BobM

There's been quite a bit about this on Twitter this week, naturally the likes of Andrew Frankel and Chris Harris see it as a very positive step. While it is of course welcome, I don't see it as much of an answer as it's still very wasteful of energy and even if electricity is very cheap it's still likely to be expensive given the processes required and the issues with storing/transporting hydrogen. You can make hydrogen from water, but it takes about 55kWh of electricity to make 1kg of hydrogen, which has an energy density of about 33kWh/kg. You can then further process the hydrogen with CO2 and more electricity to make synthetic methanol. You then burn either the hydrogen or methanol in an internal combustion engine to give you propulsion, this also has a pretty significant loss, with an efficiency range of 20-30% or so. So it's going to be expensive. Not a problem for the deep of pocket running their toy cars I guess. Not that those of us running toy cars are really the problem in the first place ... Better I think to accept that a very small percentage of vehicle will continue to produce very small emissions in the grand scheme of things and find more efficient ways of using the electricity for propulsion.

"Given the 8" wheel is optional, and not mentioned in the owners book, what additional width does the 8" add? Surely you need to take into account the wheel offset etc. My plan is to run a line from dead center on the front hub to the rear, both with a nominal added value to ensure the line is equidistance. Assuming the car has a wider track at the rear, then the front will have a larger added value to compensation. I just need to clarify what the rear track offset is?" It really doesn't matter. All you do is make sure your string line is a true parallelogram by making sure you have the strings at exactly the same width front and rear. You might have a larger distance from string to hub at the front than the rear, but it should be equidistant on each side.

I've always used a pair of lengths of aluminium angle with marks or slots on them which I can clamp to front and rear of car at wheel centre height. An alternative is resting them on axle stands. I then set it up square on the car by measuring from each hub centre to make sure it's equal on each side. Front and rear measurements may well be different depending on whether rear is wider track. Once set up it's easy enough to measure toe from the rims. I had both the car and the angles marked so I could easily reposition them on the car. I also use a spreadsheet for the calculations. For camber I use a piece of wood with a bolt screwed into one end along with a spirit level.

Thanks Rattie, that's one of the things I was specifically trying to establish. When I asked in the dealership if there was a difference between the carbon and the GRP seats the sales guy said he thought so but had no idea what.

Must admit I wasn't planning to bother with shift lights. Always seem like a nice idea but in reality I found I didn't use them, found I just got used to the engine noise and power/torque characteristics and learned to shift at the right point. Thanks for the clarification on the exhaust Chris.

Thanks Andy, yes, agreed on the ridiculousness of Donington's limits. Sadly the circuit management seem to face the ire of punters but not a lot they can do about it when the local council calls the tune. Useful feedback on 420s being OK :)

Thanks Richard

That looks a very sensible move Mark. I think the main reason I plan to spec a normal side exit exhaust if/when I order a 420R is to keep the separate cat and silencer. The trackday version comes with the cat contained within the main silencer and I'm sure the cat is doomed to failure with the replacement unit being >£1,000. It would also be easy enough to replace that cat section with a small additional silencer which could help keep the noise down for the picky tracks (Donington, Combe, Bedford).

Thanks both. Scott, the £400 extra seems good value in the context of removing the diff and refurbing. Yes, was wondering whether CC would supply an open diff, the 420R does indeed come with LSD as standard. I don't see them warranting the LSD, they will just argue that it's standard wear and tear given that the manufacturer, Titan, actually specify a service life and rebuild interval :(

As a newbie currently contemplating ordering a 420R in kit form this thread has been equally fascinating and worrying! If a DIY refurb of the LSD every year or two at a cost of £350 or so is called for I can live with that. I'm a reasonably competent DIY mechanic (I've built 4 kitcars before, rebuilt engines and maintained my own race car) but have never worked on diffs and can't find any howto's or guides online. Such a document would be an invaluable addition to the technical guides section on here. A video guide would be a useful supplement. I guess the alternative is to try to order the kit with an open diff and fit a different LSD which I gather from this thread will work out more expensive. My last car had a Quaife ATB (mid-engined, bike engine, chain dirven), the one before that a Sierra diff with viscous LSD. It would be helpful if some of the experienced contributors to this thread could indicate what they would do if they were speccing a new car.

Many thanks Chris, very helpful. I'm happy with race type seats, I've fairly skinny anyway. I think I just need to pay the £800 Caterham carbon tax! I'm keen to keep the car well mannered on the road so don't really want to stiffen it up too much. I do definitely need adjustable platforms though and am keen to have adjustable damping. I suspect my best bet is to initially go for the sports suspension then upgrade to aftermarket dampers later if I feel the need. I'm more worried about drive-by noise than static - as you say most tracks the static level is similar to or higher than IVA level. Brands is 240 miles away from me and not one of my favourites, but Donington is a bit nearer and most definitely a favourite, they also have pretty tough drive-by limits. Having said that my last bike engined race car was fine there. I think I'll do like you and go with the standard exhaust and get a quieter can, probably without a cat in it, fabricated later if noise is a problem. I agree the side exit looks better than the trackday exhaust. I'm sure I read someone's build blog (I've read lots recently!) where Caterham supplied the trackday exhaust temporarily for IVA, which made me worry it was marginal even for that. I definitely want screen and wipers but I'll speak to them when I spec it to see if I can avoid paying for the full hood. Yes, the trackday roll ar is already in the spec.

