Newbie help needed - 310 or 360 or 420

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Roy Blyth
Roy Blyth's picture
Last seen: 20 min 48 sec ago
Joined: 17/04/2014

Richard, you will always want more...?  Biglaugh  You can have just as much fun and enjoyment in a low spec Seven as you can in a high spec one.  

Not much help I know Driving 

John Vine
John Vine's picture
Last seen: 4 hours 11 min ago
Joined: 17/04/2014

Nice dilemma to have!

I've never driven a Sigma car so can't comment on that, although I'm told that the 310 is very close in character to a 160bhp K such as the R300 or 1.8 Supersport-R (which is what I used to have).  That was a little gem, with a sweet, revvy engine.

I now have a wet-sump R400D (that was the spec in 2008).  On the road, it can be a pussycat or a tiger, depending on conditions and mood.  I've toured through France in it and it's so effortless to drive.

I agree with the comment in #15.  Maybe the R spec is a bit OTT for your proposed use?  Yes, you could add the dry-sump option, but wet-sump damage is usually fairly rare (although I confess to cracking mine on a monster Dorset flint some years ago -- I've now fitted my own home-built sump guard).

If I were in your position with your proposed usage, I'd opt either for the 310 or the 420S.  If you chose the 360, you'd be forever hankering after a 420.

Hope that helps!



Obodiah's picture
Last seen: 1 week 20 hours ago
Joined: 18/10/2019

I went for the 420R to build with my son as a 'keeper'.  The good thing is that they are all upgradeable in terms of performance and specification.  I built mine this year but had a Premier Power F225 upgrade done before the IVA and registration.  Stuart can also squeeze a hell of a lot out of the 1.6 Sigma which is about 20Kg lighter than a Duratec.  They are all great fun and if you intend to keep it you don't have to shell out for the highest spec right away...and there are several options in terms of 'high spec' whatever your starting point is.

FWIW I love the sound, smell, driveability and performance of the 420R with AT throttle bodies

Last seen: 1 hour 30 min ago
Joined: 12/10/2020

Just sneaked onto the forum for a quick break from work. Can't believe how many replies!! - too many to read just now. I heard you were a friendly & helpful bunch, but I still was expecting so much advice and so quickly. :)

Thanks to everyone who has replied. I'll sit down with a cuppa later and have a good read and then probably send out yet more questions. Cheers.

7 wonders of th...
Last seen: 15 hours 42 min ago
Joined: 17/04/2014

Duratec sump....

The dry sump offers and addition 38mm of clearance on the vulnerable front edge, as well as offering a lubrication system that has increased oil capacity.

Many owners myself in included have cracked wet sumps on compressions despite having uprated springs and a well set up car.

DS is a no brainer.


Last seen: 1 hour 30 min ago
Joined: 12/10/2020

Thanks for all the comments - lots of food for thought. Main things & questions that jump out to me are;

LSD - I hadn't really picked up on the concerns about the Titan diff of doom before. Just spent ages reading the 'BMW/Titan LSD viability' thread - very interesting & I'm now questioning my plan to include one in my spec. Sounds like I had the same experience as everyone else who has test driven a car at CC and questioned the painful clunking of the diff - "they all do that and you're sitting right on top of it". It seems like the sensible thing to do is to get an open diff and then get SPC to convert it.

Not sure if I would have to wait until my CC warranty run out before doing this. Would welcome any thoughts on what it would be like driving a 420 with an open diff in the meantime - although a 420S has an open diff as standard.

R or S Pack - Now beginning to think the S Pack might suit my needs better, plus a 420S would be slightly more affordable than a 420R. Also the S comes with an open diff, although I'll give CC a call to see if they would supply a 420R with an open diff & check how much they'd cut the price by. My original thinking was that if I'm finally going to get a Seven I might as well get as hardcore one as possible.

310 or 420 - Before I posted my initial post I had concluded that the choice was really between a 310 & 420, & not a 360 (due to my wet sump paranoia). Seems that this is the general consensus. ChrisC - you mentioned that you increased the ride height on your 360. How did that affect the handling? (i've been studying your excellent blog in great detail!)

I know a 310 would suit me perfectly, but I am defiantly drawn to a 'bonkers' 420 & am doing lots of man-maths in my head to justify the extra expenditure.

Hood options (Mandalman) - Even if I'm going to do some trips to wetter parts of the UK (i.e West Coast of Scotland), would it be sensible to ditch the full hood that no one seems to use, & get a half hood & shower cap instead?

Tyres/Wheels - now I've started looking at the 420S on the CC configurator I've noticed that the standard wheels are 14" with 185/60 tyres front & rear.  I don't want a car with too much grip, but surely with 210 horses I'd need to upgrade to 13" wheels with 8" on the rear? I'm surprised that 185/60 on the rear is even an option.

Finally, CTRMint - I've had to stop looking at your blog because it's causing me too much painful garage-envy.


Cheers, R

Last seen: 1 hour 14 min ago
Joined: 17/04/2014

My 360R had a flat floor setup during Post Build Check, at the time Caterham gave three ride height options, Road, Aggressive road or Race.  I choose Road, mainly to ensure I could get my car on the drive.  

I never hit the sump in 2 years of driving on Essex roads, it handled well, mainly due to the flat floor setup, but ultimate lap time would have been compromised. Not that matters over being able to get it on the drive. 

At the moment my 420R is set high, Caterham now only perform a flat floor setup after 1000 miles.

Oh and on the diff question, loads of noise about this at the moment, but this is a problem I have been aware of since 2018, and yet I still ordered a car with the R spec/Titan LSD unit.  I was always going to monitor it, and decided my course of action when need.  After all a new kit will have a warranty meaning its not a financial problem for the first two years at least.   

I bet Caterham haven't got a demo 420 with that tyre combination.     

7Up's picture
Last seen: 30 min 19 sec ago
Joined: 17/11/2018

My feedback for you (2 years of 420R):

- I find it underpowered (in a straight line), so would not recommend smaller engine 

- can't control the diff potential issue, so don't worry about it. Cross that bridge if/when it comes. The car is worth it!

- my car is on the 'coke can' height limit. I have to avoid the narrow speed bumps, but the long ones are fine and not had an issue to date

- have never used the full hood, only half hood

- wish i had the shift lights







JonT's picture
Last seen: 1 hour 43 min ago
Joined: 07/05/2019

I've only taken the halfhood and a showercap on my Alps trips, including coming down Stelvio in a snow storm. The biggest problem is that rain can run down the roll cage and into the boot, so everything needs to be in properly watertight bags. The roof is quite claustrophobic and the ventilation terrible, so you'll steam up worse and overheat too.

Last seen: 3 hours 28 min ago
Joined: 23/08/2015

OP, I don’t remember if you’ve said but are you building this car yourself? 

If so, it’s a no brainer to get an open diff and have an SPC LSD fitted it will cost you £3/400 more but will be right from the start. 

I doubt you would get any warranty issues, plenty of kits get built with a few non CC bits in them. 

If you’re buying ready built I’d talk to CC about them fitting the LSD with an SPC or get open and do it afterwards. 

I take the point of the car being under warranty but sooner or later you’ll be running an out of warranty car with a Titan.