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Thread: firming up the brake pedal

  1. #1
    Join Date
    Oct 2004
    Location
    Bay Area, CA
    Posts
    261

    Default firming up the brake pedal

    Hey guys,

    It is my understanding that the e34 540 has a stronger braking system than the e34 525 and 535.

    Would swapping brake boosters with a 540 give me a better / firmer pedal feel? Would it be a direct bolt on?

    The brakes feel plenty strong, I just don't like how much I have to push them down since I've had the 17" wheels installed. Much less pedal travel with the stock rims!

    Thanks

  2. #2
    Join Date
    May 2004
    Location
    Sydney, Australia
    Posts
    2,699

    Default are you running stock brakes or larger brakes?

    id say if it's the stock brakes then don't worry. Checking the on-line ETK, the master clyinder out of the 540i is different than the 525i. but i don't know how easily upgradable, what pedal feel differences you get andand if it's worth it.

    regards

    kristian

  3. #3
    Join Date
    May 2004
    Location
    Japan
    Posts
    9,249

    Default

    I have to push them down since I've had the 17" wheels installed. Much less pedal travel with the stock rims!
    That I do not understand. The brake system has no relation to the rims directly and the system is an enclosed system.
    So if you changed only the rims and did not touch the brakes/calipers etc., then all should be the same.
    Did you check the brake oil level?
    Did you bleed the system?

  4. #4
    Join Date
    Oct 2004
    Location
    Bay Area, CA
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    261

    Default

    It's the whole thing with rotational mass. The same reason the car accelerates quite a bit slower with the rims. Since they are heavier than stock, they take more to start and stop.

    I was super confused when I first got my rims and experienced weaker feeling brakes and slower acceleration. When I asked on various forums that was the answer I got, but in much more detail.

  5. #5
    Join Date
    Feb 2004
    Posts
    4,894

    Default

    Start with flushing old brake fluid with new Valvoline Syhthetic Dot 4 brake fluid

  6. #6
    Join Date
    Oct 2004
    Location
    Bay Area, CA
    Posts
    261

    Default

    Quote Originally Posted by Tiger
    Start with flushing old brake fluid with new Valvoline Syhthetic Dot 4 brake fluid
    I did a fluid flush although another wasn't due yet, it didn't help me any. Like I said, it's nothing with the condition of the brakes. When I put the 15s back on, the brakes go right back to their old feeling. Its just the added weight of these 17s.

  7. #7
    Join Date
    Dec 2003
    Location
    Eastern Tennessee USi
    Posts
    14,839

    Default complete BS

    You will notice a bigger difference if you throw a bowling ball in the trunk.

    Quote Originally Posted by Hypr5
    Its just the added weight of these 17s.
    95 E34 530I V2.37
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  8. #8
    Join Date
    Oct 2004
    Location
    Bay Area, CA
    Posts
    261

    Default

    Quote Originally Posted by 632 Regal
    You will notice a bigger difference if you throw a bowling ball in the trunk.
    If you were close by I would love for you to come drive my car with the different rims. In all my cars, acceleration and braking power were lost when larger rims were added. I'm sure I'm not the only one who has experienced this.

    Heres my thread when I first got the wheels...
    http://bimmerforums.com/forum/showth...ghlight=wheels
    Last edited by Hypr5; 02-14-2005 at 05:31 PM.

  9. #9
    Join Date
    Dec 2003
    Location
    Central NJ - USA
    Posts
    1,540

    Default

    i can attest to 17's hurting breaking performance
    even with my pagid sport pads it feels like my 90535ia
    with 16's stops shorter....
    but i do need to bleed my system, so we'll see

  10. #10
    Join Date
    Oct 2004
    Location
    Honolulu
    Posts
    3,105

    Default

    The larger diameter wheels impact both the low end acceleration and the braking.

    The larger wheels act much the same way as changing the final drive to a lower ratio, reducing some of the low end, but you’ll get it back with better mid to high end.

    Brakes feel weaker also because of the larger diameter. Just think of the force required to break free a frozen nut with a short bar verses a longer one. Thus the larger wheels require more force from the brakes to stop the car.


    Vee ave vays of dealing vid your kind...........

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