Basic Caterham questions

[Skydragon]

Post No 1...

I'm thinking about buying a 2nd hand Caterham sometime over the next year. The objective being to have a sports car for a bit of B-road weekend fun and possibly 3 or 4 trackdays or hillclimbs a year. Since I'm totally new to the world of Caterhams I'd be grateful if anyone can give me guidance to the following questions (ideally I'm not looking for technical info but for what the answer is in driving and real world usage terms). I've booked a Caterham slalom day to get (a little) more knowledge and experience, but in the meantime...

1. In terms of driving experience, what is the difference between a Caterham with a live axle and one with a De Dion setup? If it helps with the answer, I live in a rural area, with some lovely hilly B-roads, some quite bumpy.

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

3. A bit of a vague question perhaps, but my previous 'fast car' experince is via Subaru Impreza ownership (don't shout... I know!!). I appreciate that a Caterham is a very different and more demanding driving experience (and well under half the weight of an impreza), but is it likley that I will be disapointed with a lower specced Caterhams' performance (acceleration etc). How many BHP should I be looking for to give 'hot' performance? Does a basic 125HP Roadsport cut it, or is 150BHP+ really needed?

4. What difference to the driving experience does a Limited-slip differential make on a Caterham?

5. Wheel sizes? Considering I'm hoping to do a few basic hillclimb events and trackdays, what wheel size is best to go for and with that what tyres are recommended?

6 Fuel injection or Carbs? - or is it not important?

7. Any other points to consider (I keep on hearing about chassis corrosion on older Caterhams, is this a real issue on many cars?)

8. How limiting is a 4 speed box (compared to a 5 speed)?

Sorry for all the questions, but hopefully they will help others as well.

Cheers,

Chris.

[absolutely]

Skydragon said:

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

8. How limiting is a 4 speed box (compared to a 5 speed)?

2. I am big, I struggle to fit in Caterhams, I'm 6 ft 2. How broad are your hips?

8. Not as limiting as you think. Most older racing cars have 4 speed boxes, we have one on our Mallock race car, never had a problem with it, the diff limits the speed rather than the gears.

[Skydragon]

absolutely said:

Skydragon said:

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

8. How limiting is a 4 speed box (compared to a 5 speed)?

2. I am big, I struggle to fit in Caterhams, I'm 6 ft 2. How broad are your hips?

I'm a 36" waist and medium hips I guess, as well as fitting in I was concerned about how my big feet might interact pedal-wise

[hbwold]

I may be able to help with a few points but I'm fairly new to owning a caterham too:

3. I own an ex roadsport race car with 120bhp and it does go very well. Its a completely different driving experience, you are a lot more in tune with the car and your so low down, the sensation of speed is greater. I own a Focus RS which is a similar to the Impreza and the caterham feels quicker than the RS and a totally different type of car.

5. I'd go for the 13" superlight wheels with CR500 tyres, they are brilliant in the dry or you could go for slicks.

[absolutely]

Skydragon said:

absolutely said:

Skydragon said:

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

8. How limiting is a 4 speed box (compared to a 5 speed)?

2. I am big, I struggle to fit in Caterhams, I'm 6 ft 2. How broad are your hips?

I'm a 36" waist and medium hips I guess, as well as fitting in I was concerned about how my big feet might interact pedal-wise

Your feet might be a problem, depends how wide they are really, length isn't much of a problem after you've got under the dash. Racing type boots, pointy toes and tight to the contours of your feet.

[Tango7]

Skydragon said:

1. In terms of driving experience, what is the difference between a Caterham with a live axle and one with a De Dion setup? If it helps with the answer, I live in a rural area, with some lovely hilly B-roads, some quite bumpy.

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

3. A bit of a vague question perhaps, but my previous 'fast car' experince is via Subaru Impreza ownership (don't shout... I know!!). I appreciate that a Caterham is a very different and more demanding driving experience (and well under half the weight of an impreza), but is it likley that I will be disapointed with a lower specced Caterhams' performance (acceleration etc). How many BHP should I be looking for to give 'hot' performance? Does a basic 125HP Roadsport cut it, or is 150BHP+ really needed?

4. What difference to the driving experience does a Limited-slip differential make on a Caterham?

5. Wheel sizes? Considering I'm hoping to do a few basic hillclimb events and trackdays, what wheel size is best to go for and with that what tyres are recommended?

6 Fuel injection or Carbs? - or is it not important?

7. Any other points to consider (I keep on hearing about chassis corrosion on older Caterhams, is this a real issue on many cars?)

8. How limiting is a 4 speed box (compared to a 5 speed)?

1) The live axle cars are lighter than De dion cars but if its the standard Marina ital unit, you will be limited to no more than 170BHP and also to the stickiness of the tyres you can use on warm tracks. I have seen cars with Ao21r's (good all round tyre but not very sticky as far as track use goes - unless its wet!) where the oil surge in the axle has caused problems. This is only really possible on fast track use though. The Ford (English) live axle is much more robust and can take around 250 BHP but its much heavier. Ride-wise if the surface is choppy, the rear end of the LA cars tend to skip and move sideways whereas the DD cars will give a more "supple" or smoother ride. Typically though for track use, the surface is much smoother than public roads so its not a problem.

