Subject: [TR] Threads and Bolts

From: Bud R <[email-masked]>
Date: Thu, 24 Nov 2016 09:04:38 -0700

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Listerati,

I=92m working on the Spitfire=92s traverse leaf swing spring rear =
suspension and can=92t find locally the 7/16=94  fine thread (20 tpi) by =
3 1/2=94 bolts that were holding the vertical link and to the trunnions =
and to the swing spring bushings.

I can find the right sizes in a coarse thread (12 tpi) grade 8 bolt and =
thats my plan. The old ones are grade 5 or in one case a bolt with no =
slash marks on top. I don=92t know what it is.
=20
Do these bolts need to be fine thread for any particular reason, e.g. =
for safety, torque specs, etc.? Is a grade 8 bolt a good idea where it =
will be stressed with all the up and down motion with the vertical link? =
Too brittle? Usually I go for grade 8 whenever possible but I=92ve heard =
there are instances where it might not be the best solution.

An aside for Thanksgiving:=20
My son and his wife teaching in Shanghai said the Chinese love to =
celebrate American holidays (they know them from American TV and movies) =
but their take on Thanksgiving is that you thank people who do nice =
things for you. So they got cards from their students thanking them for =
teaching. Kind of a different twist but a good one I thought.

Happy Thanksgiving to all.

Bud Rolofson

Extreme Parts Racing (more than just a haircut)

71TR6 CC57365 (Good 6)
71 Spitfire MK IV Race Car #3
69 Spitfire MK 3 (back up FE engine/dinghy car)
93 Minnie Winnie Race Support Vehicle=20
77 Z-50A Hardly Davidson Honda Mini-Trail Bike (Triumph Pit Bike)

