Page 8 of 11 FirstFirst 1234567891011 LastLast
Results 176 to 200 of 253

Thread: Brake Pedal Feel Issue

  1. #176
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    Quote Originally Posted by odortiz View Post
    the craftsmanship looks amazing on the e30 booster delete kit. does anybody use it on the street with street pads?
    will there be a provision to set up the pedal travel sensor on some e36s to retain ABS?
    Thanks for the good word. I appreciate. Some people use it on the street and I recommend to decrease the MC size and to use pads with a higher coefficient of friction even with the increased 6:1 pedal ratio (let's not forget it is a race set-up). It worth noting that not everyone has the same strength in their leg. Therefore what can be judged unbearable in term of force required to push that brake pedal might very well be very acceptable for others. if I spend a week driving my e39 Touring (which is over assisted in all departments), it takes time to adapt to my e30 M3.

    BTW Here are a few numbers that could help decide how to tackle MC selection vs pedal ratio (both being levers). Per exemple a stock 25,4mm MC with an improved pedal ratio of 6:1 would be about the same effort/travel as a 20.6mm MC on stock 4:1 pedal ratio (should be 337sq.mm more exactly). The advantage of using a smaller MC on a stock pedal ratio is less mechanical stress on the pedal stem.

    MC size / Piston area

    25.4mm (1”) / 506sq.mm

    23,8mm (15/16“) / 445sq.mm

    22.2mm (7/8”) / 387sq.mm

    20.6mm (13/16") / 334sq.mm

    19.05 (3/4”) / 285sq.mm
    Last edited by Massive Lee; 01-26-2012 at 12:19 PM.
    1969 2002 racecar + 1989 e30 M3 racecar


  2. #177
    Join Date
    Feb 2009
    Location
    Mountain View, CA
    Posts
    771
    My Cars
    06 GTO, e36 race car
    fwiw, my tilton dual-master setup has a 3/4" front master, 7/8" rear master and 6.2:1 pedal ratio. Braking effort is perfectly acceptable. In fact I'd say that a higher effort and more slave piston motion per pedal press would be preferable.

    One thing I find quite useful is the ability to adjust the pedal height: reach in, loosen the locknuts, rotate the piston plungers a few times. This allows me to optimize the height relative to the gas pedal for heel/toe. This is needed as the pads wear and gain more taper and cause a longer pedal (hopefully this will be less of a problem with my nice new Massive Brakes calipers!). I don't know if the kits being discussed here have that capability?

  3. #178
    Join Date
    Jun 2007
    Location
    Northern KY / Cincinnati
    Posts
    2,662
    My Cars
    e36 Track Car
    Flink-o-meter, are you still running those Wilwoods?
    Regards, Nate.
    www.DriveFasterNow.com

  4. #179
    Join Date
    Feb 2009
    Location
    Mountain View, CA
    Posts
    771
    My Cars
    06 GTO, e36 race car
    Quote Originally Posted by TOOLEAN View Post
    Flink-o-meter, are you still running those Wilwoods?
    No, those horrid things are in the trash. I replaced them with Lee's 13" kit. It's night and day, like standing on a rock.

    I should have tossed those rotten calipers years ago. They were as bendy as bananas, they had equal-sized leading and trailing pistons and it turned out that whoever had built the car for World Challenge had taken a grinder to the car to make the brakes "fit", removing fully half the steel from the caliper mounting lugs on the kingpins! I bought new M3 kingpins.

  5. #180
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    Hi Flink. I remember. The nightmare of the grinded knuckles... ;-) You got me worried that evening when you emailed and told me the caliper and rotor were not centered... ;-) And felt relieved when you found the mounting tabs on your knuckles had been ground. And probably the reason why you couldn't get a positive feel in your brakes. If the caliper is not 100% parallel, it will have to bend/twist to properly squeeze the pads on the disc. And it doesn't require much misalignement. Otherwise, the Superlite remains a good caliper. It just must be propely installed ;-) No wonder AP Racing copied the Superlite and the SL4R (even using the exact same pads), yet selling at twice the price.

    In regard of your question about the adjustabilty of the pedal height, answer is in the affirmative. The rod between the MC and the pedal is indeed threaded. A tab that limits the pedal height will also be supplied and bolted where the spring/rubber grommet is hung.

