Day 6: Handbrake, Prop shaft and Diff

Day 6 of the build was another one of the so called “big days”, where the aim was to complete the day with the prop shaft and differential fitted, and with no injuries entailed.

Craig popped over again to assist, as this assembly stage is definitely a two-man job.


I’m now building a little out of suggested build sequence, as I haven’t finished the front end from a radiator, oil cooler and fluid pipe work perspective, but I chose to do it this way around because of Craig’s availability, and also my urge to do something big and not tinker, as the Day 5 was a “small jobs” day.

Once I had located the clevis and split pins, which were in different bags – hint the split pins are hiding in the fixings bag for the handbrake bolts, but the clevis bolts and pulley wheel (or mine at least) were in the lighting box, illogically…

With an SV, you don’t put a twist in the cable, just leave it as a large loop. It was a very simple task, but I had to enlarge the lower hole for the large clevis pin that fits through the pulley wheel, as it was out of alignment. A round file did the trick.

The handbrake knurled wheels to tighten eventually fit really tight to the front of the diff, I hope it’s easy enough to adjust later in the build.

Prop Shaft

So long as its inserted from the rear end high enough up, and rotated a little on insertion, the prop shaft fits down the tunnel, but it was snug during the “push through”. It slipped immediately into the end of the gearbox mounting, splines mating perfectly.

I was concerned about pulling the cover off the end of the gearbox because the Mazda 5-speed is pre-filled with oil, which surprised me during unpacking when I had a nosey and a little oil gushed out. In fact Caterham don’t provide any other gearbox oil, as its not not a requirement to fill.

So I was ready with my oil drip pan just in case, but mounted in the car and with the rear end slightly higher on the axle stands (left it that way after engine insertion), the gear box did not leak any more oil and fitting was a 5 second job.



So now the challenge of the diff. Yep, it’s fairly heavy, yep, you don’t want to be lying underneath it if it falls off your jack as you raise it. But other than those safety warnings, it wasn’t too difficult. To give us more height we sat the diff on a piece of wood on the jack and slowly raised it into position. Then jammed a very long and heavy duty screwdriver through the top mounting hole and diff as it aligned.

This meant we could then tweak the height of the diff with the jack without fear of the diff falling. Once the bottom holes were aligned I inserted pre-copper slipped bolts with 2 spacers on each side. No messing, no issues, no mallet needed.

At this point I measured from the bottom side of the diff bracket (as it was symmetrical, and the diff case isn’t) to the box section rear hole point where you mount the rear ARB.

The measurement showed I was 4mm closer to the RHS, so I switched the spacers over to be 3 on the RHS and 1 on the LHS. Re-measured and got exactly the same on each side…perfect.

Then onto the top bolt, which came pre-chamfered. Again Copper Slip everywhere and I fiddled around with spacers. My diff needed 5 spacers on the RHS and 1 on the LHS. I couldn’t get any more in, and i knocked these in by sticking them together with copper slip, and then pushing them in with the flat blade of a screwdrivers.


It was really satisfying getting it all together and then final torquing and paint marking the bolts. In other folks builds the diff comes with BMW caps over the drive shaft holes, and people have reported that you have to knock these off and throw them away. With my diff, these caps were not present, so one less thing to do 😉

4 bolts are required to fit the prop shaft to the diff, and to do this you have to slide the prop out of the gearbox a little, and make sure that you aligned the 4 (out of 8) holes on the diff side that are threaded. Insert bolts from the gearbox end backwards and tighten to the correct torque. One of these was a problem because I couldn’t get my socket onto it because of the placement of the grease nipple around the CV joint. In the end I felt the torque on the other 3 bolts and gauged it on this final one. Its either the same or very slightly tighter, and that’s fine. Trusty paint pen got a lot of use today, marking up all of these bolts to make it easier to spot any future issues.


The joy I feel at key points in the build is still rather special. I have no specialist skills, I have to read things through a bunch of times and play through in my head how things may go. But all of this is fine. Its a really good “focus” job and all of my other worries (which are work related) just dissipate.

