Floors, chassis and sumps. Newbie questions
Floors, chassis and sumps. Newbie questions
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pixelmix

Original Poster:

278 posts

131 months

Half thinking about a Caterham at some point in my future, likely something relatively modern (Sigma or Duratec engined), and probably R spec (or an S with some mods leaning towards an R spec as it might do a few track days).

A couple of questions:

1) Chassis size: On paper an S3 chassis would fit me better at 5ft7 tall, so the only benefit I can see for an SV is a bit more packing space for weekends away. Is the boot space difference material? Is the theoretical downside of the extra size and weight of the SV really a material consideration in reality?

2) Floors - most cars I see in classified ads have lowered floors, which probably puts me lower than I need to be. This puts the seats brackets a couple of mm closer to scraping the floor and more likely to scrape. Any advice in this regard? Is it so immaterial that a lowered floor car won't be an issue and if I feel too low, I should just put spacers under the seat?

3) Slightly nervous of trashing a wet sump. Even leaving aside the potential occasional track day use, is a dry sump a sensible idea on lumpy roads? This is probably less critical than 1 and 2 as it is easier to fit later. I'm mindful that my (very leisurely driving) father put a hole in a sump in a hire Caterham a few years ago.

framerateuk

2,868 posts

207 months

pixelmix said:
1) Chassis size: On paper an S3 chassis would fit me better at 5ft7 tall, so the only benefit I can see for an SV is a bit more packing space for weekends away. Is the boot space difference material? Is the theoretical downside of the extra size and weight of the SV really a material consideration in reality?
I'm 5ft8 and the SV felt massive and uncomfortable. I couldn't reach the pedals properly, the gearstick was too far back. It's not so much an extra space issue, it really changes the whole way of fitting the car. If Caterham only made the SV I wouldn't own one. The only way to know is to sit in a few. The chassis size is one thing, but the seats make a big difference too. I've got the leather seats, and I'd probably be too low in the composite ones. Worth sitting in several and seeing what works, and then hiring one for a few hours to see how it goes. I've heard people say some seats give them back ache. I've done lots of long drives in mine and the combination works for me.

pixelmix said:
2) Floors - most cars I see in classified ads have lowered floors, which probably puts me lower than I need to be. This puts the seats brackets a couple of mm closer to scraping the floor and more likely to scrape. Any advice in this regard? Is it so immaterial that a lowered floor car won't be an issue and if I feel too low, I should just put spacers under the seat?
I think you'll be fine, mine has lowered floors, and the height is great. My wife is 5ft4 and she does need a cushion to sit on in order to see properly though.

But yes, I think some steel spacers could be used if you needed to. I've thought about putting some on mine to give me a little more clearance when adjusting the seat (the lowred floor has a crossbar right in the way).

pixelmix said:
3) Slightly nervous of trashing a wet sump. Even leaving aside the potential occasional track day use, is a dry sump a sensible idea on lumpy roads? This is probably less critical than 1 and 2 as it is easier to fit later. I'm mindful that my (very leisurely driving) father put a hole in a sump in a hire Caterham a few years ago.
On the Sigma I've never heard of anyone using a dry sump. On the Duratec the r400/420 have a dry sump as standard I think. You do become aware of it as you drive, I've heard of people taking out their sumps on very cambered roads. I guess it's always going to be a bit of a risk. It's been a long time since I looked at this but I think the Duratec sump is a little lower to the floor than the Sigma one? Trackday wise, there are lots of Sigma cars being used on trackdays, including in Caterham's various race series and I don't think any of them are dry sumped.


Edited by framerateuk on Monday 23 March 15:03

pixelmix

Original Poster:

278 posts

131 months

Yesterday (09:46)
quotequote all
That's really helpful info, thanks.

It sounds like I need to spend some more time sitting in a few cars but that an SV isn't really a sensible option.

Noted re the sump. I'm probably more bothered about damage on the road than oil sloshing about on track (where I probably wouldn't be pushing hard enough). The kind of roads I drive around are exactly the kind with horrible cambers and massive ridges: the sort of stuff that would make me very twitchy with a vulnerable wet sump.

framerateuk

2,868 posts

207 months

Yesterday (11:17)
quotequote all
Yeah i get that.

Speedbumps are a pain, although the bolts on the lowered floor tend to bottom out before the sump does.

We had to avoid a large rock in the road once, where in most cars you'd probably try to place it centrally, with the 7 you're making sure you give that sump some clearance!

We did 10 days in Scotland and several trips around North Wales and it's all been fine. I run the small 13" wheels all round so my ride height is probably on the low side too.

You could always run higher profile tyres to give extra clearance when on the road. I've thought about it just from the comfort aspect as the 13x6 ZZS give a very hard ride.

Tupwood

216 posts

91 months

Yesterday (12:17)
quotequote all
I have both 14" and 13" wheels for my Caterham. The 14" are heavier and you feel it in the steering and less acceleration, but the extra 12mm grand clearance is rather nice at times.

I also run 60 profile Toyo R888R tyres on both sets, and the taller, (slightly) softer sidewall works well with the Caterham suspension and helps ride out the bumps a little.

Sump wear is common, but only catastrophic if you collide with something big and heavy. You can fit a sump guard, but that simply transfers the impact forces to the chassis which may not improve the situation. Getting the car flat-floored and set to a ride height you are comfortable is the best way forward, You will need to have adjustable-platform suspension (not all cars come with this) and then get it set for your weight and driving style (about £300).