New brakes, soft brake pedal

T

tee.gilding

Active member
 Hampshire
Hey all,

Picked up my coupe last night after having all four discs replaced, new pads all round, front calipers rebuilt, and original hoses swapped for braided hoses, and the brake pedal is VERY soft. It's probably 60% pressed in before the brakes have any real effect. And braking hard is very noisy.

The mechanics reckon they've bled the system 3 times and obviously replaced the fluid completely. They reckon it's weird and it might come right after a few miles, but I drove it nearly 30 miles home and it's still really soft under foot. They've offered to have another look at it and get it sorted if it doesn't come right, but I'm just wondering what might be causing the issue.

Any thoughts as to what might be going on?
 
There is clearly air in the hydraulic lines, the the system purged again. The bedding of pads and discs will also make it feel a little different, but never to the extent that you describe.
 
Air in the system. Get them to bleed it again. The air may move around which is what hey are hoping. But it will still be there. Braided hoses should give you a harder pedal, all other things being equal. What kind of noise are you getting? A squeal/rustling/ metallic / gritty?
 
As above, clearly hasn't been bled out properly. Assuming they kept a constant pressure on the brake pedal during parts replacement it shouldn't need the ABS system purging out, but I know a lot of places skip that part.

The proper way to bleed the ABS is with the official software, but it can be semi-done by intentionally triggering the system.
 
If they are using a power bleeder you shouldnt get any air locks. Thats pretty poor putting your car out like that. Its a dual system so they havent got any of it right. Otherwise you may experience a bit of pulling to one side at the front.Its a closed system so it wont improve as they suggested.
 
They used a power bleeder, and the mechanic there was very confused as to why it felt so soft. He bled it three times using the power bleeder, and he's done a fair few BMW's (being a BMW specialist) so should know what he's doing.
buzyg said:
Air in the system. Get them to bleed it again. The air may move around which is what hey are hoping. But it will still be there. Braided hoses should give you a harder pedal, all other things being equal. What kind of noise are you getting? A squeal/rustling/ metallic / gritty?
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The noise is a metallic groan/squeal, quite a low pitch, but only at very low speeds. When applying the brakes there is a metallic grinding noise which is much louder than I initially expected it to be, but then the brake discs were coated with a "protective coating" which basically just looks like spray paint...
 
Personally I would throw it back at them and tell them to do it properly. You cannot send a customer away with faulty brakes that you have supposedly "fixed" that is tantamount to man slaughter. What happens if you have a child run out in front of you and can't stop? Not big, not clever and dangerous! And on top of that it would be YOUR fault.
 
Jl-c said:
Personally I would throw it back at them and tell them to do it properly. You cannot send a customer away with faulty brakes that you have supposedly "fixed" that is tantamount to man slaughter. What happens if you have a child run out in front of you and can't stop? Not big, not clever and dangerous! And on top of that it would be YOUR fault.
Click to expand...
Yep, you're right. I'll have to get it back to the mechanics and get them to sort it out...
 
It's bad enough a garage (specialist) would let a vehicle leave after doing a brake overhaul and knowing there's a problem, to bleed the system 3 times tells me they knew there was an issue.
But to let a high powered sports car leave is totally out of order, these fools need naming and shaming.
Very poor service :thumbsdown:
 
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