Caterham Academy 2012 Top Tip – How To Make A Polyurethane Seat

How To Make A Foam Seat
How To Make A Foam Seat

The default seats that come with the Academy car is the fibreglass Tillett seat which as soon as you take delivery of your car, you’re told it is not going to be adequate for the purpose. This simple sentence as grieved a number of Academy 2011 fellows as why buy a Tillet in the first place? So for any Caterham Academy 2012 competitors out there, save money and buy or make a foam/bead seat from the get-go!

It was David Szymanski earlier in 2010 when I bumped into him at Spa who said that when I entered the 2011 Academy, I should opt for a foam seat. But never one to listen to anyone as my wife will testify, I didn’t take much notice as felt my own car looked much nicer with a pair of Tillett seats, which today reside in my garage! I recall the first meeting in December 2010 as introduction to the whole Academy experience, that Nick Potter suggested also you need either to fill behind and beneath the Tillett seat with foam or acquire or make a foam seat, as in case of a rear collision with wall or Armco, the bolts holding the seats in place may sheer and rendering the seat useless.

A couple of 2011 competitors have opted for the DPR made resin bead seat (most expensive but looks nice) and others have made their own foam seats (cheapest and covered with Gaffer tape), though I opted to have a foam seat made by Caterham (mid range and covered with Gaffer tape). Whichever option you take, you’ll find the bead/foam option is much lighter in weight than a Tillett, will support you better while in the car and of course, in case of incident.

So my top tip here is simply to forget buying a Tillet driver seat, opt for either a bead or foam seat as DIY or purchased from someone like DPR or Caterham Midlands. I am already contemplating removing the carbon fibre Tillett seats from my R500 too and replace the driver seat with a bead/foam seat already.

Expanding Polyurethane Foam
Expanding Polyurethane Foam

One point for consideration is the passenger seat. If you are going to take driver instruction, the majority of instructors will require a seat in the car. You can either keep the passenger Tillett, make a ‘generic’ DIY foam seat that can be placed in and out easy or run without one at all. My favoured option is a cheaper DIY foam seat which is easily made with some two part polyurethane expanding foam. I am told a 2KG kit will make one seat, though I have opted for a 5KG in case of mistake.

The following ‘How To Make A Polyurethane Seat’ has been bastardised from Freddy Galliers Facebook post to the Caterham Academy 2011 forum and a few snippets from others. Please take it as more an ‘idiots guide’ than a specific instruction as don’t forget at time of writing, I have not done this myself as yet!

– Roll of dustbin liners
– 2KG kit of polyurethane expanding foam
– Measuring Cup
– Stirrer
– Hack saw blade
– One large screwdriver
– Two rolls Gaffer Tape, any colour
– One able assistant

The seat needs to be made in two parts, the ‘base’ and the ‘back’. First you’ll need to cover any protruding parts in the car with Gaffer Tape to stop the dustbin liner splitting then ‘double bag’ by placing one liner inside of another. There are two trains of thought as to ‘how much’ expanding foam to use, either 1.5 “cups” (about the size of a water vending machine) of each (about 3 cups in total) or a “pint” of the combined fluid for the base. I would probably opt for a pint. Ensure the two parts are mixed evenly and pour into the bottom of the doubled liner. Place the liner into the seat area, making sure it overlaps the square bar underneath your knee area. With the aid of your helper, ensure the liner comes up around the small of your back. Find a position that you feel comfortable and being a position you like to drive, using the steering wheel as a guide. Lift your light leg up a little as when driving, the right leg is more bent than the left. The sit back and wait until the mixture expands and fills around your legs and arse. Pat around any foam that maybe expanding more than it should to put into place and maybe wiggle to move some of the expansion to the small of the back. Please note that you are in fact sitting on the base of the aluminium floor at this point.

Real Essential Bead Seat
Real Essential Bead Seat

The back is made in exactly the same way as the base, though using around two thirds of the quantity used for the base. This time with you in the car, ask your helper to mix the parts and pour into a second double bagged liners, then place down at the bottom of your spine and around where the base has expanded. Although in two parts, you are trying to make the foam expand all the way around you. Try not to let all the mixture sit at the bottom of the bag, but encourage it to come up to your shoulders, no higher than the harness bolts. Similar to the base, make sure you are poised in your exact driving position and allow the foam to expand around you. As the foam comes up around your shoulders, your assistant can pat down the expansion to make a nice finish.

Once your happy and the foam is firm, you can get out of the car. The next part is to remove all the bin liners and then with a hack saw blade and screwdriver, make a hole large enough for the crotch straps of the harness to come through the bottom of the seat. You may need to shape the sides of the base as well for the lap belts. Once you are happy with this, simply take both parts of the seat and cover with Gaffer Tape. Job done!

One final thought is, as your’ll be sitting on the aluminium, if you find you get a numb arse then either place a bit of carpet under your seat or as I have, cut a piece off one of those cheap sponge like camping mats. The remaining larger part makes an ideal mat on which to kneel when working on the car in the paddock!