Farreaster

A quick rack will also feel heavier than a slower one

Sigma is better as exhaust comes out on drivers side. If I had a K series and SWMBO burnt her leg getting in she would never want to be a passenger again.....and only want to drive it

Are you topping it up every time it drops, if so it could be that once it finds it's natural level, it will cease to drop. The rationale being that expansion tanks are just that, there should be enough empy space in the tank when cold to allow for the expansion of the coolant when hot. If there isn't then the some will be blown off and the level when cold again will obviously drop.

The "jerkyness in slow moving traffic" described by Richard and the "hair throttle in stop start traffic" by Scoops appears to be a common problem with this map. Certainly going to the larger dia. throttle quadrant helps but the basic issue remains. With regard to my car I have a steady tickover at about 900 rpm, if I very delicately (in neutral) increase the throttle opening the revs initially fall to a lumpy 750 rpm before rising to higher rpm's. In other words there is a flat spot just off tickover, it is probable that this lack of proportionality is giving rise to the symptoms described by Richard and Scoops. Could I ask that other sigma 150 owners try this simple test, if it is a common feature it may well be worthwhile approaching Caterham for remap

Thanks Rik, The 1st photo is the old quadrant in situ, the 2nd both old & new side by side and the 3rd the new quadrant in situ. In the 2nd photo the difference in diameter is obvious, an increase from 18.5 mm to 31.5 mm. This should be easily apparent when comparing the 1st and 3rd photos. The quadrant is located in between the 2 pairs of throttle bodies and is mounted on the spindle of the rear pair. Because the TB's are so close the quadrant cannot be replaced without removing both TB's, took about 2 hours total. Malcolm

Now fitted the throttle quadrant. Caterham supplied 2 components, the throttle quadrant that is fitted to the spindle of the rear pair of TB's and the "drive" quadrant that fits to the front pair. The drive quadrant supplied appears identical to the one already on the car and, therefore, not needed. My advice to anybody thinking of this upgrade would be to only get the throttle quadrant and save about 25 quid. I measured the radius of the old one - 18.5 mm against 31.5 mm, meaning about 40% increase in pedal travel. The TB's were quite sooted up, probably as a result of the spitting back on the old map, and sticking as a result - cleaned them up Car now drives much better, I can tootle along at 30 mph in 5th and accelerate fairly smoothly from that point, not much fun but it can do it...... It will still kangeroo, together with transmision shunt, coming off a trailing throttle (even though I have now fitted an additional throttle spring in the pedal box) at about 2,000/3,000 rpm in the lower gears. I have noticed that in neutral there is a solid idle at about 900 rpm but as soon as I touch the throttle pedal and the butterflies start opening rpm drops to a lumpy 750, this may be a casual factor. This could be a map issue as it switches from the idle air bypass or it could be that I need to improve my balancing/setup skills....

I have just received the upgraded throttle quadrant components (if somebody can tell me how I will post a photo). The quadrant has a fixed radius of 31.5 mm, I haven't been able to measure the old one yet as it is still on the car but it looks about 25 mm. This should increase throttle pedal travel by about 20% and reduce sensitivity by a similar amount throughout the travel. Somewhat disappointed that it hasn't been designed with a decreasing radius to aid progression and to this end I have just contacted Jenvey in an attempt to find one that does this. I will report back as to how it performs once it's on the car

Brian et al, I've spoken to James and sent him pictures of my throttle quadrant - it seems I have the old one. Just ordered the new quadrants (2 parts - £50 , not cheap). I will report back to this topic once I have received and fitted

Or do it yourself, post the ECU to Caterham for the remap, when it returns reset the TPS and disconnect the MAP. Only took me about 20 mins and I'd never done it before

I'm driving my sigma 150, with an alum/plastic sandwich radiator, around here in an ambient of about 35 deg. C. No overheating problems with the car, only me. The breeze when moving keeps you cool but stopped in a traffic jam and you bake - have an umbrella in the car for those situations.

When I worked on engine design, which was a long time ago, the design convention was to ensure 1D thread engagement for ferrous materials and 2.5D for aluminium. Follow this practise and you won't need to use helicoils unless the thread becomes damaged (wear, cross threading etc.)

Brian, No I don't have the throttle quadrant. I will ask them, did you get it from Caterham South or Midlands ? Thanks Malcolm

Much, much better. Starts and warms up from cold without stuttering (mind you the ambient here is 35 deg C......) Solid tick over at 900 rpm Throttle blips are much more responsive (when double declutching, etc.) - doesn’t "bog" Steady state cruising at low rpm and small throttle openings smooth, with no hunting No popping/banging or spitting back through the throttle bodies Lots of progressive power at high rpm and large throttle openings Only one significant issue remains, that being the transition from a trailing to an open throttle. It is abrupt and almost like throwing a switch, somewhat reminiscent of a sticking throttle cable (although I don't think it is). Makes feeding the throttle on through a corner difficult to perform smoothly and could be a problem when the road surface is slippy. The Caterham throttle pedal arrangement exacerbates this as the geometry is such that initial movement of the throttle pedal results in a relatively large deflection of the butterflies and the final pedal movement a much smaller butterfly deflection. Should be the other way round….. Still very pleased though Now I’ve got to go and clean the house Malcolm

Just arrived back in Spain with my remapped ECU, most anxious to get it on the car. Problem is SWMBO gets back Monday after a 3 week visit to her family and the house needs cleaning up or I'll be in the dog house for the next month. The dilema.....what should take priority ? Please advise

I don't know Caterham racks in particular very well but I do know steering gears, in general, well. The large nuts on on each end of the steering rack are the inner ball joints (IBJ), they are often retained by locking tab washers, by peening the IBJ housing into a slot in the rack, by loctite or similar or simple by accurate torquing. In your case what does the "lock" look like ? If you intend to remove the IBJ's (& you must if you are going to remove the rack from the housing) be very careful that you support the rack itself properly (not the housing) - fail to do this and you will end up with a bent pinion. Proberbly the best way is to put a large open ended spanner over the rack at the teeth flats and undo against this.