Interior trim and seats

My plan today was to have another go at the aero screen brackets, finish the interior trim and fit the seats.

Aero screen brackets, take 2

I had wondered if the reason I couldn’t fit the LHS bracket was because of pressure on the panel from the windscreen frame, so I removed the 4 bolts and lowered it out of the way.


As close to an aero screen I’m going to get for now

Still no joy fitting the bracket, though; it resolutely refused to slide in. I switched to the RHS instead to see if it was the same issue, and although that bracket did fit easily, the holes didn’t align with the holes in the bodywork.

At this point, rather than keep struggling with them, I decided to just give it up as a bad lot, and go without the brackets. I don’t have any plan to fit an aero screen, and I was concerned about causing unnecessary damage to the car. If I do fit one at any point in the future, it’ll be a bigger job, so I may get some outside help.

Fortunately, the windscreen fitted back on easily with no issues and I changed focus to the interior panels.

Knee trim panels and fuse box cover

Derek’s guidance to just drill new holes became even more obvious once I marked up where the holes in the knee trim panel are relative to where the interior panel is pre-drilled. The holes were not even close.


Location of knee trim panel holes (pen marks) compared to pre-drilled holes in the interior panel

It was fairly easy to drill the new holes, site the rubber strip that sits between the two panels, and hold everything in place with a couple of screws. Fitting the self-tapping screws themselves took some effort, however. It became a test of whether the chassis, screw or screwdriver bit was the weakest element. I did get them all fitted eventually, but at the cost of two broken screwdriver bits, and 2 damaged screws. Rather than leave 2 holes, I just riveted the rearmost one on either side instead. They will need to be drilled out if I ever have to take the knee panels out, but not a big deal.

With the knee trim panels installed, the fuse box cover just slots in and is held in place with some sticky pads – a very quick job.


Fuse box cover fitted. Will need some rubber trim for the IVA check

Padded carbon race seats

Final job today was to fit the carbon race seats, starting with the fixed passenger seat. The first challenge was to work out which of the supplied bolts was required as the pack listing in the instructions is different to what is supplied, but a quick Google search revealed it’s fairly simple.

The two aluminium brackets bolt directly onto the seat, and then 4 bolts are passed up from underneath the car into the brackets.

A dummy fit revealed a problem, however. One of the brackets did not line up with the pre-drilled hole in the floor cleanly, and I wasn’t able to move the seat enough to get a bolt through.


Hole in floor not aligned with bracket

Out with the drill to slightly widen the holes, and on the 3rd or 4th attempt (with a small adjustment each time), all four bolts passed through, and the seat was bolted in


Seat fitted…


..and tested!

The driver’s seat was a bit more complicated, as it has adjustable runners, and it took a bit of trial-and-error working out to get these and the mounting bolts fitted in the right order . The driver’s seat attaches differently, with four bolts protruding down from the seat through the holes, secured underneath the car by nyloc nuts.

Fortunately, the seat lined up perfectly with the holes in the floor this time, and slotted through.



One small issue: with the seat fitted, the forward/back adjustment didn’t want to cooperate (it was fine before installation). The handle runs very close to a chassis member in the floor which is limiting movement. I suspect this just needs to be bent a bit to shape, but I’ll ask Caterham to do that at the PBC.

A quick test of the seat showed it is in a good position currently anyway, but it would be nice to be able to adjust if required without removing the seat.

Although they look very rigid, the seats are surprisingly comfortable. I chose them when I was speccing the car because they seemed a good combination of race seat with comfort for longer journeys. They are cosy around the hips though; an incentive to keep the weight off!



Rear brakes, speed sensor, interior trim and wheels

Had another Friday off work, so after a slow morning, I went back to the build for a few hours.

Rear brakes

I’d had the usual quick response from Derek during the week, which had confirmed my assumptions with the brakes, so I began by installing the brake pads and upper parts of the callipers.

Rotating the wheel hub does cause the pads to rub the disc slightly at the moment. I’m assuming that when there is brake fluid and pressure in the system they will move clear – we’ll see.

Looping the handbrake cable eye over the hook was simple once I’d adjusted the plastic stopper on the LSD to give some slack to play with. I’ll adjust this back once the brake fluid is done.


