Email Derek 3 : No Inner Radiator Cowl

Derek had responded to my previous email about the ARB bush colour really quickly this morning and so I had a quick look at the next steps for the ARB. I wasn’t going to be able to do anything today but I at least wanted to familiarise myself with what should happen.

I also resolved to spend more time hunting out bits for the next steps prior to needing them. So, I opened up the manual before going to work today and started to look for ARB components.

I got to the section in the manual that talks about the front ARB install but couldn’t find the radiator inner cowl that needs to go in before the ARB can be attached on a 420R. I opened all my remaining kit boxes and checked through them twice. The manual is fairly vague about what the cowl might look like and I only figured that out by looking at other people’s blogs. It should look something like this (though it’s marked as a Sigma part on the Chaterham web site)

Inner Radiator Cowl no longer fitted (courtesy of the Caterham web site)

Another email to Derek…

From me:
Thanks Derek. I think I may have a short. I can find no trace of the inner radiator cowl. The manual seems to be pretty vague about it so I hadn’t appreciated what it looks like until re-reading blogs about ARB.

Where would I find it if I did have it. I’ve emptied the really big boxes with loose components onto shelves, so I’m sure I would have seen it if it were in them. It’s also not on the aerial picture of all the components I took.


From Derek:


We no longer fit the cowling to the 420R as we felt the cooling was better without it.
Hmm. Ok. So all that time looking for the cowl and I don’t need one.

Email Derek 2 : ARB Bush Colour and the Red Dot

Having got to the front Anti Roll Bar (ARB) installation I went looking for the bushes that fit on the bar and inside the brackets. The manual says to use the bushes that are the same colour as the dot sticker that has been stuck onto the front anti roll bar. Two of the family thought it was red and two thought it was orange.

Front ARB dot shows colour of bush to use… looks pretty orange to me

Therefore an email was required to Derek…

Hi Derek,

  A question on the front ARB: The manual says to use the bushes that match the coloured dot on the ARB. Perhaps its the light at night but half the family thinks the dot is red and half think its orange. My initial thought is that its orange but then I’ve read blatchat posts that have confused me.

  Should I use the orange or red bushes for the front ARB on my 420R SV?


From Derek:

Use the red ones for the front and the orange for the rear.


Of course I needn’t have emailed Derek in the end. Once you actually look closer at the bushes or take them out of their poly bag, you can clearly see that they have different internal dimensions that match up with the smaller front and larger rear ARBs – doh!

ARB bushes in poly bag, note different internal dimensions

Build Session 8: Front Brake Hoses, ARB and Dinitrol 3125

Just had a couple of hours to work on a few things tonight. I’m now working on the assumption that I’ll be able to get the engine into the car this coming weekend – a holiday weekend. It’s now Wednesday and we have plans to meet up with family at the weekend too, but I should be able to spend the holiday Monday on the engine install. Therefore, I need to get today’s jobs done along with washer bottle and some engine prep. I also want to get some corrosion protection into the engine bay before the engine goes in – all to do before Friday when we leave for a couple of days.

Front Brake Pipes

Simple job this. Pulled all the pieces out of their poly bag and set them out on the bench.

Supplied brake hoses, washers, nuts and couplings

The manual says there are two hoses of the same length for the front and a further hose used at the rear of the car. It seemed to me that all three were very similar length. However, it’s clear that two of the hoses have the same coupling setup and so they’re the front ones.

It’s a simple job then of attaching the hoses as per the manual using a nut and star washer on the inside of the bodywork…

Front brake hose connects to brake pipe with nut and star washer. Star washer next to the bodywork.

…and a coupling and copper washer on the calliper end.

[2017-10-10: Note from the future… this calliper coupling bit has been updated. Andrew Pepperrell got in touch on Facebook and queried my use of the bronze coloured coupling (from my original post) vs the matt grey one. He had been talking with George Martin-Simmons who had discussed with Derek Howlett… all that to say this is now the right way. Thanks Andrew and George!! ]

Two types of coupling provided. Need to use the grey one. Also… See the slight rim on the grey coupling next to the hex part and towards the top of this picture – the copper washer fits perfectly over this.

There are two types of calliper coupling supplied in the brake kit. I had originally gone with the bronze coloured ones that seemed to fit fine but a message from the future (see above) informed me that it should be the grey ones. The two couplings have different thread pitch and thread diameters. The bronze ones have a 9.4mm diameter while the grey ones are 9.8. The bronze ones will fit and tighten up fine, but the grey ones, while still a little loose in the hole, clearly fit better. The grey couple looks like this.

Use grey calliper coupling from brake fixings pack

The grey coupling also has a slightly raised rim next to the hex part on the calliper side that fits the copper washer perfectly. Thanks again Andrew!

The final brake hose assembly looks like this, and doesn’t foul the suspension when the steering is turned…

Final front brake hose assembly

Front Anti Roll Bar

Next up is the front Anti Roll Bar (ARB). This should also be a simple job, but I fell at the first.

