You may be right, although Mr Suhring just sent me an e-mail saying that the
1/8 NPT tap worked perfectly. I just assumed that, as most of the other
fasteners on the car are Unified then the grease fittings would be to the
American standard, also.
BTW, you were not comparing apples to apples in your diameter comparison.
The MAJOR diameter of the 1/8 NPT straight thread is .390-.397". The MAJOR
diameter for a 1/8 BSP straight thread is .383". The diameter of .405" that
you reference is the OD of a 1/8" pipe. Also, tapered threads are usually
specified for pressure-tight joints, which grease fittings usually are.
My source:
Machinery's Handbook, 20th Ed.
----- Original Message -----
From: "fogbro1" <fogbro1@bellatlantic.net>
To: "Michael Marr" <mmarr@idcnet.com>
Cc: "suhring" <suhring@lancnews.infi.net>; "triumph mailing list"
<triumphs@autox.team.net>; "John Krause (home)" <jktr250@aol.com>
Sent: Thursday, October 26, 2000 9:16 PM
Subject: Re: Grease Nipple Lower Wishbone
> Beg to differ. I dug out the tap for this application. It's marked
> 1/8-28 BSPP G HS 55 degrees. It is not tapered. I would guess that the
> second "P" is for "plug" as in plug tap, which this one is.
>
> A 'Merican 1/8 NPT is greater in diameter, .4050" vs. .3830" and has
> fewer threads per inch (O.K. 1 fewer), 27 vs. 28 than the BSP. I don't
> believe you'll find a grease fitting in your local auto parts store that
> fits the wishbone properly and that's because it's not a 1/8 NPT.
>
> Yeah, I'm a nit picker, but I have a pet peeve about proper fasteners.
>
> Ed Woods
>
> Reference: Metric and British catalog no. 3010; Metric and Multistandard
> Components Corp.
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