CSR vs 420R

[Croc]

I am starting this thread at the request of a new member to this forum who wanted to know how different the CSR is compared to other Caterham chassis'. I figure there is more than me who can comment on this topic so have made it a thread. Hopefully Josh and Bruce chime in given their deep knowledge as dealers.

 

 

There are three basic Caterham chassis for sale today:

 

1) The S3 - the narrow body. De dion rear end

2) The SV (or S5) - the wide body. 4 inches extra in the cockpit in length and width. De dion rear end.

3) The CSR - essentially the same identical dimensions as the SV but has a different chassis design with more bracing and triangulation intended to make it stiffer. Also it is designed for inboard front suspension and independent rear suspension. There is also the option of traditional flat dash or "curvy dash". While my current car has the curvy dash, I prefer the flat dash for its traditional looks.

 

The S3 or SV come in a variety of model designations broadly associated with hp/weight - 270 (135hp), 310 (150hp), 360 (180hp), 420 (210hp), 485 (250hp), 610 (310hp).

 

The CSR usually comes as a CSR 200 or CSR 260 with the numbers linked to amount of hp, i.e. 200 or 260hp. However, there is nothing stopping a buyer from installing their own engine spec with hp of their choosing, e.g. a 210hp CSR.

 

For driving impressions, the CSR feels like a bigger car with its more sophisticated suspension. Bumps do not throw it offline. Its quite soft in its feel - very comfortable if not better ride comfort compared with most daily driver types of cars. If you hit a bump while turning e.g. pothole on a road or kerb on a track, then the rear end stays planted on line.

 

By contrast the regular S3/SV chassis with the de dion are not quite as planted over bumps and move around more - a more lively feel. Some people like this feel, some do not.

 

A comparison I participated with a few people in the UK at Donington quite a few years ago was if you took an S3, SV and a CSR with identical hp (200), identical tires and wheels (15inch), then what was fastest around the track with identical drivers (and a few drivers participated). The fairly consistent result no matter the driver was the CSR was marginally fastest followed by the SV then marginally behind was the S3. The SV had it over the S3 by virtue of the wider track even though there was a very slight weight penalty. The CSR had it over the SV by virtue of its rear end suspension composure. I want to stress that these were marginal differences. A different driver might be able to achieve a different result. However, there was no question in my mind that the CSR made it much easier on the driver to go faster - you feel more confident about driving at the limit and carrying more speed.

 

But these are not massive differences. 10-20hp could make difference. Switch from 15 inch to 13 inch wheels makes the CSR even faster. There are a lot of factors that can determine a test result like the one above.

 

That said, the CSR is a touring monster, very fast point to point on second hand road surfaces.

 

 

 

 

 

 

 

 

 

 

 

 

[Roadsterdriver]

Great, concise, comparison. Thanks.

I wonder why Caterham didn’t stick with CSR?

[TurboWood]

Vote from me for CSR. I’m not experienced with the various chassis, but the CSR is very comfortable on the street. I can keep up with any other vehicle on rough road so long as I don’t fear hitting the sump. With the doors on my wife almost fell asleep on a short blat. I’m only 1k miles in, but it hasn’t bitten me yet.

 

Daniel

[Bruce K]

According to this recent article, the CSR is reborn, at least in Europe:

 

https://www.autoevolution.com/news/caterham-seven-485-csr-now-available-in-continental-europe-136274.html

 

Great, concise, comparison. Thanks.

I wonder why Caterham didn’t stick with CSR?

[Croc]

The CSR never stopped being sold in Switzerland and Australia for local homologation reasons. It disappeared from UK and US marketing. But you could order a CSR for US roller kit delivery all through the period when the US marketing materials were silent (aka giving the impression you could not order one). It was a special order not on the standard menu. There must have been good reasons for this - one day we may know.

 

So the article is just bringing the chassis option out into the open. Not sure it is a reborn as much as bringing it back as a formal offering in the marketing materials.

[TurboWood]

Great, I wonder if they managed to squeeze the BMW diff in it or if they still use the older Ford unit. Blowing that thing up is my biggest concern since upgrades are limited. I may never try slicks just for that reason. Anyway, it's good to see some life coming back. They must have done some development if that article's claim is correct that it is available in the standard/S3 chassis which I don't think was ever true before.

 

I did recently grab a CSR Ford non-limited slip diff from Caterham on heavy discount which suggests they were purging inventory. That gives me a backup, but it would be great if there was a better option. It's probably a big wish to have it fit in the same chassis though.

 

Daniel

Edited September 2, 2019 by TurboWood

[Croc]

Blowing that thing up is my biggest concern since upgrades are limited.

 

Really Daniel? Its never worried me. Works just fine in LSD mode. You can get modest incremental replacements out of the UK by transmission specialists. They are good up to around 350hp in a competition environment. For us we would not stress it out that much.

 

The real issue with that diff was the original chassis only had 2 fixing points. Then the extra boot braces came in around 2010 for 4 point mounting but even then I have always been concerned for torque effect ripping the mounts off.

 

They must have done some development if that article's claim is correct that it is available in the standard/S3 chassis which I don't think was ever true before.

 

I think the article is wrong. Arch is only making 1 chassis - the S5 CSR which is CSR sized.

[TurboWood]

Mike,

You are probably right, but my turbo engine is putting about double the torque of the 485 through it. I have a Quaife ATB in it, but the case and the gears have to survive. 80's diffs and modern turbo engines don't give me warm fuzziest. My buddy had a turbo NA (1st Gen) Miata that he kept blowing diffs in despite being a mile high. All I can say is hopefully the safety factor in Ford was bigger than Mazda back then.

 

Daniel