Halfshafts
When I went up to Bardney to collect the kit I took along the half-shafts that I had previously stripped so that Jeremy could cut and sleeve them to the correct length.
I did consider getting some shafts made up and made some enquiries along with Simon Neill. I found a place that would do two pairs in EN24T steel for £180, but I decided that the sleeved shafts would be up to the job with only 80lb.ft or thereabouts from my engine. Simon’s sleeved joints also seem to be holding up to plenty of abuse with his CBR1000 engine and semi-slicks too.
The sleeved half-shafts I received from Sylva’s contractor were actually very good. Jeremy explained that mine were the only pair of thinner shafts they had done as most people had sourced the more commonly available thicker tripod and lobro type shafts. It was nice to see that they had put some thought into it and actually analysed the loads too and sleeved them accordingly. In the end my shafts had also been turned down and a smaller diameter sleeve used to keep the weight down, yet still plenty strong enough for the bike engine – a typically Sylva bit of detail. They were also cosmetically very tidy with the welds ground down flush and the visible section of the shaft powder-coated.
The rear hubs were removed from the uprights and the two pairs of tripod joints were easily rebuilt in the time honoured put it back as it came apart manner. I had previously stripped, cleaned and labelled the tripod joints and obtained four new boot kits comprising rubber boot, metal sleeve, o-ring, grease and sealing clips so the job was easy enough: First push on a rubber boot and sleeve and then refit the inner tripod joint part with o-ring on the end. The chamfered end of the inner tripod half faces innermost and each of the three bearing surfaces should be lined up with the grooves in the metal sleeve. While you remember, put the o-ring on the outer tripod joint half, because it gets messy when you put the grease in. The spring goes back into the centre of the outer part of the tripod with the metal cap facing toward the end of the half-shaft. The whole assembly was then packed with grease and the metal sleeve slid over the outer tripod, pulling the two halves together. Slide the outer sleeve over the outer half of the tripod joint and over the o-ring to seal before you push the shaft in too much and squirt grease out of the end. I found that the whole assembly was difficult to keep closed because it was air tight and the compression was making it push apart again. It was easy to bleed air out of the rubber boot by sliding a screwdriver under it and squeezing the air out whilst pushing the assembly together. With the outer sleeve fully home it was simple to tap the end over the chamfered edge of the tripod with a hammer to secure it. Finally attach the clips over the rubber boots to seal them. I couldn’t bend these to the exact, flattened, shape of the originals and simply squeezed them with a pair of pliers and then bent them over, which had the same effect.
Both complete half-shafts were then inserted back into the diff through the uprights and bolted back to the uprights, which compressed their length by about half and inch. Whilst putting the hubs back on I also attached the brackets for the rear brake callipers, which had been powder coated and put to one side ready for final assembly. A new pair of hub nuts was also used as these are torqued to a ridiculous 250lb.ft and therefore must not be re-used.
With the shafts back in the diff it was then possible to put some oil back in it. The Ford Sierra diff needs a GL-5 spec oil and following the advice of the Gavin Scott I refilled my diff with Redline 70W75 ultralight shockproof gear oil, which incidentally looks just like runny custard (all I need now is a banana in the gearbox :-). The idea behind this gear oil is that a bike-engined car has much lower loads on the diff than a heaver car does and the superior performance of the Redline gear oil would enable me to run their very lightest oil, which will mean that the diff should transmit more power to the rear wheels and it will go faster, which is always a good thing. The oil is supplied in a U.S. Quart, which is 948ml, not quite enough to fill the diff right up to the fill/drain hole, but only about 5mm short, which is fine.