E9 Brake upgrade possibilities??

sfdon

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Most of the high end cars at my shop leave with rebuilt calipers, rebuilt booster and fresh lines. If the master tests bad it goes too.
Good coupe brakes will throw you through the windshield with little effort.
Arde just had his done at my shop- he will say they are light to the touch and stop in a heartbeat.
 

Gary Knox

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sfdon,

THANKS for that update. A complete rebuild of all the calipers, master cylinder, and new hoses was on my list for winter work. Glad to hear that might get my brakes back to where I thought my '73 3.0 CS brakes were when I sold it in 1982!
 

Ohmess

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Most of the high end cars at my shop leave with rebuilt calipers, rebuilt booster and fresh lines. If the master tests bad it goes too.
Good coupe brakes will throw you through the windshield with little effort.
Arde just had his done at my shop- he will say they are light to the touch and stop in a heartbeat.

This is my current brake plan, with the addition of lighter wheels and tires. I probably won't get to this until next year, however.
 

GRKOALA

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My problem is that my brakes stop the car when applying a lot of pressure but won’t lock up (or brake suddenly).

I have good pressure and my brake peddle comes up nicely.

I have overhauled all the brake Calipers, installed a new Brake booster, new lines and new brake fluid and the brake system has been bled.

Has anyone else had this issue? Could the brake pads be the problem (which is what my mechanic is leaning towards)?

The wheels are
4 x ALPINA 7J x 14H2 ET 11
 

Rek

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I read somewhere (can't remember where, here?) that E32 750il brake calipers will fit so long as the wheels are large enough. I would love to see if this is true so want to source some for fitting.

Separately, for those with RHD - I replaced the two servo's with two Jaguar servo's that on paper gave more pressure. It was for cost concerns as the bill for reconditioning the two stock servo's was eye-watering.
 

JFENG

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My problem is that my brakes stop the car when applying a lot of pressure but won’t lock up (or brake suddenly).

Has anyone else had this issue? Could the brake pads be the problem (which is what my mechanic is leaning towards)?

Sounds like a pad problem
(1) maybe you have high performance pads that need to be hot before they have a useful coefficient of friction?
(2) maybe your pads are glazed (overheater), which dramatically reduces their coefficient of friction.

I would inastall new pads (check/quick). And OEM pad like Paris will be dusty but provide high levels of cold friction. An aftermarket dustless or low dust pad will have less friction but you won’t be cleaning the wheels after every drive.
 

Wladek

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My problem is that my brakes stop the car when applying a lot of pressure but won’t lock up (or brake suddenly).

I have good pressure and my brake peddle comes up nicely.

I have overhauled all the brake Calipers, installed a new Brake booster, new lines and new brake fluid and the brake system has been bled.

Has anyone else had this issue? Could the brake pads be the problem (which is what my mechanic is leaning towards)?

The wheels are
4 x ALPINA 7J x 14H2 ET 11
I would suspect pressure regulator.
 

Boobouna

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My problem is that my brakes stop the car when applying a lot of pressure but won’t lock up (or brake suddenly).

I have good pressure and my brake peddle comes up nicely.

I have overhauled all the brake Calipers, installed a new Brake booster, new lines and new brake fluid and the brake system has been bled.

Has anyone else had this issue? Could the brake pads be the problem (which is what my mechanic is leaning towards)?

The wheels are
4 x ALPINA 7J x 14H2 ET 11

Yes this is what I experienced also and I have had the same pedal feel even after rebuilding the brake boosters and replacing discs and brake pads. Before and after still the same long pedal travel to stop. I have driven four other coupes which felt the same. I think we have to realise this is an early 70’s car and can’t expect modern car stopping power.


Sent from my iPhone using Tapatalk
 

GRKOALA

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Sounds like a pad problem
(1) maybe you have high performance pads that need to be hot before they have a useful coefficient of friction?
(2) maybe your pads are glazed (overheater), which dramatically reduces their coefficient of friction.

I would inastall new pads (check/quick). And OEM pad like Paris will be dusty but provide high levels of cold friction. An aftermarket dustless or low dust pad will have less friction but you won’t be cleaning the wheels after every drive.

