KnifeySpoony

My 420R on roller barrel throttle bodies has developed an issue. When the car is hot, ie only after driving for 20-30min, well after the engine is up to temp, I'm getting hesitation at partial throttle - basically from 0-5% throttle, tip in feels normal, however it's like from 5-20% throttle, no fuel is being added, and the car hesitates severely/will not accelerate at all. If I keep gradually opening the throttle, once its gets past about 20% or so, then it's like it catches, I get a surge, then the rest of the throttle travel is normal. Car pulls hard and smooth to redline at larger throttle openings. When I get the hesitation, it's interesting in that if I keep the throttle depressed at that position, and press in the clutch, the revs do not climb at all as they normally would when the load is removed- this initially led me to believe it was a TPS issue. No popping from exhaust. No smoke that I can tell. 

I checked the TPS with easimap - idle voltage is correct, and it seems to be sweeping/responding normal with throttle. Barrels are adjusted properly. I replaced the TPS and initially thought it was solved on a long drive, but it now it's behaving the same again. Seems impossible a second TPS could fail so quick and exactly the same manner. I swapped out the sparkplugs and no change. I have read that there can be an issue with the wiring to the TPS failing, but I can't see how it would cause the behavior I'm seeing.

Any thoughts? I know that CC sells the silicone TPS setup:

https://caterhamparts.co.uk/looms/5817-tps-duratec-race-flexi-silicone.html

Were you guys on carbon or metal plates with your early failures? 

#27.  Woops yep other end of motor! 

I had a high rpm, high load misfire caused by wire failure in the coil subloom to coil #1. My theory is that the coil cover puts stress on that wire leading to failure. I think that's why cc puts that hole there, with grommet to try to give more relief for the wire, but there solution is poor. I removed the grommet, which gives additional space for the wire to have a more gently curve. I repaired the broken wire and bought a backup subloom to have to quickly swap out if necessary. 

Depends on climate and how and when you intend to use your car. Given the well-cooled oil on a street-driven 420R, a thinner oil would be reasonable I suppose. I'm running the cc-recommended Motul sport 5/50, but I have considered other options myself. Given that most of my miles are hard track miles, I've considered "upgrading" to a more racy oil like the 300V. However, given that I still drive it to the track on some cold mornings, and that my car spends a lot of time idling in the paddock trying to get heat into it, I worry about fuel dilution so I think running the thicker, wider-grade 5/50 makes sense for me. I'm still open to other options though. None of the car failures I've experienced thus far have been oil related, and I doubt they will be for some time, if ever...

Hmmm, I know that Exige/Evora with remote front mounted oil coolers leave a LOT of oil the system during an oil change, and those cars aren't blowing up willy nilly. Any oil change is just another serial dilution, but of course the more you get out, the better. 

CC doesn't market it is a rccr for the road. I'm saying that it is closer to one than most other cars marketed as such. Unfortunately, it's up to potential buyers to understand what they're getting. Many 420R buyers would probably be better off with a 360S.

My point is that the 420r, with regards to its cooling, really is a "race car for the road", and not just a marketing fantasy like 99% of other cars labeled as such. Many people think they want that but actually don't. Get a rosd car for the road. For a 2.0 duratec 7, that means a wet sump car with modine cooler. Which cc also offers. 

I think there may have been some logic. One thing to consider is that the oil coolers on the 420R racecars  (run in the now titled 7 UK championship) look similar but actually are larger then those in the road-going counterparts. So apparently they decided that those cars needed even more cooling. They also modified to nosecone to allow for additional airflow. This suggests to me that cc has made some attempt to make these cars able to cope with the maximum heat demands that could likely be placed on them. Of course, that means they become less suitable as dual purpose machines. But real racecars don't have oil thermostats afaik. They are properly warmed up, then run hard. Which seems how the 420r is intended to be used. 

My kit was missing one so i bought a 2" grommet on Amazon. Fit perfect. 

 https://a.co/d/i2C4hIj

From my research an inline Tstat will only bump oil temps up marginally. I guess any improvement is improvement, but it wasn't worth the hassle for me. 