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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dwindows-1252"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><div>Listerati,</div><div><br></div>I=92m working on =
the Spitfire=92s traverse leaf swing spring rear suspension and can=92t =
find locally the 7/16=94 &nbsp;fine thread (20 tpi) by 3 1/2=94 bolts =
that were holding the vertical link and to the&nbsp;trunnions and to the =
swing spring bushings.<div><br></div><div>I can find the right sizes in =
a coarse thread (12 tpi) grade 8 bolt and thats my plan. The old ones =
are grade 5 or in one case a bolt with no slash marks on top. I don=92t =
know what it is.<br><div>&nbsp;<div>Do these bolts need to be fine =
thread for any particular reason, e.g. for safety, torque specs, etc.? =
Is a grade 8 bolt a good idea where it will be stressed with all the up =
and down motion with the vertical link? Too brittle? Usually I go for =
grade 8 whenever possible but I=92ve heard there are instances where it =
might not be the best solution.</div><div><br></div><div>An aside for =
Thanksgiving:&nbsp;</div><div>My son and his wife teaching in Shanghai =
said the Chinese love to celebrate American holidays (they know them =
from American TV and movies) but their take on Thanksgiving is that you =
thank people who do nice things for you. So they got cards from their =
students thanking them for teaching. Kind of a different twist but a =
good one I thought.</div><div><br></div><div>Happy Thanksgiving to =
all.</div></div></div><div><br></div><div>
<span class=3D"Apple-style-span" style=3D"border-collapse: separate; =
border-spacing: 0px;"><div style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><span =
class=3D"Apple-style-span" style=3D"orphans: 2; text-align: =
-webkit-auto; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div style=3D"word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans: =
2; text-align: -webkit-auto; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div style=3D"word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans: =
2; text-align: -webkit-auto; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div style=3D"word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans: =
2; text-align: -webkit-auto; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div style=3D"word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans: =
2; text-align: -webkit-auto; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div style=3D"word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans: =
2; text-indent: 0px; widows: 2; -webkit-text-decorations-in-effect: =
none;"><div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space;"><span class=3D"Apple-style-span" =
style=3D"orphans: 2; text-indent: 0px; widows: 2; =
-webkit-text-decorations-in-effect: none;"><div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-style: normal; font-variant: normal; font-weight: =
normal; letter-spacing: normal; line-height: normal; text-transform: =
none; white-space: normal; word-spacing: 0px; border-spacing: 0px; =
-webkit-text-stroke-width: 0px;"><br =
class=3D"Apple-interchange-newline">Bud Rolofson</div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-style: normal; font-variant: normal; font-weight: =
normal; letter-spacing: normal; line-height: normal; text-transform: =
none; white-space: normal; word-spacing: 0px; border-spacing: 0px; =
-webkit-text-stroke-width: 0px;"><br></div><div style=3D"border-collapse: =
separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: =
normal; font-variant: normal; font-weight: normal; letter-spacing: =
normal; line-height: normal; text-transform: none; white-space: normal; =
word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: =
0px;">Extreme Parts Racing&nbsp;(more than just a haircut)</div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-style: normal; font-variant: normal; font-weight: =
normal; letter-spacing: normal; line-height: normal; text-transform: =
none; white-space: normal; word-spacing: 0px; border-spacing: 0px; =
-webkit-text-stroke-width: 0px;"><br></div><div>71TR6 CC57365 (Good =
6)</div><div style=3D"border-collapse: separate; color: rgb(0, 0, 0); =
font-family: Helvetica; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
text-transform: none; white-space: normal; word-spacing: 0px; =
border-spacing: 0px; -webkit-text-stroke-width: 0px;">71 Spitfire MK IV =
Race Car #3</div><div style=3D"border-collapse: separate; color: rgb(0, =
0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
text-transform: none; white-space: normal; word-spacing: 0px; =
border-spacing: 0px; -webkit-text-stroke-width: 0px;">69 Spitfire MK 3 =
(back up FE engine/dinghy car)</div><div style=3D"border-collapse: =
separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: =
normal; font-variant: normal; font-weight: normal; letter-spacing: =
normal; line-height: normal; text-transform: none; white-space: normal; =
word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: =
0px;">93 Minnie Winnie Race Support Vehicle&nbsp;</div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-style: normal; font-variant: normal; font-weight: =
normal; letter-spacing: normal; line-height: normal; text-transform: =
none; white-space: normal; word-spacing: 0px; border-spacing: 0px; =
-webkit-text-stroke-width: 0px;">77 Z-50A Hardly Davidson Honda =
Mini-Trail Bike (Triumph Pit Bike)</div></div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-size: 12px; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
text-transform: none; white-space: normal; word-spacing: 0px; =
border-spacing: 0px; -webkit-text-stroke-width: 0px;"><br></div><div =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
Helvetica; font-size: 12px; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
text-transform: none; white-space: normal; word-spacing: 0px; =
border-spacing: 0px; -webkit-text-stroke-width: =
0px;"><br></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline"></div></span><br =
class=3D"Apple-interchange-newline" style=3D"color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 18px; font-style: normal; =
font-variant: normal; font-weight: normal; letter-spacing: normal; =
line-height: normal; orphans: auto; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; widows: auto; word-spacing: =
0px; -webkit-text-stroke-width: 0px;"><br =
class=3D"Apple-interchange-newline">
</div>
<br></body></html>=

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** [email-masked] **

Archive: http://www.team.net/archive

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From: "[email-masked]" <[email-masked]>
Date: Thu, 24 Nov 2016 19:03:14 -0500

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Hi, I recommend you use whatever Triumph used as far as grades and pitches i=
f it is suspension or safety related. As far as pitch, fine pitch is a bit s=
tronger and more resistant to loosening, but more likely to cross thread and=
 corrosion affects it more due to the shallower grooves.

