To get better braking on the rear of a TR-3 or 4 it is necessary to increase
the size of the rear cylinders or increase the diameter of the rear drums to
the 10 inch drums from the 9 inch units. The larger drums give more
leverage, hence more braking effort. The brakes do not acutually more much
fluid at all, they work on pressure. The larger the piston area, the
greater the force transfer. 1 square inch in the master cylinder with 100
lbs. force on it = 100 lbs. per square inch. Then a 2 square inch wheel
cylinder will recieve the 100 lbs. of pressure on its' 2 square inches =
200 lbs. of pressure. A 3 square inch wheel cyliinder will give 300 lbs. of
pressure. A 1/2 square inch wheel cylinder will give only 50 lbs. of
pressure in the example.
Regards,
Greg Solow
----- Original Message -----
From: Henry Frye <thefryes@iconn.net>
To: jaboruch <jaboruch@netzero.net>
Cc: Friends of Triumph <FOT@autox.team.net>
Sent: Tuesday, August 01, 2000 5:06 AM
Subject: Re: TR3 Rear Brakes
> Hi Joe,
>
> At 11:56 PM 7/31/00 -0700, jaboruch wrote:
> >Amici, I'm still trying to sort out my rear brake situation but I've
> >confused myself.. Which way should I be changing the rear wheel
> >cylinders to improve the rear braking. From what I have read and
> >calculated I should go to a larger wheel cylinder for more braking. A
> >while back, Ted S. made the comment that I should change to a smaller
> >wheel cylinder. Is there any concensus amongst the group?
>
> I have always thought that smaller pistons in the bore will displace more
> motion with the same amount of fluid, so small cylinders will improve rear
> braking.
>
> >On another topic the Webers worked out GREAT!!! At Watkins Glen I was
> >7 seconds faster than I was last time there. I qualified with a
> >2:20.5. We raced during heavy rain so race times were very slow. I
> >started 2nd in class and 4th overall. ON the 1st lap I made it up to
> >first in class only to spin in the chicane. I was able to make up for
> >most of my spin and finished 2nd in class and 5th overall.
> >Fortunately for me I was not the only one up front that went for a
> >spin and fortunately for all there was no serious damage. Now with
> >all this new found power the rear axle situation is more of a concern.
> >Are they mostly breaking at the outer end? A couple seasons ago I
> >found one that had twisted at the differential end at the splines.
> >Joe (B)
>
> First of all, a hearty congrats on getting those Webers in and sorted so
> quickly! From what I have heard, that is not an easy undertaking.
>
> I am in process, along with several others, of attempting to figure out
the
> easiest and cheapest solution to the rear axle thing. SVRA will allow any
> axle we want to use as long as the track is correct, and it keeps the drum
> brakes. What are your guidelines? Are you required to keep the TR axle
> housing?
>
> I'm far from convinced that any direction is better than another. One
> possible route is to get a Ford 8" rear shortened, new axles and hubs,
etc.
> I have a rough quote of $3000 for this. I sort of doubt it could be done a
> whole lot cheaper...
>
> The other contender is to modify the existing rear axle housing to take a
> bigger bearing at the axle end, and make new axles and hubs to fit.
>
> Keep an eye on the Amici list, I am sure everyone will be talking about
> what their solution will be!
>
>
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