2) Depends on whether you have long legs/short body, vice versa or somewhere in the middle! I am 6'2", wear size 12 shoes and am (ahem, comfortably!) heavier than you and I have no problem in a standard S3 car - and sometimes I used to wear my safety work shoes too.... Retrofitting a lowered floor is around £100 for labour plus the new floor pan (£200 I think) so not really a show stopper if you find the right cr.

3) A Caterham is mainly about lightweight and ability to outbrake and outhandle a normal car than anything else. The lower powered cars (around 120 bhp) will be easily out paced on the bigger circuits but will make the time by being quicker into and round the bends and also far less demanding on brakes so they will be more effective as the session goes on. One of the best video's of the Nurburgring is a chap overtaking everything (bikes, ferrari's, porsche, other sevens etc.) and as the credits role, it shows that he was driving a 100 BHP Xflow sprint car....

If you can afford it though buy a bigger power car as you will want more power (as everyone does!) and it will be cheaper to buy a car with the mods done now than have them done later ;-)

4) Donuts! Also speed from the corners will be improved.

5) 13" is the general preferred choice for trackdays and hill climbs but if you are competing, you could find there is a restriction on the type of tyres you need to use and this may determine the wheel size too. Otherwise for trackdays, get a set of 13" rims anyway (probably around £100 for a straight but tatty set), buy some slicks for a tenner each and go and have a blast - in your DD car with 200 BHP and an LSD

6) Fuel injection will most likely be a little more economical

7) Caterham were very cost-conscious during the 90's and cars from 96-97 tend to have very thin powdercoating. Its easily resolved though with a wire brush and a can of POR-15

8) Personally I would go for a 5 or 6 speed box all the time. However, for competition purposes you might find a well specc'd 4 speed box would be better.

HTH
T

PS Sorry if someone else has come along and given the same answers as its taken me a while to type this one out...!

[fergus]

Skydragon said:

2. I'm 6ft, 13 1/2 stone and size 12 feet. Will I get in a standard Catreham ok, or do I need to consider a car with lowered floors? If so, how easy it is to retrofit a lowered floor to an older standard Caterham?

3. A bit of a vague question perhaps, but my previous 'fast car' experince is via Subaru Impreza ownership (don't shout... I know!!). I appreciate that a Caterham is a very different and more demanding driving experience (and well under half the weight of an impreza), but is it likley that I will be disapointed with a lower specced Caterhams' performance (acceleration etc). How many BHP should I be looking for to give 'hot' performance? Does a basic 125HP Roadsport cut it, or is 150BHP+ really needed?

4. What difference to the driving experience does a Limited-slip differential make on a Caterham?

5. Wheel sizes? Considering I'm hoping to do a few basic hillclimb events and trackdays, what wheel size is best to go for and with that what tyres are recommended?

6 Fuel injection or Carbs? - or is it not important?

7. Any other points to consider (I keep on hearing about chassis corrosion on older Caterhams, is this a real issue on many cars?)

8. How limiting is a 4 speed box (compared to a 5 speed)?

I'm almost 6'6" and until recently was approaching 19 stone. I've got size 13.5 feet and manage fine in an S3 (with lowered floor and aero screen).

The thing you need to remember with Caterhams is their power to weight ratio. Their low weight also makes them very nimble in terms of handling. I don't think there is any need to go for lots of power to begin with. Drive a few to make your final decision though.

On the road an LSD will probably not be missed, however on the track, an LSD is a must IMHO. I run a plate diff, as they tend to hook up more than the ATB type, but this is personal preference.

In terms of wheels, if you intend to do t/days and a few h/climbs, I'd go for 13" rims, as there is plenty of race rubber available at sensible prices. You also get a good compliance due to a higher sidewall profile.

FI or carbs? I don't think it matters as long as each is set up well.

On older cars, you do need to be aware of chassis tube condition, and also check some of the ally panels where they join/overlap the chassis rails/box sections. There can be corrosion lurking here.

The choice of g/box depends upon what you'll use the car for in conjunction with the power of the engine. I'd go for 5sp as the best compromise. You can get different final drive ratios fitted to the diff if you need to alter the gearing though.

[ewenm]

For the "will I fit?" question, get along to your local Lotus 7 Club meet and chat to the owners there - they'll let you sit in their cars to see what fits and what doesn't. The list of monthly meets can be found on www.lotussevenclub.com

[Skydragon]

Thanks for the prompt and concise information, very helpful and much appreciated.

Cheers

Chris.

[bikemonster]

FI or carbs?

Nothing wrong with either, but carb-fed cars are more likely to provide a "classic motoring" type experience which may not be what you are after.

[Eric Mc]

Plus a higher fuel consumption - if that's an issue.

