Whatever the choice of cutting fluid and however well the hole appears to have been reamed there is no ignoring the fact that reaming is a flawed process for this application. The reamer will usually follows the curvature of the hole. So if the tubes distort during welding you will end up trying to fit a straight pin to a banana shaped hole, not ideal! So perhaps this is a hidden contributor to early onset KP slack on some cars.
Time for a re-think please Morgan
If the correct reamer is used, both bushes will be reamed perfectly in line because the reamer goes through both bushes at the same time so if the reamer is straight the bores will be in line.
The reason the bushes are reamed after fitting is, partly, to allow for the fact that the original bores in the welded tube may not be in line.
Even if the hubs were line bored first, we would still need to ream as the bushes close up slightly when pressed in and not always by the same amount depending on exact material and fit tolerances.
Of course Morgan could do a proper job and use a one piece fully machined forging but if fitted correctly and reamed properly the initial fit of the bushes will be fine.
What happens after that depends on what materials are used, such as hard chrome versus mild or stainless steel, bronze versus Devol or Vesconite bushes and how the assembly is then maintained by regular greasing and cleaning (or fitting gaiters.)
But if everything was perfect we wouldn't have anything to tinker with or write about and we'd all be driving Porsche Boxters or Mazda MX 5.
