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THE SEQUENTIAL SHIFTER IS THE SAFEST
WAY TO RACE
Consider driving your car and not having to remove your hands
from the steering wheel. The unit shifts up and down with equal
ease and precision.
Shifters in some machines such as F-1 cars are actually shifted
by computer. The unit senses RPM, Gear ratio in use wheel speed,
throttle position among other inputs. The computer also senses
the switching signal requesting the up or down shift. When all
factors are within the correct parameters the computer shuts off
the ignition for a preset length of time and shifts the transmission.
This is called electronic shifting and it is done by wire.
Systems such as this are very expensive and very complicated.
The computer costs alone would probably exceed the rest of the
average car. We therefore decided to design the system to operate
in the least expensive manner possible.
The new sequential shifters are the latest in a line of high
quality transmission components that PBS has developed. This unit
replaces the existing covers on the WEBSTER. It uses a drum
type shifter with sliding forks to change gears. The transmission
has five gears with no reverse. We investigated the need for reverse
and rejected it as superfluous and quite expensive. Our engineering
model showed that the cost of the shifter would be almost twice
as much for a single gear that is seldom used. It is felt that
the inconvenience of no reverse is outweighed by the simplicity
of operation of the shifter.
There is a position indicator showing what gear is engaged.
The shifting may be done with a hand lever or with air actuators,
or Starter Solenoids controlled by steering wheel mounted switches.
The above photo shows the air shifter installed on the transmission.
The system consists of two switch modules and their actuator solenoids.
The shifting is done by a double acting ram assembly. It is the
device with the two AN lines hooked to it.
There are two units out in testing. One is in a Formula MAZDA.
The second one is in a DSR. This transmission won the last National
at PIR. PBS is conducting shifting tests on a car that we built
in 1968, PBS MK-4. This car is powered by a 110 BHP PBS_8-P 1050cc
engine. The car belongs to Steve Feig of Corona CA. He runs the
car in VARA vintage events in our area. He has loaned us the car
for the duration of the tests.
 
The operating arm is shown on the left, The forks are shown
on the right. As you can see the forks are made of Aluminum (7075/T6).
The shifting drum is below the forks.
 
This is a vintage DSR one of the three test beds we have in operation.
The shift paddles that mount on the steering wheel to control
the impulses are shown above. The right photo shows a different
view of the same unit, the red button is for the radio. The shifting
in this case is actually done with nitrogen from a small cylinder.
You will notice that there are two solenoids mounted on the side
of the transmission. These solenoids are operated by 12VDC from
the steering wheel, via two small micro switches. While this system
does not use a computer it does operate quite successfully. The
steering wheel with the shift paddles that control the impulses
to the transmission .
The paddle wheel assembly includes two sealed micro switches
and a coiled cable less connectors. The paddle assembly is $250.00
less the connectors. The connector pair are $77.86.
Isometric
View of Shifter
Shifter
History
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Paddle Assembly |
This installation is in a Cheetah DSR with a Nissan
1300cc engine. It
uses a air actuated mechanism to operate it.
Travis Duder - National
Champion DSR 1998
Travis Duder running a PBS Sequential Shifter won the
SCCA DSR championship race at Mid-Ohio in 1998
Also not shown was Ben Beasley in CSR winning the championship
the same year.
Ben's car was also equipped with a PBS Sequential Shifter
SEQUENTIAL SHIFTER P/N SQ-200
PRICE: $2,800.00 w/o Air Actuator Kit
The shifter is designed to be added to your existing Webster
or Hewland transmission. The rear case sections are replaced by
the Shifter components. The stock gears, shafts and hubs will
be used. The shifter operates much as a Motorcycle transmission
does. There is a rotating drum that moves the shift forks to the
correct position at the correct time. This drum is actuated by
a ratchet mechanism that positions it correctly.
INSTRUCTIONS
1. Remove the reverse idler gear, bearing, washer etc. from
the gearbox. The rev idler spigot may be left in place, it will
serve no purpose.