Take care

> On Nov 24, 2016, at 1:51 PM, Dave <[email-masked]> wrote:
>=20
> Bolts with no slashes are grade two.  The grade of the bolt is indicated b=
y the number of slashes plus two.  I do not recommend grade two for suspensi=
on duty. =20
>=20
> I've heard said that the trade-off with Grade 8 bolts is that they are str=
onger but more brittle.  Since I am not a mechanical engineer I cannot make a=
 recommendation on substituting a grade 8 for a grade 5 but I would be conce=
rned that the increased brittle nature may be a detriment. Considering the s=
eriousness of the consequences of a suspension failure I would think again a=
bout making substitutions.  And just about anything you need is available ne=
xt business day from McMaster Carr (and other sources, certainly).  But you m=
ay have to buy more than you need and pay shipping.
>=20
> I don't think fine thread vs coarse thread makes much difference.
>=20
> Just my opinion.
>=20
> Dave Massey
>=20
>=20
>=20
> -----Original Message-----
> From: Bud R <[email-masked]>
> To: Triumph Mail List <[email-masked]>
> Sent: Thu, Nov 24, 2016 12:38 pm
> Subject: [TR] Threads and Bolts
>=20
> Listerati,
>=20
> I=E2=80=99m working on the Spitfire=E2=80=99s traverse leaf swing spring r=
ear suspension and can=E2=80=99t find locally the 7/16=E2=80=9D  fine thread=
 (20 tpi) by 3 1/2=E2=80=9D bolts that were holding the vertical link and to=
 the trunnions and to the swing spring bushings.
>=20
> I can find the right sizes in a coarse thread (12 tpi) grade 8 bolt and th=
ats my plan. The old ones are grade 5 or in one case a bolt with no slash ma=
rks on top. I don=E2=80=99t know what it is.
> =20
> Do these bolts need to be fine thread for any particular reason, e.g. for s=
afety, torque specs, etc.? Is a grade 8 bolt a good idea where it will be st=
ressed with all the up and down motion with the vertical link? Too brittle? U=
sually I go for grade 8 whenever possible but I=E2=80=99ve heard there are i=
nstances where it might not be the best solution.
> My son and his wife teaching in Shanghai said the Chinese love to celebrat=
e American holidays (they know them from American TV and movies) but their t=
ake on Thanksgiving is that you thank people who do nice things for you. So t=
hey got cards from their students thanking them for teaching. Kind of a diff=
erent twist but a good one I thought.
> Donate: http://www.team.net/donate.html
> Forums: http://www.team.net/forums
> Unsubscribe/Manage: http://autox.team.net/mailman/options/triumphs/dave1ma=
[email-masked]

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Content-Transfer-Encoding: quoted-printable

<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>Hi, I recommend you use whatever Trium=
ph used as far as grades and pitches if it is suspension or safety related. A=
s far as pitch, fine pitch is a bit stronger and more resistant to loosening=
, but more likely to cross thread and corrosion affects it more due to the s=
hallower grooves.<br><br>Take care<div><br></div></div><div><br>On Nov 24, 2=
016, at 1:51 PM, Dave &lt;<a href=3D"mailto:[email-masked]">dave1massey@=
cs.com</a>&gt; wrote:<br><br></div><blockquote type=3D"cite"><div><font colo=
r=3D"black" size=3D"4" face=3D"Arial, Helvetica, sans-serif"><font size=3D"4=
">Bolts with no slashes are grade two.&nbsp; The grade of the bolt is indica=
ted by the number of slashes plus two.&nbsp; I do not recommend grade two fo=
r suspension duty.&nbsp; <br>
<br>
I've heard said that the trade-off with Grade 8 bolts is that they are stron=
ger but more brittle.&nbsp; Since I am not a mechanical engineer I cannot ma=
ke a recommendation on substituting a grade 8 for a grade 5 but I would be c=
oncerned that the increased brittle nature may be a detriment. Considering t=
he seriousness of the consequences of a suspension failure I would think aga=
in about making substitutions.&nbsp; And just about anything you need is ava=
ilable next business day from McMaster Carr (and other sources, certainly).&=
nbsp; But you may have to buy more than you need and pay shipping.</font><br=
<br>
<font size=3D"4">I don't think fine thread vs coarse thread makes much diffe=
rence.<br>
<br>
Just my opinion.<br>
</font>
<div> <br>