Put in the amount that you took out, then check the level- simple as that. Top up as needed. Re: oil burning - my car (also a 2.0 duratec) is primarily track driven and burns/blows-by very little oil. I typically top up maybe 100ml every track day. Next time, check your oil level prior to changing it so you know where you're starting imo. 

The 420R has racecar cooling. ie it has enough oil cooling to keep oil from overheating while driven flat-out in a draft, with poor airflow to the coolers. In any other situation (yes even on hot trackdays), it is overcooled in my experience. It's awesome that Caterham have built such a race-ready machine with dry sump and cooler, but it's not really ideal for a dual purpose car. A water/oil cooler would have been better for 99% of buyers. In an ideal world, they could supply either cooling setup as an option. Although to be honest, I would have still chosen the current setup, as my car is primarily driven on track, and even here in Northern California, 90-100F (~32-38C) trackdays are common. I still drive my car to/from the track which makes me cringe at the temps sometimes. I have found that cruising on the freeway at 70mph, with ambient temps around 4C (which sounds like you were in today), even with my cooler blocked, my digital oil temp shows 41C in the tank!

On my recently built 420R, I put in a Spa designs dual digital gauge that displays both water and oil temps. Very convenient. The factory location for oil temp sender is in the tank, which is the coldest place in the circuit. Be ready to see some scary-low oil temps. Many advocate tapping the sump but I haven't gotten around to it.

Velcro if carpet, double sided tape if not. That would be my vote.

Yes, it feeds from the bottom of the tank. I have read about some people having issues with oil siphoning back into the sump when sitting, but I haven't seen that issue. At least, if I look in the tank after the car has been sitting a while, there is still a fair bit of oil in the tank. No issues on cold start.

I didn't notice that the radiator was being twisted on its mounts, and it was free to move on the rubber bobbins. I am running Zerex G-05. 

The radiator on my 420R developed a tiny pinhole leak in the upper/LH side corner, which apparently is a common failing point from my reading here. Car has about 3k miles on it, mostly track. I have read the theories about excessive vibration transmitted from engine and/or uneven mounting points putting stress on the radiator. I ordered a new standalone radiator from CC. They list only the combined water and oil radiators for the 420 road model:

https://caterhamparts.co.uk/radiators/7114-radiator-and-oil-cooler-seven-420-road-model.html

However, you can get the water rad alone. It says its for the 420 race model only, but mounts up just fine. You just don't need the two little upper drop brackets anymore:

https://caterhamparts.co.uk/radiators/5755-radiator-only-420-race.html

I put on the new rad, and copied the idea of a user here to try to reduce transmitted vibration by replacing the distal segment of the top coolant hose with the 620R top coolant hose: (https://caterhamparts.co.uk/hoses/5758-cooling-hose-top-seven-620.html). The hose isn't perfectly shaped, but it's pretty close. Side benefit is that the hose is flexible enough that I can now pull it out of the way enough to pull out the oil catch bottle to drain it, and will no longer need to suck it out.

DO NOT remove the other bolt/plug on the side. You will grenade your transmission - you will need to pull the box and have it reassembled.

The turret oil doesn't need frequent refreshing. It is separate from the main fluid and doesn't degrade rapidly. I think most only do it when rebuilding the transmission.

Calls for bIue loctite too. 

CC sells the uprated race-style rear rotors and 2 pot calipers. This sacrifices the handbrake, so you would need to find a solution for that if you needed one.

I'd just plan to replace them frequently - it's just a function of the solid disc and heat. Going to the vented rears will make your pads (and rotors) last forever apparently.

According to Mazda - either GL4 or GL5 fluids are specified.

https://www.mazdausa.com/siteassets/pdf/owners-optimized/2000/mx5-miata/2000-mx-5-miata-owners-manual.pdf

No need to suck out - there's a drain plug on the bottom. Most of the noise you're hearing is the diff, not the trans, so fluid won't change anything there. One of the local spec miata gurus here in California who has rebuilt countless MX5 transmissions swears by Swepco 201 for syncro life, so that's what I'm using. It's a dino oil so needs more frequent changes presumably. I'm ok with that.

Keep in mind those dyno pics are from US owners - in the US, dyno sheets are pretty much always given with uncorrected WHP/WTQ numbers. I notice UK dyno shops tend to show corrected numbers, from my time here.