The manual talks about attaching two bushes onto the ARB that are the same colour as a “dot” stuck on the ARB.

Front ARB dot shows colour of bush to use… looks pretty orange to me

To me the dot looked orange. But that seemed to contradict some blogs I’d read. Rats! This is going to have to be an email to Derek.

Corrosion Protection In The Engine Bay

Well, I now had some spare time this evening and decided I’d get some Dinitrol corrosion protection into the engine bay. After surfing for a few nights it seemed that Dinitrol 3125 came recommended so I’d already got some delivered from Amazon a few days earlier.

Dinitrol 3125 Corrosion Protection

The forums are full of people talking about “The Grot Traps” down the side of the bodywork in the engine bay, by the side of the driver’s and passenger’s footwells and by the side of where you sit in the main passenger compartment. At least I think that’s where these Grot Traps are supposed to be. After a fair amount of Googling I couldn’t actually find any definitive pictures of where actually they are. Hmmm.

My car arrived with considerable amounts of silvered heat cladding around the driver’s and passenger’s footwells – between the footwells and the bodywork. It didn’t look to me as though there was any way any “grot” could get in there. Perhaps Catheram have improved this area and its no longer a problem. I should probably pose this as a question on BlatChat.

I also couldn’t see how “grot” could get into the sections next to the driver and passenger compartments. Perhaps I need to look at this again. The heat cladding is stopping anything getting in from the front. Maybe there’s some other ingress point. If I don’t talk about this again then I’ve probably decided its not a problem.

Anyways, I’d also heard people talk about water and “grot” collecting in in the curved sections of the body work next to the lower chassis rails in the engine bay (there are some pictures later).

So, out came the Dinotrol 3125 and I sprayed a reasonable coat of the stuff along the engine bay inner body work.

Dinitrol 3125 sprayed into the curved lower bodywork in the engine bay. You can see the heatsheilding running all the way up to the body work, this is the end of the passenger footwell – Grot Trap?

I masked off the chassis rails but decided I wasn’t so fussed about the inner sides of the bodywork. I’ve seen people carefully making off areas and I see the it’s perhaps only the sections close to the chassis rails that might collect water. However, my logic went that in really bad weather these lower body work sections could fill up to the level of the top of the chassis rail and I wanted to protect things to that level. Time will tell if that’s a good call.

That was it for the evening. Hadn’t achieved as much as I’d wanted to but then I’d spent less time than I’d thought. Also got another job done that’s not in the manual.

Build Session 7 : Front Dampers and Suspension Uprights

A short session today, I managed to get a couple of hours in between, and then after, my evening meetings.

Stool / Creeper

Firstly: new toys. I’d read in a number of blogs that a number of builders had got on well with folding stool/creepers. After spending a lot of Sunday bent over the car looking at headlamp fixings and front suspension my back was in a poor state that night. So, come Monday I ordered a folding stool/creeper from Amazon and which turned up today, Tuesday.

It got put to work staight away on the the dampers as I sat on the stool. Worked really well and pleased with the purchase at the moment.

Stool / Creeper

The creeper can be found at the link below (for as long as this link works):

PRO Mechanics Folding Creeper


  • Length: 40inch
  • Wheels: 6 x 2.5inch
  • 120kg capacity!
  • Padded headrest
  • Mechanics Creeper and stool in 1

Front Dampers

Top of near side front damper. The bolt is laborious

I was a little concerned about which way up the dampers should be inserted. The obvious way is to make the Bilstein writing be the right way up – i.e. readable (this is a 420 “R” so has adjustable Bilsteins). There seems to be a lot of debate about the pro’s and con’s of putting the dampers in both “the right way up” and “upside down”. It also seems that the R500 install has them “upside down”. However, the Caterham recommended way for at least the 420 is to have them with the writing readable and therefore at the bottom of the damper – the “right way up”. I decided to go this way and only to think about the other option when I know a bit more about what I’m doing.

After that decision they went in pretty straightforwardly. There are spacers to fit in the top and bottom of each damper. All the same size and there are 4 spacers that fit the bill in the suspension pack. Don’t forget the copper ease.

I will make one final comment on the dampers and that is to add the considerable number of people  commenting on the blogosphere about how difficult it is to firstly get out, and the get back in, the top damper bolt. It is a cap head bolt with a 6mm hex bit needed to tighten/untighten. As you can see in the picture above the bolt is very close to the bodywork. But what you can’t see is that it also gets very close to an inside chassis member before it can be fully extracted. Both issues add up to meaning that you can’t get a socket allen key or ratchet on the cap head. I tried a 3/8th’s socket and wobble bar combo but there just isn’t enough room. In the end I cut down a 6mm allen key almost all the way down to the shaft and used that and some pliers to turn the bolt, flat-by-flat, both out and the back in again with the damper now inserted. Fortunately, the bolt goes in at a bit of an angle and therefore as you turn it, it will pull itself out and in.

