RD-4 Transaxle

RD4 Transmission

RD4 Transaxle currently under complete redesign! Call authorized PBS dealers for updates.


  • 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:
1st: 3.08, 13/40
2nd – 3rd – 4th Gears:
2.45, 18/44
2.0, 18/36
2.12, 17/36
2.22, 18/40
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.