7 Minder

Thanks all, great day and the car performed faultlessly, wish I could say the same about the driver! Did about 110 track miles plus another 55 getting to/from the track and lunchtime refuelling. Used about 40 litres so around 18 mpg overall. Excellent organisation and briefings and it felt a very safe environment for a novice. Would highly recommend.

Thanks James.

Thanks all. Jonathan, I've read the info on the club website 'Trackdays' section but any additional info would be appreciated.

I'm in the Novice group at the Club's Castle Combe track day tomorrow. Car is a 420R spec SV. I appreciate it's a bit of a "how long is a piece of string" question but can anyone suggest how much fuel I'll probably need for the track sessions? Thanks.

Thanks all. I was wondering if the ECU might store any temporary settings as the car was fine yesterday after driving away immediately after start up, even when properly warmed up. But a few days before it was almost undriveable. Wedging my foot against the side of the footwell helps marginally. TPS is worth looking at again. I set it up meticulously last year with Easimap but another issue I occasionally have which I think might be TPS related is the idle sticking around 1800 rpm. Is it a standard Ford TPS?

Our 420R spec car running RBTBs and an MBE 992 locked ECU is prone to part throttle kangarooing. I've only run the car a few times this year (all in the last couple of weeks or so) and sometimes it's really bad and other times virtually non-existent. At least a couple of the recent runs have been after starting the car and letting it warm up at idle before driving. Yesterday I drove away immediately after starting and it was hugely improved. Pops and bangs on the overrun were much reduced too. I'm wondering if the ECU does anything different in the idling warm up vs drive away scenarios that might account for the difference?

It was the Mann W77 that I had bought but it is 4-5mm taller than the Fram. I would have had to remove the filter housing from the block to get the Mann fitted but I would then only have about 2mm clearance between filter and tank and I'd be concerned any chassis/engine movement would have brought them into contact.

Just to add my own recent experience. Our car has a one-off custom dry sump oil tank, mounted to the left rear side of the engine (Duratec). The clearance between the oil filter and oil tank is extremely tight, to the extent that the replacement Mann W77 filter I initially bought to replace the existing Fram PH2874 would not fit as it was 4-5mm taller. Even getting the Fram out required unbolting the oil tank and moving it as far as possible from its secured position (maybe 8-10mm) and then applying a little leverage to open the gap another couple of mm. There is about 6.5mm of clearance when the Fram was installed and although close, no signs of any contact between filter and tank. It appears the Fram filter is no longer supplied by Caterham and none of their dealers or aftermarket specialists I called had any left in stock, nor the usual ECP/GSF and local motor factors. I spent several hours scouring the internet trying to find alternatives from James' list with similar height to the Fram but found lots of conflicting dimensions for the same items on different websites. I ended up buying 5 (!) filters from a marine chandlers advertised as Fram PH2874. On arrival it turns out one is a Bosch 0 451 103 141 (labeled as P3141 on the box), one was a Fram PH2874 and three were Coopers/Fiaam FT4763 (all these are included in James' list). All including the Bosch appear virtually physically identical (approx 55mm tall), apart from branding and markings. The Fram and Coopers/Fiaam are evidently part of the same Sogefi group. I fitted the Bosch and will keep the others as long term fall backs but maybe this info might be useful if anyone else has the same space constraint.

One of the front Bilstein dampers is leaking on our car so I've removed both fronts ready to send off for rebuild. However I've just discovered that the springs and dampers are different specs front and rear so need advice on how to proceed. The fronts are Caterham part number 74501AW - "Front Spring/Damper Track M1 Specification". These have the 77843 - "Spring Front Race 250LB Race" springs. The rears are 75531A - "Damper and Spring Rear De Dion 2003". These have 71198 - "Spring Rear Progressive Rate Standard Spec" springs. The fronts are adjustable height but the rears are fixed. The car is originally a 2003 kit built SV which has been rebuilt to 420R spec. I'm assuming this suspension combination is not recommended (unless anyone knows better) so it seems the choice is to change the front units to road spec to match the rears (so presumably 75530AWS or 38F020A on the Caterham parts website) or upgrade the rears to match the fronts (74502AR - Track M1 Spec). Or maybe change the lot for something other than the Bilsteins. Road use only so far but some track days planned, starting at Castle Combe in just over a month. The fronts are pretty harsh on the road but I don't know how the standard road setup would be on track? Finally, it needs aligning. The original owner used the car pretty much exclusively for sprints and hill climbs apparently and I can visually see there is noticeable toe-out. Can anyone recommend settings that would be ok for road and track day use running 6/8" Apollos with ZZS tyres. Many thanks.

