<div dir="auto"><div dir="auto">It's a bit more complicated than that.<div dir="auto">There is actually no such thread as an AF thread. AF refers to Across the Flats and is measurement across the hexagonal nut and denotes the spanner (wrench) size. </div><div dir="auto">i.e. a 5/16" UNF bolt is 1/2" AF.</div><div dir="auto">There was a change made in the name of the thread form early in BN1 production from SAE (Society of Automotive Engineers) some say (Standard American Engineers but are wrong) to UNF (Unified National Fine). SAE actually refers to the "Family" of threads which includes UNC and UNF. These threads have a thread angle of 60 degrees. The "F" and "C" refer to the pitch or threads per inch.</div><div dir="auto">For the most part the threads used on the brake lines of Healeys are 3/8" x 24. 3/8" diameter and 24 threads per inch. </div><div dir="auto">Whitworth refers to a different and older "family " of threads which have a 55 degree thread angle. </div><div dir="auto">I should mention that there were also some differences in the shapes used at the bases and peaks of these different thread forms which Google can help you with if you haven't already fallen asleep.</div><div dir="auto">Hope that doesn't serve to further muddy the waters.</div><div dir="auto"><br></div><div dir="auto">M</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun., Feb. 26, 2023, 3:26 p.m. Hank Leach via Healeys, <<a href="mailto:healeys@autox.team.net" target="_blank" rel="noreferrer">healeys@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Gary- The note about the type of thread used was what I was referring to-mentioned earlier. The early BN1 used AF type threads.(equivalent to a 1949 Chevrolet). All the later cars (and I do not know where the changeover was-maybe Michael does) had unified Girling threads. The lines should thread easily or else you have a different thread count and pitch. I don't think you will find the early type hoses from any supplier. They will have to be special made or found in NOS. Hank<br><br><div></div><p>-----------------------------------------</p>From: <a href="mailto:warthodson@aol.com" rel="noreferrer noreferrer" target="_blank">warthodson@aol.com</a><br>To: "<a href="mailto:gradea1@charter.net" rel="noreferrer noreferrer" target="_blank">gradea1@charter.net</a>"<br>Cc: "<a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a>"<br>Sent: Saturday February 25 2023 1:24:04PM<br>Subject: Re: [Healeys] 100 front brakes<br><br>
<div style="color:#000000;font:12pt 'Comic Sans MS',sans-serif">
<div>This car is a BN1.</div>
Yes, I was referring to the brake wheel cylinders or slave
cylinders as opposed to the master cylinder.
<div>What are you referring to when you say "<span style="font-family:arial,helvetica;font-size:small">Be sure that you
were supplied the correct threaded hose...most suppliers do not
have the early style."</span></div>
<div><font size="3">How do I identify an early style hose from a
latter style hose?</font><br>
Gary Hodson<br><br><div style="font-family:arial,helvetica;font-size:10pt;color:#000000">
<font size="2">-----Original Message-----<br>
From: Hank Leach <<a href="mailto:gradea1@charter.net" rel="noreferrer noreferrer" target="_blank">gradea1@charter.net</a>><br>
To: '<a href="mailto:warthodson@aol.com" rel="noreferrer noreferrer" target="_blank">warthodson@aol.com</a>' <<a href="mailto:warthodson@aol.com" rel="noreferrer noreferrer" target="_blank">warthodson@aol.com</a>><br>
Cc: '<a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a>' <<a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a>><br>
Sent: Sat, Feb 25, 2023 12:59 pm<br>
Subject: RE: [Healeys] 100 front brakes<br><br></font>
<div>
<div><font size="2">Do you mean "wheel" cylinders and not
"slave"...100s have a mechanical clutch. I understand that on all
model Healeys the brake hoses have one threaded end and one flared
end. That flare goes into the metal line nut.</font>
<div><font size="2"><br clear="none"></font></div>
<div><font size="2">On the early 100 wheel cylinders they used an
American AF thread but switched over to the Girling unified thread
on later releases. The bleeder connection can be either in or out
in shape (photo) but if the bleed screw is flat it uses the check
ball (supplied in rebuild kits) and fits the recessed shape. The
pointed bleeder uses no check ball. Be sure that you were
supplied the correct threaded hose...most suppliers do not have the
early style. Use Girling red grease on the threads. Hank<br clear="none"><br clear="none"></font>
<div></div>
<div>
<div><font size="2">-----------------------------------------</font></div>
<font size="2">From: "warthodson--- via Healeys"<br clear="none">
To: "<a href="mailto:healeys@autox.team.net" rel="noreferrer noreferrer" target="_blank">healeys@autox.team.net</a>"<br clear="none">
Cc:<br clear="none">
Sent: Friday February 24 2023 5:15:16PM<br clear="none">
Subject: [Healeys] 100 front brakes<br clear="none"><br clear="none"></font>
<div style="color:#000000;font:12pt 'Comic Sans MS',sans-serif">
<font size="2">I will be assisting a friend to replace the flexible
hoses on his 100 front brakes. He has ordered and received a set of
hoses, but the ends that thread into the slave Cyl do not match the
shape of the mating surface in the slave. The ends of the hoses are
flat & it is my understanding that the cyl. is cone shaped inside.
The vender says this is not a problem. I think it is a
problem.</font>
<div><font size="2">What do you say? </font></div>
<div><font size="2">Also, if it is an issue, where can we get a set
of flex hoses that have the correct ends for this application & are
also the correct length (I.E. Not too short)?</font></div>
<div><font size="2">Gary Hodson<br clear="none"></font>
<div><font size="2"> </font></div>
</div>
</div>
</div>
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