Vague brakes

[QuattroFever]

having a quick blast yest night the brakes don't feel right.

Like they don't have any oomph? leaning on them at moderate speed like 50mph they stop great but if you try and squeeze on the pedal at about 80 they just feel sort of...vague?

no abs pulsing feeling through the pedal but just as if no matter how hard you press it wont slow any quicker than it is. which isn't quick...the work transit connect does better and it's carrying about 2 tonne.

Not a squeal from tires or sense of urgency to stop, more like a rather worrying feeling of overshooting wherever you might be aiming to stop

on 996 calipers up front with ferrodo ds2500 and stock rear discs calipers with ds2500.
new fluid about 3months back and pedal goes hard after about 15pumps. brake warning light comes on if you use them in anger more than twice in a row.

225 toyo t1-r's all round with loads of meat on.

any ideas?

[tscheel]

In for a listen - same problem here. G60 -> 996 -> G60 - no difference. Bomb OK. Assist unit or brake master could be the culprit?

[s2driveruk]

sounds like a couple of things to me (and at least worth checking)

Brake fluid needs to be re-bled - is the pedal travel long and does it feel 'spongey'
Have you checked the pad carrier pins for corrosion. Might be worth pulling the pads and checking the faces to see how they are wearing too.

Cheers
David

[QuattroFever]

Pedal not really spongey. A little but not vastly. Feels like theres a point where you feel max resistance and then maybe half inch more before the pedal feels hard but won't press anymore..almost like a spongey dead area 1/2" up and down. Hard to describe.

I put about 1/4 litre through every corner when I changed the fluid and about 1/2litre through the clutch. Hadn't been done a while though but fluid did run clean.

Pad sliders were cleaned off and pistons pushed in and out a few times about 3weeks ago because of brake moans and a long drive ahead. Pads about 50% worn allround no signs of anything bad with them. All look evenly wearing no score marks on the disc.

[driftin jo]

Sounds like your bomb could be dead, how many pumps of the pedal with the engine off until it goes hard ?

[QuattroFever]

about 15 pumps

[QuattroFever]

ok so a search threw up 30pumps or more and it's ok. 15 is obviously not ideal.

always thought the bomb was just an emergency reservoir in case of loss of power to aid steering and braking but didn't realise it can affect braking performance while the engine and hydraulics are running?

[driftin jo]

I would say based on that your servo could be leaking and that's why the brakes are rubbish as you have no assist, or at least very little.

[QuattroFever]

surely I could still bully it into obeying though. I can literrally put two feet on the pedal and push very hard and it feels like it brakes and gets to a point and where it wont brake any harder no matter how much force i apply.

I've driven a prepped mg midget with old non servo assist on track and you have to really lean on it but it does respond to harder and harder pressure until it locks. This is more like it just has it's limit of what you can apply then over that does nothing.

Is it possible the abs can become too sensitive somehow, does it have to see at least one wheel locked before it will respond or is it more intelligent than that?

Can you actually feel the ABS on your feet on tarmac with these cars? Can't say I've ever noticed other than on snow. Maybe It's the abs and I'm just expecting too much? I need to rig a cancel switch and turn off the ABS. Having the diff locked at 70 and jumping on the brakes is quite brave and not something i was prepared to try more than once. To say it was a bit twitchy would be an understatement