[Healeys] Reamers

[Bob Spidell]

re: "*Unified Fine (UNF)* - Identical to American SAE Fine and *Interchangeable*. The angle of the threads is 60 degrees." 


Are you sure about this one? For instance, the threads on the large U-bolt that fastens the axle to rear springs is noted as 'UNF' in, for instance, the Moss catalog. I believe they are either 5/16" or 3/8." Anyway, we tried to run SAE fine nuts on them--they'll go about 3/4" inch just fine, then jam. A thread chaser will go 3/4", then cut, then go 3/4", then cut, etc. 

Same story with some of the nuts and bolts on the shock hardware. 

bs 

-------------------------------- 
Bob Spidell - San Jose, CA 


Bob and Listers, 

For those who aren't familiar, *by definition*, Whitworth thread forms are 
those where the angle of the threads is 55 degrees versus the 60 degrees of 
of most modern threads. Therefore the five Whitworth Thread Forms 
include... 

*British Standard Whitworth (BSW)* - As mentioned as being used on the 
generator bracket and not exclusive to the 100s. 
*British Standard Fine (BSF)* - Most engine, transmission & suspension bolts 
on 100s. 
*British Standard Pipe Parallel (BSP)* *or (BSPP) *- Brass drain plugs and 
valves, fuel and brake line fittings on most Healeys. 
*British Standard Pipe Tapered (BSPT)* - As above but tapered, not used to 
my knowledge on Healeys. 
*British Standard Brass (BSB)* - Used in thin walled tubing and ALL have 
26TPI no matter the diameter. The mounting post on Lucas SFT/SLT 576 
driving lights would have been this thread form. 

Other British Fasteners that are *NOT Whitworth* include... 

*British Association (BA)* - Used in Healey instruments and fuel pumps. 47 
1/2 degree angle of the threads. 
*British Standard Cycle (BSC)* - Used on a lot of British motorcycles and 
most but NOT ALL threads are 26 TPI. The angle of the threads is 60degrees. 
Wikipedia lists BSC as Whitworth and they are WRONG. 
*Cycle engineers Institute (CEI)* - Older cycle thread superseded by BSC. 
The angle of the threads is 60 degrees. 

The following two are what the British switched to after moving from the 
Whitworth standard. 

*Unified Coarse (UNC)* - Identical to American SAE Coarse and * 
Interchangeable*. The angle of the threads is 60 degrees. 
*Unified Fine (UNF)* - Identical to American SAE Fine and *Interchangeable*. 
The angle of the threads is 60 degrees. 

Cheers, 

Curt