Callipers and handbrake fitted

The final job on the callipers was to shape and fit the brake lines. I used a socket to bend the pipe to approximately the right location, and then adjusted it slowly until the thread on the brake line was flush with the calliper. This was actually a bit fiddly, especially on the RHS. It took a few attempts to get it square with the hole so it didn’t cross-thread, but they both went on eventually. I tightened them as far as they wanted to go without over-stressing.


Brake line fitted

Speed sensor

A nice simple job to finish the rear suspension build. This just passes through the bracket mounted to the RHS de Dion ear, with the sensor positioned approx. 1mm from the driveshaft. The cable is then tidied up with some cable ties along the radius arm, and secured against the rear cabin panel with a cable tie clip (riveted through a hole drilled behind where the driver’s seat will go).


Speed sensor

And that was the rear mechanical build done!

Interior trim

The guide moves onto the wings next, but I’m leaving that to the end of the build to minimise the risk of them getting damaged, so I went back to the interior trim. With the handbrake fitted, I was able to rivet the panel that sits above the prop shaft. This involved 22 rivets done by hand, and with a misbehaving tool, this took a while. The 3-4 holes on each side towards the rear of the panel were not fully aligned either, so I needed to widen slightly with a drill.


Many, many rivets

With the panel riveted, I was able to fit the transmission tunnel cover, which just required slotting over the handbrake and gear stick (with gear knob removed). The manual says to drill and screw it at the back into the transmission tunnel, but the screws provided didn’t want to reach all the way through, securing it to the carpet, but not through the panel. It felt pretty solid though – I may revisit this when I find some slightly longer black self-tapping screws.

Unfortunately, whilst I was moving around with the drill, I didn’t pay enough attention and caught it on the bodywork at the side of the cabin, leaving a small nick in the paintwork – it will be under the door, but annoying nonetheless 😦


Transmission tunnel cover looks great

Aero screen retention brackets

Following some advice from a colleague with a Caterham, I had also bought some retention panels that allow a quick swap between the windscreen and an aero screen. Not sure I will actually do this, but apparently getting access once the knee time panels are fitted is very difficult, so it made sense to fit these, just in case.

Or so I thought.

When I actually tried to fit them, they did not want to cooperate at all, fouling on the black panel welded to the chassis. I didn’t want to push too hard as they fit against an aluminium panel which is painted on the outside, and I didn’t want to cause any more paint damage by slipping and denting the panel. I ended up leaving them off for now – I’ll have another look when I’m next working on the car to see if I was just coming at it from the wrong angle.


Retention brackets not fitted…

I also did a dummy fit of the knee trim panels to see how easy these would be to align with the pre-drilled holes. Spoiler: not very. Another job for the next build day.

Wheel-y done

By this point, my son was home from school, and had been very keen to get the wheels fitted, so we went round and bolted these on together. They’ll need to come off individually to fit the wings, but they look very cool in the meantime! It really is looking close to being complete 🙂

It occurred to me I had some spare paint supplied by Caterham with the kit, so I touched up the mark I’d made on the side of the car. Not perfect, but only really noticeable if you know where to look:

I also though some more about the retention brackets and knee trim panels. I may need to remove the windscreen to do fit the brackets so I can gently push the aluminium body out to site them. If it’s not easy, I’m just going to leave them off for now.

Looking at other blogs for the knee trim panels, it seems fairly common to get them as close to the right position as they’ll go, and then drill new holes. Apparently this is also Derek’s advice, but I may as well email him to confirm.

And Derek’s response, the following morning:

“We drill new holes as the pre-drilled ones never line up”

Ah, Caterham…

Torquing up and rear callipers

With some borrowed tools, (the behemoth jack that will reach the car on axle stands and a 41mm socket), I wanted to try and finish the rear of the car today.

The first job was to jack the car up by the de Dion tube to place the weight of the car on the rear suspension, which brought the radius arms parallel with the floor (measured 0 degrees at the point the car lifted off the stands), and then torque these and the A-frame. The only bolt I didn’t do was the central A-frame bolt at the rear because the jack obstructed access, but this will be easily reachable once the car has been lowered on its wheels.

