Smithy77

Tazio, I've just bought the Longacre kit which comes with a 15-50 psi OP warning switch. I would also like to add a belt warning switch wired up to the same warning lamp as a "belt and braces" measure, if it proves to be relatively simple. I have the Titan/Caterham DS set up with a single scavenge pump and OEM pressure pump, so if the scavenge pump/belt lets go I will have a few seconds in which oil pressure will remain good as the oil in the bell tank is used up. If I just had the low OP warning light alone, I would lose this extra "safety buffer" before the OP drops to zero. Could be the difference between a £3K bill or not.

Thanks for the replies. In answer to Jonathan/Simon, from reading the archives I kind of accepted that the belt warning system is not particularly common, nor is a proprietary kit available (I'm guessing), but I understand people have done it on their K-series Caterhams; it was the links to these solutions that were always broken in my searches. Example. So really I'm trying to reach out to anyone who has successfully done it and who can share their wisdom. Existing warning light? I don't currently have one! Although my plan is to use the warning lamp in the Lonacre kit for both warning systems. Just wire the pressure switch and belt microswitch in parallel with each other, so if EITHER switch is activated, the light will come on. So I can just upgrade the bulb within the Longacre lamp, if I understand you correctly? Simple enough. Thanks! Will give them a call

Hi all and merry Christmas etc etc. The time has come to turn attention to the Caterham for some winter jobs, one of the first for me will be fitting a warning light for both low oil pressure and also belt failure using some sort of microswitch. I've done some searching of the archives but most contain broken links. The low oil pressure warning is the easy bit; I will simply fit the Longacre kit with adjustable pressure switch here. Simply fit the T-piece between existing union on the filter housing and capillary tube for the OP gauge, then add the adjustable switch on the T and wire to the warning light on the dash. Simples. The bit that is less clear from my research is the belt failure warning set up, and as far as I can see, kits for such a warning system do not exist like with the low OP kit. 1. Does anyone have access to a how to guide/thread or shopping list for best method of doing this? 2. In terms of wiring, I'm guessing I can fit a microswitch on the pump belt wired in parallel with the low pressure switch and utilise the same warning light for both warning systems? 3. Will the red light that comes with the Longacre kit be bright enough on sunny days, or can anyone recommend a brighter alternative? Thanks

Did you try tightening the torx bolt on the back of the original door mounted mirror? It holds the ball joint to the back of the mirror. Mine used to vibrate and fold in slightly at speed, but since I tightened the torx bolt they have been rock solid and vibration free. I've read that this problem is commonly overlooked by owners and the mirrors ditched before trying this.

Ian Payne is selling one of the Facebook Marketplace group

No brainer - ZZRs!! I don't do much touring and only bring it out on dry days, so considered tyres with any additional tread pointless. If I do get caught out in the rain, I just drive like a wuss.

John Vine has a point, and it is a fact the rate of acceleration, in all gears, will be less with a 3.62 diff. The car is still new to me so I think I'm making the right decision to give it a full season/summer to evaluate and make a decision. Thanks again for the input

John Vine has a point, and it is a fact the rate of acceleration, in all gears, will be less with a 3.62 diff. The car is still new to me so I think I'm making the right decision to give it a full season/summer to evaluate and make a decision. Thanks again for the input

Well I'm glad I started this thread and thanks for all the input. It's given a good mix of perspective. I think I will hold off from making the switch this winter as I have a few other jobs that need doing - rear shocks need a service; rear chassis members need re-painting; rear pads to change; coolant circuit mods to do; low OP warning light to fit - so the diff ratio really is at the bottom of the list in terms of priority, and I could do with the extra time and money to be honest. This will also give me the chance to try different circuits next year to see how much of a problem the top speed is; if it is a problem, this can be a job for next winter Krismuss - I will PM you about French trackdays

