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brake upgrade

To: Triumphs@autox.team.net, randallyoung@earthlink.net
Subject: brake upgrade
From: lee.k.janssen@lmco.com
Date: Tue, 24 Oct 2000 13:07:27 -0600
> I assume you mean that the rear brake upgrade was necessary to balance
> the front upgrade, and NOT that simply switching to larger rear
> cylinders will reduce stopping distances ...

The rear brake upgrade was NOT required to counteract the front brake upgrade. 
By themselves the Toyota front brakes worked just fine.
I was suggesting that I experienced significantly shorter stopping distances by 
increasing the diameter of the rear brake cylinders.
Bigger cylinders = more pressure = more braking force.

According to TRF TR6s were equipped with two different rear wheel cylinders, 
0.7" bore up to 1976 and 0.75" bore on later cars.
The ratio of the cylinder areas is as follows:

Area 0.70" / Area 0.70" bore = 1.00
baseline

Area 0.75" / Area 0.70" bore = 1.148
or 14.8 % more area than 0.70" bore

Area 7/8" / Area 0.70" bore = 1.562
 or 56.2 % more area than 0.70" bore

For the same brake fluif pressure the 7/8" bore will create 56.2 percent more 
force than a 0.7" bore.
For the same coefficient of friction more force will generate a shorter 
stopping distance.

As a side note I obtained my 7/8" cylinders from JK Jackson at the rather 
exorbitant cost of $150. Since then I noticed some list traffic talking about 
7/8" cylinders that are from a common junk yard car. However, I forgot to note 
what the vehicle was and unfortunately the list archives at 
http://www.listquest.com/lq/search.html?ln=triumphs appears to be down 
(internal server error) so I couldn't search for the information.

Hope this helps
Lee





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