KnifeySpoony

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. 

Checked voltage this AM after car cooled. Voltage still at proper setting after adjusting yesterday afternoon hot. Went for shortish drive, came back and voltage stable with car hot. I don't get it.

Line voltage at the plug was 4.92V - which was on 2 out of the 3 pins (not sure I understand that). Not sure if that being under 5V is significant or not.

I drive mostly track, but still drive to/from the track. My first set of tires were ZZS. I started with 2.25 deg camber up front and the standard 1.5deg de dion ears in rear. Running zero toe up front and 7 deg of caster (to answer your question, ride height does not affect caster angle). Rear is 0.25 deg toe in.  I found that the fronts seemed to wear well edge to edge, but the rears had severe outer wear - not just shoulder wear but a broad angled wear across the tires. Currently running ZZR (A64 compound)-  now have 3.0 deg up front and swapped to the 2.0 deg de dion ears. Overall tire wear looking very good now, even on the rears - I was worried that the ZZR would require even more camber, but it seems not. Some minimal shoulder wear front and rear but no obvious signs of too much/too little camber. 

In terms of ride height I am running quite low, but I have the track rate springs (250F/215R). I set the front ride height to have the lower wishbone parallel with the ground. This puts the ride height at 119mm (giving me about 68mm clearance to ground at the bellhousing). Rear ride height is at 138mm. In order to accomplish this, I had to remove the rear locking collars and the main perch is ran all the way down. Rear ARB is set one hole from stiffest. 

Overall the balance is excellent, easily adjustable at any phase of cornering with driver inputs. 

Afaik, there is no set number of washers. You need as many on each side to center the dedion, while filling the gap. 

Ok now OP"s turn. ;)

Tires? Which springs/dampers do you have? 

BTW I reset voltage when I got home with the car hot. Will check in AM with car cool to see if it changes again.

I've been dealing with a part throttle/low load hesitation/misfire on my 420R (w/roller barrels) - https://www.caterhamlotus7.club/forum/420r-hesitation-part-throttle-when-hot

I thought I had it figured out after realizing that my TPS voltage had drifted up. It's supposed to be 4.62V at idle. I found that it was 4.71V and this seemed to be the cause of my hesitation issue. Resetting it to 4.62 quickly allowed the engine rev normally. However I saw that the voltage was hunting a bit just sitting there connected to easimap, so I decided to replace it. The first sensor I put in I set to 4.62, then did a short drive. After the car got warm (about 5-10min) I noticed the idle speed had crept up to 1800rpm (normally ~1100rpm). Sure enough when I got back, the voltage was 4.55 (too low a voltage causes the ECU to think more throttle is applied as the voltage from the TPS goes down as the throttle is opened). So I thought maybe that sensor was bad. I got a new OEM Ford TPS sensor and swapped it in yesterday, set to 4.62 of course. Took the car out again and noticed that it was still doing the part throttle hesitation, although just a tiny bit and barely noticeable. Totally driveable, not the severe misfire it had before, and only over a tiny range of the throttle sweep (ie dead spot between 10-12% throttle, where before it was severely sputtering between 1 and 40%). However the idle speed had gradually crept up to 2000rpm. I got home (with the car still hot) and checked the voltage, which was now 4.51V. Needless to say I am confused. The sensor is fastened tightly - I don't think it's moving. Could this be a temperature issue? The TPS does get quite hot being mounted directly to the roller barrel assembly. I don't think Ford intended this part to get this hot. Could the lower voltage be caused by increased resistance in the wiring with heat? I have jiggled the wiring while connected to easimap and didn't see the voltage change at all.

Any thoughts are appreciated.

Funny looking injectors to have on carbs too... 

So it seems that the idle voltage being off by just a few hundredths is enough to cause such behavior. I guess 4.62V really means 4.62V. Live and learn...

Fwiw here in the states, center caps are generally advised to be removed before trackdays. They tend to not last long. I just leave them out on my cars. More rccr than way... 

I am going on the wiring diagram in the back of the 2015 build guide which AFAIK is the most current published? My 420R is a 2021 build btw. 

Ah ok i figured it was something like that given the consistent, but higher residence. What is the mfu?