I know fitting these Tillet seats was going to be a pain; they were so tricky to fit in my Sigma 150, and yet I still ordered them knowing what they are going to put me through. I don’t want this blog to be a build diary, so I have listed all the failed attempts and the reasons at the end of this post.

I started the process by bending the runner release handle down, because I have lowered floors fitted and the hole in the lowered floor strengthening bracket prevents the runner from releasing. To test the bend was enough, I fitted the runner to the chassis floor and checked I could release the runner in any position.

The new manual (v1.2 and v2.0) recommended spacers are fitted between the seat and the runners. I followed the new manual‘s (v1.2 and v2.0) recommendations, and fitted one thick and one thin spacer to all accept the front right-hand side (or the front bolt of the runner with the release handle), which is fitted with two thick washers. This is to tip the seat back and away from the side skin.

I used Loctite 243 on the bolts holding the runners to the seats, and left the seat runners in a forward position (rear bolt holes exposed) ready for fitting into the car.

I then positioned the seat belt, one over the tunnel, and the other in easy reach. The seat belts have to be passed through the holes in the seat, as it is lowered into the chassis. I also placed a microfibre on the floor to make sliding the seat and locating the rear bolts easier.

The rear bolts are located first. I was working at arm’s length and I found it very difficult to align the runner holes with the floor, until I had a (literal) light bulb moment: I used a light to highlight the hole From the other side, making alignment easier.

Stubby Allen key to hold the rear cap head bolts

At this stage I tightened the rear bolts, after removing the microfibre through the seat belt hole in the seat base. I found it best to leave them two or three turns off tight, so there is some wiggle room for the front bolts.

I have to say, these front cap head bolts are a pain to fit, and even more of a pain to hold and tighten. I strongly recommend replacing the front bolts with hex head bolts, because they hold themselves in the runner. And if they do slip, then a large flat blade screwdriver can be used (abused) to hold them in place. In fact, if I was fitting the seat again, I would replace all the cap head bolts with hex head bolts.

As you can see, I ended up using an endoscope to try and see what I was doing, and a magnetic pickup tool to pick up the bolts I dropped time and time again, until eventually they were inserted in the correct position and tightened fully.

Now I was able to slide the seat forward again to tighten the rear boltS. I am not 100% sure why, but this time the seat didn’t slide quite as far forward as before. I suspect this is because the front of the seat can’t move and the seat is touching the tunnel carpet at the front. Anyway, this presented the final problem to solve: how to hold the cap head rear bolts now I could no longer fit the Allen key I was using earlier. In the end a 6mm ball-end hex key socket came to the rescue, and I was able to finally tighten the rear bolts..

Tools Used

  • 13mm combination spanner
  • 6mm stubby Allen key
  • 6mm ball end hex socket 1/4” drive
  • 6mm hex socket 1/4” drive
  • 1/4” drive ratchet
  • 13mm 3/8” drive semi deep socket
  • 13mm 38” drive socket
  • 3/8” drive ratchet
Don’t used this mounting location if you have Tillet seats


  • Attempt 1 – The seat belts where too short, I was unable to feed them through the holes in the seat because the adjuster caught on the seat / runner.
  • Attempt 2 – The seat belt buckle prevented the seat from moving far enough back reach the front bolts. Decided to use old manual (2015c) seat belt mounting location
  • Attempt 3 – Because I was unable to reach the front bolts, I tried inserting the bolts into the runners before inserting the seat into the car. I was able to locate all the bolts, but the loose bolt heads prevented the seat runners from moving so I was unable to tighten any of the bolts.
  • Attempt 4 – Loose rear bolts and hex head front bolts, I was able to fit and tighten the front bolts, but I was unable to slide the seat forward because the handle of the runner wasn’t bent, and would not release the runners. This was the worst scenario because I had loose rear bolts that I couldn’t reach which had been fitted with nyloc nuts. To remove the seat this time, I had to grind slots into the bolts to hold them from underneath so I could remove the nyloc nuts.