Brakes Modification FAQ

One often overlooked item when modifying your car is the brake system. The All Trac / GT-four is quite a heavy car and the brakes do not perform as well as they could for heavy braking street applications. They are very heavy duty brakes indeed, but could use some help. Hopefully this section will provide answers to some of the more commonly asked questions.

For information on what types of products and brands are available, visit the Brake Tuning page

Q: Why would I want slotted or cross drilled rotors?

 
A: To help hot gases escape from the rotor.
  
    When the brakes are applied the brake pads rub against the rotor to provide friction. 
This severe friction is what makes you stop.  This friction also comes with a severe amount 
of heat.  The more you apply the brakes the more heat is involved.  This heat if allowed to 
build far enough creates hot air (gas) which prevents the pad from actually contacting the
rotor.  The result is what's known as brake fade.  The brakes will have a soft spongy feeling 
and will temporarily lose their braking efficiency.  Slots or drilled holes into the rotors allow
the gases to escape away from the rotor, into the air.  This significantly reduces the chances
of brake fade.
 
 

Q: So which is better, slots or cross drilled?

 
A: Each one has it's advantages and disadvantages.  For the typical application slots 
     are more useful.
 
     Slots are "valleys" that are carved into the rotor surface, usually in a pattern that agrees 
with the direction that the rotor turns.  The slots are lower than the brake disc surface and 
allow a place for the gases to collect and make their way out from the rotor.  Slots allow more 
brake surface to be used.  In a typical setup slots are preferred because a street rotor will need
as much braking surface as possible to help stop.  If more cooling is desired, more slots can be 
added.
 
     Cross drilled rotors have been drilled through sideways.  This allows any heat to escape into 
the inner (open) area of the rotor.  From there, the air can make it's way out to the edge of the
rotor and dissipate.  Some argue that these "holes" in the rotor cause the rotor to lose it's
integrity or strength.  Many an owner have seen their rotors crack in between holes due to the
heat coupled with low rotor strength.  You might wonder why race cars have these.  Well, in 
extreme situations, the cross drilled rotors can be provided with a cold air source (brake cooler
ducts) to help cool them down.  These ducts force cold outside air into the rotor and make their
way through these holes/vents to significantly cool the rotor.
 

Q: I have heard of cryo treatment, what is this?

 
A: Rotors are frozen to subzero temperatures then re-heated slowly to help stress relieve 
the part and make it ultra hard.
 
     Whether it's slots, drills, or stock rotors you can't go wrong with this treatment.  This will
extend the life of your rotors beyond any expectation.  This can also help to prevent cracking
on cross drilled rotors.  This process has been around for years and used on race cars around the
world.
 

Q: Why would I want stainless steel brake lines?

 
A: Rubber brake lines can expand, which is not a good thing.
 
     When braking force is applied, there is extreme pressure within the brake lines.  Most of this
pressure is transmitted to the brake caliper to help stop the disc from turning.  There is however
some swelling of the rubber brake lines due to their flexibility.  This means you are not getting the
full braking effect.  By changing the lines to stainless braided, you can reclaim this force.  The 
braided lines are capable of holding many times more pressure than any rubber line without expanding.
Since this "extra" pressure is not lost, it must be applied to the only device than can accept pressure,
which is the calipers.  The result is the feeling of stronger brakes, without upgrading the brake 
system.  Another benefit is the long life span of stainless lines that do not crack or fade.
 
 

Q: How can I fit ST205 front brakes on my ST165/ST185?

 
A: ST165 may differ, but with ST185 here are some notes...
 
     First you must locate ST205 front discs, calipers, and brackets.  The installation is fairly straight 
forward.  You will need to fabricate some sort of bracket to hold the new calipers.  You will also 
need a spacer so that the ST205 disc can sit in the proper location on the hub.  More detailed pictures
will come.  For now here is a teaser pic of the finished product.
 
 
 

Q: How can I fit Supra front brakes on my ST165/ST185?

 
A: The process is similar to ST205 brake upgrade, with more notes.
 
     The process is quite the same, however more work is required.  The supra disc is on a 5x114mm
bolt pattern while the celica is on 5x100mm.  The supra disc would have to be re-drilled to fit on the
hub.  Also the supra disc is much deeper than the celica one, so a spacer must be fabricated to bring
the new disc close to the original celica position.  Finally an adapter must be made to hold the 
caliper/bracket in the correct location.  There is debate that the supra front calipers are too large for 
the capacity of the celica master cylinder.  An upgrade may be required.  An alternative method would
be to still use the stock caliper.  This would not provide a bigger braking area, but it does have a
larger rotation which is known to upgrade performance in stopping.  Here are some pics and measurements
we have found thus far:
 
 
 
 
 
 
 
 

Comments:

Mathieu havill (1/30/2012)
I do enjoy the fact we can get info like this the only issue i am having is i wish to place st205 on my st185 but i would need way more info for this...


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