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Questions for a potential new build and any Ariel Atom comparisons welcome

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So I am thinking of getting back into a Caterham via a 420R new build. I used to race in the Caterham Challenge in the UK about 100 years ago in my 20's so I'm familiar with the car although that was in the dim and distant past. Sadly however, I now hang 300lbs from my 5' 10" frame and I am wondering if I am simply too fat for a Caterham. I will obviously spec both the wide body and lowered floor but even with those options does anyone have a view whether I will fit and be able to drive comfortably? Also getting in and out have to be considerations as I would plan to use the car every day on my back roads 20 mile trip to work in southern CT.


I have also had no luck on the US nor UK websites finding the difference between the Sport Suspension (standard on the R pack) and the Track Suspension. Anyone have any details on this?


Finally, and I recognize that this is a Caterham forum, does anyone have any experience to compare the Caterham with an Ariel Atom? I have never been in an Atom but they are only marginally more expensive and look pretty impressive. Any thoughts would be welcome.


Thanks in advance for not laughing at me (hopefully!) and for any help and advice you can offer.

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Hi Atterbud, the opening where the seat goes for the SV is 17.5"-18" wide where the lower torso goes so if the opening is wide enough it'll depend on the seat selection. The seat is bolted down to sheet metal so I would think you could use anything that fits. I have Tillet bucket seats which definitely wouldn't work for you, I'm sure someone has good seat ideas.

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I suggest you try to sit in an SV, even better if you can try one that does not have the seat mounted yet. If you can fit in the chassis, it a relatively easy fix to make a foam in place seat that will fit you perfectly. The SV, with lowered floors, is a lot more roomy than the regular chassis you raced in the UK.


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Personal anecdote in regards to the Atom.


Fell in love with it years ago after the infamous TG episode with Clarkson having his face destroyed. Soon after there was a local with one.


Ended up with a Caterham and couldn't be happier. There is now another local with a super fast limited edition Atom.


If I were to have a track only car, I'd probably chose the Atom for the same reasons I'm very happy as an owner of the Caterham. It just makes a better car, arguably a worse track weapon (legacy frame instead of new bottom up engineering, front engine instead of mid/rear, less Aero, less power etc)


However driving 7 on the street is a different ballgame. It feels much more compact (exterior and interior). You sit IN the Atom instead of feeling like you're wearing the car like the 7. Atom roll bars are high (shoulder level) and the interior is much more spacious. On the 7 you feel much more involved with the elements due to how the frame is designed. You can touch the ground as you're sitting in the car (can't do that in the Atom)


Comfort wise just a few features go a long way. Atom is essentially a motorcycle you drive feature wise. Cold? you get cold. Rain? you get wet (actually wetter and colder than a bike on which you at least have proper gear typically). Caterham is a transformer in regards to elements. Some Brits drive them year round, including winter (few crazies). Summer? No windshield, no doors (maybe half doors). A little colder or want highway? Put windshield on. Rain? Put a half hood on. Rain and cold? Half hood and doors and then turn on your heat. Etc. As far as storage, its laughably small but it's still more storage than Atom if you want to plan a long drive.

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I have driven the Atom and Caterham back to back - about 10 years ago. Atom has a greater rearward bias F 35%/R 65%. Caterham is better. If you believe Caterham it is F 49% / R 51%. However, some on blatchat have measured their own cars and found closer to F 45% / R 55%. This translates into understeer at higher speeds. You can drive around that with emphasis on front weight transfer but still there are times at high speeds on tracks when you really cannot do that. I found the Atom more twitchy at higher speeds. But these are degrees. Both are very competent cars but I think the Caterham wins on vehicle dynamics. The Caterham is the more practical touring car too - better for all weather touring.


Anyway, you would have a problem with the Atom - the seat. They are all shells and they are not conducive to those with fuller figures.


Your end solution will revolve around which seat will fit you. Being more than amply assed myself, I am very sympathetic having faced this problem ass-backwards myself.


I have had 1 x 320lb 6'8 gent in my old Caterham SV - he went on to buy his own Caterham. I have had a 5'11 360lb pound friend alongside me once on track in my Caterham CSR. Dented the performance mind you and a bit of a muffin top look but it worked. In both those situations my cars were fitted with the Caterham S type seat shown in the following photo




Note the lack of sides. You can expand/ooze out to the sides of the tub which is 17.5-18" wide as forum member sf4018 helpfully mentioned in his post above. A Tillet seat will add sides inside and narrow the butt space which you will be wanting to make use of. Until very recently there was not a Tillet that fitted me properly.


If you find the standard Caterham seat problematic then you can make your own. I wanted a better seat for track work in my Caterham. I was using the S-type seats as there were (until very recently) no Tillet seats that I fit, but I was moving around too much in corners. So I made a resin bead seat - refer posts 14 and 43 in this thread:






This is a very viable option for you - anchors you, is comfortable and I think you will fit one of these options.


For the difference in suspension packages, have you seen the following?



I am not sure what a track suspension is? There is Road (i.e. 420S), Sports (i.e. 420R) or Race. Do not make most people's mistake and confuse them based on the letter after the model number. I am guessing you are referring to Race when you refer to track. The best comparison of Sports to Race is described in this article:



Having driven all three set ups - I prefer the Sports. Its slightly more focused than the Road version but still retains a compliance in the suspension that the Race one does not. Race will jitter and shudder over road imperfections. Its designed for a smooth track. I have a 420R for track days in the UK and it is still good to use on the road without killing my back. As a former resident of CT, I don't think you would want a race set up to be used on the road. You would want a Road or Sports set up.


