Poly Bead Moulded Seats - DIY?

[Erictharg]

I'd like to try a poly bead moulded seat, but the kits on offer are expensive for what they consist of. I don't see any reason why you shouldn't buy the beads (bean bag re-fill) and resin yourself, and along with the bag and some pigment and DIY, as has been done for years with two part foam. Curious to know if anyone else has done this and if so how it went? Also, if you have used one of the ready made kits (Real etc) how it went and any advice to someone looking to replicate the process. I'd plan to used polyseter resin (cost and ease of use) rather than epoxy, and the smallest bead size I can get (3 to 4mm dia).

[sebring115]

The reason they use epoxy resin is that the polyester resin will eat the polystyrene balls!!!

[Erictharg]

Well that's just the sort of feedback I needed - thanks. Epoxy it is then.

[andrewc]

The bead kits have a variety of bead sizes, some smaller than 3mm

[Erictharg]

I'm working on the basis that any combination of beads will be stronger and easier to get to the right shape than two pack foam, so even if not an exact copy of the Real and Hans kits it's an improvement. The kits are OK for smaller seats but my Westfield Eleven has a cockpit similar size to a narrow body Seven type car, so I need a pretty big volume of beads.

[RPD Motorsport]

Also bear in mind that using epoxy resin will also degrade poly ball over abour 2 week when it will fall apart. You need to use polyamide beads and an airating agent in the resin - else you will need about 8 ltr of resin which will weigh a ton and also cost almost as much as a real kit.

Also dont be fooled into thinking they are easier to use than a 2 part foam! Their not! They are great for getting an accurate seat hight for mm perfect aero - but the downside is they require you to stay in the seat for at lease 3 hours while the resin cures and also they are much harder to trim.

In 99% of cases I would advise a 2 part seat. Most top end (GP2/3, int F3, Formula Renault and WSR) seats still use 2 part foam - if made correctly you will end up with a seat which is just as good and lighter - but you have much less working time and to get a 'pro' seat requires experiance and speed. For referance we offer seat fittings for £320 in 2 part foam and £540 in indy seat including materials and tesa-seat tape. So its not vast- but beware its not as simple as it may seem!

[JohnD]

I'm sure RFD knows whereof he speaks, but wouldn't a mixture of ball sizes be better?
If you wriggle about before it sets, the bigger balls will migrate to areas where more space needs filling, while the small ones the opposite , and fill in thespces around the big balls. The difficult bit would be, what proportion of big to small balls?

John

[tristancliffe]

RPD - you know, I'm sure, that the HANS Seat uses a vacuum bag, so once the resin is in, and the correct seating position has been found again, the vacuum will hold the seat position perfectly as it goes off.

With a home made version, without a vacuum bag, you would need to sit still in the car for several hours as you say. But maybe a home made vacuum bag isn't too difficult.

I use the HANS Seat stuff, and whilst it might be a smidge heavier, and take a bit longer to do, I think the better seating position and longer lifetime over the two-part foam (which tends to disintegrate fairly quickly) are positives worth having. Plus the end result is probably better at absorbing crash energy, rather than letting your spine do it all!!

However, for a quick seat or for a one-off session in a car, then two-part every time for me.

[RPD Motorsport]

tristan - your dead right, I was assuming lack of vac bag. But... i did think after posting that its not beyond DIY skills of most on here to make one using one of those vac bags they do for storing bedding and the like or a composites type bag (but i guess anyone with that kit would get an indy seat...)

I guess it just needs someone to play about with resins, find a bead which can be wetted (but not eaten!) by the resin and also keep the cost below a real indy seat! Do report back if anyone trys!

[Erictharg]

Good feedback thanks. Making the job sound harder than I'd hoped. But of course it was that simple the kit would not cost close to £200 for my size! Getting the correct height is important for me as I need to be just able to see over my wind shield (literally a shield - not a screen), but I guess I could use foam and start with a rigid foam block under the base to give that minimum height starting point. Then rely on the two part foam to fill in all the surrounding gaps... sounds like a viable plan "B".