KnifeySpoony

I and some others have changed out the top (super rigid hard rubber) rad hose for the much more flexible silicone hose from the 620R, which is available from Caterham parts. You just need a coupler, very easy install. Too soon to report on effectiveness but no issues yet on my second rad. And btw, your can get a new water rad alone from Caterham parts (ie without oil cooler) if desired.

I have a "race" nosecone which allows more airflow to the oil cooler, although i block the lower opening on cool mornings. I suppose it could still cool more than the standard nose though. Blocking it bumps temps up about 5C on the freeway vs having it open. The highest I've ever seen on track is about 83C.

I can tell you that on my 420R driving to the track on cool fall mornings (in California) - steady state on freeway at 70mph, I'm seeing as low as 41C in the tank. Yep.

The delta between oil temp in tank vs sump will change a lot actually. It will certainly vary with the delta between oil temp in the cooler vs ambient temp, as well as airflow.

Apparently de-aerated oil is easier to measure the temperature of accurately which is one reason that most dry-sump systems have the temp probe near the bottom of the oil tank. It would be nice to have another sensor in the sump to see the oil at its hottest I suppose.

There's already a bung on your dry sump tank ready to accept a temp sender. On my 420R I got a dual temp gauge (oil/water). It came with senders for both oil and water. Just put one into the dry sump tank, and the other replaced the the sender in the "submarine" for water temp. Very simple install. The oil in the tank is the coldest in the system, as the cooler is before the tank, and the oil cools further within the tank, so be ready for some scary low oil temps...

I have a newer 420R and I use the same method as you and get about 6.4L out during a change. Just for another data point. But I'm not sure if my sump design is any different.

I mean, a second+ is a lot when you are at a plateau and chasing tenths. Depends what your goals are.

ZZR about a second quicker in my experience. In terms of durability, the ZZR surprisingly don't seem to wear much quicker. The ZZS developed "chunking" on the edge of tread blocks up front, while the ZZR are not at all so the ZZR holding up better up front actually. ZZS is definitely no slouch on track though, I was surprised how well it performed.

Re: Top radiator hose - I followed in the footsteps of a member here and fitted the top hose from a 620R to my 420R. It replaces just the forward section of the standard stiff hose - I just got a coupler and swapped it in. It's been working well so far. My first rad started leaking after less than 3k miles. I didn't have any bleeding issues and the flexibility of the hose lets me take out my oil catch bottle to empty it instead of having to suction it out.

I mean on current model cars. I think all the superlight series cars came with watts.

AFAIK only the 420R race cars and the 620R come with watts linkage. Maybe the new 420cup does too. My 420R has watts linkage installed from new so I've never experienced the radius arms. Car seems plennnnty lively for me with the watts on - wouldn't want it anymore so.

I have found burping my 420R very simple and quick. Basically just fill into the header tank with the bleed screw open with the car running and the front elevated slightly on stands. Once the coolant comes blasting out of the bleed hole, it's done.

Interesting, I never would have guessed. Is it easy to tell by looking? would it automatically require replacement?

I just a bubble level on the bridge and it is level/parallel with the lower front horizontal chassis tube. So it seems it's not actually bent. Maybe control arm chassis mount? I really wish something simple just broke, then I could replace and move on. It being a mystery is unpleasant...

Do you mean the lower steering column itself has twisted? That seems odd based on where the forces are acting. I'm hearing from other sources as well that the bridge shifting/bending is a common situation and acts as a "fuse" in the system. If mine is only shifted a couple mm, it seems within acceptable tolerance to just realign and move on with my life? This all assuming the welds are ok? Or is that foolishly optimistic...

Wishbone is straight. I can put a straight edge on it to confirm. Any thoughts on a bent steering bridge? How to confirm and how to repair?

Measured steering arms to discs - equidistant both sides. The rack does not appear to have slid within the mounts - at least I don't see any marks on the rack to indicate this. However we're talking just ~1.5mm of shift based on the amount of tie rod turns needed to make the car track straight. Looking at the steering rack "bridge" - the welds look ok, no obvious cracks. If it has bent, what is the solution? Just adjust the tie rods and go on with my day? I also noticed that the right lower wishbone appears to have flexed back enough to hit the paintwork during the hit to the right front tire. Is there any chance this could have bent the lower control arm bolt? It's not currently fouling, there looks to be a small gap. I never noticed the scratch before - I supposed it's possible it was there before. Pic below-

Oh also, eyeballing the distance between track rod end and brake disc on each side, I don't see an obvious difference, but I need to take wheels off and measure I guess.

I was involved in an incident at Sonoma yesterday, sustained some light damage to my left front wheel/wing. Video of incident and pics below. After the incident while driving back to the paddock, the steering wheel was turned slightly to the left (maybe 10 degrees?) to travel in a straight line. Looking at the front suspension after the incident, there was no play in the wheel/hub. Everything seemed tight. I don't see anything obviously bent. Steering arms looks straight, but there is a slightly shiny area on the front left arm (tried to photograph it). I don't know if this is just an irregular area in the casting, or if it is evidence of bent/stretched metal there. You can see from the video that the right front was hit as well, but only on the inside of the tire sidewall. Before driving home from the track, I adjusted the toe on the left front (just by feel, testing by driving up/down the paddock) until the car tracked straight. I had to turn the tie rod about 1.5 turns (pushing the steering arm outward (pushing the toe out on the left front, which I figured was necessary given the prior steering wheel position). Today I checked the toe with the steering wheel straight and there is 1/2" (12mm) of toe out. Previously the car was set for zero toe. So I'm not sure what exactly was bent, or what I should replace. Should I just realign it and run as is? Or do I need to replace the steering arm(s)? Anything else that could've been damaged? The steering seems smooth but could the rack be damaged? There was a slight shimmy in the wheel at freeway speeds on the way home, speed dependent, felt like a tire slightly out of balance. The wheel itself is scuffed but looks straight though might not be. Or it could just be tires flat spotted. Thanks!

I think React IS SRF...

Can't help but i can say that those rearward bolts on my 2021 build car needs tightening after every trackday. Every other fastener on the car has stayed tight. Not sure why but it seems common for them to loosen.

Yeah that's just rubber pickup. Ie someone else's rubber, not yours.

Plenum or roller barrels? If rollers, I'd guess TPS Idle voltage is low. I've had mine creep down for some reason.

Not spring loaded. Just a freely turning pot.