PASSENGER SEAT SWIVEL
The passenger seat needs to swivel 90 degrees and 180 degrees. 90 to be used for reading with feet on the driver's seat and 180 to face a fold up table mounted on the side of the sink cabinet. The fold up table is used for eating and computer use. No need for a driver's seat swivel because there is a wall directly behind the driver's seat.
Could have bought a swivel for about $330 plus shipping and handling. Probably should have done that. Lots of design time and redesign to fix what did not work. Cost ended up close to the same. Parts weighed about 42 lbs.
My van does not have power seats or rear air or seat airbags so there was not any wiring or anything else under the seat except for the jack and jack mount. A vertical 1 1/4" shaft was installed in two four bolt flange bearings. A framework was made that sits on the seat base to support the two bearings and is bolted to the seat base with the original 8mm Transit seat mounting bolts. A 1/4" SS plate was bolted to the bottom of the seat with 5/16-18NC x 3/4" hex head bolts and elastic stop nuts using the original seat mounting holes. The jack was relocated and bolted inside the sink cabinet.
Did not want to weld, machine or paint any of the parts. A 1/4" SS plate is used to bolt the bearings back to back. The 1/4" x 8" plate is part of the framework. Two 1/2" thick single split shaft collars on shaft below the bottom bearing. A standard no split shaft collar is installed above the top bearing. The seat plate has a 40BTL 36 tooth sprocket bolted to the plate. The seat plate is installed on the shaft with a 1610 taper lock bushing. Seat turns easily. Seat is raised less than 1 1/4".
The bolted framework is made from 80/20 extrusions and waterjet cut 1/4" SS plates. Made a .dxf drawing to send to the waterjet shop to get the SS parts cut out.
The latching mechanism is where the difficulties were encountered. What I had on the drawing looked good on paper but did not work. Too much slop in the parts to hold seat rigidly in position. What I thought was a clever design was worthless. As they say "back to the drawing board". Ended up with using the edge of the seat plate to prevent rotating. Made parts to attach to the framework to create a slot at the back. Put a wood stick in the slot that is higher than the seat plate to keep seat from turning. Since seat plate is symetrical in the same location when seat is facing forward or backward, one stick works for both directions. Remove stick, turn seat and then replace the stick. Seat at 90 degrees is not restrained. The shaft location is centered between the seat bolt mounting holes. It is not offset. The symetrical seat plate does allow seat turning without needing to open the passenger door.
Swivel has not been crash tested (certainly no plans to do that). It is not certified by anyone so the results that would occur in a crash are unknown. No calculations were done to determine the safety of the design. If someone copies the design they need to be aware of the risks. If you want a swivel that has been tested, buy the commercially available swivel. THIS SWIVEL MAY FAIL IN A CRASH.
CLICK ON THE DRAWING FILE TO DOWNLOAD IT-- > ODJ127-60A.pdf>