1969 TR6 Seat Rebuild

Work still in progress - before pix:

tr6 seat houndstooth

The 1969 TR6 seats are unique, the only year they were used by Triumph, and different from both the earlier TR250/TR5 seats, and the TR6 seats used from 1970 on. 

The seats in my car were re-covered at some point with what appear to be custom-sewn (likely home-made) covers made from a houndstooth center panel and black vinyl. They re-used sections of the old covers, so the original perforated black vinyl center panels were still there, sewn under the houndstooth. The cloth panels are stained but otherwise in good shape, but the vinyl is torn in places and dry and cracked. 

The foam in the headrest was in good shape, but foam in the seat bottom and back was crumbling and mostly flat. The rubber diaphragms were missing, replaced with carpet and twine. For this rebuild, I'm replacing all of the seat foam and using original style black vinyl covers from John Skinner in the UK. 

carpet seat bottom

The 1969 seats don't recline, but have hinged headrests that fold down using the same lever mechanism that allows the seat to tilt forward. The seat bottoms are the same as other Triumph seats, but the back and headrest are constructed differently than others (from the other documentation i've found), so i thought it would be helpful to document the '69 seat construction and rebuild process.

The seats mount the car in the usual way, with 2 bolts in the front, and the latching mechanism in the rear.

Headrest

The headrest is attached to the seat back with a pair of hinges. All screws are posidrive machine screws, going into nuts welded on the frame. The square loop at the back is the catch for the tilt bolt, similar to a door bolt.

The bottom of the cover is attached with 3 screws that capture a flat steel bar wrapped in the end of the rear flap. The cover slides up over the foam (i opened the side seams a bit since i'm not reusing it).

The foam is in 2 sections: 1 that wraps over the top of the headrest with cut pieces that fill in the space around the rails, and a separate block for the lower part near the hinge. For both sections, the foam was glued directly to the frame and at the edges where pieces met.

The frame is a formed steel channel with panels in the center. A flap of fabric in the cover goes through the gap between the panels to help anchor the pleated section of the cover in place. All hardware (other than the cover retaining screws) are anchored by brazed-on nuts.

The tilt mechanism is actuated by a cable, similar to a bicycle brake cable, from a tab on the seat tilt. The cable housing is anchored at the top end with a fitting screwed into the frame, and the bottom with a clip-on fitting. The cable is permanently mounted at the top end, and fits into a barrel clamp at the bottom end where it connects to the tilt lever.

The tilt bolt is mounted to the frame and also holds down a trim panel that covers the space behind the headrest when it's folded down. This trim piece is a vinyl-covered thin hardboard, and was not included in the seat cover pieces.

Seat back

Most TR6 seats have a 1-piece seat back cover that slides over the complete assembly, and anchored at the sides with hardboard pieces and hooks that attach to the frame. On the '69, the cover fits only around the front and sides, with a separate back panel that clips on to the frame with the same style of clips used on the door panels.

With the back panel removed, you can see the 5 rubber straps that make up the structure across the back. These are solid rubber like rubber bungee cords, and not the more typical reinforced Dunlop straps used later. They attach with metal clips to loops in the side frame. Mine seems to be in good shape. The center padding is a wedge of foam, thicker at the bottom, and glued to the rubber back straps. 

The cover wraps around the sides, with large flaps at the sides wrapping around the tubular section of frame at the bottom, attached with large clips.

The cover is glued at the edges around the upper trim panel and around the sides, underneath where the back panel clips on. The center flap's top and bottom edges were attached to the frame with hog rings after wrapping around to the back.

The side padding is built up from a layer of burlap anchored at the inside edge with hog rings, a base pad of horsehair, then a wedge of rubber foam. A thick layer of felt stapled around the wire subframe eases the corner. The burlap base continues around the side and glued to the frame tube, with a skirt of thin foam sheet on top. It looks like there should be a 1/2 round section of padding around the top frame tube (on top of the glued burlap), but it's almost completely disintegrated on mine.

The side bolster structure is 1/8" steel wire formed in 3 sections to follow the contour of the seat edge. A separate formed rod spans top to bottom, with a short straight section bumping out for each rubber strap, the strap tension held by the 3 sections that are in turn anchored in the frame tube. 

The burlap, under tension, fills the span between rods and the horsehair gives some structure, with the foam pad providing all of the padding. The replacement version of this is a base fabric of nonwoven fabric, a 5/8" layer of dense foam, and a standard foam rubber shape on top.

Seat bottom

The rearmost 5" or so of the cover wraps around the frame tube, trapped by the side strip from the back cover. The front part of each side and the front edge are wrapped around the thin lower L part of the frame and secured with 3 small clips per side. 

The rear edge of the cover has sewn-in tube. A spring goes through the tube and secures to each end of the frame tube, just below the rods for the side bolster frame.

The rest of the seat base structure matches other TR6 seat designs. A thin foam sheet wraps around the sides of the base. The seat foam base is glued to the top of the frame, with the shaped 3-sided piece on top. The cover flaps are glued to the seat base between the seat foam layers before the ouside of the cover is stretched down to be clipped to the frame.