</div>

<div style=3D"clear:both"><font size=3D"4">Dave Massey</font><br>

<br>

</div>

<div> <br>

</div>

<div> <br>

</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----O=
riginal Message-----<br>

From: Bud R &lt;<a href=3D"mailto:[email-masked]">[email-masked]=
</a>&gt;<br>

To: Triumph Mail List &lt;<a href=3D"mailto:[email-masked]">triumph=
[email-masked]</a>&gt;<br>

Sent: Thu, Nov 24, 2016 12:38 pm<br>

Subject: [TR] Threads and Bolts<br>

<br>

<div id=3D"AOLMsgPart_1.2_e9fc94a6-abdd-40f8-a252-0451dcf2ea86">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;" class=3D"aolReplacedBody">

<div>Listerati,</div>

<div><br>

</div>

I=E2=80=99m working on the Spitfire=E2=80=99s traverse leaf swing spring rea=
r suspension and can=E2=80=99t find locally the 7/16=E2=80=9D &nbsp;fine thr=
ead (20 tpi) by 3 1/2=E2=80=9D bolts that were holding the vertical link and=
 to the&nbsp;trunnions and to the swing spring bushings.

<div><br>

</div>

<div>I can find the right sizes in a coarse thread (12 tpi) grade 8 bolt and=
 thats my plan. The old ones are grade 5 or in one case a bolt with no slash=
 marks on top. I don=E2=80=99t know what it is.<br>

<div>&nbsp;

<div>Do these bolts need to be fine thread for any particular reason, e.g. f=
or safety, torque specs, etc.? Is a grade 8 bolt a good idea where it will b=
e stressed with all the up and down motion with the vertical link? Too britt=
le? Usually I go for grade 8 whenever possible but I=E2=80=99ve heard there a=
re instances where it might not be the best solution.</div>

<div><br>

</div>

<div>An aside for Thanksgiving:&nbsp;</div>

<div>My son and his wife teaching in Shanghai said the Chinese love to celeb=
rate American holidays (they know them from American TV and movies) but thei=
r take on Thanksgiving is that you thank people who do nice things for you. S=
o they got cards from their students thanking them for teaching. Kind of a d=
ifferent twist but a good one I thought.</div>

<div><br>

</div>

<div>Happy Thanksgiving to all.</div>

</div>

</div>

<div><br>

</div>

<div>
<span class=3D"Apple-style-span" style=3D"border-collapse: separate; border-=
spacing: 0px;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-align: -webkit-auto; text-indent: 0px; widows: 2; -webkit-text-dec=
orations-in-effect: none;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-align: -webkit-auto; text-indent: 0px; widows: 2; -webkit-text-dec=
orations-in-effect: none;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-align: -webkit-auto; text-indent: 0px; widows: 2; -webkit-text-dec=
orations-in-effect: none;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-align: -webkit-auto; text-indent: 0px; widows: 2; -webkit-text-dec=
orations-in-effect: none;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-align: -webkit-auto; text-indent: 0px; widows: 2; -webkit-text-dec=
orations-in-effect: none;">

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-indent: 0px; widows: 2; -webkit-text-decorations-in-effect: none;"=

<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-=
break: after-white-space;"><span class=3D"Apple-style-span" style=3D"orphans=
: 2; text-indent: 0px; widows: 2; -webkit-text-decorations-in-effect: none;"=

<div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;"><br class=3D"Apple-interchange-newline">Bud Rolofson</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;"><br>

</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;">Extreme Parts Racing&nbsp;(more than just a haircut)</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;"><br>

