525iEnjoy

Make sure bleed sequence of LR RR RF LF was used (left=drivers etc)
How many miles are on the M5 calipers and pads?

could be your stock lines are ballooning. have those looked at. how many miles are on your stock lines?

Where the caliper piston and seals in good shape. check the slider pins.

kdarcia007

LR= Left rear??

Probably around 5k miles on M5 calipers and pads, they look new.

Is that sequence absolutely necessary?, sequence of LR RR RF LF was used (left=drivers etc)

525iEnjoy

Right Rear, Left Rear, Right Front, Left Front sorry, I switched the first two

start furthest from the Master Cylinder

yes most cars need it done this way

545felix

or perhaps they didn't attach one of the lines properly. Is the system leaking fluid?

kdarcia007

Just came back from the shop, I asked them to do a test:

1st- put on the old stock brakes and do a test to see if they brake hard?
Result: they brake hard

2nd: do the same thing but with new M5 stocks, to see if they brake hard?

Result: they don't pedal is still very soft and braking sucks!

Pads, calipers and rotors are in great condition.

Question: does it affect if they don't use the vacuum to change the brake fluid?

They were gonna take the car to a place where they do it with the vacuum, will it work?

At this point we don't what could be the issue, any suggeations?

545felix

either you have a leaky piston seal on one of the calipers or one of the calipers has air in it and hasn't been bled of it.

kdarcia007

Hey guys, no air in the calipers or lines.

We did a test, we left the rear M5 calipers and installed the stock 530i calipers in the front.

Result: braking power is hard upfront and soft in the back...
Logic: seems the stock brake pump is to small for the bigger M5 calipers, that makes sense?

My car is a 2004 530i, should I replace my brake pump with the BIGGER (in CC's) M5 brake pump?

toyota2bmw

Still doesn't make sense. Memeber 525iEnjoy has done this without issues without such issues. This still sounds like there is air in the system. Is your shop BMW qualitfied? There's one more method of bleeding the brakes using the GT1 computer. There's what's called a DSC flush. My indy guy did this for me a while back where your car will be hooked up to the computer and the DSC unit will circulate as each corner of the brakes are bled. The process fills the DSC unit will fluid to make sure there is no air in the system.

Masterspy

If all the lines are okey and no air in the system, maybe it is a defective M5 caliper. Just my 2 cents

kdarcia007

How can we find WHICH caliper is defective?