Hi All,
I wish I had read the correct posts on here before screwing up my crankshaft. 
I read the post where it stated that the thread (and so the tap needed to clean up the thread) was 5/8x16UNS. I had checked out the price for that tap on the website of a well known mini parts retailer some time ago for interest, which also said the same 5/8x16UNS (although that was some time ago and I see they have corrected this now) but was surprised just how expensive it was.
I never thought I would actually need one but then damaged the thread in my 998 last week with the flywheel puller (another story) so searched the web for an alternative supplier (read better price!) and puchased a tap (two actually), then set to, cleaning up the thread.
I was about to post a link to the supplier's site to save us all a couple of quid, but, heeding the warnings on here not to post technical information if you are not an expert/sure of what you are saying, when checking out other links/posts on the same subject, to my horror found a post stating that the thread is actually 5/8x16 Whitworth Form ("Special" - no real abreviation like UNS)
To put it in simple speak (apologies to those who don't need that and yes I do understand thread form, roots and crests and angles etc) the threads are different in various detailed aspects and due to using a UNS (Unified Special) tap which "opens" the thread (simple speak) it means that it was not noticeable when screwing the Whitworth Form bolt in.
To prevent this happening to others I posted this, and to save us all a few quid the same supplier does supply the correct tap - 5/8x16TPI Whitform (special)
http://www.tracytool...product_id=1108
£10 (plus P&P & VAT) in carbon steel which is probabaly OK if you only need it once like me - I suggest a second tap is probably best but I also puchased a plug tap in case - of the wrong thread of course....... 
I got them by 10AM the next day by paying the extra £5 guaranteed next day delivery which might be handy if you're tight for time (as I was, although now that is all immaterial as I wish I had looked further into it)
Reading further it seems that others may have done the same (including reputable engine builders/suppliers) and people may have used the crank/engine with sucess - I am wary of doing this as there is obviously a risk of the bolt/thread giving up and the flywheel coming off at 6000RPM..........
Is there anyone that can confirm first hand that they tapped their crank UNS and used it successfully?
Its written on several posts but..........
Alternatively, anyone know where I can find a suitable strength 5/8x16UNS bolt for the flywheel? although that brings it's own risks I know, as the thread form is not as strong as the whitworth form (detail)
Any chance of removing the posts that refer to the thread as UNS?
Cheers, Mark