</div>

<div>71TR6 CC57365 (Good 6)</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;">71 Spitfire MK IV Race Car #3</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;">69 Spitfire MK 3 (back up FE engine/dinghy car)</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;">93 Minnie Winnie Race Support Vehicle&nbsp;</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-style: normal; font-variant: normal; font-weight: normal; let=
ter-spacing: normal; line-height: normal; text-transform: none; white-space:=
 normal; word-spacing: 0px; border-spacing: 0px; -webkit-text-stroke-width: 0=
px;">77 Z-50A Hardly Davidson Honda Mini-Trail Bike (Triumph Pit Bike)</div>=

</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-size: 12px; font-style: normal; font-variant: normal; font-we=
ight: normal; letter-spacing: normal; line-height: normal; text-transform: n=
one; white-space: normal; word-spacing: 0px; border-spacing: 0px; -webkit-te=
xt-stroke-width: 0px;"><br>

</div>

<div style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: H=
elvetica; font-size: 12px; font-style: normal; font-variant: normal; font-we=
ight: normal; letter-spacing: normal; line-height: normal; text-transform: n=
one; white-space: normal; word-spacing: 0px; border-spacing: 0px; -webkit-te=
xt-stroke-width: 0px;"><br>

</div>

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---

From: Dave <[email-masked]>
Date: Thu, 24 Nov 2016 22:04:14 -0500

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Thanks for filling in the gaps in my response.  On the other hand,I've extr=
acted a grade 8 bolt that had snapped on a rockershaft pedestal, not exactl=
y a high stress application.  I attributed it to the differences in thermal=
 expansion between the steel bolt and the aluminum pedestal. But, perhaps i=
t was a faulty bolt.  There was a rash of counterfeit grade 8 hardware in d=
istribution a couple decades  ago and perhaps those have found their way in=
to your local hardware stores where inventory tends to move slowly.
=20

Dave Massey

=20

=20

-----Original Message-----
From: Michael Porter <[email-masked]>
To: Dave <[email-masked]>; levilevi <[email-masked]>; triumphs <t=
[email-masked]>
Sent: Thu, Nov 24, 2016 6:13 pm
Subject: Re: [TR] Threads and Bolts