Hi David, yes, that's the connector style on our car. The male connector was fitted to the car loom so female connector required to attach the 12V socket.

Just to update this thread, following a closer look, it turns out fuse J in our car feeds power to a purple/red wire. This is the wire colour shown in the wiring diagram for Ford Sigma variant cars for the 12V power socket. The original owner told me he fitted a new 420 loom when he rebuilt the car so I don't know why it doesn't have the purple/green wire that the 420 apparently has for the 12V power supply . I also found the 12V socket supply cable and male T connector tie-wrapped to the nearside wiper drive above the fuse panel so it should be easy to connect up the 12V power socket once I get a female T connector for it. I did lift the tunnel cover in search of the 12V socket cable but found there was a horizontally mounted aluminium plate riveted to the chassis rails from just behind the handbrake all the way back to the rear bulkhead. Not sure if this is standard?

Jonathan, I'd prefer it under the dash and yes I do have a multimeter. I'm only intending to use it to power a tyre inflater and charging phones and I'm happy connecting my conditioner directly to the battery. David and Nigel, thanks for the tip on location of the 12V power cable, I'll check it out. The original owner apparently installed the 420 loom and fuse box when he rebuilt the car and replaced the 2.3 Cosworth motor and sequential box from his original kit build in 2004 with a new 2.0 Duratec and Caterham 6 speed box. So it's not an original factory spec 420 and therefore an ongoing process of working out what's actually what with the car. Although it apparently has a 420 fuse/relay box and the fuse designations mostly match the 420 info in the 2023 Owners handbook on the Caterham website, it doesn't have the cover that factory 420s have to mount the socket/s on. But I only need a single socket (nice as the Amazon kit looks!) so I'm sure I can find somewhere else to mount it.

Thanks for the replies, very helpful. I'm happy with a plain old cigar lighter socket and would prefer it to be switched live so finding the 12V power supply (if it has one) would be ideal. The car has a battery isolator switch but I can't work out from wiring diagram whether the 12V power supply is switched purely by the isolator or via the ignition switch?

I'm looking to fit a 12V socket to our car which was rebuilt to 420R spec around 2014/15 and apparently had a new 420R wiring loom and fuse box suitable for the existing Stack dash setup fitted. The wiring diagram in Figure 215 in the Master Caterham 2015 Assembly Guide (420 main harness with Stack dash) appears to show wiring provision for a 12V power supply in the rear boot area, with wire designations B14 and PG53 powered from fuse O (10A), the bottom fuse on the board, connected to wires PG53 and N52. I assume PG is Purple/Green but don't know what colour N is? I can't find the 12V power cable/connector in the boot of our car. Also, the fuse box layout in our car appears to match the fuse layouts listed in the 2023 Caterham owners handbook for the 420 with the 12V power supply fuse in position J rather than O. Our car has an aftermarket 15A fuse fitted in lieu of the 10A fuse listed in the owners handbook in position J. This fuse is connected to one brown and one purple wire. Can anyone advise where I might find the 12V power supply wiring and connector? I assume I should be looking for a cable tail with one brown and one purple wire and a two pin connector. Also, is there another 420 wiring diagram available with the fuse panel layout matching that in the 2023 owners handbook? Thanks!

Jonathan, the tyres are ZZS 185/55 F & 215/55 R. My Stack dash internal battery needs replacing so its internal settings have defaulted to factory. The wheel circumference default setting is 1650mm but a rough measurement suggests the rears are around 1730mm which I think would cause the speedo to over-read by around 5%. So at a true 70 MPH, the revs will be around 3800 RPM, which is consistent with ScottR400D's car. The car was originally built from a 2003 supplied SV kit with a 2.3 Duratec motor and 6 speed sequential box. I have most of the original Caterham sales invoices, one of which mentions the 3.62 diff. But the car was re-built to a lower spec (now 420R spec) by the original owner around 2014 and I know he changed the motor and gearbox. Messaging him recently, he thinks it has the ZF diff but he has built lots of these cars and can't really remember all the details for our car. The diff is really noisy, making clicking/clacking sounds with the slightest steering lock is applied, even when pushing it around my garage, and is especially noticeable at very low speeds. But in a straight line, it's quiet, so I'm assuming it's the difference in rear wheel speeds with lock applied that's causing the noise. At higher speeds, even in tighter turns, I can't hear the diff.