Incoming 420R, California

[Nocturnal005]

 

Introducing myself. My name is Norman and reside in the bay area, CA. I've had 15yr dream of building a Caterham and was actually building from plans when life put that on hold. Fast forward, I'm finally in a position to be able to revisit the dream and actually create some memories with my kids via the build. 

 

I don't really plan to a build blog, just excited to share and will prob need some advice along the way. Here are some fun pics from 15 yrs bk. This is as far as I got before I called it quits. Was to be a boosted Hyabusa powered clone for autocross. I imported the panels and body work from Caterham and the frame was TIG welded from 1020 steel. 

 

 

 

 

Here is the spec for the 420R kit I ordered in May 2024. It's currently in build, so not too long of a wait!

 

And here is what it looks like at the factory today! Sorry for the low res photos. This is what we got from Caterham. Initially, they sent the photos of someone else's car in yellow, so I'm pretty glad I at least got these. It sounds like the kit should land late Dec or early Jan. For now I'm contemplating what to do with the motor. Leave it all alone, install roller barrels, or R+R the 2.0 before I even install it to get somewhere midway between a 420R and a 620R. I explored the destroked 2.5 short block route but feel like I don't need quite that much and it feels like a much more intensive project. Open to suggestions! 

 

Also exploring what options I should go ahead and upgrade now. At the time of ordering I wanted to keep the costs reasonable, but some of the nice items such as LED lights are looking attractive and don't look fun to install twice. 

 

Before it arrives I've been reading every build log and writing down all the tips and tricks that I find. 

 

 

[KnifeySpoony]

Welcome- whereabouts in the bay are you (I'm in Fremont area)? It looks like a "sporty" spec - do you plan to track it?

 

re: build blogs - when I built mine in 2021, I used this one (almost more than the actual build manual):

 

https://caterham420detailedbuildblog.co.uk/

[Nocturnal005]

I’m in Belmont/San Carlos. I plan to drive it on skyline, do some auto x and occasional track days. Thanks for the link!

Edited October 26, 2024 by Nocturnal005

[JohnCh]

Great spec!  A couple of comments:

 

Regarding the LED headlights, @Outbound is a lighting engineer and shared this post with the source of the Caterham headlights at a fraction of the price.  I believe he may be using these now, and if so, can comment effectiveness.

 

Delving into engine upgrades, it's a potential slippery slope with a lot of options. Fortunately, there are a number of people here with firsthand experience who will hopefully chime in.  I won't rehash what we've already shared via email, but for the rest of the group I will highlight that you are used to cars with much stronger acceleration than a 420R, so the usual comments about it likely having more power than you need, don't necessarily apply.  A big question you'll need to answer is how much work you want to do now vs. how open you are to doing an engine project in the future?  By all accounts, switching to factory roller barrels or aftermarket ITBs wakes up the engine and adds to the aural experience, and can be pretty straight forward.  Any meaningful cam upgrade in the 420 require tearing apart the engine to accommodate valve lift -- the 420 cams are close to the limit with stock pistons -- at which point the slippery slope has arrived.

 

In addition to SBD and Raceline in the UK, there are Esslinger and Hasselgren in the US.  I know there is also another Duratec builder in the Portland area but can't recall his name.

 

During the build, a couple of modifications to keep in mind: replace the scuttle rivets with rivnuts and bolts to make future under scuttle work much, much easier; and if you need to remove the honeycomb boot floor for any reason, cut it in half to make future removal/installation easy rather than an exercise in frustration.

 

[KnifeySpoony]

Roller barrels are an easy and well sorted (although perhaps slightly overpriced) addition that is easy to do during initial build that will net you some additional power and a lot more sound. And the throttle response is greatly improved from what I've read (I build mine with the rollers so I have no basis for comparison).

[Croc]

1 hour ago, JohnCh said:

I know there is also another Duratec builder in the Portland area but can't recall his name.

 

 

Loynings has closed sadly.  Arnie retired.  

 

 

[Slonie]

Ooh, another local 7! Let me know if you ever want to join in on a drive once you've got it built up!

[Nocturnal005]

A quick update, the kit finally showed up on 3/3 and I’ve been busy getting it together. Fingers crossed I’ll be able to fire it up tonight! A lot of odds and ends left to tidy up, but moving along pretty well. I’ll post some more pics soon. I have a few mystery hardware items I’ll need help identifying!

[JohnCh]

You're progressing quickly!  Aside from the mystery parts, how has the build gone thus far?  Any surprises? 

[Nocturnal005]

I sort of knew what to expect given the different blogs. I must say the most frustrating aspect has been installing the diff. Due to a few real and perceived parts shorts I skipped around in the manual a bit and thus had do revisit a few steps. Only to find the missing hardware was in some obscure unmarked bag found later.

 

In the end it appears that I was only missing the following:

1. cushioned clamps of the right size for the bottom of the dry sump tank

2. scratched up lower control arm that Kampena motors got a replacement for

3. self tapping screws for the indicator to pod mounting

4. 1 bell housing to engine mounting bolt that was 10mm too short

5. cotter pin for hand brake pulley

 

surprises

1. tech support needed for watts link

2. water temp probe wires needed to be extended

3. steering wheel not drilled

4. kit comes w LED rear lights (and I bought a set separately to upgrade)

5. fuse box cover seems terrible

6. seat mounting hardware looks cobbled together

7. radiator fan presses against 7 logo in nose cone

8. general patience and persuasion needed to fit parts together

 

Some parts of the kit seem really well done and it doesnt look like any expense was spared - dry sump oiling, radiator hardware, etc. Other parts of the kit have been pretty terrible like the seat sliders and battery/battery mount. 