   =20
On 11/24/2016 11:51 AM, Dave wrote:
   =20
   =20
Bolts with no slashes are          grade two.  The grade of the bolt is ind=
icated by the number          of slashes plus two.  I do not recommend grad=
e two for          suspension duty. =20
         =20
          I've heard said that the trade-off with Grade 8 bolts is that    =
      they are stronger but more brittle.  Since I am not a          mechan=
ical engineer I cannot make a recommendation on          substituting a gra=
de 8 for a grade 5 but I would be concerned          that the increased bri=
ttle nature may be a detriment.          Considering the seriousness of the=
 consequences of a          suspension failure I would think again about ma=
king          substitutions.  And just about anything you need is available=
          next business day from McMaster Carr (and other sources,         =
 certainly).  But you may have to buy more than you need and          pay s=
hipping.
       =20
        I don't think fine thread vs coarse thread makes          much diff=
erence.
       =20
   =20
    Brittleness is relative.  The optimum condition for a strong bolt is   =
 toughness, the combination of tensile strength with resistance to    both =
deformation and crack propagation.  It's just a function of    metal crysta=
lline behavior that higher tensile strengths are    inversely proportional =
to rate of deformation.  The general    perception is that bolts with very =
high tensile strength offer no    protection from sudden breakage once the =
yield point is reached, but    that's not exactly true.  A lot depends upon=
 the loads imposed.  If    a grade 5 bolt works reliably in an application,=
 breakage is very    unlikely with a grade 8, because the grade 8 yield poi=
nt is higher.     This also allows for somewhat more clamping force, thus r=
educing the    tendency of the fastened parts to move around under load. =
=20
   =20
    The latter is important, because any bolt loaded in shear will fail    =
at about 65% of UTS (ultimate tensile strength).  Even so, I've seen    gra=
de 8 bolts that have deformed badly without shearing.  For    example, on t=
he buses we built, the rear axle was attached to a pair    of spring beams =
(the item carrying the air springs that supported    the weight of the bus =
and transmitted those loads to the axle).     Each one was attached with fo=
ur 3/4" grade 8 bolts in a box pattern,    with a precision center pin to p=
ositively locate the axle.  Due to    an engineering error (through holes t=
oo large), under big side loads    (like the driver whacking a curb while i=
n motion--much more common    than one would think, especially in NYC), the=
 spring beam would    laterally rotate around the center pin, putting the b=
olts in direct    shear.  Those dynamic loads, due to excessive movement, w=
ere much    larger than the clamping load because movement adds kinetic ene=
rgy.     I saw one of those grade 8 bolts after such mistreatment, and it h=
ad    an "S" curve in it, so that the centerline at the head of the bolt   =
 was offset from the centerline at the bottom of the bolt by nearly    1/2"=
, and yet, the bolt had not cracked or broken.  That's where the    toughne=
ss of the bolt comes in--which depends upon a number of    factors, such as=
 the alloy, the kind of heat treatment,    precipitation hardening, temperi=
ng and anti-corrosion coatings (to    prevent corrosion cracking).
   =20
    To my mind, a properly-made grade 8 bolt will be superior in    perform=
ance to any grade 5 bolt, especially in suspension work.     It's important=
 to know the loads imposed, though.  In racing, a    grade 5 will be fine i=
n areas where the maximum load imposed will be    sufficiently below the UT=
S of the bolt, and the clamped pieces are    inspected regularly for stretc=
hed or deformed bolts, but the extra    insurance of higher yield strength =
and higher clamping force make a    grade 8 preferable.  I'd much rather ha=
ve a bolt that never reaches    its yield point under maximum load than one=
 that yields and deforms    before failure.
   =20
   =20
    Cheers.
   =20
   =20
--=20

Michael Porter
Roswell, NM

Never let anyone drive you crazy when you know it's within walking distance=
....
 =20

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<font color='black' size='4' face='Arial, Helvetica, sans-serif'><font size="4">Thanks for filling in the gaps in my response.&nbsp; On the other hand,I've extracted a grade 8 bolt that had snapped on</font><font size="4"> a rockershaft pedestal, not exactly a high stress application.&nbsp; I attributed it to the differences in thermal expansion between the steel bolt and the aluminum pedestal. But, perhaps it was a faulty bolt.&nbsp; There was a rash of counterfeit grade 8 hardware in distribution a couple decades&nbsp; ago and perhaps those have found their way into your local hardware stores where inventory tends to move slowly.</font>
<div> <br>

</div>

<div style="clear:both"><font size="4">Dave Massey</font><br>

<br>

</div>

<div> <br>

</div>

<div> <br>

</div>

<div style="font-family:arial,helvetica;font-size:10pt;color:black">-----Original Message-----<br>

From: Michael Porter &lt;[email-masked]&gt;<br>

To: Dave &lt;[email-masked]&gt;; levilevi &lt;[email-masked]&gt;; triumphs &lt;[email-masked]&gt;<br>

Sent: Thu, Nov 24, 2016 6:13 pm<br>

Subject: Re: [TR] Threads and Bolts<br>

<br>

<div id="AOLMsgPart_2_19ae3d4a-4309-4f78-aa31-2d3a79fa5aaf">

<div bgcolor="#FFFFFF" text="#000000" class="aolReplacedBody">

<div class="moz-cite-prefix">On 11/24/2016 11:51 AM, Dave wrote:<br>

    </div>

    <blockquote cite="about:blank"><font color="black" size="4" face="Arial, Helvetica, sans-serif"><font size="4">Bolts with no slashes are
          grade two.&nbsp; The grade of the bolt is indicated by the number
          of slashes plus two.&nbsp; I do not recommend grade two for
          suspension duty.&nbsp; <br>

