1986-1987.5 6-WAY ADJUSTABLE POWER SEAT GEARBOX UB39167 RY w/COUPLING Rolls-Royce Bentley

Out of stock:
We will not be shipping Gearboxes for 30 days.


Out of stock: We will not be shipping gearboxes for 30 days.

Years: 1986-1987.5
Part No: UB39167 RY and Coupling UB33078-L
*The same unit is used on both the driver's seat and passenger seat. These units are the same for both RHD right hand drive and LHD left hand drive.

FULLY REBUILT:  Proper Parts has re-engineered brand-new housings for these units and we recondition the internal parts.  We've been building these gearboxes since 2006. Our new housings are manufactured in the USA from extremely durable polyamide with fiberglass fill. The complete unit is assembled, tested, and shipped to you ready to be installed. Guaranteed for Life.

IMPORTANT, PLEASE READ THIS: This power seat system is an antique. It is not an amusement park ride. It was NEVER designed for continuous use. Continuous use will overheat the bushings and lock or break the transmission. Move it to the position you like and leave it there. Do not repeatedly hit the end of the track going back and forth, and up and down. Unlike modern power seats that have current sensing, limit switches, and constant position monitoring, these systems do not even have a rubber cushion at the end of travel. ~Also, don't forget to check your Seat Rail Bushings/Track Glides!


After installing your new unit, ship your old unit (core) to Proper Parts to receive your core refund. Your purchase receipt must be enclosed to process your refund. 

Please do not ship your core until after you've finished installing the new one in order to avoid sending parts that you'll need to keep for installation.

We ship within 1 to 3 business days.

Please return your core within 30 days. After 45 days, a late fee of 15% will be charged.  Your core deposit will be refunded to your original payment method when we receive your core. 


Black, Red, and Yellow Driving Gear / Input Shaft

Rolls-Royce and Bentley used the same part number UB39167 to cover two different parts. You can tell the difference by looking at the color of the input shaft. This transmission had a RED or YELLOW drive gear/input shaft, not a black one. It used a white plastic coupling. It was mounted to the motor with a 1/8 inch aluminum spacer plate between the two.

The original transmission housings were made of nylon. They were white when new but became brown and brittle over time, and many have disintegrated. Most failures are due to the housing breaking apart. There is no new OEM replacement available for this part.


The internal components are what is important. If the outer case is broken and in pieces, that is not important. We just need the internal parts. If you have any questions, please contact us in advance or send a photo. 


NEW COUPLING INCLUDED, PART NO. UB33078-L  Sometime in 1986, the coupling part number stayed the same, but the part changed to the white plastic coupling with 4 spindles. It increased in length to ~1.5 inches (37mm). This part supersedes UB33078 in years 1986.5 to 1987.5. Proper Parts has re-engineered an improved coupling design that ensures a smooth slip fit to the motor and transmission. The D-shaft openings are very accurate. We manufacture these couplings from a urethane chosen for its hardness and toughness while still having good flexibility. When the seat comes to the end of its track there is no cushion, and this coupling allows the motor to slow down gradually ensuring a longer life for all of the components involved. It is much better than the original.


  • Your receipt must be enclosed to process your refund.
  • Ship to: PROPER PARTS, 5725 HARRISON AVE, EXPORT PA 15632.
  • You are responsible for return shipping on your core.
  • Email tracking number to: alex@properparts.com.  

If you have any questions, feel free to CONTACT US.