HELP ME CHOOSE THE RIGHT CATERHAM

[toolshed]

Hi all,

I'm after some advice on which Caterham to buy. I've always dreamed of building a Caterham and I decided to take the plunge and put down a deposit just before Christmas with kit delivery scheduled for mid August. 

For now I've ordered a 310R but I was planning to go and try the 420R before finalising the order - however COVID has put a stop to that and with my order finalisation deadline coming up in April I though I might turn to this forum for some help and advice.

I test drove the 310R and loved it but I am bit worried that I might find it a bit lacking in torque especially when compared to what I am used to - I've always been a fan of V8 and used to own a TVR Chimera and currently have an Audi RS4 B7 as a daily driver. I guess I've been spoilt but I am used to putting my foot down in any gear !

I've read that the 420R doesn't have some of the pointiness and reviness that the 310R has but I've also read that the 310R runs out of grunt especially on track day. I am planning to take it on the track so that is an important consideration for me but, given I live in London, I also need a car that will behave in town and on the way to those country lanes for a blat. In short I am confident that I could handle the 310R but wondering if the 420R will be too hard core. I get that it is a personal decision but really struggling to make my mind up absent the ability to test drive them side by side.

Spec wise I've pretty much settled but I'm still in too minds about the wheels - leaning toward 6 and 8 inchers and front and rear - and about wether the 4 piston brake upgrade is worth it. 

Any advice gratefully received.

Once that is settled I can start worrying about the build - loving all of the blogs but feeling quite nervous as, aside being a dab hand at building lego technic, I don't have much mechanical knowledge !

[Nigel B]

I found myself in the same position eighteen months ago. 

Firstly, I know this is easy for me to say, but I wouldn’t agonise TOO much about the decision. All Caterhams are fantastic & you’ll quickly acclimatise to whatever you decide to buy. 

I ended up buying a two year old 420R. I wouldn’t say it’s too hardcore. I know Caterham’s marketing tends to portray it as the hardcore track day junkie’s option, but I find it very well judged for road use.

Someone on Blatchat recently described the 420R as having a Jekyll & Hyde character & I’d agree with that. It’s a complete pussy cat around town, torquey & smooth, but when you reach the national speed limit signs, squeeze the throttle & explore the upper reaches of the rev range, there’s a satisfying craziness to it that takes your breath away! 

I haven’t driven a 310, so I can’t comment on how it feels in comparison. I suspect the Duratec cars don’t handle quite as sweetly as the Sigmas, but there are pros & cons to all 7s & as I mentioned earlier, you get used to whatever you end up with. 

I certainly don’t regret my decision to get get a 420. It’s definitely a keeper!

Anyway, I hope you manage to reach the right decision for you. Enjoy the deliberations! 

[Toughie]

1. Caterham's salesman once told me that the average buyer will own three Caterhams in their lifetime, so whichever you choose, you'll probably want another.
2. Caterhams then Technical Director, Simon Lambert, told us at a Get To Know You 7 course in 2017 that the "sweet spot" for Caterhams is between 130 bhp to 180 bhp.  You can control the car and have fun.  Over 180 bhp, the car controls you, and you have to react to it.
3. He also told the bloke that built his own 160 that, with its skinny tyres, he'd made the best choice of car, for the most fun.
4. We're all megalomaniacs.  What ever power we have, soon, we usually want more.
5. I had a Roadsport 140 as my first car, though the dyno run said it was actually 156 bhp.  I then bought my present car, a CSR 260 with 251 bhp.  'Course, I'm nowhere near good enough to do her justice, but I just love that power.

[Billy.Whizz]

From what you've been used to i would suggest 420R with quad brake upgrade and for your reviness and great induction roar fit RBTB's.  

 

[mossy7]

I too was brought up on torque; I enjoyed a succession of turbo hot hatches over the years and love the shove.

I started out with a Sigma Roadsport with the Caterham 140 BHP upgrade. I found this was fun once it was spinning above about 4K revs but below that it was a bit flat. In particular, trundling through a 30mph speed limit in 3rd gear and flooring it at the national speed limit sign was disappointing; a family TDI would leave me for dead till the engine got up the rev range. I was contemplating various upgrades to solve this.  Due to unfortunate circumstances I had to sell that and a year or so later, in the search for torque, I got a Duratec 360R. This is a completely different animal, loads of torque and third gear at 30 MPH had loads of shove. Those pesky diesels were no longer a problem, and it was docile and fine in traffic. But it was still flat, it didn't have the drama I was looking for. It was all about the torque curve which was very linear and boring. After several chats with Stuart at Premier Power, I took the plunge and now have a 225 upgrade. It's fantastic, loads of punch low down, a real spike at 5K as the cams "come on" and a pussy cat to drive around town. It's what I was looking for all the time. It is massively quick, licence threatenly so!

