COA-COA-12025
Page 1 of 3
08/31/2018
Figure 1.
INSTALLATION INSTRUCTIONS FOR POWERGLIDE
PRO TREE LOW AND HIGH GEAR BRAKE KIT (#12025)
Thank you for purchasing a Coan Racing performance product. Since 1976, Coan Engineering has been
the leader in hi-performance race transmissions and converters. Our ongoing research and development
assures that you have purchased the best products available.
* COMMITMENT * PERFORMANCE * RELIABILITY *
* A WINNING COMBINATION *
Caution: Trans-brake can be activated in low and high gears.
It is imperative that you install a
power
interrupting device
between trans-brake solenoid and 12V source. A power-interrupting device will
totally disable trans-brake solenoid for a predetermined amount of time. This device will prevent
accidental re-engagement of the trans-brake in high gear during the run. Re-engagement of the trans-
brake in high or low gear will cause the rear tires to lock up.
The scope of these instructions will be aimed at the installation of this kit and it is assumed that the
transmission will be rebuilt properly to work with this valve body. If necessary refer to a transmission
manual for detailed instructions on disassembly and reassembly of the Powerglide transmission.
The transmission needs to be completely disassembled, including the reverse piston, and thoroughly
cleaned.
1. Next it is necessary to drill the reverse passage.
With a 3/16” drill, drill all the way through the case
as shown [(Figure #1, & Figure #2,) (2 places.)]
Then, from the inside, of the case, open up the
holes to 13/32”, until the drill intersects the ports
from the bottom of the case (Figure #3).
2. Now drill 13/32” hole from the bottom port, until you
intersect the previously drilled holes (Figure #4.)
After deburring the holes and cleaning the case,
reassembly can be started.
3. It is recommended to stack the reverse pack with 5
frictions and 6 steels. With a reverse piston
thickness of .900” you should get a clutch pack
clearance of .050” - .060” which can be checked
through the inspection hole in the bottom of the
case. Replace the stock return springs with the
springs furnished in the kit and reassemble the
transmission.
Figure 2.