 

I'm also not sure how to check what ECU software is loaded. I purchased the roller barrel setup w the kit but have just installed the stock system for now...

 

BTW how are you LHD owners mounting your heater controls? It seems to want to route to the passenger side, but i don't see how you could actually operate it from the drivers side while belted in.

 

[KnifeySpoony]

Sounds like all par for course. The diff was a real MFer for me too. Definitely involved the most swearing and hammers of any part of the build.

 

Re: the Watts linkage - it looks like you got yours on, but what issues did you have? (I have it on my as well)

 

Re: the ECU - you most likely have the regular plenum tune loaded. I had to flash the ECU with the RBTB tune. You can either send it to a "dealer" to have it done, or you can get the easimap cable and free software and do it yourself, which is what I did. The friendly folks at the home office in UK emailed me the correct file. BTW, does the roller barrel kit still come with the green injectors? If so, don't use them, they are incorrect. The new RBTB tune (at least for me in 2021) used the standard black injectors. Don't be surprised if your tach reads wrong after the flash. I had to adjust the dipswitches on the tach even thought caterham seemed unaware of the issue and even sent me a new tach trying to fix the issue. 

 

 

[Nocturnal005]

On 3/18/2025 at 10:15 PM, KnifeySpoony said:

Sounds like all par for course. The diff was a real MFer for me too. Definitely involved the most swearing and hammers of any part of the build.

 

Re: the Watts linkage - it looks like you got yours on, but what issues did you have? (I have it on my as well)

 

Re: the ECU - you most likely have the regular plenum tune loaded. I had to flash the ECU with the RBTB tune. You can either send it to a "dealer" to have it done, or you can get the easimap cable and free software and do it yourself, which is what I did. The friendly folks at the home office in UK emailed me the correct file. BTW, does the roller barrel kit still come with the green injectors? If so, don't use them, they are incorrect. The new RBTB tune (at least for me in 2021) used the standard black injectors. Don't be surprised if your tach reads wrong after the flash. I had to adjust the dipswitches on the tach even thought caterham seemed unaware of the issue and even sent me a new tach trying to fix the issue. 

 

 

For the Watt's link, i had to just refer to the separate instructions and find all the hardware. Pretty straightforward after that.

 

Re the RBTB...I finally got them on. Had an issue where it appears the aft black end plate on the RBTB where the TPS attaches was clocked wrong. Ended up breaking a TPS sensor. Got it reclocked and now seems fine. Car fires up and runs, but seems super rich...guessing this is the confirmation that I have the wrong map. Does anyone know if a standard Tactrix cable can be used in place of the easimap cable?

 

Attached is a video of the start and idle from this morning 

 

 

[KnifeySpoony]

Wrong map I don't think it will run at all. The TPS tuns opposite direction AFAIK. If you have the wrong injectors it will run, but super rich.

 

 

[CBuff]

My factory built 420 has the heater pull knob (for valve) just to the right of the steering column.  If my six point belts aren’t super tight I can just reach it when it’s pressed in.  
 

photo is upside down 

Edited Friday at 12:35 AM by CBuff

[Nocturnal005]

7 hours ago, CBuff said:

My factory built 420 has the heater pull knob (for valve) just to the right of the steering column.  If my six point belts aren’t super tight I can just reach it when it’s pressed in.  
 

photo is upside down 

 

Interesting! Next time you have your hood off would you mind taking a photo of the heater cable routing to the valve? Wondering how they routed it from the factory. 

[CBuff]

I can get you a better photo early next week.  But here is one I have in hand.  Heater cable run marked next to it in red.  this was done by the factory (so 80% sure it’s correct). 
 

[Nocturnal005]

This photo is great, no need to take a different one. 

[Nocturnal005]

So the build process is on hold, due to a planned business trip to Asia. I got to where I wanted prior to leaving. All the body panels are attached and the car is nice and secure under the car cover. There are just a few things left: 

 

- ecu remap for RBTB, awaiting responses from Caterham and SBD

- headlight wire routing

- submarine belts and seat heater wiring

- fabricate battery bracket for ATX12 battery

- heater control hole

- alignment 

- strategic PPF 

- registration! 

 

So far, I'm 102 hrs in, and prob another 20 or so to get all the little odds and ends cleaned up. If anyone is interested, here is the break down below:

 

 

While on the plane I had wifi access, so I killed the time by doing some online upgrades shopping!  Ordered the following:

- battery disconnect

- LED headlight upgrade

- front nosecone canards

- fuel gauge fix module 

 

The first two I should have probably just gotten with the kit but was trying to have some restraint, the price was already getting up there.  

 

 

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[Nocturnal005]

Here's the battery bracket design I've been working on while away from the car. It fits the Antigravity ATX-12HD battery laid down in the factory location. I validated it with a 3d print, seems to work fine. Its a little taller that the factory bracket to clear the ECU better and at the same time eliminate the aluminum shims that are a pain to align under the stock bracket. Plan to get this fabricated over the next week or so after I fine tune the lightening holes. 

 

If interested I could make a few for the community, or share the CAD. 

 

 

[CBuff]

I was going to go with an anti gravity but my dealer put an agm and bracket it. Which has worked thus far.  When I dies I will likely upgrade to an anti gravity. But who knows with how fast things change. If my battery needs match this bracket I will circle back when the time calls. Looks great!!