I don't mind the frantic road manner - you can tone that down by skipping 3rd and 5th quite happily, but then use all the gears when you want to have fun - it's just the high revving cruising that I wouldn't mind toning down. The other main issue is not having enough top end for track days. Not sure how Castle Combe compares to other circuits such as Snetterton or Bedford. I don't actually have a spare diff, just a loose 3.62 CWP, so this isn't an option unfortunately. Yes. As an example, using 215/55/13 ZZRs: - Current 3.92 diff gives me 4160rpm at 70mph in 6th and at 8000rpm a top speed of 50mph in 1st, 67mph in 2nd, 85mph in 3rd, 103mph in 4th, 120mph in 5th and 136mph in 6th. - By contrast a 3.62 diff gives me 3830rpm at 70mph in 6th and at 8000rpm a top speed of 55mph in 1st, 73mph in 2nd, 92mph in 3rd, 111mph in 4th, 130mph in 5th and 147mph in 6th. Krismuss - great, I'm now having second thoughts again! I'll have to have a look into Abbeville. What's the deal with trailers?

Ian, this I am aware of, but this being the only 6 speed Caterham I have driven, I have no benchmark to compare against. I'm am just slightly concerned that the 3.62 diff with take away some of the bonkers acceleration which I love most about the car. In theory, the gaps/rev drops between gears will not change, but each gear will become higher geared/longer. I should probably just stop worrying and get on with it...

I'm on my 3rd Caterham, and with each car acquisition, I've gradually got closer to my ideal spec. Started out with an ex-megagrad with 140bhp K in Roadsport trim and race dampers, and now I have a Superlight with 230bhp K, 6-speed box, Quantums, Tillets, roadsport cage etc, and it is spot on for what I want - mixture of fast road use when warm and dry with about 6 trackdays a year. Absolutely loving it! The previous owner, however, wanted it set up for the odd bit of sprinting/hill climbing. He therefore got the LSD set up with a 3.92 CWP. As you can imagine, the acceleration is absolutely bonkers, and I do love this about the car. What this does mean though is c.4300rpm at 70mph on the motorway, and on my first (and only) trackday at Combe in October, I could hit the limiter in 6th with ease well before the end of the straight. I have acquired a 3.62 CWP with the intention of dropping the diff out over winter and taking it to Road and Race to make the swap. My worry is, will this take a noticeable edge off the bonkers acceleration which I have grown to love? As you can probably tell, I have generally not worried about making track focused compromises when it comes to car spec, but this would (or could?) represent a move in the opposite direction. I would welcome thoughts and opinions, particularly from those that have done similar, before I make the switch just to convince myself I'm doing the right thing.

I believe the TPS reset is a feature on a MEMS ECU, not MBE, which I'm guessing you have on an R400 engine. If this is something which only happens in freezing cold, and if you rule out the battery, I'd be looking at mapping or TB set up. The latter is relatively easy to do at home. The adjusters are: Centre (grub screw and hex lock nut) - balance between throttle bodies to ensure both pulling same air; Nearest head (bolt and locknut) - idle set stop; Nearest filter (bolt and locknut) - full throttle stop (to stop barrels going beyond fully open). To start with, fully open the throttle and check/set the full throttle stop and, at the same time, use the centre screw to roughly set the barrel balance. Use your finger to feel when the barrel becomes parallel in the body. When both pairs are the same that will do to start with. When closed, there should be an even 1-2mm gap across all the TBs Do you have Easimap and MBE comms? This makes adjusting the idle stop screw a bit easier, although you can still do it by measuring voltage across the TPS - the ECU map will have an idle/load site zero voltage setting for the TPS (standard I think is 0.45V, but sometimes mappers set it differently. Mine is 0.33V done by Track n Road), so before adjusting the idle stop, you want to note what the idle voltage is and then loosen and back the TPS off so it reads something lower than the idle voltage (as low as possible). This will allow you to make idle stop adjustments without tipping the ECU into the first throttle load sites. Then you can tinker with the idle stop screw 1/8 turn at a time to see if you get any improvement. Note the position of the screw before you start so you can always go back to how it was if it makes no difference or makes it worse. If you do find an idle setting which improves things, tighten the lock nut and finish off by re-adjusting the TPS so that you end up with the same idle voltage as before. If none of that makes an improvement, ask your mapper to take a look at the cold start mapping. I suspect this is the more likely cause of the two, but it's good to get to know your engine