Thanks guys, all worth addressing. I’ll get some softer genuine pads and also check the pressure regulator . I have a 1974 Mercedes 107 (280SL) and the brake system is fantastic. All 4 disk brakes grab very evenly with a great even feel without having to stand on the brake pedal. I’m sure BMW’s technology and attention to safety would have been on par with Mercedes at the time.
Boobouna, I’ll let you know the outcome and hopefully we can make our cars a little safer

Much appreciate everyone sharing their knowledge
 

Ohmess

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Thanks guys, all worth addressing. I’ll get some softer genuine pads and also check the pressure regulator . I have a 1974 Mercedes 107 (280SL) and the brake system is fantastic. All 4 disk brakes grab very evenly with a great even feel without having to stand on the brake pedal. I’m sure BMW’s technology and attention to safety would have been on par with Mercedes at the time.
Boobouna, I’ll let you know the outcome and hopefully we can make our cars a little safer

Much appreciate everyone sharing their knowledge

Guys -- I had a weird pressure regulator issue that you might want to look into. My car sat for five years before I bought it, and during that time the rubber lines to the calipers deteriorated. When this happened, very small amounts of rubber broke lose inside the system and became lodged in the brake regulator. I then had no hydraulic pressure to the rear brakes. Try bleeding just the rear brakes, using just a small amount of fluid in the catch bottle. If you cannot see the catch bottle filling up, this may be your problem.
 
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I read somewhere (can't remember where, here?) that E32 750il brake calipers will fit so long as the wheels are large enough. I would love to see if this is true so want to source some for fitting.

Separately, for those with RHD - I replaced the two servo's with two Jaguar servo's that on paper gave more pressure. It was for cost concerns as the bill for reconditioning the two stock servo's was eye-watering.
Hi Rek
I may have to replace the two servos on my 3.0 csl .Can you tell me which model of Jaguar servo you replaced them with.? Is a straight forward swap or was there a need for some modification?

Regards

Carol
 

Rek

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Hi Rek
I may have to replace the two servos on my 3.0 csl .Can you tell me which model of Jaguar servo you replaced them with.? Is a straight forward swap or was there a need for some modification?

Regards

Carol
I think it was two of these.


the only modification was for the fixing of these to the inner wing, and the re-routing of the brake lines.

I am looking at one of these instead. It much smaller and seems just as powerful.


I have other fish to fry before this though.
 

Honolulu

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My second bimmer, in the early 1980s, was a '69 2500 sedan with auto trans. Several thousand dollars of work had been done to various systems under the PO, but AFAIK was all stock. The booster was the thinner type and I don't know what pads it had, but it stopped wonderfully with light pressure on the pedal, better and more smoothly than the several dozen cars I've had since. Somehow, parts available in the early 1980s could be used to get excellent braking.

Static test the brakes: idling at rest, step on the brake pedal for a minute, the pedal should not, even ever so slowly, sink to the floor. Second: foot on brake pedal, start the car, pedal should sink a bit and brakes should come on fully. Third test: pump the brake rapidly while idling, engine speed should rise. Fourth test: with no one anywhere close behind you, stomp on the brakes, the front two should lock. Fifth test: cruising along at perhaps 35 mph, hands off the steering wheel, get on the brakes firmly and the car should continue to track straight.
 

shanon

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Refresh bushings, rebuild calipers, add stainless steel brake lines and a good high temp fluid and pads.

I have been very happy with this setup. Works great on street, mountains and on the track/racing.

Hth
 

JFENG

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If all else in the braking system is proven to be working properly, You could look into pad compounds with higher cold coefficient of friction. The difference in performance can be quite significant. Porterfield has a pad compound (R41) which is up near 0.6 even when relatively cold. That is 20% or more higher than other low dust 'performance' pads. They are a track-type pad so they are dusty but have good high temp capability. Also, they will likely squeal a bit from time to time, under light application.

Bad brakes, to me,are ones that are unable to generate enough braking force to instantly lock up all 4 regardless of how hard you push on the pedal. Brakes that require significant pressure to lock up 4 wheels aren’t necessarily weak, they're just designed that way.
 

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20190808_121309.jpg
 

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