On the home straight with the Stag’s shafts
Picking up where I left off my Stag report in the November issue, now that I had manufactured all the components for fitting the CV-jointed driveshafts it was time to assemble everything.
The original shaft sliding splines were located midway along the shaft and were a relatively small diameter that allowed the complete assembly to be withdrawn as a single piece through the trailing arm. The upgraded shafts were a completely different design comprising a large diameter cylinder that is bolted to the differential flanges, which contains both the CV joint and sliding section. The larger diameter of inner section prevented it from passing through the trailing arm bore, so the replacement shafts required fitting in two sections, meaning the hub assembly had to be removed from the shaft, thus allowing the shaft to be inserted from the differential side. Since the outer CV joint diameter is slightly smaller than the bore in the trailing arm, this was able to squeeze through.
Once the hubs were off the shafts, they were trial fitted to the trailing arms to ensure that the locating spigot would fit into the bore of the trailing arm. The driver’s side was fine, but the hub spigot on the passenger side would not push into the trailing arm, and even light tapping with a soft faced mallet would not allow it to locate correctly. I did not want to force it in which would make it very difficult for later removal, so it was gently levered out and checked to see where it was binding. There appeared to be a single high spot adjacent to a stud that was identified by a mark on the aluminium bore. A hand scraper was used to remove the excess material from the bore, and after a couple more fitting trials, the hub spigot located correctly, so the shafts could be inserted through the arms.
Initially I screwed the studs into the driveshaft inner sliding joint cylinder, but now found that there was insufficient room to allow the shafts to be fitted with the studs in place. The exhaust pipes are routed below the shaft location and hindered the space available to manoeuvre the shafts into position, so the studs were removed to investigate whether that would allow shaft fitment.
The driver’s side shaft went in without a hitch, although it did take a couple of attempts from different angles before the outer CV joint slid through the bore. It was then pushed well through the trailing arm so that the four studs could again be screwed into the inner end cylinder and a spacer slid over the studs. Next the shaft was moved towards the differential and the studs aligned with the holes in the differential flange and pushed inwards, allowing the studs to pass through the
flange so that spring washers and nuts could be fitted. The nuts were tightened in rotation, ensuring that the spigots on the shaft and spacer were correctly located and the flange faces tightened squarely.
The passenger side shaft was treated in a similar way. However, when the shaft was pushed through the trailing arm, it became apparent that the stainless band holding the rubber boot in place had unclipped. I am not sure whether the band was originally poorly fitted or whether I had caught it when I was fitting the shaft, probably the latter.
I tried to refit the original band, but was unable to securely reposition it so decided to improvise by wrapping three turns of thick stainless lockwire around the boot, which was gently tightened so that it held the boot firmly in place without running the risk of cutting through the rubber.
The hubs could then be fitted to the outer end on the driveshafts and the centre retaining nyloc nut tightened with an electric impact wrench. This did not have the output to tension the nut to the correct value, but ensured that the hub was correctly seated onto the shaft. I pulled the hub out so that the sliding joint was at its maximum extension, and then measured the gap between the hub and brake backplate to double check that there was sufficient sliding motion available for all positions of the suspension. There was.
As a final check on the shaft inner cylinder concentricity, a dial gauge with a magnetic base was clamped onto the differential casting and the shafts rotated, allowing a measurement of any run out. I must admit to giving a sigh of relief when it was confirmed that the maximum run out was only a few hundredths of a millimetre. This will ensure that the shafts will not be the source of vibration due to run out. The hubs were then pushed up against the trailing arm, sandwiching the back plate so that the nuts could be fitted and lightly tightened. They will be finally tensioned with a torque wrench as it is easy to strip the thread in the aluminium trailing arms by over tightening.
“A hand scraper was used to remove the excess material from the bore”