Rear hubs/callipers

Next step was to mount the ears onto the de Dion bar that hold the brake callipers. These both took a bit of cajoling with the rubber mallet (especially the RHS), but did both go on. I used a bit of bearing grease to help slide them on, but the driveshafts are such a tight fit into the hub, I’m not sure if that helped or hindered.


LHS de Dion ear and rear hub

With the ears bolted on, I could then attach the anti roll bar drop links. These again were pretty straightforward, just joining a bracket mounted to the hub with the anti roll bar.


Anti roll bar drop link fitted

I did need a very narrow spanner to stop the drop link thread from rotating whilst the nut was being tightened (my standard spanners were too thick) but I managed to find one in a bike tool set that did the job perfectly.


Bike spanner was ideal

With the drop links fitted, the brake discs just slid on, and were tightened using the borrowed 41mm socket. These will eventually need to be tightened to about 270Nm, but I don’t have the tools to get anywhere near that. The manual suggests to tighten to a temporary value of 81Nm, so I just did them as tight as I could. Caterham should ensure these are correctly tightened at the PBC. Interestingly the LHS nut is reverse-threaded, so needed to be tightened anti-clockwise.

Next on was the lower part of the callipers which sits neatly over the disc, and is bolted from the back of the de Dion ear.


Brake disk and lower/fixed section of the calliper

It was at this point I realised I hadn’t put a silicone seal between the ear and the de Dion tube as I’d meant to. Damn.

I didn’t want to pull it apart, so left it – I don’t think it’s a big deal. It will be for waterproofing anyway, and as I’d taken time to put cavity wax in, and it will be a fair-weather car mostly, it should be ok. Bit of a miss though; should have re-read the manual before I started so as not to miss this step.

Oh, well…

With the lower part of the calliper fitted, I went to fit the brake pads, and realised I wasn’t entirely sure how these go together. I’d have expected these to be secured, but it appears that they slot in loose, and are then held in the upper calliper by the springs. Thought I’d confirm with Derek though as I was going to email him a couple of other small questions anyway about spare parts supplied: some additional bolts (I think which replace those pre-fitted in the calliper), and some nuts and washers that were packaged with the brake pads, but with no obvious purpose.


Brake pads slotted in

To compound things, I couldn’t separate the upper and lower callipers for the RHS (they are supplied bolted together, and although the LHS had unbolted relatively easily, the RHS needed a narrow 15mm spanner to separate). Another rummage through the “household stuff” drawer in the kitchen turned up another bike spanner, and wouldn’t you know it, 15mm.


Another perfect tool for the job

However, as this had all taken longer than I was expecting, I had run out of time for the day, so – not for the first time – fell a bit short of completing the build steps I’d planned. Not too far off, though. I should be able to finish the callipers quickly once Derek has confirmed the pads are fitted correctly, then fit the speed sensor, and fit and secure the handbrake cables.

After that, I think the wings and possibly the lights (based on experience) are the only really tricky-looking build jobs left. Otherwise, it’s interior trim panels, seats, exhaust, wipers and mirrors, before doing the start-up prep (engine, brake fluid etc.), and getting ready for the IVA.

The end of the build is starting to look in reach..!

Radius arms, A-frame, anti-roll bar, driveshafts and rear hub assembly

A nice plan-free Saturday today, so plenty more time on the car playing with the chunky rear suspension parts.

Radius Arms

Picking up from yesterday, I started by drilling out the additional holes for the lower radius arm mountings, first by passing a 9mm drill bit through from the outside to centre the hole, then by using a conical drill bit to expand it to the right size on the inside. A bit of a sweep and dust, and it looked very neat.


2 are better than 1

As the top hole will be unused, I left myself a note to look for something to plug this with later in the build. With the holes now free, it was a simple task to pass the bolts through and loosely tighten up the radius arms. I can’t fully torque these until the weight of the car is on the de Dion bar, at which point they can be tightened in a more neutral position.