My wife reports that I walk into the garage with a frown, and I leave with a smile….

Have a nosey into the diff:







Day 5: Engine Electrics, Steering, Front Lights

Day 5 overview

Today it was a little scrappy. I had a few moments where the assembly guide was unclear and I wasted time researching on BlatChat, and I had an attempt to install the radiator cowling only to realise it needed some “reshaping” of slots for ARB and actually there was a more efficient sequence, but more on that a little later.

Engine Electrics

The assembly guide is generally OK in this section and most of the engine loom to chassis loom wiring is straightforward, its just that Caterham has not updated the wiring colouring that describes the odd cable in the guide, and these kind of basic challenges make you question if you have connected things up correctly.

Having said that it is all really obvious and doesn’t take too long. The only part of the instructions I had to query online regarded the battery positive cable to starter motor. It took me a while to realise that its switched on the negative side, and that you connect this fat cable directly to the positive pin of the starter motor, and along with the 2 brown ring terminated cables from the car loom. And then the problem is that this terminal thread is fairly soft and also on my car chamfered at the end, so getting all 4 cables on (3 existing and the battery cable) + the spring washer was impossible. It simply wouldn’t catch on the thread. In the end I removed the washer and Caterham can decide what to do at the PBC with this.

And then there are the odd set of cables from the engine that aren’t used at all. In particular the following 4, which I will tape up using self-amalgamating tape and cable tie to the chassis at a later stage. The assembly guide tells us to connect the battery, but I don’t see the point at this stage, I can leave that until near the end of the build.


I then connected other items – the hydraulic clutch banjo bolt and the fuel line connector, which is a click on, and special tool to remove. I made sure I was happy with my loom wire routing before doing this.


I haven’t had my exhaust bits back from the polisher yet, but I have read in other blogs that you can finish the steering and then guide the primaries around the steering rod without too much hassle. Its not the end of the world if I have to remove it again at that stage, so I cracked on.

I have heard horror stories about problems with lower and upper bushes, but I found the whole assembly really easy once I used the correct lubricant. I played for a few minutes with Holts rubber lubricant, but in the end washing up liquid was the solution for the problem of inserting the steering rod through both bushes. The lower bush is already in place at the bulkhead end, and others have had problems with both insertion of the upper bush (use washing up liquid!) and guiding the steering rod through both upper and lower (washing up liquid!).

From start to finish this job took less than an hour, including final torquing of the steering rack fixings.

The only problem surfaced at the end, when I test fitted the steering wheel to find that the bolts to attach the wheel to the quick release boss were not the correct countersunk ones. Derek is sending some of the correct variety!

Front Lights

I was going to finish the day trying to work out how to fit the radiator cowling and SV brackets (slightly different instructions to a S3), but to my dismay the inner cowling slots were not shaped to take into account the position of the anti-roll bar. When I did a loose dry-run I also noted that once the ARB is fitted, access to the front upper suspension bolts is impossible without ARB removal again. The knock on effect of this is that it was time to fit the front headlamps, as these fit on a bracket that is attached to the front upper suspension mounts.

I had previously been shopping for a few extra bits and bobs to help with headlight fitting, namely heat shrink in two different sizes. this is because it has become widely know that another self-builder, Daniel French, devised a much neater way of both handling the wiring and fitting the headlamps. His instructions come with some great pictures, and in full colour/high definition, putting the Assembly guide to shame. To read these instructions just click here. As Daniel says, the first light takes a while and the second is completed so much faster as you get the hang of the process. Really good way to end Day 5, super happy with my progress at this stage.



Day 4: Engine In

But Before the engine, the brakes had to be completed…

During the week I received the missing shake proof and 3/8th inch washers for the front brake pipes. I was in the garage on Saturday morning around 9:45am and sorted that small job out in ten minutes flat. The aim was to be ready for engine hoist erection by the time Craig and another good friend Paul came around at 10am.