2. Remove the rear cover and intermediate section of the Sequential
Shifter. (note: Remove the ¼" button head bolt through
the rod end at the input shift lever and swing the link over the
layshaft bearing to remove the intermediate section. Don't loosen
the hex head bolt at the ratchet end of the link. Also the detent
spring flat cover must be removed and the spring pulled out.)
3. Leaving out the layshaft and its gear stack, perform a trial
assembly of the pinion stack up and the sequential. shifter bearing
housing on the gearbox. Stack up the hubs, needle bearing and
5th gear on the pinion shaft. Grease the 5th gear thrust washer
to hold it in place on the inside of the bearing housing. Install
the Sequential Shifter bearing housing along with the gear stack
and seat it on the main case. Reach through the layshaft bearing
I.D. and spin the 5th gear with one finger to make sure it is
free. The 5th gear should have a small amount of end play. If
it is tight or excessively loose you will need to change the gear
hub spacers to set up the end play.
4. At this point, the entire gear stack and layshaft, layshaft
thrust washer etc. can be installed in normal fashion.
5. Install the draw bolts, tighten the layshaft nut and pinion
nut and install the cotter keys. Note that it is impossible to
put the gearbox into two gears with the Sequential Shifter to
tighten the shaft nuts. Use and impact wrench to get the desired
torque.
6. Install the intermediate section and the detent springs
and covers. Check to see that the cotter keys clear this section.
The detent ball bearing must be against the shoulder so that its
O.D. rides on the ¼ inch dowel pins.
7. Install the button head ¼ inch bolt through the link
rod end. Note that the rod end is on the layshaft side of the
lever and the button head is toward the outside shift lever.
8. Before installing the rear cover, put a couple of nuts and
washers on the studs to hold the intermediate section in place.
Then try the shifter to verify that all gears plus neutral can
be selected. It will be necessary to rotate the input shaft and/or
output shafts to allow the dogs to engage.
9. If everything is working OK, select neutral and then install
the rear cover.
10. Before installing the indicator light switch connect the
circuit to a 12 volt source (red +, black -) and observe how it
functions. The switch is a twelve-position switch. We use every
other position. Neutral lights a single red LED. This turns
off when 1st is selected and the other 5 LED's are actuated in
sequence. Turn the switch to the neutral position and install
it on the rear cover. Then sequence the shifter through the gears
and verify indicator operation.
OTHER NOTES AND COMMENTS
A. For best shifting, we find it necessary to cut both the
dog rings and gears to 4 dogs rather than 8. You can experiment
with this to see what works best for you. The dogs can be ground
off on a bench grinder while carefully holding the parts by hand.
We have ground the dogs off on the ring so that the dogs do not
line up on each side. We are experimenting with some special case
hardened 4-tooth dog rings made for us specially. These are available
for $130.00 each. The standard Webster dog rings are slightly
softer than the special ones.
B. The shift lever requires a motion of +/- 1 inch for a total
stroke of 2 inches using the center hole on the external lever.
This is a longer stroke than the standard H pattern shifter requires.
So the length and ratio of your shifter lever may need changing.
You can use either a ¼ inch or a 3/16-inch push-pull cable.
Be sure that the cable housing is anchored firmly at both ends.
C. We use silicone sealer at the joints.
D. Put a vent fitting in the 1/8NPT tapped hole in the intermediate
section
E. An in line fuse is included for the indicator light circuit.
Install this in the 12V line.
F. Don't try to eliminate play at the ratchet. Some looseness
is necessary to allow gear oil to penetrate the mechanism to prevent
binding and sticking of the ratchet.
G. For the ultimate shifting PBS can also supply either an
air driven actuator or an electric 12V Solenoid driven system.
Paddle switches on your steering wheel trigger these. A control
module is part of these systems. This includes an ignition interrupt
function and electric interlocks to prevent accidental shifting
into or out of neutral, as well as the indicator driver function.
This actuation system can be custom packaged for your application.
For prices on the shifter
CLICK HERE
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