CtrMint

I'm probably best going with the original unless I can find someone that knows the exact dimensions, don't forget my radiator has the integrated oil cooler at the bottom. At the moment I can't even find my part code with Caterham, never mind a 3rd party.

I've got a mate coming tomorrow morning with radiator test kit, we're going to test it, though I'm pretty confident it's failed. The photograph doesn't show the staining which is on the very top vane. I also wash it down the with a hose, and then watched the system re-pressurize, I can't see anything from the hose. As for coolant loss. Yes and No. I added a tiny amount to the expansion tank during my work, not that it really needed it or that I thought it was low. it was maybe 2mm below the max line, I just aligned it being very precise. If I wasn't coming over for the Taffia, and driving +500miles in the UK I'd just monitor it, but I don't want to risk being stranded or cooking the engine should it get worse.

Does Radtec have designs for all the various radiator options Caterham has used over the years. I appreciate I only need one, but picking the right isn't easy, epecially givent the fitment issues I had during my build.

So I've been going through my 420R all weekend, all prep for the Taffia. I started at the back and worked forward. Guess what I found! I'm now in a mad rush to source another. Mine was replaced in 2019 at around 1500 miles, its now on 4600 give or take. Does anyone know the warranty period for this sort of part? Also are there any alternatives?

When I built my kit I had an absolute nightmare with the radiator. In the end I sourced replacement bobbins from the following site. They worked a treat. https://www.polymax.co.uk/anti-vibration-rubber-mount/cylindrical-vibration-bobbin-mount/ Handy datasheet here; https://www.polymax.co.uk/media/documents/AV_Mount_A.pdf

Haha, yep true 1st world problems. Though I'll still take that drink. Of course the real test would be turning up to the same track day with both cars and seeing how the driver gets on. That's never going to happen but would be an amazing comparison.

So I've been under the 420R this evening for a nut and bolt check and then out for a rip both up the mountain and on some poorly surfaced roads. I've certainly thrown the car around, way too much fun too. I do believe the rear feels much better, the sensation is gone, plus the rear feels more stable, sort of level if that makes sense. Did I find something on the check, yep I sure did. On both sides the front radius fixing wasn't to spec, it wasn't loose but no way near spec, I could tell as soon as I put a spanner on. I've had both seats out and torqued them to spec. Think the prize goes to Neil Thanks again to all.

Thanks James, and everyone else for your support. I just need to wait for CC parts to have the kit in stock.

I've still only done 900miles in my infamous 620, but even so I can tell I prefer the feeling at the rear on the 620. I wouldn't say it's about laptimes etc, I just want to make the car the best fit to my preference. It sounds like I prefer the WL. I agree the WL isn't cheap for what is some simple parts, though its cheaper than some of the suspension upgrades I've been browsing. I've rummaged out my build photos and I think I have the mounting at the rear, the boss towards the back in the image.

Would it be a reasonable statement to say upgrading the 420R to WL would be an upgrade, adding improved handling etc? If so a worthy upgrade and potential solution to my observation?

Could be the rear steer effect of having radius arms instead of Watts linkages, hitting a bump will cause that wheel to move up and forward slightly, steering a miniscule amount in the direction of the side the bump is on. Just been for a nose around both cars, and yes the 620R has the Watts linkages, the 420R doesn't. Based on the description from James I have to say it sounds like a promising hypothesis. It is something which I sense over rough tarmac, not weight transitions or acceleration etc.

Thanks Benton, I actually traded an Exige V6 Cup for my 620R. The Cup car was a totally difference experience, completely planted, but less exciting for the same reason. It's interesting you also recognize the difference between the 420R and 620R, to some degree that's good to hear, I'm not imagining it. Tyre pressures...? They are checked most times the car is driven, due to lack of use and seem fine. I can see how the radius arm might cause it. Though again, I don't feel its something loose, it's kind of like if you twanged a spring, resonance from side to side, just briefly. We're talking a feeling in the arse, rather than significant movement. If something was loose surely you get a knock and sudden drop off. This feels almost like a natural resonance.

I'll do the nut and bolt check, it's worthwhile anyway. I'm confident the packing washers are there as I built the 420R. I wonder if I need more though. Just sat here considering my reply... I wouldnt call it lateral movement, as I say its a sort of oscillation, its so difficult to describe. Like I say, only really considered less than ideal having owned the 620 which seems to have a more sophisticated ride.

My 420R only has the frontward radius arm, would need to check the 620. Is the jiggle under acceleration, or coasting, i.e. is it a power deliver observation? I can't say I've noticed it under hard acceleration, its more when you are driving in normally in say 30mph traffic and you catch a rough bit of tarmac, not a pothole, just some rough stuff. My 420R has done about 4500 miles, and hasn't been on track. do you have the geometry settings for both cars? I don't, our local specialist Paul Dangerfield did the setup on the 420 when it went on the road. To me it feels like the horizontal positioning of the dedion isn't as firm as the 620, and it can result a brief amount of low frequency resonance shocked in the right direction. Would the camber etc, cause that? Don't forget. I am being hyper sensitive here, I don't consider the behaviour an issue on the 420R, it's just that 620 behaviour feels far superior as it doesn't do it.

They're both S3, both on 13" 8" rears. 620 is on ZZR and the 420 is on ZZS. There is extra bracing in the chassis on the 620. Both are on the suspension provided with their R packs. The suspension is different, but I'm sorry I don't know much about the specs.

I thought I'd post to get some input regarding the difference in feel between my two Sevens. Hope you can follow me with this. The rear suspension on my 620R feels so much more direct and controlled/stable than the 420R, is this the difference between the chassis or suspension. My 420R doesn't feel wrong and handles great, it's just now and again you can feel a sort of oscillation from left to right at the rear. It's not a movement in the parts, more a lack of sophistication in the rear end, almost like a resonance that causes a sort of low-frequency jiggle during rough road surfaces. The 420R has been flat-floored and as I say handles great, but it's the comparison between the two that's made me aware of the difference. Now of course I can't but focus on it. The 620 is just planted, never does anything similar. Everything is tight at the back, with the only knocks coming from the LSD as per normal. Any advice? Am I destined to be ordering a suspension upgrade? thanks

I'm not sure if mine would chew sensors as I parked it at 900 miles and stuck to my position. Driving it while complaining about the issue in my view wasn't a credible approach.

I have a 620R, but CC have never accepted there is an issue at any point in time. They always maintained the position that the car is fine and no technical issues have or will occur as a result of the perceived issue. My experience does appear to be worse than most, potentially due to the driving environment, I'm not sure. Either way they've had significant written comms from me detailing my experience, in response they've offered to modify my car along with one other to see if it improves the situation. This isn't an upgrade as such and I don't believe CC are ready to release the revision as a kit or upgrade. I can't tell you how much effort, stress, formality and time went into getting to the current position.

I saw your question, but I'm not in a position to offer a statement with respect to how CC with deal with the matter for the wider community. I suspect given the language they've used with me they are happy with the design and don't see it as an issue.

Well if I'm at least able to start using it, then its a step forward.

Installation of the revised cooling solution.

With a bit of luck, crossed fingers and fair weather, CC will be fixing mine in September. It might actually get driven at that point,

This thread makes for familiar reading

I've done plenty of rallying over the years as a co driver, all the quick cars I've been in mostly Evos and Imprezas were always running GEMS but they don't seem to feature in this space. They would have been my money no object solution. As I really want to build my own solutions around the ECU I should look at their accessibility etc

I used to run a DL1 in an Evo track car, they're great products. Never come across DTA, who did the mapping?