The assembly guide for the flexible brake pipe fitting is OK,  but the pictures below should really help other self-builders. For reference I have the upgraded brakes, but the process is pretty much the same irrespective of your brake option.

Initially I removed all red and yellow plastic protective caps from hoses and callipers. I started with the flexible hose on the outer skin, and used the flat washer against the paint work. I then placed the shake proof washer on the inner skin and the nut that comes in the small bag with the brake hoses. I finger tightened and then seated the fixed brake pipe brass sleeve over the flexible pipe end, and tightened the sleeve, again finger tight initially.

I then moved to the calliper and screwed the female to female fitting finger tight into the calliper, just adding the copper coloured flat washer first. There seemed to be only two ways the flexible hose would position itself, based on the rotation of these fixings. The photos you see was the only way to fit these without them fouling on the steering, and it all seemed pretty obvious and straightforward.

Flexible brake hose in its natural curved position. Both sides look similar, and tests of steering lock-to-lock show no fouling

Tea break and hoist shenanigans

When the 3 of us were in the garage, we had a chat about the order of events, and then had a cup of tea to settle into the day ahead. I had borrowed the engine hoist from another friend, but none of us on the day had used one before. The hoist came without a load leveller, so I had purchased one from Machine Mart a month or so back in anticipation.

The hoist folded out and it was obvious that we needed to move the chassis further back into the garage to create enough space at the front, and also to replace the 2 axle stands at the front with just one under the centre chassis crucifix point.

This took all 3 of us to shift the car back, lifting at the back end, and using a jack at the front end. We then needed Steph (my wife) to quickly move the rear axle stands into their new position. I should have considered this requirement up front, and also it is so much easier with a single axle stand at the front, as it gives much more space for the legs of the engine hoist.

IMG_1547 (1)
Dry run: chassis lifted further back into garage, single axle stand at front now, stops hoist legs fouling on axle stands

Load Leveller

The Duratec engine has two diagonally opposed hoist mounting points, which is OK, but unfortunately twists the engine and gearbox assembly around, so that it’s roughly 10 degrees rotated axially. But more on that later…

Other than this rotation, it was plain sailing to lift the assembly and adjust the pitch of it so that the gearbox was pointing down roughly 30 degrees. This is the initial angle of insertion. Be warned, its like threading a needle. Imagine reversing child birth and trying to get the baby back into the womb. And this is with an SV. Or to continue the analogy, a “larger boned lady”.


Prep before insertion

I had read more than enough other blogs to feel confident about what I needed to do before the insertion. We removed the RHS engine mount arm, the alternator belt, the alternator itself and then cable tied it up to the plenum above. We got a fair way into the insertion when we decided that it would be easier to remove the LHS engine mount arm too. The belt was particularly simple, as its on a spring loaded tensioner and took just a few seconds to slip off. reversing this process was equally simple.

Trying to undo the bolt with the spanner attached actually pushes the sprint tensioner to the left and allows you to pop the belt off easily.


There were moments during this process, which, by the way, took hours, where I was convinced that it would never fit. The real challenge was the unavoidable rotation of the assembly, which needed the help of a short piece of wood and a jack under the bell housing to straighten up. In addition, the 5-speed gearbox is really, really tight in terms of its lateral clearance along the transmission tunnel.

The assembly guide implies this, but at the end of the day both the left and right side of the gearbox touch the transmission tunnel (or at least are rubbing up against the heat resistant sponge/foam that was pre-fitted. I have no solution for this, as there is little or no movement left to right, and therefore nothing that would make an appreciable difference. at least the gearbox looks centred from above and from the back of the car.

