How bad are stock E31 brakes?

[Original 8]

Trying to figure out whether I have an issue with my brake system, or the brakes on E31 are just not that great to begin with?

What is done:

-Brand new brake rotors all 4 corners
-brand new brake pads all 4 corners
-fresh dot4 brake fluid, properly bled with power bleeder (no air)
-brand new brake bomb
-brand new brake switches

No leaks from brake booster or master. Pedal feels fine. The brakes feel...not good. They are just not grabbing as well as I expect brakes on the car of this caliber to work. The car stops, but it feels like the brakes are just weak. I'd say there are about 500 miles on new rotors/pads - how long do brakes usually take to properly bed?

Is this how the brakes on 90's cars were, and I just forgot, or is there something wrong with them? I mean, I have no issues with brakes being really good on my other old cars.

[rjjablo]

Brakes on mine are great, Some no name pads and regular rotors.

I have kevlar brake lines though which you do not list, 30 years old and rotten and soft rubber, I would start there

[TxGR8White]

You need to replace the rubber brake lines at the calipers - weak link if they are original.

[Auraraptor]

They have a more linear, progressive pedal than modern cars. That said proper SS lines (goodridge had a sale for around 120 a short while ago), high cold friction brake pad, proper tires can do wonders to help out as well.

[Original 8]

Ok, thanks guys. New hoses ordered, I'll report back.

[Hyper]

...Pedal feels fine...They are just not grabbing...

I had to work hard to fish this out of a sea of subjective vocabulary.
What is "good" vs "not good"?

...New hoses ordered...

That's not where I would have ended up.
Hoses are about pedal feel, pads are about grabbing.
How about posting pad info: brand, material and rating (FF, GF, etc).



*** More pics
Measuring clamping pressure during BBKoB dev.
Two gauges, to catch any side-to-side imbalance on the 4-pot caliper.
Highly unfortunately, one can not drive down the road, measuring pressure vs deceleration.

[LappingLuke]

Sounds like you don't like your pad... maybe you have ceramic pads... every car I have driven with ceramics felt like it didn't have brakes. But I also have a habit of using pretty aggressive pads on my other cars. YMMV

[Original 8]

I had to work hard to fish this out of a sea of subjective vocabulary.
What is "good" vs "not good"?


That's not where I would have ended up.
Hoses are about pedal feel, pads are about grabbing.
How about posting pad info: brand, material and rating (FF, GF, etc).

I'll take a look - I'm not the one who bought and installed the pads - the car came with brand new pads installed, so I don't know which kind they are.
Hoses are cheap and likely needed to be replaced anyway, so all good.

Its hard to describe what brakes feel like - I have several other cars (all BMWs) and couple are late 90's cars, but they brake similar to how modern cars brake. E31 however, feels lacking - almost as if there isn't enough clamping force on the rotors when I press the pedal - they feel like they are always overheated. I have tried several times, and I can not engage ABS, which is also telling. Perhaps it is the pads.

Which pads would you recommend?

[Hyper]

...Which pads would you recommend?

For premium street, here is what I installed years ago on the 850 currently owned by LappingLuke.
Fyi, that vehicle has the full BBKoB front, plus rear caliper upsize.

[Original 8]

For premium street, here is what I installed years ago on the 850 currently owned by LappingLuke.
Fyi, that vehicle has the full BBKoB front, plus rear caliper upsize.

My car is 4/93 production date. I don't see Jurid available for it.

Just checked the pads on my car. I can't see ANY markings on them. At least not without removing the wheel and taking them out of the caliper. They are most definitely brand new, though.
What I also noticed, is that the grooving on the rotor is almost as if the rotors are still brand new - no wear at all. It is almost as if the pads don't have any bite into it - which you would think after 500 miles there would be some wear on the rotor.

[Hyper]

I just now dove into my brake biz inventory and found a set.
PM with address.

[Auraraptor]

Hmm did you bed your pads?

[rogbmw]

Hmm did you bed your pads?

I was thinking the same thing. Many put new pads on something then don't bed them in. It does make a difference.

[Original 8]

Hmm did you bed your pads?

Again, I did not install the new pads, PO did. I did however, bed them once I realize the brakes were not good. Didn't make much difference.

[Auraraptor]

Then I think you have either ceramics or a low bite ferro pad.

As I mentioned in my first post: for a streetcar you typically want a good high friction when cold pad. Jurids or like that it are fine options

[CD05001CIA]

Then I think you have either ceramics or a low bite ferro pad.

As I mentioned in my first post: for a streetcar you typically want a good high friction when cold pad. Jurids or like that it are fine options

Had Jurid pads on a 750il(car seized), stopped very well, could activate the ABS by slamming on the brake pedal.


The 850ci(came up missing) could put the passenger into the foot well if not wearing a seat belt. Stock Brembo calipers in front. Good working accumulator(brake bomb) all soft brake lines were quality stainless steel flex brake lines. even the small flex brake lines that are not at the calipers. As I remember CD05001 had a higher ABS pulse rate than other vehicles I have driven. When really getting on the brakes there is this BBZZZZZZZ BZZZZZZZ you feel in the pedal, in the car stopping. You just dump speed.

I drove CD05174(totaled) for a time, it had brake issues, it did not stop or feel anything like CD05001.

My sense of it is that your car is NOT up to par wrt: the accumulator(brake bomb), flexible brake lines --> quality stainless steel lines. all 4 ABS sensors in proper working order. Properly set up pads, rotors and calipers. Go to someone who has years of experience with brake pads/rotors/calipers to get all four corners properly maintained.



Ford Automotive Engineer, "A car that won't go, well we'll get to that problem. A car that won't stop? . . . SHUT DOWN THE ASSEMBLY LINE!"

[Hyper]

...a higher ABS pulse rate...BBZZZZZZZ...

That's an interesting observation, and describes the comparison to my mid 80's MBZ with an early generation implementation.
Maybe it was BMW engineers trying to hide ABS ops, mitigating drivers from letting up with a novice WTH? reaction.
Or was it those brainy engineers tuning the ABS frequency to a particular pad release behavior?
{ed: And if the system is tuned, how would the introduction of non-stock components (hoses, pads) affect the performance?}

[Hyper]

... found a set [of Jurid's]. PM with address.

Installed yet? Problem fixed?