ChrisC

Gong to say, I don't trust the fuse layout in the owners manual. Just checked the 620 chassis loom diagram, showed fuse F, Instruments D.C.M, 20A.

News to me 620(s) have WL Every days a school day.

The extra bracing is to support the diff and prevent the diff mounts breaking loose. The dampers and springs are different, but the trailing arm / dedion tube are the same. Neither the 420 or the 620 use Watts links. Is the jiggle under acceleration, or coasting, i.e. is it a power deliver observation? Assuming all the geometry is equal, and thats a big assumption. I suspect the tyre to be the biggest difference, ZZS to ZZR is apparently a bit performance jump, especially in the softer compounds now available. Obviously owning both a simple wheel swap could rule that out. Beyond that spring rates then dampers, although there are those who complain about the spring rates used on the 620. The one thing that might be worth checking is your race nylon washers on the A frame, they don't last long, I think 2 years is about maximum, and that depends on use.

Couple of things to note, the bracket looks to have been bent to locate that rubber mount bolt, and the gap to the radiator and that bolt head looks increased. I think you have to be very careful fitting the new 420 design rad. I purchased slim spanners to hold that bolt while tightening. Did that have any effect on your rads life, I don't know, but if you ever hold the rad while the engine is running there is a lot of vibration and those rubber mounts have to earn their keep. The new design also has much smaller rubber mounts, so they are also under increased stress.

Andy, consider using RRT oil, once you've had your rebuild. It also helps with noise.

My 360R 6speed was bad out the box, it lasted 1000 miles before the fault was diagnosed, but was run a few 100 miles beyond that before a rebuild. 3rd gear had caused the problem, resulting in 3rd, 4th and all synchros being replaced.

If you have a wind back tool, just replace the seals and piston yourself. Simple job, just a little fiddly getting the dust seal back in place when refitting the piston.

Its the plastic sleeve in the steering column bush. It's just a push fit, but be careful not to push it all the way through, or you will have to remove the metal / rubber element of the bush to extract it. Have a look here, about 1/2 way down the page https://caterham420detailedbuildblog.co.uk/2020/01/29/steering-column/ Thought it looked broken to begin with, but looks ok on closer inspection.

Just a finger on my 2019 supplied kit. Press and release (assuming you have released the pressure first)

Four Dzus fasteners, Two at the top, two at the bottom. You can open them with a coin, or large flat blade screwdriver (best is a Dzus driver if you want to push the boat out) You might want to watch Caterhams instruction video

In this case I would also check for air locks, because there maybe a hotspot until the stat opens.

I think it's a general car industry thing, I.e it's not important, unless it's too hot or too cold, nobody cares if the coolant is 90 or 91c. I suspect that's the reason why the gauge isn't calibrated, and then combine that with the two sensors you have enough reason for the inaccuracies, and no real desire to resolve it (always bigger fish to fry).

So you have two temperature sensors for coolant on a Duratec. On for the gauge and the other for the ECU. The gauge is a bit of an afterthought, and the wiring is easy to damage, it's also easy to have a poor earth connection to the sensor causing interesting gauge readings. The sensor in a metal hose (called the submarine hose), at the back of the engine. It's worth disconnecting the wires and checking the resistance to test the sensor. The submarine looks like this https://caterhamparts.co.uk/other/1624-cooling-submarine-temperature-sender-csr-race.html?search_query=Subm+&results=5 If I had strange gauge behaviour, this is where I would start. Beyond that typical continuity checks to the gauge, replace the sensor (it cheaper than a gauge) then try swapping the gauge. Oh and the gauge isn't accurate to the ECU coolant temperature at anything but one temperature in my car, it's reads low to begin with, and high at the other end of the scale.

It's fine, the lights themselves are just LEDs and I doubt you could get enough water in the shift light to cause a problem. The control box is safe under the dash. I never had a problem with my 2011 150, which had the same setup.

DPR do a special stanchion mount for SPA mirrors. Very neat and very very stable solution. No drilling of the stanchion required. Only down side is you can't open the doors fully. I had problems with the "Eccles" mounts, they pressed into the side screen. I suspect my frame inside the door isn't flat, and the hinge redesign (2017 ish) also hasn't helped.

That's one tight gauge :-)

The only week point in the Sigma/Duratec oil pressure sensor is the resistor and diode in the subloom between the sensor and the chassis loom. Always check this before you replace the sensor. I also find Caterham strap the gauge wiring very tightly behind the gauges, I always wondered if this was the reason for the case failure. I can't think of any other reason it would happen.