    In regard of the World Challenge cars, I have many friends who bought some. In most cases the cars were prepared to the limit of being acceptable, with cages that were primitive and preparations that were basic. Despite the name, I think that this group was not much more advanced than BMWCCA CR's Prepared class.
    1969 2002 racecar + 1989 e30 M3 racecar


  6. #181
    Join Date
    Feb 2009
    Location
    Mountain View, CA
    Posts
    771
    My Cars
    06 GTO, e36 race car
    Quote Originally Posted by Massive Lee View Post
    The nightmare of the grinded knuckles... ;-)
    heh. The brakes work well now. I have five sessions on them. They took a loooong time to start working - a full three sessions and they shed a tremendous amount of dust in the first two sessions. I believe this is because the (Blanchard?) grinding on the rotor faces needed to be worn off before the pads would bed. They're great now, but this has implications when the time for new rotors comes around.

    In regard of your question about the adjustabilty of the pedal height, answer is in the affirmative. The rod between the MC and the pedal is indeed threaded.
    Excellent. So this permits the height of the pedal to be adjusted when the pedal is in the "brakes applied" position, which is what is needed for tuning heel-toe comfort.

    A tab that limits the pedal height will also be supplied and bolted where the spring/rubber grommet is hung.
    I'm not understanding this. It sounds like it permits adjustment of the pedal height in the "brakes released" position. But that could cause the brakes to be permanently pressed?

    In regard of the World Challenge cars, I have many friends who bought some. In most cases the cars were prepared to the limit of being acceptable, with cages that were primitive and preparations that were basic. Despite the name, I think that this group was not much more advanced than BMWCCA CR's Prepared class.
    Yeah. Plus in my case it was ~10 years ago when the rules and standards just weren't as good. My car in fact looks like it was initially a quality build (apart from the brakes) but then someone later came in and did some, err, lesser quality things to it.

  7. #182
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    Quote Originally Posted by flink View Post
    I'm not understanding this. It sounds like it permits adjustment of the pedal height in the "brakes released" position. But that could cause the brakes to be permanently pressed?
    Nop. Adjust the threaded rod so that the pedal is at the right height when it starts pushing on the MC. Then adjust the tab to press on the back of the pedal stem so that there's only a little play. Wait a few weeks and you'll see it clearly ;-)

    Lee

    One aspect that is worth discussing when it comes to race prepped e36 M3 is the brake bias. Changing from softish stock springs to stiff race springs obviously affects weight transfer under hard braking. Basically, a system tailored for soft springs may not have enough rear bias when used with stiff springs. This also should affect brake feel, with a car not feeling perfectly stable under hard braking. The e30 chassis has a stock fixed bias valve that reduces progression of the rear pressure depending on how hard you brake. It's a little round valve located on the rear line on the driverside inner fender. Remove it and replace it with an adjustable valve.

    On the e36 chassis, it seems that such a valve doesn't exist. At least not externally. I'm thinking this valve is perhaps integral to the ABS pump. Any expert knows about such beast?

    Lee

    Last edited by Massive Lee; 01-27-2012 at 08:04 AM. Reason: Automerged Doublepost
    1969 2002 racecar + 1989 e30 M3 racecar


  8. #183
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    I made a quick mock-up, using an e30 adapter on an e36 pedal assembly to verify rod angle throughout pedal travel and measurements for the clevis. 6:1 pedal ratio shown. The black adapter plate is part of the e30 kit and cannot be used on an e36 as the bolt pattern is different and it will be centered horizontally, while it is offset on the e30.




    1969 2002 racecar + 1989 e30 M3 racecar


  9. #184
    Join Date
    Jun 2007
    Location
    Northern KY / Cincinnati
    Posts
    2,662
    My Cars
    e36 Track Car
    e36 Bias - I may be standing alone on this one, but in my opinion, the e36 bias (in race trim) is not as bad as the e30 situation. In fact, I believe it's easily corrected with pad selection. I would never add a proportioning valve because there are too many negatives associated with them, mainly being the "Knee" in the graph and the release characteristics.

    Mock Up / R&D - Lee, if you need any help, please don't hesitate to ask, I have piles of e36 stuff here, and I have access to CMM to help reverse engineer anything.

    Regards, Nate.
    Regards, Nate.
    www.DriveFasterNow.com

  10. #185
    Join Date
    Jan 2010
    Location
    Herndon,VA
    Posts
    3,457
    My Cars
    97 M3
    I thought it was going to be something like



    How much closer is the MC to the firewall?