I also found that because the caphead bolt goes in at an angle it can be tricky to feed it through the spacer that’s now in the top of the damper. I found that a 19mm spanner on the top of the damper could be used to manipulate the damper and wiggle it until the bolt could be fed through.

19mm spanner can be used to wiggle the upright and give the caphead bolt a better chance of going in

Front Uprights

The off-side (O/S) upright went on with no particular drama. The only tricky bit was getting my socket set onto the upper upright nyloc nut. A wobble bar was needed but it was a bit of a fiddle to get it onto the nut.

Wobble bar and socket used to tighten upright top joint

The bottom nut was also a bit tricky because of the angle of the special nut going into the recess of the upright.

Bottom upright joint. There’s a very small gap between the left of the special nut (on this picture) and the lower wishbone (we’ll talk about the callipers later)

Because the front suspension is unsupported without the car being on the ground, the suspension sags. This puts the lower-wishbone-to-upright angle off from 90 degrees and pinches the socket you’re using to tighten the lower special nut – because of that limited gap on the left hand side talked about in the picture caption. My solution was to make a prop for the suspension unit and to therefore lift the unit to make the angle more like 90 degrees.

Since doing this part of the build I’ve re-read some other blogs and one proposed solution is to put the lower upright joint into it’s recess first. That way you can set the angle of the upright to the lower wishbone and the socket is able to get better access to the special nut. Hmmm. I get that that is an option but I was struggling with supporting the upright without having both the top and bottom nuts at least temporarily holding it all in place. I think its also advisable to have both top and bottom joints in place before torquing them up. You then get the problem of the bottom nut being pinched. I liked my prop solution, so happy with that.

To make the prop I took an offcut of wood, drilled a 32mm hole in one end, then cut off that end through the centre of the hole. This made a cutout in the end of the wood that I could then sit safely underneath a wishbone bush joint. This set the upright to wishbone angle closer to 90 degrees and stopped the socket on the special nut from getting pinched.

My upright prop
My prop keeping up the upright

On another note, some bloggers have commented that they needed longer sockets to be able to tighten up the lower upright “special” nut. I didn’t find that with my socket set. The socket set I had was fine to do the nut up all the way and have enough socket on the nut to feel confident that it was “on” ok. My 19mm socket has 19.5mm of hex depth and 24.5mm total depth until it gets to the 1/2″ wrench shaft. As you can see from the picture with the callipers and the lower special nut, there’s about 16mm of depth required from the bottom of the thread to the hex part of the special nut.

Then near-side (N/S) went on with no drama and the use of my Heath Robinson prop. I could then attach the track rod ends to the uprights and torque them up. Or so I thought…

Track Rod Ends Again

I then stood back to survey the progress and realised that the two uprights were pointing in different directions – considerably different. They were both pointing outwards by probably 5 degrees. Hmmm… what had I done wrong?

It took only a few seconds to realise that I must not have got the track rod ends on far enough. A quick review of the build manual and I realised our mistake. As Harry and I were reviewing the manual we had clearly read the section on the track rod end locking nut too quickly. We thought it told us to put the locking nut on 13 turns but after re-reading it I realised it was the track rod end that needed to go on by that amount. Doh!

Track rod end not on far enough

Easy remedy, remove the nyloc nut off the bottom of the track rod ends, wind the track rod ends on the requisite 13 turns and re-apply and torque the track rod end nyloc nut. That’s better. They’re close enough but will need to be set up properly along with the camber angle on the upper wishbone on a tracking jig during PBC.

Track rod end now set correctly to 13 turns for SV chassis

I torqued and then paint-penned the nuts and bolts but wasn’t happy with how visible the markings are. I was using a white paint pen. It worked fine on some sections but almost invisible on others. So, I ordered a couple of different coloured paint pens to see if it would make a difference.  We’ll see what happens when they arrive in the next couple of days.

Telephone Call 2 – Williams, Track Roll Over Bar

The first task today was a simple one – a call to Nick the parts guy at Williams Automobiles. I’d decided, for better or worse, that I wanted to go with the track roll bar and not the standard one that I had ordered and had delivered with the car.

Lindon at Williams had recommended that I go with the standard roll bar for my mainly road and occasional trackday use. However, having read various forum posts and one in particular about some hill climbs insisting on the track roll bars, I decided that while I was in the process of putting one on, I’d be happier if it was the higher rated one.

It took a couple of days for Nick to get back with prices and availability but I’ve ordered the new roll bar and will see if I can sell the original one. Caterham had one in stock and Williams are due a large delivery this week that the order can be added to. Should arrive before the end of the week.

The old bar does look at little flimsy in comparison to the track one, but I’m sure is fine in almost all situations, but I’ll feel happier with the uprated one.

Track Roll Bar (courtesy of the Caterham web site)
Standard Roll Bar (courtesy of the Caterham web site)