Arms fitted, but unloaded

“(Carefully Spaced)” A-Frame

The A-Frame joins the centre of the de Dion tube at the back to the chassis at either side, and provides a lateral frame in order to make sure the wheels are evenly spaced left to right (target is +/- 2mm). I joined the A-Frame to the de Dion tube using the provided white nylon washers, and again loosely tightened it up. Access to the bolt and nut is actually quite tight as they sit recessed within the A-Frame, but fortunately I had two thinner 19mm sockets that fitted.

Mounting to the chassis was also simple, but it’s necessary to use spacers to make sure it sits central to the chassis. I ended up with 3 on each side, and several measurements confirmed 83mm and 84mm from the side of the chassis to the outside of the de Dion tube.


A flick through the old manual later highlighted that there are normally 7 washers fitted, 4 one side and 3 the other. Not sure if this was for the older imperial rather than metric chassis, however. The newer manual just says use washers to space. I did try and squeeze a 4th one in, but it didn’t want to go (reminiscent of the front wishbones), and didn’t seem necessary, so for now I’ve settled on 3 each side. I’ll re-check this is evenly spaced once it’s all torqued up – need to wait for the car to be lowered on the suspension.


A-frame fitted


And a nice under-car shot showing the A-frame, lowered floors and front suspension. Reminds me of my Tamiya RC when I was a kid 🙂

Rear anti-roll bar

Another straightforward job. The first task is to get the rubber mountings over the flat ends and past a 90-degree elbow, but rubber lubricant is impressive stuff. Some leverage with a screwdriver and they sat nicely in position. There was plenty of space to then slide the bar through, and site it in the clamps either side. 4 bolts pass up from under the car and are secured with a nut on top.


Team effort fitting the ARB


Nice “7” clamps


It’s been a day of installing the larger parts that have been neatly stacked on the garage floor for the last 12 months, and the last two – the driveshafts – were next on. This just required removing a plastic cap from the LSD before sliding the driveshafts home.


Cap removed…


…and driveshaft installed

The driveshafts are handed and different lengths, but are marked up, so are hopefully the right way round! Not sure if they are fully home in the LSD; they seemed to slide in easily enough, but I’ll find out when I install the rear hubs.

Rear Hubs

I don’t have a 41mm socket to remove the fitted driveshaft nuts (I plan to borrow one next week), so couldn’t mount the hubs yet, but I thought I’d go through a practice build to better understand the installation as the diagram in the manual was quite complicated. Fortunately, I’d also found a link to Marcus Adams’ 420R SV blog, which pointed me to a couple of marked-up photos created by Andrew Bissell, which were really useful in clarifying which bolts were used:


Actually, once all the parts were identified and joined, it wasn’t that complicated, and I was able to put together the LHS hub (minus brake disk and pads). Happy I now knew how it bolted together and to the car, I disassembled it to make it easier to fit once the driveshaft nut is out of the way.


Overall, a really positive build day, with plenty done. I finished by reading through the old manual steps for the rear suspension to make sure there was nothing there that wasn’t shown in the new manual, and reflected that I was now able to read and fully understand it – bit of a change over 12 months ago 🙂

De Dion cavity wax

After I packed up yesterday, I spent some time looking at the other blogs and found that a few people had sprayed cavity wax inside the de Dion tube to protect against water damage. As I had some left over from the engine compartment grot traps, I sprayed a light coating of Dinitrol 3125 into the tube.

De Dion tube, dampers, and “really, Caterham..?”

Had the day off work today with grand plans of an all-day build – nope. A poorly daughter (ironically her first day off school ill ever) and the need to collect a new work car cut the day back somewhat. I’m coming to the conclusion that however long you think you might get on the build, you can halve it and still be wrong.

De Dion tube

I did get a couple of hours in though, and actually made some nice progress. I started by fitting the brake line onto the de Dion tube with the locknuts Derek had sent through previously, and then lifting the tube into position on the car. A slight panic when it looked like there wasn’t enough room to angle it in without fouling the garage wall (the space to slide it between the LSD and the fuel tank is quite narrow), but a different angle of attack paid off. It was a bit of a lump to position, but I’d put some pipe insulation around the chassis members, so could move it around a bit without worrying about damaging anything. With the tube in place, I then connected the brake hose to the line pre-fitted by Caterham.


