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Thread: Which MC for Massive Brake Booster Delete?

  1. #101
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    Quote Originally Posted by Inflame View Post
    I feel comparing street performance to track performance isn't ideal as a track brake pads CoF is very low when cold and on track, with elevated temps and higher CoF the braking torque will be much much higher.
    Agreed - but track time is precious, and I don't feel like I'm even in the window yet. Even with more torque the pedal is way too hard to push. I don't know if I'd feel safe driving over to grid if someone pulled out in front of me.
    2017 F250 Superduty Race Red.
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    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
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    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  2. #102
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    Ok. Here you go.

    If you have a 328 and go with the duals...

    Firm pedal with little travel is .750 front .875 rear
    Softer pedal with more travel is .700 front .812 rear.

    For an m3 these would be wrong. You guys are on your own.
    Last edited by CoMZ302; 04-11-2017 at 09:20 PM.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  3. #103
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    Quote Originally Posted by CoMZ302 View Post
    Ok. Here you go.

    If you have a 328 and go with the duals...

    Firm pedal with little travel is .750 front .875 rear
    Softer pedal with more travel is .700 front .812 rear.

    For an m3 these would be wrong. You guys are on your own.
    Interesting. Any reason for reducing rear braking power?
    1969 2002 racecar + 1989 e30 M3 racecar


  4. #104
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    Quote Originally Posted by Massive Lee View Post
    Interesting. Any reason for reducing rear braking power?
    Not sure what's going on - but when the rear master is the same or near as the front - I have tons of rear lockup.

    I believe the stock master is 23 REAR 20 front. I posted another thread on the subject.

    Can't explain it. What I have seems pretty good finally.
    Last edited by CoMZ302; 04-12-2017 at 09:32 AM.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  5. #105
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    Is your car an e36 328is ?
    1969 2002 racecar + 1989 e30 M3 racecar


  6. #106
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    Quote Originally Posted by Massive Lee View Post
    Is your car an e36 328is ?
    Yep. Far as I know

    Stock calipers (54 front 36 rear) and Carbotech XP12s. ABS removed. Obviously no booster.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  7. #107
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    Quote Originally Posted by CoMZ302 View Post
    Yep. Far as I know

    Stock calipers (54 front 36 rear) and Carbotech XP12s. ABS removed. Obviously no booster.
    Your car then shall NOT have an MC with differential bore as far as I know. It should be 23,8mm front AND back. (part #34311160616] - Perhaps a previous owner swapped it.

    Per exemple, the e36 M3 has 25,4mm MC (same bores front and rear) and 60mm front + 40mm rear caliper pistons. In term of piston surface, that's a front to rear ratio of 2,25 :1

    Your e36 has 54mm front and 36mm rear pistons. A front to rear ratio of 2,25:1 too.

    As you can see, if the e36 M3 had a non-differential MC, I don't see a reason for the e36 328i to have an MC with differential pistons. And I think it was your problem. The 20mm rear piston in that MC was pushing 30% more pressure than the front. ;-) No wonder you were locking the rear brakes. ;-)

    My suggestion to you with your twin MC pedal box is to use the same MC on both channels. Or perhaps even a slightly smaller one on the rear. Stiffly suspended cars have less weight transfer on hard braking and can use a bit more rear braking power than a softly suspended car.
    Last edited by Massive Lee; 04-12-2017 at 10:35 AM.
    1969 2002 racecar + 1989 e30 M3 racecar


  8. #108
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    I'll keep it in mind.

    I'm going to start with what I have (.750 front .875 rear) and if the front is doing all the work and there's no rear braking, then I can swap the rear line to the front (750) and put a replace the rear 875 with a 700 for the front and try that.

    Driving around the block (yes, that's not the same as heated brakes and tires on the track) I can (finally) get all four to lock. When I tried 750/700 before (at the track), the rear locked long before the fronts. Who knows maybe I had them backwards before.
    Last edited by CoMZ302; 04-12-2017 at 11:16 AM.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  9. #109
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    23mm master is AMAZING!!!!

  10. #110
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    I went against the grain and am utilizing a Honda master cylinder. Reasoning was there are 3 different sizes with identical bolt and line patterns, and also if I had a failure at the track I would be more likely to get a replacement at the parts store for a Honda than a 70's anything. Also the master is alum compared to the steel units I've seen used here. Big whoop I know, but I'm trying to be a weight weenie on this car ha! Unfortunately I have yet to test it, but I look forward to it! Have e46 330i front calipers and e46 32x rears.

    13/16" 20.6mm
    15/16" 23.8mm
    1" 25.4mm

    Back into a BMW, this time a track rat....and it won't be BMW powered and no, not a V8 either!
    Couldn't help myself, boosted e36 m52 street car in progress also!

  11. #111
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    Installed the dual MC set up about a year ago.. but finally been getting some track time in.

    Dual MC with 19mm F/R ABS removed.

    1995 BMW M3
    Stoptech ST40 Front, oem rear running Hawk DTC 60 F/R
    Nitto NT01 255 square
    Feels good maybe a bit on the hard side (perhaps go to 17mm to increase feel?) Pedal is also a little high for perfect heel toe, need to play with adjustment a bit.
    No issues with lock up... and way better to modulate braking.. I can actually feel the brakes! :-)

  12. #112
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    At the track today, I went down to 0.700F 0.750R. I like the pedal feel now - data shows -1.4G braking on old tires, but...
    ... I need more bite still. Can't lock them up. I think I need to go up to a grippier pad compound from the XP12s.

