The PBS RD-4 Transaxle is designed to combine the wide 85mm PQS-4 shaft spacing, with the length of a 2-D type transmission. This allows it to be adapted to cars designed for the length of the 2-D while providing greatly enhanced durability. The 65.65mm shaft spacing on the 2-D type gearboxes limits the strength of the gears (especially reverse) and also limits the available size of the differential assembly.

The RD-4 uses the same heavy duty main case as the PBS PQH-4 and PQS-4 transaxles, but with ¾” wide 1st thru 4th driven gears. The reverse gears are the same large diameter as the H-4 and S-4 reverse with ½” wide gear engagement. These gear sets are combined with a compact version of the well proven PBS Cable shifter mechanism. This makes the gearbox short enough to have the overall length compatible with cars designed for the 2D transaxle.

SPECIFICATIONS 4 SPEED MEDIUM DUTY "H" PATTERN

4 Speed plus high strength reverse
Internal reverse lockout (requires neutral selection prior to reverse)
Output flanges for 930 CV joints with light duty dana 40 differential
Output flanges for 934/935 CV joints with heavy duty dana 60 differential
Dog gear engagement
Standard gear placement

The 85mm spacing allows the option of using either the 2-D size (Dana 44 based differentials) with 930 drive flanges, or the larger PBS designed Dana 60 based diff which has the 934/935 axle flanges.

A 1 3/16”-18 tooth spline is provided on the standard RD-4 input shaft.  This is compatible with the basic standard type 9” bell housing supplied with many 2-D and S-4 style transaxles.  Also the RD-4 can be supplied with the PBS/LS1 bell housing or the Outfront Motorsports bell housings designed for either a hydraulic throw out unit or cable clutch actuator (VW type) assembly for Subaru engines.  If the PBS/LS1 bell housing is selected the input shaft will be supplied with the 26 tooth Chevy fine spline, allowing the use of the stock Camaro clutch and flywheel assy, this unit also allows a stock Chevy starter to be used.

Any Ring and Pinion gear set available from Weddle Industries may be used.  The pinion shaft is shortened and rethreaded to fit the shorter RD-4 application 

Available Ratios are:
4.13        4.57      4.63      4.86      5.13      5.43
Reverse rotation  5.13 and 5.43

Currently the following gear ratios are available:
1^st           3.08    13/40

2^nd - 3^rd - 4^th  Gears2.45       18/44

2.0         18/36
1.79       19/34
1.65       20/33
1.5         16/24
1.31       23/30
1.21       25/30

The reverse gear ratio is 2.93 which is the same as the H-4 and S-4 transaxles.

All gears are straight cut and engagement uses dog rings with 6 dogs. Theses are the same dog rings as are used in the H-4 and S-4 transaxles

The RD-4 transaxle is supplied with a PBS cable shifter shift handle assembly and a separate reverse shift lever assembly which also uses a cable.  These are readily adapted to cars with either mid engine or rear engine configurations by simply selecting the appropriate cable length and routing.  The internal shifter mechanism in the RD-4 incorporates a reverse lockout feature which prevents selecting both reverse and a forward gear simultaneously.  Putting the gearbox in neutral with the 4 speed selector allows reverse to be engaged with the separate lever.  When reverse is disengaged the forward gears may be engaged in any order. When in any forward gear reverse may not be engaged.

Size comparison with 2D	Gear stack	Mounted in car
Rear Shifter Assembly	Shifter	Front Shifter Assembly

PBS has redesigned the shift handle assembly for easier mounting and assembly.  All orders received after July '07 will be shipped this new unit.

SHIFTER ASSEMBLY

The cockpit mounted shifter handle assembly is designed to be bolted in to any chassis. However the shift handle / cable mount distance & orientation are maintained. After bolting the shift lever assembly to the chassis and the rear cable bracket to the transmission, measure the distance between the front and rear cable housing anchoring points (not rod ends) with a piece of rope or wire following along the path the cables will be routed through the car. The cable that attaches to the shifter handle goes to the shift lever on the rear cover and the other will go to the bell crank. Avoid tight bends for best results. Measure the rope length for each cable and add 15 ¼” to the length measured. Round up the resulting dimension to the nearest inch for each cable. This will be the overall length of the cables needed.

PBS recommends:

Control Cables, Inc.
9816 Alburtis Ave.
Santa Fe Springs, CA 90670
(562) 949-0455.

These will be Cablecraft push-pull cables. The part number for these cables is 173-LTT-3-(length in inches overall). This specifies a ¼ inch cable with threaded bulkhead style mounts on both ends with a (3”) three inch stroke. Note that the length includes the complete cable assembly except for the rod ends which will be screwed onto the cable ends (they are supplied with the kit). These cables can usually be made up within one day and shipped UPS to any destination.

At this point, the cables can be installed and adjusted for length. Lengths can be altered by adjusting either the cable housing mounting nuts or by adjusting the rod ends on the cable ends. The shifter handle can be set to a comfortable upright position. Holding it to the left and moving it forward and backward should engage 1st and 2nd gears. Moving the shifter handle to the right will allow engagement of 3rd and 4th gears respectively. Remember that the axles may need to be rotated to allow engagement of the various gears. At this point, tighten all of the cable locknuts and rod end jam nuts and your PBS cable shifter installation is complete!

Reverse has a separate control handle, it may be mounted in any convent position in the car. The cable length is determined in the same manner as the shift unit except the cable will only require a (1") one inch throw. The part number will be 173-LTT-1 (length in inches overall).

Measure the rope length for this cable and add 8 ¼” to the length measured. Round up the resulting dimension to the nearest inch for the cable. This will be the overall length of the cable needed.