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RE: Stopping Power

To: Jay Laifman <Jay_Laifman@countrywide.com>,
Subject: RE: Stopping Power
From: Theo Smit <TSmit@novatel.ca>
Date: Wed, 21 Oct 1998 13:25:40 -0600
They will move as far as they can until the pressure in the system is equalized,
i.e. p = F/A results in the same "p" for all four calipers, and the master
cylinder as well. So for any caliper, if you increase A (the area) you have to
increase F (the force that acts on the piston) to keep the pressure the same. If
you increase the areas of the pistons in the caliper(s) or the shoe cylinders,
the pedal travels a larger distance because the fluid volume required to give a
certain piston movement is larger but that doesn't change the force distribution
even a tiny little bit.

Chance: You take your Tiger to "Laifman, Palmer, and Laifman" for a brake
rebuild. Skip 14 turns...

Theo Smit
tsmit@novatel.ca
B382002705

> -----Original Message-----
> From: Jay Laifman [SMTP:Jay_Laifman@countrywide.com]
> Sent: Wednesday, October 21, 1998 11:41 AM
> To:   Bob Palmer
> Cc:   tigers@autox.team.net
> Subject:      Re: Stopping Power
> 
> 
> 
> 
> I take back my second comment about leverage.   However, it seems to me
> that since the calipers are not changing, that relative to the rear brakes,
> the rears will now move less than the fronts for the same amount of pedal
> travel.  Is that not true?  Won't the fluid travelling through the brake
> lines still only go at the same rate as before.  So the relative balances
> will change.  And, the fronts will be stronger relative to the rears?
> 
> 
> 
> 
> 
> 
> Bob Palmer <rpalmer@ames.ucsd.edu> on 10/21/98 09:52:23 AM
> 
> To:   "Jay Laifman" <Jay_Laifman@countrywide.com>, tigers@autox.team.net
> cc:    (bcc: Jay Laifman/Attorney/Legal/CF/CCI)
> Subject:  Re: Stopping Power
> 
> 
> 
> 
> Jay,
> 
> Back to Mechanics 1A for you Jay. Turn to Chapter I, Page 2;
> 
>           F = pA
> 
> That's force (on your brakes in this case) is equal to the product of area
> (that's pi times the radius of the slave piston squared) and p, the
> hydraulic fluid pressure. For a given force of your foot on the brake, you
> get a certain pressure p. Thus, making A (the size of the slave) bigger
> means more braking, not less.
> 
> Apparently Steve hasn't taught you everything he knows yet. (Right Steve??)
> 
> Bob
> 
> 
> 
> At 08:06 AM 10/21/98 -0700, Jay Laifman wrote:
> >
> >
> >
> >Bob, now you are going to be hit from both sides.  You wrote:
> >
> >>Based on Lou's
> >>experience, I installed the earlier (bigger) slave cylinders in my Tiger.
> >>Even this did not give too much braking in the rear. Never could figure
> >why
> >>Sunbeam made this change. (Maybe Rich wrote them and told them his Alpine
> >>was locking up in the rear first?) Anyway, it's my impression that
> usually
> >>the rear drums on a Tiger aren't doing as much work as they should.
> >
> >BIGGER slaves give LESS braking!  Bigger slaves means it needs MORE fluid
> >to move the same distance.  Therefore, you reduced the effectiveness of
> the
> >rear brakes relative to the front brakes.
> >
> >Jay Laifman
> >Gotta keep that Laifman end up, sir.
> >
> Robert L. Palmer
> Dept. of AMES, Univ. of Calif., San Diego
> rpalmer@ames.ucsd.edu
> rpalmer@cts.com
> 
> 
> 

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