Brake hose fitted

Rear dampers

Next step was to fit the rear dampers, suspending the de Dion tube from the chassis. Another relatively simple job: just copper-slipped the sleeve and bolt for the upper mounting, and then with help from the kids (one side each 🙂 ), we were able to line up the damper with the bracket and push the bolt through. Took a bit of wiggling to completely line up, but once in place, the bolts pushed through easily enough.


Some help installing the damper

A second bolt joins the dampers to the de Dion tube at each end – I was initially struggling to line this up without cross-threading the bolt, but realised that the pipe insulation was lifting the de Dion tube too high, so pulled this off and rested the tube directly on the chassis members, and was able to thread it without a problem. Once the car’s weight is on the wheels, the springs will compress and lift the tube further away from the chassis. With all four bolts positioned, I torqued them up, and another significant part was fitted.


Rear dampers mounted

The only real challenge I’m finding with this section is making sure I’m using the correct bolts from amongst the many supplied. Because my parts bags use the older numbering system, but the new manual has updated this (although the bag contents are very similar), it involves squinting at the tiny print in the manual to see the description of each bolt, and then finding the same description on the parts inventory in my parts bags. Bit of an eye test, but seems to be working so far (PBC jinx).

Radius arms

Still, on a roll at this point, so on to the radius arms. Another eye test for the correct bolts, double-check to make sure the radius arm orientation is correct, and the indentations are towards the front of the car, and secure the radius arm to the de Dion tube.

Absolutely flying now.

Rotate the radius arm down, pass the bolt through the lower of the two holes as this is an R spec, and…

…wait. WHAT?!?


No hole (needs a dust too!)

The lower hole doesn’t pass all the way through the car!!!

Let’s back this up. There are two mounting positions for the radius arm on each side of the car: an upper position for the base and S-spec (to provide a more comfortable/compliant ride) and a lower position for the R-spec (to limit roll-induced oversteer). There seems to be some debate as to which is better (one amusing comment said it was a choice as to whether you wanted to crash backwards or forwards), but consensus seems to be to go for the lower hole, and as the manual shows this as the correct position for my spec, that was where I want to put it.

The hole for the R spec sits behind a second side panel, which it looks like Caterham don’t bother drilling. A quick google showed this is normal though, and it’s necessary to drill out the lower hole. I’d guess that the R-spec is maybe lower volume, so most owners won’t use it, and it could allow rubbish into the cabin? Still…

As it was getting late in the day at this point and drilling a side panel is a job I don’t want to rush, I’m going to save that for tomorrow.

Roll over bar, and early onset upgraditis

Some background on the roll over bar: I put a question up onto the Caterham FB page asking for some advice with this, and got a direct message from the guy who owns Bookatrack who are getting rid of Caterham stock as they’ve been bought by Ginetta. They had a single SV metric roll over bar in their warehouse, and offered it to me at a decent discount (somewhat eroded by shipping though – it’s heavy!).

The new roll over bar arrived today in a beaten up box from DPD which was worrying, but once unwrapped, looked ok. Some minor paint chipping where it joins the bodywork (despite a lot of cardboard and bubblewrap protection), but nothing some hammerite won’t fix.

It’s a simple job to remove the roll over bar, so fitted the new one, and gave it a quick paint touch-up this evening. I’ll bolt it up once the paint has dried tomorrow.


New FIA-spec roll over bar


Weather cover for boot fits the bar with no issues

Very happy with how this looks. Just got to see if I can sell the other one now, to offset some of the cost.

Speaking of cost <ahem>…

Had a bit of a spending spree tonight too:

  • Soft Bits half-hood (an essential, apparently)
  • Soft Bits carbon tunnel bag (a birthday present)
  • High-level third brake light to be mounted on the new roll over bar
  • Neoprene mat (to line the boot and protect the aluminium body/paint)
  • Plus p-clips, self-adhesive rubber, duct tape, heat shrink

Haven’t finished the build yet, and upgraditis is kicking in…

Had a response from Derek today too. He said the blanking plugs are supposed to fit in the holes that the inertia seatbelt would attach to if fitted, but they look too large for that – they’ve gone back in the spares bag for now. I’ll look for an alternative location for them at some point.