  11. #186
    Join Date
    Jun 2007
    Location
    Northern KY / Cincinnati
    Posts
    2,662
    My Cars
    e36 Track Car
    Kwan, judging by the pictures I have seen of Lee's e30 stuff, I would assume the width of the booster. Guessing it's about 6 inches.
    Regards, Nate.
    www.DriveFasterNow.com

  12. #187
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    The thickness of the adapter is a tad over 3/4" but not knowing how thick the e36 booster is, I can't really tell how closer to the firewall the MC will be.
    1969 2002 racecar + 1989 e30 M3 racecar


  13. #188
    Join Date
    Jan 2010
    Location
    Herndon,VA
    Posts
    3,457
    My Cars
    97 M3
    Just bend the lines to compensate? What about the ABS sensor in the booster? Looks like we have to do without. Is it critical to the operation of the ABS?

  14. #189
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    I will take care of the brake light switch when the mock-up is done. That's an easy one even if the pedal height will be adjustable.

    As for the "booster stroke" sensor, I don't know what people with twin masters do about it. Any idea?
    1969 2002 racecar + 1989 e30 M3 racecar


  15. #190
    Join Date
    Feb 2009
    Location
    Mountain View, CA
    Posts
    771
    My Cars
    06 GTO, e36 race car
    Quote Originally Posted by Massive Lee View Post
    As for the "booster stroke" sensor, I don't know what people with twin masters do about it. Any idea?
    All gone on my car, with along with the ABS. There's a pressure switch in the front hydraulics for the brake lights.

  16. #191
    Join Date
    Jan 2004
    Location
    Ottawa, ON, Canada
    Posts
    4,937
    My Cars
    e90 M3,X5,e46 racer
    Quote Originally Posted by Massive Lee View Post
    I will take care of the brake light switch when the mock-up is done. That's an easy one even if the pedal height will be adjustable.

    As for the "booster stroke" sensor, I don't know what people with twin masters do about it. Any idea?
    The 95 M3 ABS doesn't have one. 96+ does. Most people just get rid of the ABS, or run the stand alone 95 system.
    Check out the 8legs Racing page: https://www.facebook.com/8legsRacing/


  17. #192
    Join Date
    Jun 2001
    Location
    No. VA (Police state)
    Posts
    1,677
    My Cars
    '95 M3, '94 325is
    my 95 has the stroke sensor in the booster. it was built 6-94.
    David Ortiz

  18. #193
    Join Date
    Jan 2010
    Location
    Herndon,VA
    Posts
    3,457
    My Cars
    97 M3
    The 95 M3 ABS doesn't have one. 96+ does. Most people just get rid of the ABS, or run the stand alone 95 system.
    I'm skeptical that most people toss a perfectly good ABS system for one that's not as good. Wonder if the sensor could be mounted inside the car attached to the pedal directly? I'm going to pull a sensor out of one of my spare boosters and check it out.

    I wonder how hard it would be to disassemble a booster, remove the "booster" part, weld it back together and just provide a direct linkage internal to the booster?

  19. #194
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    Some racers will feel that the ABS gets in the way of their braking. I can understand that. Some racers though have no clue what "threshold braking" means and continuously step on their brake pedal and expect the ABS to do the threshold for them. Those should keep the ABS functional. ;-)

    Relocating the pedal travel sensor would be the way to go if keeping the ABS. But it would be required to know how it is calibrated. I suppose it is simply for linear movement and speed of deplacement for a brake pedal on a 4:1 pedal ratio.

    Quote Originally Posted by MasterKwan View Post
    I'm skeptical that most people toss a perfectly good ABS system for one that's not as good. Wonder if the sensor could be mounted inside the car attached to the pedal directly? I'm going to pull a sensor out of one of my spare boosters and check it out.

    I wonder how hard it would be to disassemble a booster, remove the "booster" part, weld it back together and just provide a direct linkage internal to the booster?
    ABS is not perfect. It was calibrated for street tires and cars that brake in straight line... ;-) Even if you empty the brake booster, you'll end up with 4:1 pedal ratio and a limited selection of MCs.
    Last edited by Massive Lee; 01-29-2012 at 09:38 AM.
    1969 2002 racecar + 1989 e30 M3 racecar


  20. #195
    Join Date
    Jun 2007
    Location
    Northern KY / Cincinnati
    Posts
    2,662
    My Cars
    e36 Track Car
    RE: ABS - This topic has been beaten to death; most are in favor of the ABS system, BUT if you get into it, the car is difficult to turn and the ABS takes forever to release. Therefore some remove it, and some keep it; valid arguments for both sides, but the consensus was if anyone could "flash" or reprogram the stock ABS computer make it less aggressive, it would be a big hit in these circles, unfortunately that nut has not been cracked.
    Regards, Nate.
    www.DriveFasterNow.com