Even when we thought we were really close to solving the puzzle, we were actually another hour away, not including another tea break. Clearing the front diagonal cross member on the LHS was the biggest challenge. It really is a case of “down a bit, back a bit, level a bit” almost ad infinitum until the engine block confidently clears the chassis by half a millimetre (with foam lagging removed)

IMG_1554 (1)
The tightest clearance was the bottom front corner of the engine block on LHS, the bit immediately above the bar code sticker on the pipe lagging above. It seemed that it would never clear the lower diagonal…


Gearbox bolting

We were finally in a position to bolt the mounting plate to the gearbox from underneath the car, and then bolt the plate to the chassis.This was fairly easy, although we needed a long wobble bar inserted from above to be able to torque the captive nuts from below to the right torque setting. The trick is to NOT fully torque them until both engine mounting arms are re-attached to the engine block and then attached the the engine mounting rubbers.

Ancillary re-attachment

It was, as previously mentioned a 2 minute job to reattach the alternator belt, and not much longer to sort the engine mounting arms out, or reattach the alternator. Simply reverse the previous procedure.

The challenge was getting the long bolt to fit in the LHS mounting hole in the mounting rubber. I had to remove the plate that holds the washer bottle on, via the 4 small 8mm bolts, and then drop it out of the way.


I then fully torqued and paint pen marked the gearbox mounting bolts from under the car, but didn’t fully torque the front engine mounts, as the long bolts require an imperial allen torque bolt, and I don’t own one. So I hand tightened using a large allen key and I’m off to B&Q or Halfords again tomorrow for yet another purchase.

5-speed gearbox chassis mounting plate, central large bolts to gearbox, outer cap head bolts to chassis. 

Engine Hoist removal

We were then, five and a half hours after we started, able to remove the engine hoist and congratulate ourselves. This was a simple job and as the hoist was retracted it was difficult to describe the feeling of pure unadulterated joy. We all felt it, and I can’t remember the last time I felt this good about any achievement. It’s magical.

Bob (background, left), Steph (left), Paul (right)

Exhaust gone

I finished the day by driving my exhaust components around 45 minutes north to a place in Eastwood near Nottingham that does metal polishing, as previously mentioned. I should have a satin finished exhaust back with me within 2 weeks.

Engine insertion  video

This is the big day, all 6 hours converted into a 1 minute stop motion animation video. With cameo appearances by by father-in-law Bob, my next door neighbour Andrew, and my lovely wife, Steph.At times it felt like a party. Enjoy!

Fun Photos

Some of the nutters in my life, and a well deserved glass of wine, just before I started typing this blog this evening.


Day 3: Final prep work prior to engine install


Had a great family holiday over half term to Italy, Lake Garda area, and therefore was not at home in the garage working on the car. I was aiming to work this last weekend both days, but a big party night on Saturday pretty much killed me off on Sunday. I managed to mow the lawns in the afternoon, but still felt grotty and hungover. So day 3 efforts were all about Saturday.

Pipe Lagging, Washer bottle and Heater

A quick trip to B&Q in the morning for some standard plumbing foam pipe lagging and it was easy to protect the engine bay chassis tubes in readiness for the engine installation.

The washer bottle apparently needs fitting before the engine gets installed, and it appears from other blogs I have read that this is due to both the routing of the rubber tubing and the poor access to fit the bottle to the mounting plate afterwards. It was all really straightforward with the exception of the fact that I had to snip a tie wrap that was running close to the top right corner of the bottle as you look at the overhead bottle shot. The cables were running too close to the bottle and needed repositioning under the cross member.

The Heater unit was the next item to install, and this was very straightforward, but a little fiddly to tighten up. I had two minor issues with the heater though. The first is a known issue. Basically the vent plate that mounts behind the bulk head in the cabin comes pre-attached one way up, but many other blogs indicate that the mounting plate needs to be rotated 180 degrees.

This seems weird to me, as this means that the “legs” on the vent plate point downwards and also stick out over the bottom edge of the inner bulkhead. It looks silly, but is apparently correct.

Look at the following picture as a guideline. When complete, rotate the vents so that they point downwards, again as per the image.

This is wrong, but looks right!
This is right, but looks wrong!