Hello gluing, my old friend

Keen to get back to the build this weekend, but with the roll over bar going to be replaced, I skipped the rear suspension build temporarily (I’d have to dismantle it again to change the roll over bar). The next steps in the manual were the front and rear wings, but I’m going to leave these until last. Build space in the garage is a bit tight, and I don’t want to damage these moving parts around the car.

The next steps cover the interior, and after several weeks off, I was happy doing something a little easier/more cosmetic to the car anyway, so this suited me fine.


I started by gluing some rubber trim onto the knee trim pads, and some foam onto the fuse box cover. Having done that, a quick look at the car and some build blogs showed these were not going to be an easy installation, so I put them to one side, and moved onto the carpets instead 🙂

As this is a 310R, the only carpets in the build were the boot floor and the tunnel sides. The guide says to fully spray the boot floor and carpet before fixing in position, but I was concerned about trying to navigate a fully glued carpet into position (around the roll over bar), and getting glue somewhere it shouldn’t be. I took the approach of placing the carpet unglued into position, and then lifting one half up, spraying adhesive, fixing that half back into position, before lifting and spraying the other half.


Boot carpet

The tunnel carpets had no obstructions, but were long, so I took a similar approach, gluing the rear half and fixing it in place (lining up the notch in the carpet to the chassis member running across the floor), before spraying and fixing the front half.


With the carpets fitted, I moved onto the harnesses (skipping the tunnel top for now in case I need access to the handbrake cables there for the rear suspension). The harnesses were marked as L/H and R/H, but fitting the L/H one on the LHS of the car would have put the strap with the buckle on the outside of the car, and the manual says to attach this to the transmission tunnel instead (not sure if this is a safety thing, or just prevents the buckles being thrown over the side of the car and damaging the paintwork). So L/H was fitted to the RHS and vice versa.

I started by fitting the two “L/H” shoulder straps on the RHS before finding another bag of bits taped to the underside of the R/H harness box, including some brass spacers not shown in the manual. Another quick google, and it looks like these are supposed to go between the boot cover and the harness assembly, so I removed the two straps I’d fitted, and re-fitted with the spacers added in. This also had the benefit of allowing the straps to rotate a bit more freely than without them. The lap belts went on easily too (also using brass spacers), and they looked really good – not the most practical seatbelt, but undeniably cool 🙂

Last job was to follow up on a couple of questions around the fuse box, and some blanking plugs in with the harness fittings I can’t find a home for. Another email to Derek – I’m sure he’s missed me.

Build anniversary…

Well, as it has a habit of doing, life got in the way again… An (excellent) summer holiday, followed by several busy weekends/being tired form work and another work trip to the US have meant no progress for the last couple of months.

On the positive side, I have been increasingly aching to get back to the build over the last few weeks following the time away, and have a couple of quieter weekends coming up to make some progress. I think the goal now should be to try and push on over the winter and get it on the road early(ish) next year. Pretty sure I said that 12 months ago too, but it’s proven to be more challenging than I was anticipating, and I’d rather enjoy the build than force through it, so I’ve been ok with a slower approach.

One build update today though, I decided to replace the roll over bar with an FIA track day bar. I’ve been considering this for a while; it’s the one thing I feel that I missed when I was speccing the car, and as it’s fitted before the rear suspension goes on, now was the time to make the switch if I was going to do it. Probably an OCD thing, but I think it makes the R spec look more complete. It also gives me the option to join Caterham track days (doubt I’ll do this a huge amount, but I’d rather have the option, and it seems a shame to miss out on that part of Caterham club membership completely), looks like it will make fitting a 3rd brake light a bit more practical, and should ultimately provide more safety if the worst happens.


Upgraded roll over bar

This does mean I now have a spare unused road spec roll over bar though… I’ll try the Caterham FB pages etc. to see if anyone is interested in it.

Finally, as it’s been 12 months since the build has started, another motorsport-related birthday has passed.


Hamilton won his 5th F1 Championship in car 44, on my 44th birthday

I don’t know of any significant car number “45” drivers, so best not let this build run another 12 months…

Back to it!