I have a mechanical OPG fitted, and a low pressure warning light is on my winter job list. I did read that thread about scavenge pump failure, which inevitably heightened my paranoia somewhat! The pump was given the all clear during the rebuild so I wont worry about that for now. I think I'll be sending it off for a refurb next winter though.

I can't see how deleting the OEM bypass between coolant rail and OEM stat housing could cause any issues...... or could it?? (just thinking aloud)

I fitted Cibie 5.75" headlamps (c.£100 pair) and Phillips X-treme Vision +130% bulbs. The difference was, errrm, night and day!

And you had a 32mm bypass without the problem I experienced? That would suggest something else might be at play. Think I will still experiment with reducing bypass diameter as I tried clamping mine today to reduce it somewhat and it did seem to improve rad flow

Thanks, did you do any trackdays with the PRRT?

Excellent! Thank you.

So just to be clear, longer length = higher resistance to flow, and smaller radius = higher resistance to flow?

Thanks Jonathan, Link to diagram Another idea... if reducing the bypass down to 16mm should, in theory, increase bypass resistance and boost rad flow, if I was to increase the length of the 16mm bypass, would this increase bypass resistance even further?

So I've been told that this behavior after a track session is NOT normal, so there is a problem to resolve, and I'm thinking it boils down (excuse the pun) to poor rad flow at idle. Increasing the idle speed, as alluded to above, seemed to help it but maybe not enough. Before ditching the PRRT, I'm going to try reducing the bypass diameter from 32mm to 16mm in an attempt to increase rad flow. To test the theory without buying smaller hoses/reducers, and without going on track, I will first knock the idle speed back down to 900rpm. This will be in an attempt to reproduce the previous and noticeable issue of poor rad flow at idle which needed a blip of throttle to get the fan to kick in. If I can get this happening again, I will simply try clamping the bypass hose to restrict it quite a bit. If this has the effect of boosting rad flow and have the fan kicking in again, I think I'll be on to something. If anyone can reaffirm this theory as having reasonable logic, it would be appreciated.

Just to update this thread, new PRRT behaved exactly the same. Increased the idle to 1050rpm and bled a bit of air from the top of the rad and it now warms up and controls temps at idle just as you would expect.

Tell help determine 3, easiest to have a 2nd means of checking water temp to see if the gauge calibration is correct. Either connect a laptop or OBD scanner to the car, or more simply, buy a laser thermometer (<£10 on ebay) to get reasonably accurate readings on various parts of the engine, i.e. water rail and top of rad

I am starting to think perhaps the PRRT is not the ideal set-up for a track car. There is a pressure relief valve in it which controls the bypass flow, and this is the only thing which controls bypass circuit and it is modulate by pressure alone, not temp. It also has 4 small holes in it so even when closed there will still be bypass flow. As pressure is exerted through the bypass, it pushes open the bypass valve. The thermostat part of the PRRT controls only the rad circuit. The theory is, as the stat moves from closed to open, resistance of the rad circuit is reduced and flow increases, thus relieving pressure and closing off the bypass to an extent and regulating the pressure between the two circuits. That's my understanding of it anyway. However, the "problem" I can see with this is that the rad, by its design and construction, is inherently high resistance is it not? Compared to the resistance of a 32mm bypass and a relatively weak pressure relief valve I would have thought. So even when the stat is fully open, the rad might provide so much resistance still that the bypass valve is still wide open. Would love anyone with a greater understanding than me to share their thoughts on this....