The second issue I had was that the top mounting screws were nowhere to be found. Or at least not in the bag I was expecting them to be in. I found screws that looked right and fitted in a miscellaneous chassis fixings bag. Like everyone who has built a Caterham before me, I seem to spend more time searching for fixings than actually fixing things.


The job was fully completed by using a bead of clear internal and external use silicone sealant I picked up from B&Q when I bought the pipe lagging. I also squirted this on the inner edge of the heater unit, all the way around before I bolted the vent face to the heater. A sort of belt and braces approach to try and avoid a little future water ingress into the cabin.

The assembly guide and other build diaries don’t mention that the vertically situated Banner battery is very close to the top lip of the heater unit, and when dry fitting the heater, I felt I needed more space and the battery wasn’t slid as far forward as it could have been. You can see in the bottom left of the picture above one of the four slotted battery cage mounts. I loosened and slid the mount a little to the front of the car, and also whipped out the battery to make fitting the heater easier.

Very tight fit between heater and battery

Engine / Bell Housing / Gearbox

My kit is the 420R Duratec, with the 5 speed Mazda gearbox. The installation instructions are a little odd with this configuration in one tiny area. They basically tell you not to remove the bell housing from the engine. But that’s simply untenable, as bolts have to go in from the bell housing to the gearbox, and its impossible without having access to the inner face of the bell housing.



You can see the sneaky trick with the cable ties on the bell housing to engine bolts. They are different sizes, and to avoid having to sort through and remember or get them in the wrong order, I simply cable tied them temporarily, then when it came to refitting to the engine later, I could just slip off the cable tie on each bolt. Anything that saves me thinking too hard is a good thing!

You can see how I would HAVE to remove the bell housing to gain access to the 4 more centrally mounted caphead bolts for the gearbox above too.

It was a two man job and I had help from Craig again today. What we did was keep the whole sub assembly as low as possible, and used my Halfords creeper to rest the engine on. We then used some thick card and a few bits of wood to raise the gearbox and attached bell housing to the same level as the engine.

Craig stopped the engine and creeper from moving and I then tried to slot the gearbox and bell housing into the hole and align the splines. It took a few little rotations of the gearbox shaft by finger (super light and easy to do) before it all slotted together easily.

I then tightened each bolt in a clockwise from front of engine order as dictated and the job was complete.

Engine mounts


The two remaining jobs for the day were engine mounts and horn fitment. This should have been easy, but turned out a little more complicated than planned.

Basically the RHS engine mount is too close to the chassis tube triangulation point welds. You can see from the above picture that I had to get my Dremel out to grind a little piece of weld away to get the mount to sit flat.

Once I was happy with the minor operation, I used some smooth black Hammerite to paint over the bare metal and then much later in the day I could attach the mount properly.

The LHS mount also needed minor surgery, but this time it’s because it also is a mount point for the engine earthing cable, and I had to file the coating from both sides of the mount and the chassis tube to ensure a good earthing contact patch. We tested this afterwards with my multimeter and all was good.



Final job of the day was to fit the horns, and this was a little nerve-wracking as a 420R with dry sump requires the horn to be mounted in such a way that you have to drill a hole in the chassis steering rack platform. The picture in the assembly guide is not 100% clear with where this should be, but I’m pretty damn sure we drilled in the right place.

8 mm hole drilled front centre of steering rack platform

The fun bit was then identifying where the “special” mount bolt and sleeve for this was. It was in a bag on its own in the heater box. Took 30 mins to find….grrrrr…

So that was it really, a fun and gentle day, lots of cups of tea, sunshine and a nice lunch. Exactly how I hope each day goes on the build, with zero stress. This is really good fun so far!

Enjoy a picture of the whole car so far, you can see the horns mounted on the shot below.


Out of sequence front brake pipes

Something I should have completed on day 2 after the suspension assembly was the front brake pipe and flexible hoses mounting. But I couldn’t because I simply didn’t have either the plain washers or the shake-proof ones. I put a call into Derek on Monday morning and the washers arrived today. I will sort that out before the engine goes in over the weekend.