This applies to my '97 R50 with manual, non-heated cloth seats. Interchangeable parts (IE, that can fit on either seat) are the lower upholstery, pad and metal seat pan (as a complete assembly); the seat-back upholstery; the seat-back foam pad; the headrest; and the two headrest guides (the guides are unique left-and-right - the left guide has the latching lock for the headrest post). Allow a couple hours, but it's a very satisfying repair and is pretty easy.

You don't need hog-ring pliers for this gig; sockets, screwdrivers, trim tool, and a c-clamp is handy. If you replace the seat-back fabric, you'll need two zip-ties, 6-8" (or hog rings if you have the pliers).

Check out your interior - missing any trim pieces? Are the plastic front seat recliner handles in place or have they fallen off? How's the armrest pad on the console? Headrests and sun visors OK? Need any trim clips from behind the door panels? Identify any little extras you might want to grab from the donor vehicle.

At the junk yard - remove the donor passenger seat. You don't need to strip any of the plastic trim from the seat sides yet; from the back seat area, remove the plastic trim covers over the mounting bolts. The sides of these wrap around, you spread them out a bit with your fingers, then pry the covers up. The cover next to the console is a tight fit but you'll eventually pop it off. Remove the two 14mm bolts. They may be tight, a small breaker bar could be handy here.

In front, there are no trim covers, just two 14mm bolts to remove. The passenger seat has no wiring connections (on my manual-seat '97), ease it out of the passenger door.

Remove the driver's seat from your vehicle - same drill as the passenger seat, two plastic covers and four bolts. Lean the seat back and disconnect the seatbelt warning detector harness.

Move the driver's seat to a clean bench (cover it with a towel/etc). Remove the recliner handle (one phillips screw) and the right and left side trims (2 philips each). Remove the head rest if you're replacing the seat back upholstery. If your head rest is stuck, it means the post is rusty (no idea how it gets rusty in there), but the headrest guide sleeves are plastic - drip just-about-anything down the post guides (don't get it on the fabric). I used a few drops of WD40 dry-lube, soap or window cleaner would probably work fine. Pull the headrest out.

Flip the seat over. The cable for the fore-aft control cable is attached to the seat pan with a plastic loop - use a trim tool to pop it free. Remove the seat belt wiring connector (take a pic or make a note of how it loops around the seat frame). Remove the four 12mm bolts and pull the complete seat pan/pad/fabric assembly out.

If you're replacing the seat back upholstery as well, set the seat upright and clamp it to the table edge with a c-clamp or bar clamp (to hold it upright and stable). Look at where the fabric loops under the bottom. There are two plastic rails that connect the front and back of the fabric sleeve together like two interlocking "U" shapes. Slide them back and forth to loosen any dust and grit in them. Now you have to pry them apart. Start one end with a flat-blade screwdriver, and eventually you can "peel" them apart. Basically you "open up one of the U-shapes" and work them loose, they're pretty flexible.

Slide the upholstery sleeve up over the foam - compress the side bolster foam with your hands and work the fabric up over them. Midway-up, you'll encounter two hog rings that attach the fabric to the seat frame. Cut these or pry them loose (you can just replace them with zip-ties later, you don't need hog rings or pliers).

Now remove the headrest guides. These will not come out with the headrest installed, but it's got to be removed anyway. Slide your hand up under the foam from behind the seat; aiming for the bottom of the headrest guides - there's a metal plate back there to get your hand under. If you have big hands, get your wife or a kid. There's nothing sharp under there, but you will get a rusty orange hand!

The guides slide into steel tubes, and there are plastic prongs at the base of these tubes you have to squeeze together to release them and slide them out. It takes very little hand pressure, getting your hand up there is the issue. (Keep a big wet rag handy to clean your hands when you do this). Pop the guides out, clean your hands, and then finish peeling the fabric sleeve off of the frame.

Now place some rags under the frame rails and get to cleaning. Vacuum up any hair, dirt, and foam remains. I used a spray solvent (avoid hitting the seat back foam or upholstery). Use a brush and clean everything up nicely, and then lubricate the pivots and sliding tracks. Clean and lube the seat recliner pivots, and the pivots where the fore/aft locks operate on both sides. Set the driver's seat aside.

Strip the upholstery from the donor passenger seat, same as the driver's. Remove the bottom pad and the back fabric (if you're doing the whole seat). Vacuum off the seat bottom upholstery, and now's a good time to clean it if it's stained. (See notes below).

Assembling the driver's seat is the reverse of removal - clamp the seat upright as before (the back has to go on first, then the bottom). Compare the seat-back foam on both seats. You can remove the foam assembly as one piece, it sort of wraps around the frame, so if the donor seat is in better shape, swap it out now. Clean out the headrest guides (a pencil and a rag with cleaner can ream it out). Maybe add some dry lube to the tiny spring in the latching side.

Install back upholstery first - it's like putting a condom on Ron Jeremy, but squeezing the bolsters will help you get it on there. Get the first few inches on, down to where the hog rings were. Pop the headrest guides back in (they can only go in one way, but make sure you put the latching guide in its proper place) and make sure the fabric is tucked in under them - this will help hold the fabric down. String a zip tie through each spot where the hog rings were, and (from the back) pull them tight. This will "suck" the fabric down into place. Finish stretching the cover down over the foam, and re-attach the two long plastic strips by interconnecting them and pushing them firmly together - they'll snap into place. Give the back upholstery a final aligning by pinching and shifting it if needed.

Now is a good time to clean the back fabric, too. Then flip the seat over and attach the seat pan (four bolts). You don't need to align the tracks, just make sure they're both maxed fore or aft - the seat pan acts as an aligner. Make sure the fore-aft cable is looped around properly. Attach the plastic loop that fixes the cable, and attach the harness connector from the seat belt, and make sure the cable is placed properly to not snag in any mechanisms.

Clean any rust from the chrome headrest posts, use something like WD40 and fine emery paper. I lubed my posts with dry lube as well. Wax might work well here too.

Clean the trim pieces (I just took mine into the kitchen, hot soapy water). Attach the side trims. Clean the screw and the screw hole for the seat reclining lever trim (clean the hole in the steel lever on the seat frame) with alcohol and let it dry. Add some loctite to the screw threads and screw the handle trim in (those screws are tiny and notorious for working loose and disappearing, let's make 'em last).

Clean and vacuum all the mess of yellow foam crumbs from the vehicle carpet - now's a good time to clean the console side, too. Remove the gas-filler-door lever trim (2 phillips), clean it and clean the gunk and mess of seat foam crumbs from the lever assembly - lube the lever and reinstall the trim. Install the seat, making sure to connect the wiring underneath. Install the rear floor trim pieces over the rear bolts. If the seats are damp from cleaning, leave the windows down so they'll air out and dry. Pop the headrest back in and marvel at how smooth it moves now.

Pack up the old seat back and stash it somewhere - if you ever need a fabric repair, it'll give you some material to work with.

Cleaning - I used a wet/dry shop vac. Spray foaming carpet cleaner onto the seat surfaces; as it foams up, you'll see discoloration mixing with it from the stains. Give the foam a brushing, and vacuum it up. Repeat this several times until the foam remains white. This way you're sucking the stains up vs. just rubbing them around.