Steering, Suspension, & Brakes

tips, technology, tools and techniques related to non-driveline mechanical components

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Jim Stabe
Jim Stabe
San Diego, Ca
(718 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

authors avatar
Fixed the excessive pedal pressure on the brakes
Posted by: Jim Stabe
Date: March 15, 2015 02:55AM

I built the car with double master cylinders and a balance bar and designed it to have about 100 lbs of pedal pressure to get a maximum G stop. After driving it for a while I found that to be too much so I replaced the 3/4" masters with 5/8" and it now has the feel I was after. It is not power brakes but I don't have to use both feet to get a full G stop anymore. The car has awesome stopping power now - stops on a dime and gives you 9 cents change.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5802 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Fixed the excessive pedal pressure on the brakes
Posted by: BlownMGB-V8
Date: March 15, 2015 09:27AM

That's excellent Jim.
My thought is that you should use all your pedal travel, leaving about 20% as a reserve, especially if you have gone to rear disks as we have, in which case you could get by with even less reserve. That way you use the smallest cylinders possible for the lowest pedal pressure. But as you drive it and adjust the balance bar you may notice optimal braking at a point significantly off center which tells you that you can decrease one of the MC's to get a more centered balance point. With my inside adjustment knob I frequently made a minor adjustment going from dry roads to wet, as I balanced it for the rears to begin to lock just a bare fraction befor the front, and with a wet road that balance shifts a bit. This time around I think I'll put a dot on the adjuster knob so I can see it it has been moved.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(718 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

authors avatar
Re: Fixed the excessive pedal pressure on the brakes
Posted by: Jim Stabe
Date: March 15, 2015 11:06AM

I run it very slightly biased toward the front master. I experimented moving it around and this seems to work the best. With the 3/4" masters the pedal was very high and now it comes out just above the throttle - perfect for heel and toe. I can always adjust the height of the brake pedal but it feels just about right now. The balance bar stays straight (not cocked) with pressure on the pedal so I think the master sizes are correct for the caliper sizes. I have to push really hard to get it to lock up but the deceleration before that point is quite impressive and very linear with pedal pressure. I'll probably have to tweak it again once I get some new rubber on the car.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5802 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Fixed the excessive pedal pressure on the brakes
Posted by: BlownMGB-V8
Date: March 15, 2015 09:26PM

Sounds about right. I hope mine is that close this time around.

Jim


Charles
Charles Long
McDonald, TN
(177 posts)

Registered:
09/15/2013 08:54AM

Main British Car:
1966 MGB V6 1994 Camaro 3.4L 60V6

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Re: Fixed the excessive pedal pressure on the brakes
Posted by: Charles
Date: March 22, 2015 10:23PM

Jim S. I always like spare change in my pocket. I installed the balance bar set-up in my VTECMini then forgot to tighten the locknut. What a surprize.
charles


tr8todd
Todd Kishbach

(355 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: Fixed the excessive pedal pressure on the brakes
Posted by: tr8todd
Date: March 26, 2015 07:26AM

Jim, what did you use for brakes front and rear(piston sizes) and where did you find the brake pressure calculator. I used to use one that was on the factory five website, but now I can't find it. Just picked up a set of Wilwood reverse hung pedals and want to find appropriate masters for the TR8 I'm putting together.


Jim Stabe
Jim Stabe
San Diego, Ca
(718 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

authors avatar
Re: Fixed the excessive pedal pressure on the brakes
Posted by: Jim Stabe
Date: March 26, 2015 10:27AM

Todd

I have the same Wilwood balance bar pedal assembly as you do with the shorter 5.1:1 ratio pedals instead of the 6:1 . I have the C4 J55 optional brakes with 13" rotors in front. All the parameters for the car are entered in the spreadsheet calculator. PM me your email and I'll send it to you then you can enter your own values.



tr8todd
Todd Kishbach

(355 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: Fixed the excessive pedal pressure on the brakes
Posted by: tr8todd
Date: March 26, 2015 04:05PM

Thanks for the offer but the guys over at GRM came thru with a good calculator. Here is a link to it. [www.tceperformanceproducts.com]


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