Stock Brake Upgrade
by John Bentley
jab@cisco.com
I recently decided that better brake performance was desired! Actually, last
year at a track event, after running for a while, it seemed like the brakes
were less effective. So, this year I wanted to try something new. Since
12-piston F-117 carbon-carbon brakes were not in the budget this year :), I
elected to try a pad upgrade. It turns out this mod is relatively
inexpensive, has improved performance, and is easy to do. I hadn't done it
before due to hearing about needing a welder to keep the e-brake function.
Well, I found a way to do it without a welder, so my excuses were gone.
Parts list for the job:
- 1 pair, Porterfield R-4S pads, part
number AP63 (front)
- 1 pair, Porterfield R-4S pads, part
number GD535 (rear)
- 6 Speed Bleeders, SB8125LL, M8x1.25
- 1 silicone bleeder tube (from Speed
Bleeders)
- 1 qt brake fluid
- 2 screws, pan-head 6/32x0.250 long
with a 6/32 tap and drill
Since I was expecting the most trouble from the rears, I started there. I
removed the pad spring clip, caliper and old pads. Following the shop
manual, I rotated the piston about 30 degrees (as shown) and compressed both
pistons. After compression, don't forget to rotate the piston back to the
original orientation!
Next, I compared the old pads to the new. The shape of the metal backing
plate was slightly different, but where it counted, they looked the same. I
flipped the old pad over and noticed there was a spot-weld on the back of
the pad that is used to engage the caliper piston so it cannot rotate (as
mentioned above, if it rotates, the piston can be easily compressed which
defeats the e-brake function). Since I don't have a welder, I looked for
another way. I settled on using a screw. The pad has a slot right down the
middle of the pad surface, so cleaning out the metal chips was easy. I
picked up a bag of screws at the local hardware store (I used 6/32, but you
can use what works best for you). The screw length was chosen to be about
the same as the metal plate thickness and the head was chosen to fit the
slot without much slop. I marked the drill location on the new pad to be in
a similar location on the new pad as the spot-weld was on the old (toward
the outside of the piston for best resistance to turning and centered in the
pad slot). I drilled and taped the hole, cleaned out all the burrs/chips,
and cleaned out the tap lube from the new hole. I used some Loctite and
installed the screw. After installation, I checked the screw head height
with a dial caliper and noticed that the head would barely hit the bottom of
the slot in the caliper, so I filed the head down slightly to be sure the
pad would sit flat against the piston. The new pads slipped right in and I
put the whole thing back together. Be careful that you don't tear the piston
boot with the screw head (or the spot weld, which ever you choose). You can
hold it out of the way with a small flat-blade screwdriver. Next I installed
the Speed Bleeders and bled the system.
On the front, it was a little easier. Just remove the calipers and compress
the pistons. On the back, the pads fit perfectly. On the front, I had to
file down the edge of each outside pad. The new pads were a little bit too
wide where it engages with the caliper. A little filing fixed the problem
and the pads went right in. I installed the 4 Speed Bleeders (2 on each
caliper) and bled the system. I filled the master many times to get fresh
fluid through all the lines. Make sure you never let the fluid level get
low!
The only down-side on the front change is the old pads (yes, I still had
"original" pads on my car) had a wire that is connected to a warning light
on the dash. When the new pads are installed, the wire is no longer there.
Since I inspect my pads frequently, not having the "idiot light" function
was not a problem for my car. Just something to be aware of before the
change... Happy braking!
For a description of the pad material and general info on Porterfield, check
out:
http://www.porterfield-brakes.com or contact info below:
Phone (949) 548-4470 - Outside California (800) 537-6842
Fax (949) 548-7783
Business Address:
1767 Placentia Ave.
Costa Mesa, CA 92627
The folks at Porterfield were knowledgeable and helpful.
Speed Bleeder info is at
http://www.speedbleeder.com/ Also, very helpful people.
NOTE: When ordering Porterfield pads, you may
request the spot weld be added to the back of the rear pads. Porterfield
will do this for you.
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