Another few leisurely-paced hours on the car today after more busy weekends. Saw a FaceBook post during the week that the guy I was chatting to about his build recently (we were installing the LSD the same weekend) had finished his build and sent his car off for PBC and IVA! Thought I’d better pull my finger out and at least get the LSD finished 🙂

Prop shaft bolts

So, first up today was joining the prop shaft and the LSD, and torquing up the LSD bolts (both simple jobs, but previously deferred after a long day with the LSD installation). The bolts went in easily enough with some Loctite to keep them in position – they will be rotating around fairly quickly; don’t want one coming loose! Torquing up the bolts twisted the prop shaft rather than the bolt, so ended up with a process of put the car into gear/climb under the car/torque the bolt/climb out/remove from gear/rotate the propshaft/put into gear/climb under the car etc. Not one for a bad back. Only minor glitch was that I couldn’t get the torque wrench onto one of the four bolts as the bleed nipple for the prop shaft was in the way. Ended up doing that one by hand with an Allan key.

De Dion preparation

With the prop shaft done, torquing the 3 LSD bolts was straightforward. Next step was the de Dion tube. Started with carefully reading through both manuals to identify the parts, and then rooting through the various parts locations (big parts in the garage, small parts in bags in the study) to get everything together. With the main parts gathered, I propped the DeDion tube up on bricks so I could work on it levelled, and fitted the brake pipes and 3-way union. The pipes are riveted to the tube, which needed drilling out (I didn’t have imperial drill bits, so 1/8″ became a fractionally larger 4mm). I had thought this job may be difficult, but the holes were pre-drilled so was actually very easy to ensure the rivets were correctly placed.

The rivets went through easily enough with the exception of the rivet nearest the union on the short LHS pipe, which required some gentle pressure on the pipe to locate it. I’d seen photos of the clips reversed on the LHS pipe to make it easier to fit, but the guide and most blogs seem to keep them consistent – it also seemed to provide a better route for the LHS pipe at the wheel end.

With that done, I moved onto the rear brake hose, but I seemed to be missing the locknuts that sit either end of the hose, so just loosely fitted it, and I will check with Derek where I should be looking for these. Finally, I cut a length of the remaining 5/16″ hose to provide some protection for the pipe and cable-tied it in place.


And that was pretty much it for the day – a small but positive step. I’ll check with Derek about the locknuts, but beyond that, next steps are to install the tube (going to have to work out how to route it into place from underneath as there isn’t room to the side of the car to thread it in – chassis tubes are already protected by pipe lagging, just in case) and fit the rear dampers, radius arms, A-frame, ARBs and drive shafts. I’m enjoying being back playing with the big Meccano pieces again.

Today’s lesson: Woodwork

Out today (Sunday), so not enough time to do more on the rear of the car, but picked up some varnish on the way back for the boot plank, and gave it a first coat.


The Locknut Mystery/These Aren’t The Locknuts You Are Looking For

Derek responded that the locknuts were packaged with the hoses, but no sign. It occurred to me to check the front hoses to make sure I was looking for the right thing, and managed to confuse myself (and most probably Derek) at this point as I mistook the female union for a locknut. Cue: email to Derek that I may have installed the locknuts on the front hoses, complete with photos…

…showing I hadn’t. Got a confused email back from Derek confirming that the “4” locknuts installed on the front hoses are absolutely the correct 2 locknuts that should be installed on the front hoses, and there should be 2 more locknuts with the hoses.

I spent some time checking other build blog photos (thanks again purplemeanie), and finally worked out what I’d done, and that the front hoses are correct (so, at least no need to remove them!). No sign of the missing 2 locknuts though, they’re not packaged with the rear hose, and I can’t find them in the other bags, so back to Derek for replacements – tail firmly between my legs.

On the bright side, put a second coat of varnish on and fitted the boot floor back in the car. Did that right.

LSD: Making a Limited Difference

Sorry. Puns are a slippery slope. Ok, I’m done.

One day on the car this weekend as we were away yesterday, and a colleague had offered to come over today to help install the LSD, so that was the main task.


