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Re: brake booster

To: Jim Boynton <jimboynton@attbi.com>
Subject: Re: brake booster
From: Larry Paulick <larry.p@erols.com>
Date: Sun, 16 Mar 2003 19:22:09 -0800
Jim, I am running without the booster, mainly because I am using a 
tandem MC, and there is no booster, at least reasonable, to run with a 
tandem MC.

On power brake, including the Tiger the pedal ratio is 4:1.  That is the 
distance from the pivot point to where you step on the brake is 12 and 
the distance from the pivot to the clevis pin for the master cylinder 
attachment point on the brake pedal is 3.  This yields a 12:3 or 4:1 
pedal ratio.

If you push on the pedal with 100 pounds, which is high, but not maximum 
ability for a driver, then you will have a levered force of 400 pounds.

Non-power brakes use a 5:1 or more commonly 6:1 ratio for the brake 
pedal.  The pedal effort of 100 pounds now yields 600 pounds with the 
6:1 ratio.  A 50% increase in force exerted on the master cylinder

The Tiger pedal can be modified to this 6:1 ratio, but of course, with 
any modification there are other considerations.

I know many people just run the Tiger without the booster, and stock 
pedal, and have not had a problem.

I am not running a stock Tiger, and if I wanted a booster, I would use a 
Lockheed cast iron unit.  It will last forever, if you change brake 
fluid every 2 years, like you should.

Of course, you could get the stock Girling unit sleeved, and White Post 
does this for around $450.

Larry

Jim Boynton wrote:
> Listers,
> 
>  Pretty slow last couple days so....How many of you are running or have run
> without the brake servo? Going to have to pull mine and rebuild it or send
> it away for a rebuild. I'll bypass it for now and other than need for a
> strong right leg any downside driving without it.
>  Apparently eating brake fluid just sitting in the garage. No side around of
> the wheels or M.C. of any leaks. I did start it up 3-4 times and rock it
> back and forth so I guess that was enough to make the servo thirsty.
> 
> Jim
> 



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