I know, I have twin Webers on my Crossflow.

They sound great though.

[Gingerbread Man]

Out of interest regarding the lowered floor option. How much lower is it than standard?

[fergus]

Gingerbread Man said:

Out of interest regarding the lowered floor option. How much lower is it than standard?

50mm (over approx 3/4 of the current floor pan), then it tapers up to meet the pedal box in the same place as the std floorpan

[Gingerbread Man]

fergus said:

Gingerbread Man said:

Out of interest regarding the lowered floor option. How much lower is it than standard?

50mm (over approx 3/4 of the current floor pan), then it tapers up to meet the pedal box in the same place as the std floorpan

Quite a difference then.

[RobM77]

Gingerbread Man said:

fergus said:

Gingerbread Man said:

Out of interest regarding the lowered floor option. How much lower is it than standard?

50mm (over approx 3/4 of the current floor pan), then it tapers up to meet the pedal box in the same place as the std floorpan

Quite a difference then.

Is it really that much? Here's mine:



How does a road going seat fit to this? In a race car (all I'm really familiar with), you sit on the floor of the car, so it lowers your seating position the ~3cm that you see in the above pic. Does the 5cm that you quote come from the fact that with a lowered floor you bolt the seat runners straight onto the floor, but with a "normal" floor you bolt the seat onto the chassis rails as well, thus gaining an extra 2cm?

I'm looking at swapping my race 7 for a road 7, and even at 5'10" I find it unnatural to sit so high in a standard 7, so I'd be going for the lowered floor option too

[fergus]

RobM77 said:

Is it really that much? Here's mine:

How does a road going seat fit to this? In a race car (all I'm really familiar with), you sit on the floor of the car, so it lowers your seating position the ~3cm that you see in the above pic. Does the 5cm that you quote come from the fact that with a lowered floor you bolt the seat runners straight onto the floor, but with a "normal" floor you bolt the seat onto the chassis rails as well, thus gaining an extra 2cm?

Yes, it is that much. Ring Caterham to confirm.

Whether you then choose mount seat runners, etc, is irrelevant as to how much lower the floorpan is over the original. The choice of seat you choose to fit will obviously affect the net result. I use a moulded foam seat, where my a$$ is on the ally floorpan itself...

(although I do sleep well at night in the knowledge that at least the dry sump pan will get taken out before my a$$ if I hit a brick in the road ), as there's 65mm under the sump and 70mm under the seat - although the car is only ever driven on the road around the Eifel region of Northern Germany these days....

[ewenm]

fergus said:

(although I do sleep well at night in the knowledge that at least the dry sump pan will get taken out before my a$$ if I hit a brick in the road ), as there's 65mm under the sump and 70mm under the seat - although the car is only ever driven on the road around the Eifel region of Northern Germany these days....

Is that measured with you in it, compressing the rear suspension a bit?

[RobM77]

fergus said:

RobM77 said:

Is it really that much? Here's mine:

How does a road going seat fit to this? In a race car (all I'm really familiar with), you sit on the floor of the car, so it lowers your seating position the ~3cm that you see in the above pic. Does the 5cm that you quote come from the fact that with a lowered floor you bolt the seat runners straight onto the floor, but with a "normal" floor you bolt the seat onto the chassis rails as well, thus gaining an extra 2cm?

Yes, it is that much. Ring Caterham to confirm.

Whether you then choose mount seat runners, etc, is irrelevant as to how much lower the floorpan is over the original. The choice of seat you choose to fit will obviously affect the net result. I use a moulded foam seat, where my a$$ is on the ally floorpan itself...

How does that tie in with my photo above then? The ruler clearly shows that the lowered bit is only about 30mm. I was just wondering if the seat was mounted differently, thus magnifying the effect? I'm genuinely interested, as I might be buying a road going seven soon.

[fergus]

Rob,

Hi. I can't see your photo. The firewall at work blocks it somehow. The best thing to do is to ring Caterham direct and pose the same question to them. If you took a photo of the side of the car, you'll see that the std floor is flush with the bottom of the side skins. When the lowered floorpan is fitted, the lowest point of the revised floor, is 50mm vertically below the side skins. I hope this helps?

I'm almost 6'6", but I'd guess that anyone over 5'9" would benefit, as it gets your helmet out of the airflow.

[RobM77]

fergus said:

Rob,

Hi. I can't see your photo. The firewall at work blocks it somehow. The best thing to do is to ring Caterham direct and pose the same question to them. If you took a photo of the side of the car, you'll see that the std floor is flush with the bottom of the side skins. When the lowered floorpan is fitted, the lowest point of the revised floor, is 50mm vertically below the side skins. I hope this helps?

I'm almost 6'6", but I'd guess that anyone over 5'9" would benefit, as it gets your helmet out of the airflow.

I see, thanks. I must have a custom lowered floor then. My photo shows a side view of my lowered floor with a ruler next to it. The distance between the sideskin/original floor and the base of my lowered floor is clearly about 30mm.