So, to the OP. The 420 has the torque you miss from turbos. The 310 will have the revs, but may "feel" slower. No seven is actually slow compared to other road users but they are inherently all about how they make you feel. If I was to do it again, I would probably go for a 310 or even a 270 and hand it to Stuart at PP for some of his magic. Lightweight, loads of revs and keep my driving licence! 

[Piers300]

You say that you have the specification sorted, other than the model (310 or 420). Have you included a Track Day roll bar ? Without it, you will not get into Lotus 7 Club Track days. Also useful is an isolator switch for security.  A half Hood is good, as is a tonneau cover for use when away from the car. A roof is a personal requirement. When it is very heavy rain, it is useful. 

On the 310, I would keep it all 6" wheels all round but go 8" rears on the 420. Ok, it looks good on a 310, but you will loose it's dart ability. Add in a phone charger 12 V socket. What seats have you specified ?  I would always have a heater, but you do get a lot of heat from the engine. In summer, it gets hot inside the car. You will be going for a 5 speed box as as I understand that Caterham have stopped production of their 6 speed box. If you have speed bumps in London where you live, it may be beneficial to get a dry sump on the 310, I think the 420 comes with it as standard.

[Toughie]

P.S.  A warm welcome to the club!

[7 wonders of the world]

Welcome,

The 360 is a great balance with potential for much upgrading as and when you want to, 5 speed yes, forget the Titan LSD get the open diff and ask Steve Perks to pop a Tracsport in it, Big 4 pot brakes no, the add significant unsprung weight to the front, stock alloy 2 pots are more than capable even on the track, great choice of pads if you require more, dry sump yes (Especially if you do get a Duratec), lowered floors, Tillets and 6 point harness, 360 will take either rims on the rear without upsetting the balance.

If your going aeroscreen consider an SLR cage too.

 

 

 

[Handwheels]

Hi - I was in exactly the same position as you late last year, although I had the chance to hire a 310r for a weekend plus test a 360 and a 420r. I loved the 310 but once I'd driven the 420 I was seduced by the extra torque and even more brutal acceleration. 

I got lots of useful feedback to my post asking for advice - google "newbie help needed" and you should find it. I eventually settled on a 420r S3 with lowered floors and both the full screen and aero screen. Slowly ticking off the days left until early May when the big build starts.

 

Lovely dilemma to have

[colinwrogers]

Hi. Interesting to read the comments following your post.  Go to Sevens and Classics showroom on the website and see what they say about the 420R s they have for sale as they really know. Read the "About us" section and you will see what I mean. Now closer to home. I built a live axle crossflow Seven in 1990/1991, had the car for eight years and was then seduced by a Mercedes 230 SLK, but that is another story. Twin webers, four speed box, FIA roll bar, about 130BHP and full hood was quite sufficient to have plenty of fun without embarrassment or frightening yourself, so don't worry about going for the fastest unless you intend to compete and then the specification is determined for you. Recent house downsizing has allowed me to purchase another Seven.  This one is a 2012 1.4 Seven Classic with 5 speed gearbox, lowered floors (essential), half hood (mine has a circular zip across the roof to make it easier to get in when it is in place), long shower cap (because it is easy to put on and keeps the interior and engine dry), heated screen (essential), heater (to keep your partner warm), battery master switch (for security and less batterty drain). Otherwise everything else is up to you and I agree with the Simon Lambert comment from Toughie. You may guess I just love driving my Seven. Just to put things in to perspective though, money no object I'd have a Caterham 7 Levante V8 or JPE in the original colour scheme so I'm a power junkie like the rest of us! Whatever you choose enjoy the experience, don't worry too much about the build and let us know how you get on.

[ScottR400D]

Lots of good info for the OP. My only thought is not to worry about the ‘the car controls you’ idea. The 210/20 bhp Duratec can be a pussycat if driven reasonably and you’d have to be quite reckless to find it threatening at all. 

 

[Nigel B]

Prior to getting my 420R, I had an 8 valve Vauxhall, live axle 7 with 120bhp. I had that for seventeen years, covered 45,000 miles in it & thoroughly enjoyed it, so I completely understand colinwrogers point of view. You don’t need a million horsepower to have fun in a 7.