Cleanup and inventory

I de-rusted and repainted everything that had paint, replated parts that were plated, and replaced all of the screw fasteners. It's handy that all of the screws are 10-32 thread, with just a couple of variants. I found pozidrive versions for all but the flat heads, so i need to remember those are standard phillips.

Full parts list for each seat:

  • seat frame
  • headrest frame
  • pair of headrest hinges
  • headrest latch (with attached cable)
  • cable housing
  • clamp for upper cable housing
  • clip for lower cable housing stop
  • cable clamp for lower attachment with tilt rod
  • tilt mechanism (unit with springs and mounts)
  • tension spring for lower seat cushion
  • 5 seatback straps
  • seat bottom rubber diaphragm
  • 5-6 round spring clips
  • 20 or so small spring clips
  • metal bar from headrest cover (save and reuse)
  • latch catch for headrest
  • 8 10-32 x 1/2" flat head (headrest hinges)
  • 2 10-32 x 3/4" pan head (rubber buffers)
  • 11 10-32 x 1/2" pan head (headrest latch, cable clamp, tilt lever mount, latch catch)
  • 3 sheet oval head metal screws, with washers
  • 2 rubber buffers, with washers
  • foam kit
  • seat covers
  • back panel (new with cover kit)
  • insert panel, behind headrest latch (recover with new vinyl)
  • clips to attach back panel

Reassembly

Headrest

The shaped foams glue to the upper curve of the frame, to fit around the frame edge and fit together flush at the edges. I used fairly light glue on the center, and better coverage around the edges. Square foam glues to the lower frame, make sure to keep the slot in the frame open. 

Put a standard supermarket produce bag over the foam to make it easier to slip the cover over. The opening of the cover looks way too small to fit over all that foam, but it'll slide on just fine with the plastic bag.

Adjust to center the cover on the corners. Pull the inner cover flap through the frame slot and glue to the back of the frame panel to provide tension. Make sure all of the foam corners are neat before pulling the bottom corners of the cover over the frame. I had a fold of foam there that made it very difficult to make the last corner until i arranged it better.

The front flap of fabric clips to the frame, past the lower bar. The rear fabric gets glued around the flat steel piece, which is attached with 3 sheet metal screws into the frame. This was a litle tricky, getting the vinyl wrapped around the bar in the right place and so the vinyl would lay flat with even tension.

Locate holes in frame for hinges (side with the more obtuse angle goes on the headrest side), and for the rear latch catch. The catch angles down slightly, be sure to reinstall right way up.

Seat bottom

The seat bottom is pretty much identical to other year TR6 seats, so i don't have much to add. The rubber diaphragm is under a fair amount of tension, so get a helper or find a good way to clamp the seat frame to your work bench. Vice grips might help. 

Mark the base foam where the inner sides of the upper form hit, as a guide for cover location and where to glue for the flaps. Glue the flaps to the lower foam, then glue the shaped upper foam, trapping the flaps between. Insert the tension spring in the tunnel at the back of the cover and install spring to the frame.

This is when i installed the thin foam wrap around the lower part. It was handy to be able to clamp the frame to my bench during the earlier steps, and i lost the clamp spots once the lower cover was in place.

The inner fabric skirt was really handy for getting the cover in place. When you pull the skirt over the corner of the foam, it holds the cover in place and makes for an easier surface to slide the vinyl over that corner. 

When i ordered the seat covers and foam from John Skinner, he recommended also getting this roll of wadding "for filling out small areas". I had no idea what that meant, but i did use a couple of small pieces at the rear corners to fill out some puckers near the pleats. 

The finished seat bottom came out pretty well.

Seat back

This was the most challenging part of the whole project, and the biggest deviation from other seat instructions. The issue is that top area, where you have to basically wrap vinyl around a sort of torus, with enough padding to fill out the space, but not so much that you can't get all the edges attached where they need to go.

I spent time over multiple days figuring out how to approach fitting this upper cover around the top area, and how best to avoid puckers and wrinkles. The old cover was very smooth through here, so it seemed possible, but the initial trial fittings had loose voids and odd puckers around the corners. 

I made 2 small modifications to the seat back pieces that helped with the fit. One was to trim the edge of the side foams to move the transition from center to side foam a little wider, to better match the cover. I also sewed small tabs on either side of the pleated area. On my seats, only the passenger side of my set had these cover tabs, and they weren't sewn in to my new replacement covers, but they really do help to pull the center panel down into the dished in section of the back foam. 

The upper hoop of the seat frame got 2 extra layers of foam pad, plus a layer of wadding above the layer that went around the full back tube. The foam around this tube was the most brittle of the original padding, and had completely disintegrated. It was hard to tell what it was originally there, but i assume that it should fill the cover, so i kept filling in until the contour looked about right with the side foams. 

Lots of trial fitting with different versions of wadding in all areas. Large binder clips were invaluable for temporarily holding the cover in place. I used standard brush-on contact cement for the final installation around the top, with the cover clips around the back.