    FWIW 19mm = 0.748 - so we wound up at just about the same thing!
    I think I will buy 625, 700 and 750s so I can keep experimenting. I'm thinking that 0.700F and R, with more pad, should be predictable.

    Now on to the damn non-shifting damn crap transmission crap!
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  13. #113
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    thats good info! My new plan go to the Hawk DTC 70 which has more bite, then perhaps to the 17mm MC's. My currents pads only have 3 days on them so it will take a bit but this thread is definitely bookmarked.

    transmission woes suck!

  14. #114
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    It's definitely personal preference. I don't really work out, but my leg is pretty strong from braking.

    I use dual .625" master cylinders, with E30 M3 brakes, and when my brakes are hot (DTC-70s), I find them just good enough to place my car repeatably. I'm still pressing pretty hard, and would like a little more modulation. I felt better when I was running E36 M3 front brakes, but my rotors got screwed up.

  15. #115
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    Quote Originally Posted by FredK View Post
    It's definitely personal preference. I don't really work out, but my leg is pretty strong from braking.

    I use dual .625" master cylinders, with E30 M3 brakes, and when my brakes are hot (DTC-70s), I find them just good enough to place my car repeatably. I'm still pressing pretty hard, and would like a little more modulation. I felt better when I was running E36 M3 front brakes, but my rotors got screwed up.
    Fred I have a 328; I think the brakes are similar to the E30 M3...

    I'm going to try .625s but I think I'm going to like the 700s a little better. I will say it takes some force to stop, even with those.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  16. #116
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    Yeah, the 328 has slightly larger diameter brakes in the front (294 vs 280), same in the rear (280), same caliper piston diameter front and rear (54/38). Feel-wise, the hydraulic ratio will be the same.

    I actually swapped to some different calipers to increase my hydraulic advantage, so I'm at 57 mm front, 40 mm rear.

  17. #117
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    Still fighting this. I went down to .700s front and rear, as well as up to CarboTech XP20s. I really just don't like the feel (Takes forever to slow down) and am seriously thinking about going back to the stock booster setup.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  18. #118
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    With a boosterless set-up, race pads with high coefficient of friction should be used. The same way that racedcars with pedal boxes use pads with high friction. If you guys run a Wilwood caliper, then they have a superb pad called the H compound. Too torquey for a boosted brake system. Perfect for a racecar without assist.

    H compound requires a single application of the brakes to be fully operational. So no warm-up time wasted.

    [img] http://forums.corvetteforum.com/atta...cteristics.jpg [/img]

  19. #119
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    Unfortunately my class requires the stock calipers

    I put a gauge on it at heartland. I can get only about 500psi on the front at full stomp with .625 masters. I think tilton recommends 800-1200. Maybe the ratio isn't really 6:1. Not sure but I can't race it like this.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  20. #120
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    Or maybe you have frog legs ;-) I know some people with 1.0" (25,4mm) MCs and loving it. But I recon that removing the booster might not be for everyone.

  21. #121
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    I can leg press 300 no problem.

    I have new calipers up front - is there anything else that could be wrong in the system?

    You know people with 25.4MM masters on 328 front calipers? Your dual master setup?

    What PSI should I be seeing? I'd like the system to succeed. I am starting to think the pedal ratio is not 6:1. I may have to directly measure it and see where it is.

    There's simply no way the system would be safe with 1" masters. Sorry there must be something different. I've been racing for a long time and there's no way someone else would like it. Something is wrong.
    Last edited by CoMZ302; 05-16-2017 at 10:27 AM.
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  22. #122
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    Mods. Is there anyway we can return to the old interface? This one sucks big dongs. May be ok for nerds who spent their day watching at their cell phone. But for laptops, it's a pity. I'll stop replying just because it hurts... ;-) Can't even add bolds or italics. How do we post pictures?

  23. #123
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    Agreed. I absolutely loathe this new interface and have basically stopped browsing Bimmerforums because it is so poor.

  24. #124
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    Lee I'd love to hear some ideas on what to do.

    Maybe I put the system in the car wrong or something - is there an instruction sheet somewhere?

    The other question I have is, where the pushrod comes in from the brake pedal to the adjuster pivot - there seems to be two sets of holes on the pivot itself. Which pair of holes gives the highest pedal ratio?

    In all your pix on FB, the pushrod heim is attached to the hold closest to the adjuster - I have mine attached at the further hole. Is that right?

    Thanks,
    --Bill
    2017 F250 Superduty Race Red.
    2016 ATC 24' Raven trailer.
    2015 Four Wheel Hawk camper.
    2002 BMW M Roaster - 3rd Place Solo2 Nationals ASP 2001 and SM2 2002. Still love'n it.
    1998 BMW 328is E Production road racer in training.
    1994 Club Car golf cart. Supposedly better than walking.
    Looking for 2003 330Xi for rallycross

  25. #125
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    I have just written a lengthy and detailed reply with precise pedal ratio calculations. I saved it and it disappeared. WTF. Admins, your interface sucks gorilla dongs. ;-)

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