420R spec queries

[BobM]

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?

[TomB]

Buy some doors separately from the parts store?  It could be your first part delivery! 

[Jonathan Kay]

Welcome.

Private Message sent.

[7Up]

I find the carbon seat have more space for the hips and better (slightly) for the back

i have standard exhaust, passed every track noise test no problem

regards the full weather kit - this was my one mistake. only ever use (used) the half hood.

these are the only answers i can give 

 

[Geoff Brown]

As others the full weather kit was an error. Should have separately ordered half hood - the only hood to use - and doors.

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.

Standard exhaust (2012 R400D), even without cat, is quiet enough for most circuits. Mine has never peaked above 98dba during noise tests.

Dry sump included? One of the 'got to haves'. It will save heartache later.........

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.........

[John Vine]

I was about to check the 420 specs but CC's website isn't working properly, either via IE or FireFox.  Are others seeing the same thing?

JV

[BobM]

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.

[Nick T]

Hi Bob,

A lot of this is personal taste however being only a mere 6.2 the tillets do give you a couple of inches more on both height and leg room. Also having done several  trips to CLM and 10 plus hrs in the car I have found the tillets very comfortable. However, this may be something to do with my fat a@@s. Lowered floors will also help.

cheers

Nick

[BobM]

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 

[ChrisC]

Hi Bob

1, There are three seat shapes available to order, Tillet (Race), Tillet (620 Carbon) and S-Type leather.   Tillet (Race), as fitted to academy cars, are available in either kevlar or GRP, these tend to be tight fitting but I have heard it said kevlar are slightly more comfortable.  S-Type leather and Tillet (620 Carbon) are more suitable for larger drivers.  Comfort is subjective, I for example prefer Tillet (Race) over S-Type leather for comfort.  

2, The springs fitted to the front dampers is all that's different (Sport to Track Suspension).  It's actually cheaper to buy the springs from the parts site and swap them if your building a kit, especially if you sell the standard items.  It's much like the carbon indicator mounts, which are cheaper from the parts store than to order with the kit.  

I am sure there are plenty of people who will tell you how much better / worse they are than the standard spec.  I personally would spend the money on getting the car flat floored and the geometry spot on first.   

Sport Suspension is standard 420R spec, and that has adjustable platforms.

Race Suspension used the 620R spec dampers and springs.

(FYI Road spec (S models) is the same as Sport, but without the adjustable platforms)

3, Noise is measured static and drive-by, the IVA static noise test is actually stricter than Bedford Autodrome, which is generally considered the most strict nose level track in the country.  That said drive-by can be a problem dependent on the mic location and track.  For example Brands can be tricky, but I have seen plenty of 420R videos on Bedford.   Finally it also depends how hard you can push it, so the same car with a different driver can have problems.  

I went with the side exit, if I start getting problems I will upgrade to a Raceco side exit, mainly because I don't like the look of the rear exit.  

4, I think the main hidden difference between ordering with or without weather gear is cars not fitted with factory windscreens aren't fitted with wipers.  So in general without weather gear is a brave initial option.  The hood is useful if you ever leave your car outside overnight, so it's not something I wouldn't be without.  Half hood for driving obviously ;-) 

Hope this helps

PS - think about the track day roll bar ;-)  

[BobM]

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.

[Richard_420R]

Hi there - few points from me:

1. I have the carbon seats and whilst they look like they should be quite hard are, for me, more supportive and comfortable than the leather.  One of my favourite 'upgrades'

2. I've never used the full weather gear but don't regret ordering it - you never know when you might need it and then you'll likely really need it!  I, like others, use a half hood - the Caterham one with zips to allow vertical space are brilliant.

3. don't know if you mentioned brakes - I was going to get the upgraded ones but glad I didn't - the standard ones are fine with upgraded pads and much cheaper to replace pads etc. 
4. exhaust nose - I've never seen any problems with the 420 and the side exit re noise - I believe the 620 is marginal hence rear exit normally.  I really wouldn't worry about it.

enjoy! 

 

 

[Richard_420R]

Oh and re the springs - I was thinking of race but glad  I didn't - the standard sports springs are plenty hard for track and pretty hard on road - I think race wouldn't be acceptable on the road. 

[BobM]

Thanks Richard 

[Richard_420R]

Last bit of advice from me is get the programmable shift lights - the single change up light as standard isn't much use and the rev counter is a little damped too meaning it's quite easy to hit the limiter in low gears.  However with change up lights in your peripheral vision it is much easier to get the max from the engine without mistakes.  I had mine fitted recently and makes a big difference for me.  

[andy_harries]

"but Donington is a bit nearer and most definitely a favourite, they also have pretty tough drive-by limits"

I always laugh at the imposition of noise limits at Donington, given when the planes go over you have to stop talking as the noise is so loud you can't hear anyone even if they are right next to you.

We had a few 420s at Donington at the club track day last monday, don't think any of them had any noise issues there.  In fact, unlike Bedford I've not seen any Caterhams have an issue at Donington when I;ve been there

[BobM]

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 :)

[Obodiah]

I've just got my 420R registered and the standard exhaust was perfectly fine on the IVA (Caterham do not bother fitting the rear exhaust these days for the IVA).  The Tillet carbon seats with padding are super comfortable even after 1.5hrs of mixed road driving.  

I'm still waiting for my half hood from CC despite the kit being delivered in March, however the full hood is not terrible to put up and is fine to drive in once you are inside (although getting in and out does require a little more flexibility).  It is also good if you have to trailer the car anywhere or leave it out overnight.

The Caterham branded ACES shift lights work for me as I've never seen the single shift light illuminate, apparently it does at maximum revs but I've got my eyes firmly on the road at that point and the limiter would kick in before I could react.

[ScottR400D]

My aces shift lights have been on since new, factory fitted. The green light comes on below 2500. The first yellow at 5000 and the rest at about 500 intervals.

I find the first one really useful on the road. Changing up at 5000 gets you along at a fair old rate without attracting attention or being silly. Especially useful if dark. 

On track I don’t find them so good actually because if you go close to the limit and change up, some of the lights stay on, so ‘corner of the eye’ viewing is useless, there’s always a light or two on!  

[ChrisC]

It was my car Caterham supplied the rear exit for (IVA July 2020).  They don't normally do it, because in 95% of cases its not needed, but since the IVA was early post lockdown a true belt and braces approach was taken.  Ironically the parts supplied didn't fit my car, and there wasn't time available to resolve that, so the car was tested (and passed) with the side exit.  

[7 wonders of the world]

DRE shift light are much better and a fraction of the price too

[BobM]

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.

[aerobod - near CYYC]

I don't find the shift lights particularly useful on the road, but when programmed to meet ones needs, on the track they work well for consistent changes at the right RPM.

[Rattie]

Worth checking that the "carbon seats with padding" (620 style) will be the SV variant, as the S3 one will flap around in the cockpit. As far as I know there aren't any SV width variants of the race seats. IIRC, the 620 seat is a variant of the Tillett B6, where the SV gets less of the rolled edge trimmed off. This a) leaves less room in the cockpit for the seat to deflect and b) makes the seat stiffer, which also limits the deflection.

£800 makes this a bargain option, since the seats are £2500 a pair from the parts shop, vs around £1300 for the GRP race seats, which are a less than ideal fit for the SV.

[BobM]

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.