But I’d also agree with Peter’s comment. I don’t feel that my 420R is ‘controlling me’ because I have in excess of 200bhp. The 420R has 90bhp more than my first 7, but it also has better tyres, better suspension, thicker anti roll bars & a limited slip diff. All of which make 210bhp feel completely natural & controllable & entirely suited to the chassis set up. 

When I first got the 420R, I did feel a degree of trepidation (especially as it was absolutely hammering down, the day I picked it up!). But it wasn’t long before I felt completely relaxed with the car. It doesn’t feel any more intimidating than my live axle car.

[ChrisC]

The 310 and 420 are my favourites of the current range, but I haven't driven the Super Sport 1600.  So the choice isn't going to be easy. 

I enjoyed my Sigma engined cars on track, and felt I was able to extract more from them, than I have been able to with my Duratec cars (so far).  I haven't adapted to my Duratec car yet, but I haven’t had time to get a proper setup on it either, so the jury is still out. 

Ultimately every Caterham will be out gunned on a track in top speed when the aero dynamics kicks in, but that’s not what it’s about.  With less power you concentrate more on carrying the speed through the corner.  The model number doesn't make a fast Caterham on the track, the driver makes the difference.  

Off the track one of the greatest parts of ownership is the blats with fellow owners.   This is another area where power just isn’t necessary.  It doesn’t seem to matter what engine the car has. 

Four pot callipers where originally added for endurance racing, and because durability.  So technically you don’t need them, but I prefer them for Duratec cars.   Sigma cars I don’t think them. 

Final point I guess to make is complexity of the build.   A 420 is significantly more complex to build especially if it’s a S3.   

Oh and Welcome :-)

[RedCat7]

A 420 would be my recommendation, with the roller barrel upgrade for the noise and throttle response.  I have an older sigma 150 which has similar performance to a 310 and sounds even better due to having throttle bodies.  The engine is the best thing about the car - revvy and noisy with lightning throttle response.  However you do have to work the engine hard to make progress.  I don't mind that but have never had a torquey car in the past.  On track, instructors have mentioned I could do with more power and it is frustrating to be slow on the straights and not having the torque to steer using the throttle.  I once drove a 420 on the road and was surprised by how much quicker it was.

[DJ.]

If it was mainly road use, I would say the Sigma engine. You have to use the gears more and drive it properly, so there is more satisfaction. I have an old Sigma 125, and it is surprising how little I can really use the full performance on the road.

 

However, you like track driving, and on track days in a lower powered Seven, you are quick round the corners, but anything remotely aerodynamic just goes away on the straights. My acceleration really slows after 90mph, and if I was a competitive quick driver, track days would be frustrating. Fortunately, I'm happy just using the full performance on track once a year, and just wave everyone quicker past

 

If you buy an SV and tour with a passenger and lots of luggage, the 2 litre will help them too.

 

Duncan

[garty2010]

I think that if your budget stretches to a 420R, that would be more in line with your experience.  I have a 420R and previously B7 RS4 and current B9 RS4.  Whilst they are so different as 4wd 450bhp tin tops, the experience of torque throughout the rev range is similar.  I have found that for road use it is just right if you don't expect to thrash it in every gear or you probably will get into some bother.  For track day use there always seems to be times when you could use a bit more power (as a 620 passes you!), but the balance feels good. When I first drove a test car it was a 310 and felt mightily fast with all the completely different sensations you get with a Caterham.  It clearly is still very fast and well balanced and I'm sure would not disappoint but in my experience getting the 420R has been a good choice.  Then you will only be wondering if you should have gone down the 620 route....... Oh and finally, I built mine having had no mechanical knowledge or experience to use.  Other than a bit of head scratching and emails to Derek at Caterham, there really is nothing overly difficult.  

[Toby S]

Interesting comments on torque, and having one of the first 1400 Supersports I know about lack of torque with nothing much happening before 4,500 revs - but for me that is the point - dropping into 2nd at around 40-45, and hitting 70+ before the change up light comes on and using very bit of the 130 ish BHP generally every time I go out in Delilah is why I love the car - I don't drive it the same as my everyday tin top and there's the fun and why I have it.

I guess it's down to horses for courses - do you want one which you are revving the balls off to get every last bit of performance out of safely, or one where there is loads of performance in reserve, which you are unlikely to need or use, or if you do (at least on the road) endanger headrows and your license. Yes - now I've got used to it, I probably would like a bit more power, but agree with the Caterham guy quoted  that 130-180 is the sweet spot given the age of the basic car/chassis design and having no idiot saving "get out of jail free" safety devices to save you from yourself.