Flat spot or hesitation? Hesitation is known on stock cars, it can be minimised with TPS fine tuning. I understand from fellow owners the RBTB in stock form have a flat spot around 2500 rpm, but I have never driven a 420R with RBTB so can't comment on that. The owner I was speaking to had a custom map to resolve the issue.

The resistor remains with the new sensor. Have to say that's one area of the current design I still don't like (that and the position of the sensor). Apart from that it's nice to have a speedo that just does what a speedo should do.

I had problems with the speed sensor during my first kits IVA. It wouldn't read speeds above 50mph. Ultimately it was the reason for a fail, but I was given time to adjust it three times during the test. I think there are a number of factors that are at play. The first is CC selection of the sensor itself, the speedo is wired for a PNP sensor, but the sensor NPN. This is why there is a resistor in the speed sensor circuit. I can't remember if its NPN and should be PNP, or PNP and should be NPN, but either way the sensor isn't how the speedo is configured. The resistor get hot when then the sensor is off, meaning every time you stop and you have the ignition on you have a hot resistor under the dashboard. I also feel this sensor is more industrial use, not automotive, i.e. its not like any ABS sensor I have seen on any product car. The sensor location, I can never understand why the sensor is located on the outboard tripod joint, when it could be been located on the inboard joint, where it would have had more protection and the wiring would have been more static. Obviously wiring damage due to fatigue wasn't my cars IVA problem, given all the components where new. Signal interference. After my IVA fail, I wanted to be 100% sure I didn't waste my time during the retest, so I investigated the signal quality from the speed sensor only to find interference on the speed signal coming from the ECU. I suspect this is why CC choose to use the reverse NPN/PNP sensor as far a the speedo is concerned, so they can also feed the ECU. However speed isn't used by the 992 MBE ECU fitted to an Oct 2015 supplied 360R kit. I was able to clean the signal by isolating the speed sensor connection from the ECU connector, but this ultimately didn't result in any speedo improvement, so I reinstated it. Earth mod, improved signal quality, and was my ultimately my solution to the IVA problems, but the signal was never "clean". At that stage working was all I was looking for. The IVA test is only up to 70mph, so it passed, but my cars speedo would always read 0 at speeds above 105mph. This is a common problem, you can see it so many times on YouTube track day videos of cars of that age. Fast forward a year, and in 2017 at a track day my speedo started to get worse, and then stopped all together. The reason was obvious after the session, the speed sensor had come loose and was dangling on the floor. Obviously I hadn't included the speed sensor in my spanner checks, and given it's state I hardly felt a warranty claim was valid, so I purchased a "new" style speed sensor. All I can say there is a obvious improvement it the quality of the speed reading (as stated above). My observation about signal quality and wiring design may no difference to the new sensor, and I understand CC no longer recommend the earth mod. There must be a spec change between the new sensor and the old sensor, and this is the reason for the improvement, and therefore the old sensor is working close to it limits hence all the problems.

You are 100% correct, the new sensor (cheaper than the old) is some how not Caterhamish, unlike the original electronic sensor. It works regardless of speed and temperature, gives a consistent reading just like every other product car. Obviously the introduction of this more reliable speed sensor also coincided with a new problem where the trigger wheel moved on the drive shaft, so the balance in the universe was restored and Caterham would once again have unreliable speed readings. Fingers crossed my 2019 kit supplied car hasn't suffered this. Oh and the new sensor likes to be a lot closer to the trigger wheel.

You can buy the joint on its own much cheaper, £6 from CC, but others can also supply if you want to hunt a cheaper price. I would advise against using the softest setting, there has been reports of damage to CV joints and scraping on the ground, using that setting on this forum, but that does seem to depend on the age and design of your rear ARB. Later cars no longer have the stand off fitted, but I am not sure if this is the cause of these soft setting problems.

So it's only 2 way configuration?

Can anyone confirm the configuration of the Tracsport? From the internal photos I have seen it look to be a 1.5 way or 2 way setup in comparison to the Titan 1 way.

A stock 420r must record under 98db static or it won't pass IVA. Static isn't generally the problem. I am more worried about drive by, and that has a load of factors from microphone position, gear used etc etc. I believe a 420R can cause problems at brands for example.