With the washer bottle fitted and the boot carpeted I felt it was time to refit the boot cover. Thankfully, Caterham now do the hard work, so all the poppers are pre-fitted in the Factory before the kit is delivered, so all that’s left to do is fit the seat belt uppers and a few popper bases I removed earlier in the build.

The seat belt bolt holes have already been drilled in the boot cover, and they use the outer two bolt holes. When I first offered up the bolt, my heart sank: there was no way I could start the bolt without damaging the powder coat on the trackday roll bar. I wondered if I had made a mistake, because I would have to remove the rear shock absorbers to be able to loosen off the roll bar. I also noticed that the threads had paint in them.

I thought I would give cleaning the threads a go to see if that helped, rather than rushing into removing the shock absorbers, because the paint in the threads made starting the bolt difficult. I was surprised to find that the threads are not metric but imperial UNF. The strange thing was my best fitting spanner for the head was still the 17mm (which I had also used for the lap belts), so I stuck with that.

For reference: the inner seat belt bolt holes are used on race cars because the Hanns device need the belts closer together.

Initially I thought with the thread being imperial UNF I was going the need a new tap to clean them. Thankfully I remembered a trick my dad used to do to clean threads when he was short of the proper tool for the job. He would cut a slot into a bolt and run that bolt through the thread. I found an old cut-down bolt I had been hoarding and decided to give it a go. I worked the bolt from underneath and it cleaned the thread of the paint. This was sufficient for the seat belt bolt to fit properly and clear the roll bar without damage, because cleaning the threads had given the bolts that tiny bit of extra space needed to clear.

Fitting was simple enough, same as the lower seat belt fixings, but this time I decided to use the cardboard washer between the lower boss and the chassis, mainly to protect the paint and because I had seen them fitted there before on previous cars, however the new manual (v1.2 and v2.0) doesn’t show them.

I torqued the bolts to 47Nm, checked the buckles could still swivel freely and then fitted the nut covers supplied. The rest of the popper bases were refitted and tightened with a Philips screw driver.

Tools Used

  • Dremel
  • 3//8″ drive torque wrench
  • 3/8″ ratchet
  • 17mm 3/8″ drive socket
  • Philips screw driver