Last thing, since I have crapped on enough here, I suggest you make the drive to NJMP at Millville NJ on the weekend of Oct 17/18. Its the annual sevens HPDE and there will be a large range of Caterhams and Birkins with different chassis and seat set ups to try all in one place. You will answer all of your questions from chatting to a number of the club members in one spot, including Vlad (Vovchandr -commented above) and myself. We will have Birkin and Caterham dealer representation in person - Saturday would be your best day for that. Details are here:




You do not need to register in advance and you do not have to be a driver to get the benefit of being an aspiring seven buyer.




Edited by Croc
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You may also want to hold out a few months to see how smoothly the registration process goes for an ongoing ct build. Nor can I speculate on the outcome of the Weathersfield special inspection for an atom.

Do t forget. If a birkin/Caterham/whatever is too narrow a Storker may fit your frame (and have impressive track performances by Mario and Shane).

Edited by wemtd
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I was 5' 8" and about 245 lb when I owned my SV. I was very comfortable with the factory cloth seats similar to Croc's in the picture.


My problem came with getting out of the car, my right shoulder had 2 rotator cuff surgeries and there wasn't much strength in that arm and getting out was a strain.


I built what I named the Caterham Butt Extractor to get out. An ATV winch was bolted to the roll bar behind the driver's seat using an existing hole. A series of climbing rope and pulleys attached to the roll bar and a canvas sling seat gave me the lift needed to raise my butt to door sill height and I could step out.




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Thx Croc: So "S" stands for Road and "R" stands for Sport? Makes total sense, in a Caterham sort of way:).


Given that the Caterham seats are typically on sliders, the weight balance will also be affected by where on the slider the seat is. I sat in my Cat when it was aligned. Just moving the seat up or back one position totally threw the alignment off.


Skip: patent pending???

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I am not sure what a track suspension is? There is Road (i.e. 420S), Sports (i.e. 420R) or Race. Do not make most people's mistake and confuse them based on the letter after the model number. I am guessing you are referring to Race when you refer to track.


FYI there definitely is a "track" suspension option. It slots between the "sport" and "race" options. It is available as an option on R pack cars. Check the UK configurator. I have spec'd it on my soon to arrive 420R kit. Unfortunately, no one seems to know the spring rates of these options, but one would assume the rates get higher as you go up the 4 different suspension options, with appropriate damping to match.

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If you want to "try on" an SV we have one on hand. We also have customers in the CT/NY/MA area who will show you their car to check the fit. The "track" suspension has uprated springs and shocks vs. the "S" standard suspension or the "R" track day oriented suspension. Here is a video of the "track" suspension at Barber Motorsports park:


The standard "R" Sport suspension has adjustable spring collars on the shocks to allow ride height adjustments as well as an alternate mounting point on the upper trailing arm for the DeDion. Some additional information is here: https://www.timemachineauto.com/caterham.html

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I agree, the choices when I ordered my 420R last year were:

*Road suspension pack

*Sport suspension pack

*Track suspension pack

*Race dampers


if I recall correctly from discussing with Josh Robbins, the Track suspension pack adds 2 radius arm links. Josh is delivering my car tomorrow night!

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FYI there definitely is a "track" suspension option. It slots between the "sport" and "race" options. It is available as an option on R pack cars.


Thanks for clarifying. I was never offered that by Caterham UK when I bought my 420R in 2018. Wonder how long it has been on offer?

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Wow, I am staggered by the positive responses and help here! Thank you all very much for your comments.


I have spent the last 4 years in a 2016 Corvette Z06 which is a very fun car but HUGE! If I had posted a question like that on the Corvette forum I would have been ripped to shreds!


It is funny that all of the comments about connection to the car, the road and the elements are exactly what I still recall from my younger experience with the Caterham. Additionally, the comments regarding the high sides of the Atom are exactly my concerns on that car.


I think the key will be to try out the SV Caterham and see how I get on.


Thanks again for the support!

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Wow, I am staggered by the positive responses and help here! Thank you all very much for your comments.

..... If I had posted a question like that on the Corvette forum I would have been ripped to shreds!



Hi Dave - Glad it helped. This forum is not like the Corvette forum. We have to keep the odd rowdy Texan under control but they are mostly harmless. We all just want to have fun and we love spending other people's money! :)



Mike Did you say you lived in the UK? Where are you based?


I live in the NYC area. I have lived in the UK twice in my life, amongst many other countries. My association with the UK currently is that normally I travel there 6-12 times a year. Only 3 times this year before everything shut down in March. So thats why I keep a Caterham in the UK in addition to my ones here.

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Hey Dave, I went from se7esque cars to a Corvette. Time to start shredding:smash: Just kidding. Vettes are indeed quite porky compared to the lithe Caterhams but have some amenities that are usually not found on the more raw sevens. I do miss the visceral feel of spunky 7's. There is a wealth of information contained here and as Mike (aka Croc) pointed out, no limits of people willing to help you spend your money on these delightful and esoteric cars. Good hunting!

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