  21. #196
    Join Date
    Jan 2004
    Location
    Ottawa, ON, Canada
    Posts
    4,937
    My Cars
    e90 M3,X5,e46 racer
    Quote Originally Posted by TOOLEAN View Post
    RE: ABS - This topic has been beaten to death; most are in favor of the ABS system, BUT if you get into it, the car is difficult to turn and the ABS takes forever to release. Therefore some remove it, and some keep it; valid arguments for both sides, but the consensus was if anyone could "flash" or reprogram the stock ABS computer make it less aggressive, it would be a big hit in these circles, unfortunately that nut has not been cracked.
    In favour of keeping ABS in a STOCK BOOSTED SYSTEM. Yes. Once the boost is removed, or tilton or similar pedal box is installed is correct MC sizing, the ABS becomes basically uselss except maybe in rain. I suppose it could save some tires, but it certainly is not faster with a proper brake setup.
    Check out the 8legs Racing page: https://www.facebook.com/8legsRacing/


  22. #197
    Join Date
    Jan 2012
    Location
    India
    Posts
    15
    My Cars
    2009 Scoda Fabia
    Brake Pedal Goes Too Far Down to Stop. If you step on the brake pedal and it feels like it's going too far down before you start to slow, you might have the following problems that are common with all racers even with Carlos Kauffmann:

    Low Brake Fluid Level: Check your brake fluid. If it's low, top it off to the mark on the side of the reservoir.
    Contaminated Brake Fluid: Even though your brakes operate in a closed system, contaminants can still work there way into the works. Air can enter the system through the smallest hole, and you can end up with water in the system from condensation and other means. There's not really any way to check for this, but bleeding your brakes will remove the bad stuff and replace it with new fluid.
    Worn Brake Pads: Your brakes should never wear low enough to cause your brake pedal to feel low, they'll scream at you before then. But if they do get very low, you might have this problem. Replace your brake pads as soon as possible. Of course, this can be avoided with regular brake inspection.
    Bad Brake Power Boost Unit Finally, if your brake booster goes bad you'll have low brake pedal issues. Most brake boosters are vacuum controlled, so a special vacuum measurement device that connects to the brake booster is needed to check it. If it's bad, you'll have to replace the boost unit.

    These were some issues that Carloss Kauffmann had encountered while racing.

  23. #198
    Join Date
    Oct 2011
    Location
    Colorado
    Posts
    1,102
    My Cars
    My E36 supercar
    ^We are on page 10, not page 1.

  24. #199
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    I have no clue who Carlos Kaufmann is...

    In regard of the brake booster being defective. If the diaphragm is cracked or the check valve not keeping vacuum, then it's not a soft pedal you will end up with. Quite the contrary. No more assist means a very hard pedal.

    Using bigger 25.4mm MC (e36 M3 spec) on a non-///M e36 will surely make the pedal travel shorter, but in way will it not have solved the problem. Many do not realize that the front and rear brakes are one single hydraulic system. And its strength comes from the weakest link. Therefore, only bleeding the front is totally useless. Pins shall be checked for wear on all four calipers. Brakelines shall be changed on all four calipers. And pad condition on all four calipers also matters. Use the same pads on all four corners. Grippy front pads and soft rear ones will only overlead the front brakes while the rear ones will be under used.

    May I mention that the brakes on the e36 (non M3) are barely better than those on the e30, which are known to be quite lousy on the track. Bleed often, use front air ducts, get the grippiest pad you can get, learn momentum.
    1969 2002 racecar + 1989 e30 M3 racecar


  25. #200
    Join Date
    Sep 2006
    Location
    Montreal
    Posts
    1,915
    My Cars
    2002, e30 M3, 535
    Would anyone have a defective brakelight switch and pedal travel sensor (the one in the booster). I'd purchase your old stuff. They don't need to be in working condition. Please PM me.

    Edit #1 - Found a set. Thanks Scott.

    Edit #2 - While I wait for Scott's parts. Can somebody measure the following specs? I would be gratefull ;-) Nothing precise needed. Just ballpark to checkout feasability. TIA

    Last edited by Massive Lee; 01-31-2012 at 07:04 PM.
    1969 2002 racecar + 1989 e30 M3 racecar


Page 8 of 11 FirstFirst 1234567891011 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •