Build Session #9 – Cooling & Wiring

The Christmas festivities were over and we were planning three days of work on the car in the lead up to the New Year. I had set an objective of the following tasks:

  • completing the front uprights and brake lines
  • finishing the engine electrics 
  • installing the cooling system
  • fitting the exhaust
  • fit the steering column

This would get us complete all the way to the end of chapter 8 of the build manual. 

Now that Derek had sent a replacement nut for the inner hub we were able to complete the left hand upright and then install the alternative brake hoses that he had sent the previous week.When we looked at these new hoses we realised that our set-up matched the description and photos in the “uprated callipers” section of the manual on p70. We certainly had not specified the option so wondered whether we had a hybrid version or if it was just another example of out of date manual by Caterham.

The new hoses have an adapter which screws into the inboard side of the calliper. These need to be tightened to just 10nm and need a deep socket to reach the nut “edges” over the thread which connects to the hose. Our deep socket was a 3/8″ drive, but the torque wrench which went as low as 10nm was a 1/4” fitting. Although we had plenty of adapters that allow a smaller socket to be fitted to a larger wrench, we did not have any that did the opposite. We found that such converters do exist and added one to the purchase list on the whiteboard.

When we had been fitting the gearbox to the engine we noticed that oil had dribbled out of the overflow hole when we turned it over, but we did not know whether it was filled to the correct level. The fact that the box of lubricants contained gearbox oil also suggested that we should check. We removed the filler nut; not the famous 3/8″ allen bolt as the 2014 5-speed ‘box now has a much more mundane 19mm bolt. We pondered the best way of getting the oil from the bottle into the filler hole and found that Camelbak drinking bottle hose fits perfectly onto the spout of the supplied bottle of gearbox oil. The only slight confusion then was that we had different grades of oil supplied in the fluids pack; SAE75W-80 GL4 and SAE80W-90 GL5. The manual specifies… SAE75W-90!! Neither of us are oil experts, but we guessed it would probably not make a huge difference but as Derek had said he would be answering emails over Christmas we sent one to check. He came back within the hour to say that the new gearbox was already filled with oil!!

So having wasted forty-five minutes designing our patent gearbox oil filling method, we moved on to the cooling system. I talked my routing diagram through with Carl before laying out the pipes to determine where each went (see photos for later references). The first task was to fit the radiator and as our car was an SV it needed two mounting plates fitted to the front of the car before the rubber radiator mountings and the radiator itself are fitted. The cooling fan is attached to two C-shaped plates and is then “sandwiched” between the radiator and the mounting plates. Rubber bobbins insulate the whole radiator assembly against vibration.

Completed radiator. SV mounts covered in green plastic
Completed radiator. SV mounts covered in green plastic

With the radiator in place, we fitted the large top and bottom hoses using the largest four jubilee clips in the fastener pack. Next up was the expansion bottle which fits on a brass mount bolted to the intersection of the six top chassis members. There was a contradiction in the manual as to which way this plate was mounted and the final positioning of the bottle. The bottle only fits one way on the mount and p88 clearly states the need to get it orientated in the correct direction. This means that the mount is actually at ninety degrees to the way shown in figure 57.

We routed the small 5/16” hose from the bottle round to the small outlet at the back of the engine head and cable tied it to the top radiator hose. The next hoses to fit were the ones going to the blue T-piece (different to the submarine one)

Small L and T-piece
Small L and T-piece

from both the expansion tank and the smaller outlet under the LH front of the cylinder head. We used the small L-shaped hose for the former and a length cut from the long L-shaped hose for the latter. The rest of the large L-shaped hose was utilised to connect to the T-piece to the front pipe of the modine.

Cooling Hoses

Before venturing further with any more hose fitting, we decided we needed to look at the electrical connections as many of needed to fit through the same space as the hose joining the modine to the heater would require, i.e. the gap below the throttle body between the bellhousing and passenger footwell. Using Derek’s response to my email as a guide we routed the cables towards their destinations; MAP unit, lambda sensor and at least four leads to the starter motor. We spent a long time pondering as to the best place to site the large multiplug. We were both surprised at the lack of weather protection provided for this significant connection, plus no specific location to fix it. We decided to use the power of Blatchat to see if where other builders had sited theirs, so posted a question on the forum.

We fitted the heater valve using two short lengths of hose and then routed the J-hose around to the outlet on the rear right hand side of the block, cutting the section mid-way to accept the submarine T-piece. All the main hoses were connected now, with the exception of the one connecting the heater inlet to the modine.

Whilst waiting for a response from Blatchat we fitted the fuel line, clutch hose and throttle cable. The latter was far shorter than described in the manual and those we had seen on the other build blogs. It would only go straight over the engine as opposed to round the front of the cam cover. The end going into the pedal box also looked very different so this topic was added to the “questions to Derek” list.

We also decided to fit the the airbox and trunking, given that these were also located above the passenger footwell. The manual is wonderfully vague stating fit the airbox and trunking as shown below, with a high level photograph of the airbox in place.  We used a combination of common sense and trial and error, figuring that all the bits in the package that had been sent by Derek must be used in or around the airbox somewhere. Using heat and rubber lubricant  we fitted the aluminium liners into the trunking. Three rubber bobbins screwed into the top of the passenger footwell and then the airbox itself mounts onto these with washers and nuts. We were still waiting for an air filter…


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