I wanted to get the handbrake installed first to make sure the cable could be correctly sited around the diff; I didn’t want to get the diff installed to then find I couldn’t get the handbrake cable fitted. Fortunately this was a pretty simple job. Derek had already confirmed my assumptions, so it was just a case of attaching the handbrake to the clevis (a bar holding the pulley) with the correct pin and spacers, and threading the handbrake cable around the pulley before attaching that to the clevis also. The manual shows the cable looped over itself, but Derek confirmed you don’t do this for the SV (mentioned in the old manual, but not the new).

(At least in part because of this, I am back to checking old and new manuals again for each step – although there are some contradictions, it does seem the best way to get the most information from the manual).

Finally, the cable from inside the transmission tunnel is connected to the upper terminal on the relay on the handbrake.

There are two heights to mount the front of handbrake (depending on how high you want it when disengaged). I went with the higher one. It looks ok (don’t think it will get in the way of the gear lever), and I’ve read that the lower setting can be a pain to engage the handbrake as it sits so far recessed it’s difficult to get your fingers under it. Time will tell if I want to adjust this, but it is at least a very easy job to do if required.


Handbrake lever sited at the higher mounting, fully lowered

With the handbrake installed, I could site the cable through the two brackets attached to the chassis.


Yellow boss sits within the bracket on the LHS. The white adjuster goes into the bracket on the diff once installed


With the handbrake cable installed, it was time to start tackling the diff, starting with filling it with oil. I’d already had to check with Derek what oil to use as various types had been supplied with the car, and he confirmed it should be the Motul 75W140 differential fluid. I filled the diff (via the plug just below the Caterham badge), slightly overfilling the recommended 0.8l, but believe this is ok.


Ready to fit


The upper and lower diff mounting points

Once Brendan had arrived, we jacked the diff into position (not quite enough reach on the jack, so lifted the last bit by hand, and threaded 2 screwdrivers/Allen keys (at different points) through the upper mount to hold the weight.

The first job is to thread the two lower bolts, and centralise the diff across the width of the car. With some shuffling of the diff, we got both bolts sited, and measured the distance from the diff carrier to the outside of the chassis each side. Remarkably, it looked pretty even, and we settled on 2 shim washers each side between the chassis mount and the diff. With these bolts re-sited and tightened, we took several measurements, with them looking pretty good – approx. 49.1cm both sides. Because the diff is not symmetrical, it wasn’t possible to double-check with another measurement point elsewhere on the diff, but it looked like it was as close as we could get it.

With the two lower bolts sited, the upper mounts are joined by a single 11″ bolt which threads through the diff. However, whichever way we moved the diff (now locked into a single plane of movement by the two lower bolts), we could not get the bolt to pass through.

Stopping for a while to think about the problem, it looked like the diff was not rotating high enough to align the holes before making contact with the boot floor.

Reasoning that the wooden boot floor and aluminium strip were not structural (and were flexible), we gently jacked the diff up another few mm (with the help of some bricks), putting a slight upward pressure on the boot floor. This was enough to align the holes, and pass the bolt through.


Upper bolt sited

With the upper bolt sited, the diff does touch the boot floor however (actually the bottom of the screws poking through). I don’t think this is a big problem, but will email Derek to check.

The manual says to put shim washers between the carrier and the chassis mounts for the upper bolt, but unlike the lower mounts, the upper ones are offset (again, due to the asymmetry of the diff), and we ended up putting 3 washers on the LHS and 0 on the RHS. It was a concern leaving it at 0, but without really forcing it, there didn’t seem space for a single washer – the diff rested up against the chassis mount. Again, I will check this with Derek. If he insists a washer should be there, it won’t be all that difficult (I hope) to remove the upper bolt and add it, just a bit irritating.


LSD from underneath. You can see the 2-2 spacers on the lower mounts, and the 3 on the upper LHS. Upper RHS is hidden by the handbrake cable

With the diff fitted, we were getting tired (it was hot again today!), so didn’t want to push anything further and make a silly error. The diff bolts need torquing and the propshaft needs to be attached, but those are jobs for the next build session.

One final opportunity for the day though: Brendan had driven over in his stunning E-type, so both my son and I got to go out for a spin. Fantastic car 🙂


It’s no Caterham, but it is rather nice