Build Session #11 – Not too Diff-icult

Two days gone and we had almost competed everything on my target list; the only bits outstanding were because we needed some information from Derek. We therefore moved on to the rear of the car to tackle the differential and rear suspension.

Fitting the differential is almost legendary within the Caterham build community and I had read many horror stories of trying to get the 11 inch bolt into place. The 2014 manual now recommended hanging the diff through the top holes while it is centred around the lower mounts. While one of the Team Ivans support crew (my sister) went to B & Q to by a length of 10mm steel rod to fulfil this task, Carl and I laid the De Dion tube on the workbench to fit the brake pipes.

Before you can fit the pipes it is necessary to “dry fit” both the De Dion ears and the brake callipers. Whereas the front callipers had come ready assembled, the rears were in pieces and there was no mention of putting them together in the manual. using a bit of trial and error plus staring intently at photos in the rear suspension secant of the manual we figured it out. It was then we discovered that assembly of the callipers IS covered in the manual, in chapter 17, options!  It was good to see that our educated guess was correct, but we took the time to fit the brake pads as well.

The brake pipes were laughably inaccurate in the way they were bent to meet the callipers. Andrew Bissell makes a great statement in his build blog when he says Caterham might as well provide them straight and let you do the bending!!

By this time the metal rod had been delivered, so we switched over to the differential. Before installing the propshaft and diff you need to assemble and fit the handbrake. We had searched for a long time for the clevis and pulley and were convinced they were yet another shortage, but eventually Carl found them in one of the polythene bags. We fitted the pulley and cable and then bolted the handbrake into place.

Fitting the propshaft was straightforward; after a tight squeeze through the transmission tunnel, the splined end slid onto the end of the gearbox easily.

Despite all the horror stories our differential went in remarkably smoothly. We took it very slowly, had three people. one manning the jack at the rear plus one either side guiding and steadying. Once the rod was in it we used the jack to adjust the differential to line up with the lower mount holes. In order to centre the diff we used two thick and three thin shim washers on one side and ended up getting it within +/-1mm each side which we felt was good enough. Then we turned to the top bolt. It now comes with the ends chamfered to 45 degrees and having smothered it in copper slip we began to tap it into the hole. It ended up going in really smoothly, with only some gentle persuasion from the soft hammer.

We were feeling very smug when we read the next section of the manual that says the top bolt needs shims fitted too!!  We therefore had to remove the bolt and re-insert it having fitted the requisite spacers, but even that was straightforward. Checking the centring again shown that it was still +/- 1mm.

Having removed the callipers and ears from the De Dion we laid that across the rear chassis members and went to fit the spring damper unit. It was then we had the first setback of the day. There were no bolts to fit the bottom of the damper unit to the De Dion and it was now 4:30 on New Year’s Eve! Although frustrating, we decided to call it a day and move onto the evening’s festivities.

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