Thanks Nick. I'm confident I need the race seats but still haven't found out the difference between the carbon and the GRP, apart from £800

Another vote for the repair kit here. It's what many motorcyclists use, I also carry one in my tintop which doesn't have a spare. Loads available on Amazon and Ebay. I carry CO2 cylinders on the bike, a compressor in the car.

Surely wouldn't be too difficult to fabricate one of those barrels?

I did actually get my last race car through IVA with 6 point harnesses, but they were 'normal' 3" straps, not the HANS version.

Yes, apologies, my oversight regards your rallying experience. Completely agree with you on the 4 vs 6 point harness, never really happy with 4 point. I suspect the way forward is a HANS compatible 6 point, the 2 inch part of the straps is entirely adequate for road use and with the right harness you could simply not bother with the crotch straps for 'normal' driving. Might need to stick the 4 point back in for MOT though.

As others the full weather kit was an error. Should have separately ordered half hood - the only hood to use - and doors. Great, thanks for confirming, can save a few pennies there. Cannot comment on the carbon seats. My 'S Type' (2012) leather seats are comfortable with good support. Having driven 350 miles without a proper rest break, apart from a fuel stop, I can say that they are excellent. Yes, the leather seats look comfy but I need every inch I can get both for legroom and headroom. I'm also hoping for my 'little' brother who is 5" taller than me to be able to have a pedal also. The car will only be used for spirited driving in any case. Standard exhaust (2012 R400D), even without cat, is quiet enough for most circuits. Mine has never peaked above 98dba during noise tests. That might still be marginal at Doni and Castle Combe. I wonder if there's any way the trackday back section can be used with the standard exhaust? I'd far rather have a separate cat, both in terms of replacement cost and being able to run without it. Dry sump included? One of the 'got to haves'. It will save heartache later......... Yes, standard on the 420R. Adjustable 'sports suspension' is worth the extra £ to get the chassis set up for maximum efficiency. Little things like changing from CR500 to ZZS which are higher tyres increases ride hight so not to compromise this & rake you need that adjustment. But you may never change tyre type......... Yes, the sports suspension gives adjustable spring platforms, I'm used to doing chassis setup and have corner weight scales. I'm not sure if the race suspension gives adjustable damping also. If it's just stiffer springs then not terribly good value. Unfortunately although the Caterham configurator is quite easy to use it doesn't give explanations of the various options.

I'd stick with the standard harnesses. You've clearly never used a HANS, otherwise you wouldn't contemplate using one on the road They seriously restrict rotation of your head so you'd have great difficulty at junctions, especially if you have one with an acute angle. There are other issues. As you've already identified, you need a narrow harness to fit properly on the HANS and my understanding is that the HANS specific harnesses aren't approved for use without a HANS (that might only be in the racing context of course). Also you need quite specific placing of the shoulder strap mount points to give the correct angle for the straps to sit on and secure the HANS, I think they need to be slightly closer together than you'd normally have just for a 4 point harness, the straps need to converge slightly as they pass behind the device. I share your concerns about wearing harnesses without a HANS, an inertia reel belt allows your torso to flex forwards in an impact, thus avoiding putting too much stress on your neck. Harnesses however don't and this is a risk. The risk is higher wearing a helmet as it adds to the mass of your head. Good discussion of the issues .

Hi all, first post here so please be gentle I’m planning to order a 420R to build next summer and have some queries I hope you knowledgeable folks can help me with. I’ve been lurking for a while and done quite a bit of research, so I’m fairly clear about the main spec – SV chassis, lowered floors and race seats as I’m 6’ 5” and need all the room I can get. The car is for weekend A/B road fun and trackdays. First query is about the seats. Obviously, the carbon race seats are lighter and look better, but is there any other benefit? Are they the same basic shell shape etc? Are the carbon ones more comfortable than the GRP ones? Second, suspension and the difference between race and sport suspension? Is it worth the extra for the race suspension or does it compromise the car on road? Is it better to get the sports suspension and upgrade to adjustable dampers later if I feel the need? Third, exhaust. I’m assuming I need the trackday exhaust to keep noise levels down? I’ve grown out of noisy exhausts and have no wish to get black flagged on any trackdays. However, I’m a bit worried about the integral cat in the trackday exhaust – how long do they last? I presume fairly expensive to replace the cat? And lastly the weather gear. The consensus seems to be that lots spec the full weather gear and never use it, preferring the various half hoods on offer. I presume you can order the car just with the doors – that doesn’t seem to be an option in the configurator?