          <br>

          I've heard said that the trade-off with Grade 8 bolts is that
          they are stronger but more brittle.&nbsp; Since I am not a
          mechanical engineer I cannot make a recommendation on
          substituting a grade 8 for a grade 5 but I would be concerned
          that the increased brittle nature may be a detriment.
          Considering the seriousness of the consequences of a
          suspension failure I would think again about making
          substitutions.&nbsp; And just about anything you need is available
          next business day from McMaster Carr (and other sources,
          certainly).&nbsp; But you may have to buy more than you need and
          pay shipping.</font><br>

        <br>

        <font size="4">I don't think fine thread vs coarse thread makes
          much difference.<br>

        </font></font></blockquote>
    <br>

    Brittleness is relative.&nbsp; The optimum condition for a strong bolt is
    toughness, the combination of tensile strength with resistance to
    both deformation and crack propagation.&nbsp; It's just a function of
    metal crystalline behavior that higher tensile strengths are
    inversely proportional to rate of deformation.&nbsp; The general
    perception is that bolts with very high tensile strength offer no
    protection from sudden breakage once the yield point is reached, but
    that's not exactly true.&nbsp; A lot depends upon the loads imposed.&nbsp; If
    a grade 5 bolt works reliably in an application, breakage is very
    unlikely with a grade 8, because the grade 8 yield point is higher.&nbsp;
    This also allows for somewhat more clamping force, thus reducing the
    tendency of the fastened parts to move around under load.&nbsp; <br>

    <br>

    The latter is important, because any bolt loaded in shear will fail
    at about 65% of UTS (ultimate tensile strength).&nbsp; Even so, I've seen
    grade 8 bolts that have deformed badly without shearing.&nbsp; For
    example, on the buses we built, the rear axle was attached to a pair
    of spring beams (the item carrying the air springs that supported
    the weight of the bus and transmitted those loads to the axle).&nbsp;
    Each one was attached with four 3/4" grade 8 bolts in a box pattern,
    with a precision center pin to positively locate the axle.&nbsp; Due to
    an engineering error (through holes too large), under big side loads
    (like the driver whacking a curb while in motion--much more common
    than one would think, especially in NYC), the spring beam would
    laterally rotate around the center pin, putting the bolts in direct
    shear.&nbsp; Those dynamic loads, due to excessive movement, were much
    larger than the clamping load because movement adds kinetic energy.&nbsp;
    I saw one of those grade 8 bolts after such mistreatment, and it had
    an "S" curve in it, so that the centerline at the head of the bolt
    was offset from the centerline at the bottom of the bolt by nearly
    1/2", and yet, the bolt had not cracked or broken.&nbsp; That's where the
    toughness of the bolt comes in--which depends upon a number of
    factors, such as the alloy, the kind of heat treatment,
    precipitation hardening, tempering and anti-corrosion coatings (to
    prevent corrosion cracking).<br>

    <br>

    To my mind, a properly-made grade 8 bolt will be superior in
    performance to any grade 5 bolt, especially in suspension work.&nbsp;
    It's important to know the loads imposed, though.&nbsp; In racing, a
    grade 5 will be fine in areas where the maximum load imposed will be
    sufficiently below the UTS of the bolt, and the clamped pieces are
    inspected regularly for stretched or deformed bolts, but the extra
    insurance of higher yield strength and higher clamping force make a
    grade 8 preferable.&nbsp; I'd much rather have a bolt that never reaches
    its yield point under maximum load than one that yields and deforms
    before failure.<br>

    <br>

    <br>

    Cheers.<br>

    <font size="4"><font face="Arial, Helvetica, sans-serif"></font></font><br>

    <pre class="moz-signature">-- 

Michael Porter
Roswell, NM

Never let anyone drive you crazy when you know it's within walking distance....</pre>

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