeding the brakes but not having opened the hydraulics at all, I am not optimistic of this solving the problem.

Any advice would be very welcome.
PaulR (new member)

[M-R-P]

Sounds like the retaining spring isn't located correctly to me. If the ends are on the wrong side of the caliper lugs, it'll feel spongy. I did it myself a few years ago.

[Harvey]

Very good chance you have fitted the anti squeal spring on wrong.
Sure there is a thread about this.

[JamesT5]

Possibly an air lock in the brakes. Did you bleed the brake system down properly after fitting?

[PaulR]

Thanks for your comments. Am aware of the problems of incorrect fitment with the wire type pad clips but mine is a more idiot proof version which I am sure can only go on one way. See picture. Decided to take a test drive and use the brakes a bit which seems to have improved things considerably although I am still not completely happy. Will carry on seeing if they continue to improve and then probably bleed the system even though I have not disturbed it during the pad change.

[M-R-P]

Aaah - that type lol.

Give 'em a bleed mate. Fitting the new pads would mean the piston rests in a different position and could have disturbed something. If the fluid is more than 18 months old, it wouldn't hurt to flush it through and while you're there, chuck some Dot 5.1 in there for good measure

[M-R-P]

Welcome to the forum by the way. Why not pop over to the "introduce yourself" section and say hi (don't forget pictures - we like pictures here)

[streaky744]

when fitting new pads the pedal will always feel spondgy until the new pads wear to the disc so you should find the pedal gets firmer as the pads wear in, avoid heavy braking on new pads for the first 200 miles or you risk over heating them and glazing them over.

if you have not opened the fluid system at all then they should not need bleeding, but as others have said if the fluid is old then maybe an idea to replace it and do this by bleeding all four wheels (not just the fronts) starting at furthest wheel away from master cylinder and finish on nearest to it.