[JonT]

My views are similar to Toby (with a 1.6 K-series and ~130bhp). If you start chasing power, then you're into stickier tyres, upgraded brakes etc etc. Track days are fine on road tyres in mine - yes, it sometimes gets frustrating when the bigger engined cars don't let you through, but on open pit lane days it's easy enough to take a quick break and find some space. An aeroscreen will help (so may be worth getting the brackets fitted to enable quick swapping of windscreen and aeroscreen)

And for road use the only time I've felt the need for more power is when 2-up. But I also enjoy using the whole power band of the engine and not short shifting. My 1.6 still never feels short of torque - it's not like there's much weight to get moving. But no naturally aspirated engine will ever give you the on-boost sudden kick in the back of a turbo. On the other hand nor will it then go completely flat with no real change in response as you wind it out.

[ScottR400D]

JonT, if you buy a 420 you already have the tyres and brakes needed and road tyres are fine on track too, as long as you choose a decent tyre. 

 

[toolshed]

Hi everyone and thank you for all your comments and advice.

Blown away by the response and really appreciated the advice. Nice to hear that others with little mechanical experience have managed to complete the build - I'm sure I will have a batphone to Derek at Caterham by the time I am done.

This is the spec I am looking at:

• 420R - that was leaning to but comments have helped swing it for me - will go for roller barrels in due course but I'll leave that for later
• SV with lowered floors
• 13inch apollos with 6" and 8"
• Carpets and heater
• Leather seats (not exactly slim fit !)
• Removable momo
• LED headlights (and I'll do JAL LEDs upgrades for other later)
• Battery cut off switch (will be spending some time in garage)
• Track day roll bar (lack of rear visibility is a bit of a pain but want extra protection and freedom to choose all track days)
• Full weather pack with interchangeable aero screen (largely for track days)
• Tonneau cover and half hood (later might come from soft parts for sevens as it appear consensus is that is better than Caterham one)
• Colour is up in the air - leaning towards viper blue with white double stripe but also tempted by lamborghini verdes ermes (seen a few cars in that colour and I think they look amazing) also with white double stripe
• Lastly I think I'm going to go for 620R dash as it looks so much nicer than the normal one !

Thanks

Seb

[Toughie]

Sounds great.  Nice colour choices, too.  I'm on my second Viper Blue, but that green is also luverly.

 

[Nigel B]

It sounds like the ideal spec & I agree, that Lamborghini green really is a stunning colour! 

RBTBs really would be the icing on the cake. Mine has the standard plenum induction set up, but I'd love to add a set of throttle bodies at some point. My first 7 had weber carbs & I do miss the characterful gargle & snarl from them & the throttle response is definitely softer with the standard set up.

Strangely enough, I don’t find the track day roll bar too bad from a rear visibility point of view. It possibly depends on how tall you are, but I just angle the mirror so I’m looking below the cross of the bracing bars. After a while you don’t notice it at all.

Although I didn’t build my 420R, I did build my previous 7. Admittedly, it was a more basic car than a 420, but I’d echo garty2010’s view. It went together pretty easily, despite the fact that my experience was very limited at the time. Inevitably there will be moments of frustration & head scratching, but it’s definitely worth it in the end! 

 

[Geoff Brown]

If Toughie is correct then indeed the statistics bear out that a Seven owner or is it 'megalomaniac?   Will indeed own three cars in their life time.

My life time so far:

1.4K Supersport 1994 - 1999   

1.6K Supersport (upgraded to 155bhp + other additions) 2000 -  2012

R400D Superlight (RBTB 220bhp) 2012 on

A progression which in 1999 made me realise what I really wanted. The 400 is just right. Easy to drive through suburbia in 20-30 mph restrictions, great for touring fully loaded, torquey in all gears, bonkers when you press the loud pedal just a little too much!

Don't expect fantastic mpg if you use the car. Fuel anxiety is the new paranoia when touring in a 400/420. Any way no one buys a Seven to keep an eye on the economy! 

Eight years of ownership since home build. Had a few problems along the way but would I change the car/upgrade - NO.  This car can be pants wetting enough without resorting to a 620, but docile as well. Just the right side of sane.

[John Vine]

Re #20:

That looks like an impressive spec.  Does it include a 12v socket (very handy for a battery conditioner)?  Don't be surprised if the full hood collects dust in your garage.  I suspect you'll never actually use it as the half-hood is just so much easier to deploy.  You might also want to consider a long-nose shower cap from SBFS.

Don't be too concerned about the ferocity of the beast.  My R400D is a delightful combination of pussycat and bonkers.  Fuel economy (with RBs) is 27-32mpg on the road and 15-ish on track.

Enjoy the build.  You won't regret it, and there's loads of advice on here if you need it.

JV