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      02-27-2013, 09:34 AM   #23
Evice
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Quote:
Originally Posted by SkinnyVT View Post
Changing the master will have no effect on bias as the ratio of front/rear piston sizes will still be the same, the master will only effect pedal travel/effort.
Racecars have more than 1 MC which allows you to use the adjuster valve to change brake bias.
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      02-27-2013, 09:39 AM   #24
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Originally Posted by Evice View Post
330 is a little beefier, but in equal amounts F and R. Plus you can use master cylinder to change brake bias (can't say if this specific 128i is allowed to have non-stock MC)
Yeah, I was really talking about for street cars, not this specific build... so no bias adjustment valve.
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      02-27-2013, 09:40 AM   #25
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Originally Posted by Obioban View Post
Yeah, I was really talking about for street cars, not this specific build... so no bias adjustment valve.
We are at a racecar build thread, yes? Let's stay on topic.
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      02-27-2013, 09:54 AM   #26
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Quote:
Originally Posted by Evice View Post
Racecars have more than 1 MC which allows you to use the adjuster valve to change brake bias.
yes if you throw a dual master with a balance bar in the car, that's quite a bit more specific than saying changing the master, there seems to be a lot of braking misinformation thrown around, just trying to clarify things
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      02-27-2013, 11:52 AM   #27
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Originally Posted by SkinnyVT View Post
Larger pads don't change bias, just wear rate and heat capacity, surface area has no effect on the amount of friction force.
What I really meant but said very unclearly was that if you get a pad with a smaller sweep area than rotor area, you can alter the bias depending on where the centerline of that sweep area is.
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      02-27-2013, 01:12 PM   #28
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Originally Posted by Obioban View Post
What I really meant but said very unclearly was that if you get a pad with a smaller sweep area than rotor area, you can alter the bias depending on where the centerline of that sweep area is.
You can alter the bias by using different pad compounds. Very small %. If you prefer lesser torque compound, total braking force will be less but bias will be different. Small detail, people use that to fine tune the balance under braking. Alot of people use DTC70 F, DTC60 R or HT10 front, HT14 rear etc. just to perfect the balance of the car.
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Last edited by Evice; 02-27-2013 at 01:14 PM. Reason: clarification
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      02-27-2013, 01:15 PM   #29
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Quote:
Originally Posted by Evice View Post
You can alter the bias by using different pad compounds. Very small %. If you prefer lesser torque compound, total braking force will be less but bias will be different. Small detail, people use that to fine tune the balance under braking. Alot of people use DTC70 F, DTC60 R or HT10 front, HT14 rear etc. just to perfect the balance of the car.
You can, but I don't think it's a great way to do it, on street or track. Coefficients of friction change with temp, so you have varying bias depending on conditions. Better to do it the right way imho.
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      02-27-2013, 01:17 PM   #30
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Quote:
Originally Posted by Obioban View Post
You can, but I don't think it's a great way to do it, on street or track. Coefficients of friction change with temp, so you have varying bias depending on conditions. Better to do it the right way imho.
It is a fine tuning element. You don't need to fine tune for street or track car. Racecar for 10/10ths use, sure you'd like to.
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      03-02-2013, 11:11 PM   #31
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Seems like the Burton 128i got 3rd place at COTA

http://www.grand-am.com/scheduleResu...eid=3476&sid=2

The mitchum 128i got 27th and last. Wonder what happened Didn't get to watch race sadly : (
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      03-03-2013, 02:00 AM   #32
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Quote:
Originally Posted by Greenkirby21
Seems like the Burton 128i got 3rd place at COTA

http://www.grand-am.com/scheduleResu...eid=3476&sid=2

The mitchum 128i got 27th and last. Wonder what happened Didn't get to watch race sadly : (
I watched it on Speed 2. It was one hell of a finish. Miatas were really fast at the Esses but was lacking topend so 128 was pulling on them on straights. Additionally on tighter turns 128 looked twitchy, maybe a setup issue.

About Mitchum 128; I am so f.ing mad how they got t-boned....it is utter stupid what that mustang/camaro guy did...you guys will watch it on TV soon but at T1 they got hit so hard that I felt it on my seat... Actually I am amazed how that car actually kept going.... Props to Mitchum team keeping the car running.
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Last edited by Evice; 03-03-2013 at 10:04 AM.
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      03-03-2013, 07:12 PM   #33
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2008 BMW 128i  [0.00]
thats crap
Hope its salvagable
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      03-05-2013, 09:57 AM   #34
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Quote:
Originally Posted by Greenkirby21 View Post
Seems like the Burton 128i got 3rd place at COTA

http://www.grand-am.com/scheduleResu...eid=3476&sid=2

The mitchum 128i got 27th and last. Wonder what happened Didn't get to watch race sadly : (

Quote:
Originally Posted by Evice View Post
I watched it on Speed 2. It was one hell of a finish. Miatas were really fast at the Esses but was lacking topend so 128 was pulling on them on straights. Additionally on tighter turns 128 looked twitchy, maybe a setup issue.

About Mitchum 128; I am so f.ing mad how they got t-boned....it is utter stupid what that mustang/camaro guy did...you guys will watch it on TV soon but at T1 they got hit so hard that I felt it on my seat... Actually I am amazed how that car actually kept going.... Props to Mitchum team keeping the car running.
Guys, sorry I have been a bit absent over the race weekend. The weekend certainly didn't go as planned for the Mitchum Motorsports team. The cars were getting up to speed trying to get our gentlemen and amateur drivers as much seat time as possible for the race before the pro's took over.

The brand new #63 car, this build thread, did great all weekend before toasting a clutch within the first few laps. The team was able to cool it down, bleed it and get it back out to finish the race, but several laps down.

The #62 car had a bit of a different issue that was a common problem throughout the weekend...lack of other driver talent. It made SPEED Center's #4 crazy moment this weekend, not sure if that's a good thing Here is the link:

http://www.speedtv.com/video/newest/...-2201450714001

I race professionally for Jack Roush in the Roush Performance #51 BOSS 302R, and we had an even more rough weekend. It started on the first day when I was t-boned at 100+mph in T1, almost identical to the Mitchum incident except the Aston hit me square in the door and shoveled me rather than hitting the rear and able to spin me around. It bent the car, bent the roll cage door bars, collapsed the side of the car under the pedals where my feet were and hit me so hard that it stuck the throttle and put me in the outside wall.

Here you can see how much it pushed in the car, the front wheel is straight and undamaged.




To make matters worse, we went to a backup car, had clutch problems the entire 2nd day. My codriver Shelby Blackstock did great, handed me a car and we were running in 7th when we ran out of gas with 1 lap to go.


Quote:
Originally Posted by andrey_gta View Post
thats crap
Hope its salvagable
Yes the car is salvageable, it is at the bodyshop right now getting repaired to go to Barber for the next race.

For all that have sent me e-mails, I will be responding to them today. Thanks and let me know if you guys have questions!


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      03-05-2013, 10:34 AM   #35
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Wow - that's terrible, better luck next time.
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      03-05-2013, 01:44 PM   #36
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Damn that's rough. Seems like they have promising cars too.
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      04-28-2013, 09:34 AM   #37
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Excited to see an update on this since a 128 took victory at Road Atlanta.
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