[Healeys] BN2 screw in the center of the dash

[David Nock BCS]

Here is the real story of the Pozi and Phillips Screws as they say it came right from the horses mouth. In 1996 my father interviewed the Phillips family the designer of the Phillips and Pozi Screws. They personally approved this article that my father wrote on the Phillips Screw the Austin Healey Magazine. This and many other articles are in our Healey Tech Talk Book.

The bottom line is the Phillips Screw is designed to slip out at a pre dertimined torque, and the Pozi Screw is designed to not slip out. 

And the Pozi Screw was developed in about 1956 for the automotive industry so there is no way that they could have been installed on a BN1. 


David Nock
British Car Specialists
209-948-8767
www.britishcarspecialists.com




From: Henry G Leach via Healeys 
Sent: Monday, March 22, 2021 9:47 AM
To: 'Bob Spidell' 
Cc: 'Healey List' 
Subject: Re: [Healeys] BN2 screw in the center of the dash

Guys-pozidriv screws were used on the later 3000, etc. as a production item. This type of screw was used with a special tool to "quickly" install screws on the line. It was another way BMC was trying to make a buck on underpriced and over-difficult assembly of vehicles. Then they went broke...Hank


-----------------------------------------

From: "Bob Spidell" 
To: "Curtis Arndt"
Cc: "Healey List"
Sent: Monday March 22 2021 9:01:24AM
Subject: Re: [Healeys] BN2 screw in the center of the dash

Thanks for the correction, Curt. I'd always wondered why 'posidrive' screws were used--I think posidrive is a relatively recent development--and why regular phillips drivers worked in them (I think posidrive has a steeper angle of the screw blades). I have a posidrive screwdriver, but I usually grabbed whatever was handy. Do you know of a source for the correctly marked screws?

Do you know if the backing flat washer was tapped (I don't think so, but I'm not sure). IIRC there is a tapped plate that binds the screws--again, chromed--that attach the rearview mirror.

Bob



On 3/22/2021 7:59 AM, Curtis Arndt wrote:

  Hi Bob and Joe, 

  Just a quick correction, "Pozidriv " screws were never used on AH 100s, BN1/2s.  

  The four marks on the head of these 10-32 screws were there to denote UNF from "Whitworth" during the changeover to the Unified screw thread forms in the 1950s.

  I've attached a page from my vintage Machinery's Handbook which illustrates this fact.

  Cheers,

  Curt

  On Sun, Mar 21, 2021 at 11:27 PM Bob Spidell <bspidell at comcast.net> wrote:

    I neglected to mention the screw is backed-up with a large, extra thick flat washer (because of the large hole in the bracket). It's unique because it's as thick as a couple of typical flat washers and might--I don't recall for sure--be tapped for the screw.


    On 3/21/2021 10:21 PM, Bob Spidell wrote:

      Yep. And, the original screw is chromed posidriv, with a slightly oversized--the screw is a #10 IIRC--chrome washer. I noted this when we tore down our BN2 for restoration, and promised myself I'd not lose these. I lost them (and have never found proper replacements).

      You can sorta see them in this grainy photo (I shoulda took more).

      Bob


      On 3/21/2021 4:14 PM, Joseph Costa wrote:

        Does it just attach to the brace behind the dash? 

        Joe 
        BN1 #923
        BN2 100M
        BJ8 Blue Baby




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