From: Barry Lovelock
Date: 31 Oct 2002
Time: 09:17:34
Remote Name: 81.98.81.219
There is absolutely no need to go Philistine (Metric), even though Austin did use some odd types themselves. Beware in particular of the non-standard tpi on the halfshafts and radius rods for instance. In the main, the threads are BSF, not Whitworth and they are all available from many suppliers, in the UK anyway. The Metric threadform is a bastardised one with the tops cut off! Mr Whitworth was a genius when he designed his thread, but with full forms they do bind on occasion. I always like to use original bolts where possible, but not in the engine, steering/suspension etc. that doesn't leave much! Always use HT (High Tensile fittings - all Metric ones are but that's no excuse!). They are marked for instance with an "R" for the basic HT sort, "S" for the next etc., etc., most are R rating and perfectly adequate. Don't use bolts where setscrews should be used and vice-versa. Basically, only use old ones on mudguards and other trivial parts; there are special ones needed in certain parts of the engine however, like the shallow-headed ones at the back of the crankshaft, securing the bearing retaining plate. The Aussies and others use modern seals here, but leaks only really come from the gearbox and with a proper thrower fitted clutches stay dry, but I digress!
For suppliers: Namrick and Bernie the Bolt are two that spring to mind. Buy Practical Classics and look at the small ads.
Use nylocks or other self-locking nuts on the big ends. Don't stretch the threads; don't damage them; use only bolts (these are the ones with a parallel, non-threaded part as well as the thread - setscrews are all thread) for the small ends. And either replace the big end bolts or very carefully check they aren't stretched by looking to see if the thread pitch changes along its length. I use Loctite Studlock on the small ends and big ends too; others may prefer nutlock only. As an aside, the gudgeon pins MUST be a tight fit in the conrods of these bolted small ends, or they will fail.
Barry.