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Re: [TR] RPM speed calc

To: "John.Macartney@Ukpips.org.uk" <John.Macartney@Ukpips.org.uk>, "dave@mdmackay.ca" <dave@mdmackay.ca>
Subject: Re: [TR] RPM speed calc
From: DAVID MASSEY <dave1massey@cs.com>
Date: Mon, 1 Jun 2020 20:36:11 +0000 (UTC)
Cc: "Triumphs@autox.team.net" <Triumphs@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: Triumphs@autox.team.net
References: <8b014144ff5fc77ab89860904a5da0ad@mail.gmail.com> <976FAEAF-D29B-4935-8C09-D4FA75A6BD9E@Ukpips.org.uk> x64; rv:76.0) Gecko/20100101 Firefox/76.0
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 That is true for cars that remain equipped as delivered.=C2=A0 However, ma=
ny or most TR's were delivered without overdrive and many of us have since =
fitted overdrive transmission to our cars whilst keeping the stock (non-OD)=
 differential.=C2=A0=20

I guess the short answer is: your mileage may vary.
Cheers
=20
Dave=20

=20
=20
-----Original Message-----
From: John Macartney <John.Macartney@Ukpips.org.uk>
To: Dave MacKay <dave@mdmackay.ca>
Cc: Triumphs@autox.team.net
Sent: Mon, Jun 1, 2020 2:24 pm
Subject: Re: [TR] RPM speed calc

It=E2=80=99s important to remember that cars without overdrive had a higher=
 axle ratio than those with it. As an example, the GT6+ had a 3.27 final dr=
ive for non overdrive and 3.89 for overdrive. Just to complicate things, it=
 was entirely possible to order a 3.27 diff with overdrive on top! The fact=
ory never promoted this facility for fairly obvious reasons. My own GT6 mk =
2 was supplied like that becxause I knew my way around the factory build bo=
oks. Iit made an excellent cruiser with good fuel consumption but could not=
 pull more than 4000 rpm, even downhill on a motorway. That said, refuellin=
g was a little less frequent.
Jonmac

At the Battle of Waterloo, 1815:Lord Uxbridge: =C2=A0=E2=80=9CBy God, Sir -=
 I=E2=80=99ve lost my leg=E2=80=9DDuke of Wellington: =E2=80=9CBy God, Sir =
- so you have!=E2=80=9D

On 1 Jun 2020, at 19:41, Dave MacKay <dave@mdmackay.ca> wrote:



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:sans-serif;} _filtered {}#yiv9085228339 div.yiv9085228339WordSection1 {}#y=
iv9085228339 >Date: Sun, 31 May 2020 16:52:23 -0500>From: bill beecher <not=
akitcar@yahoo.com>>Subject: [TR] RPM speed calc>=C2=A0>Came across this cal=
culator with all the right input fields.=C2=A0 But, I wonder how accurate i=
t really is given the following input. >TR3 with a 3.7 rear, OD at redline =
of 5,000rpm.=C2=A0 Vredestein 165R/15 tires, 25.4? diameter.=C2=A0=C2=A0 Sh=
ould be moving along at 124mph!>=C2=A0>https://wahiduddin.net/calc/calc_spe=
ed_rpm.htm>=C2=A0>Anyone get a different answer? >Bill=C2=A0Here (attached)=
 is a spreadsheet that I wrote to calculate speed versus rpm given differen=
t parameters. I wrote it to check my speedo after I installed an HVDA trans=
mission. If the spreadsheet doesn=E2=80=99t make it through the list as an =
attachment, just e-mail me directly and I=E2=80=99ll send it to you.=C2=A0W=
ith a standard Triumph gearbox + overdrive, and the parameters you gave, I =
calculate speed at 5000 rpm in top gear (with overdrive) as being 124.5 mph=
. Note that, I think that the tire diameter is 25.25=E2=80=9D, slightly les=
s than you indicated.=C2=A0I hasten to add that calculating a speed and bel=
ieving it=E2=80=99s achievable are two different things!=C2=A0Regards,=C2=
=A0Dave MacKay1960 TR3A s/n 68639Lnear Toronto, Canada
<Triumph rpm to mph.xls>

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rchive

artney@ukpips.org.uk

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e

sey@cs.com

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<div style=3D"color:black;font: 12pt Arial, Helvetica, sans-serif;">
<div> <font size=3D"3">That is true for cars that remain equipped as delive=
red.&nbsp; However, many or most TR's were delivered without overdrive and =
many of us have since fitted overdrive transmission to our cars whilst keep=
ing the stock (non-OD) differential.&nbsp; <br>
</font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">I guess the short answer is: your mileage may vary.</=
font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">Cheers</font><br>
</div>

<div> <br>
</div>

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

<div> <br>
</div>

<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----=
Original Message-----<br>
From: John Macartney &lt;John.Macartney@Ukpips.org.uk&gt;<br>
To: Dave MacKay &lt;dave@mdmackay.ca&gt;<br>
Cc: Triumphs@autox.team.net<br>
Sent: Mon, Jun 1, 2020 2:24 pm<br>
Subject: Re: [TR] RPM speed calc<br>
<br>

<div id=3D"yiv9085228339">
<div>It=E2=80=99s important to remember that cars without overdrive had a h=
igher axle ratio than those with it. As an example, the GT6+ had a 3.27 fin=
al drive for non overdrive and 3.89 for overdrive. Just to complicate thing=
s, it was entirely possible to order a 3.27 diff with overdrive on top! The=
 factory never promoted this facility for fairly obvious reasons. My own GT=
6 mk 2 was supplied like that becxause I knew my way around the factory bui=
ld books. Iit made an excellent cruiser with good fuel consumption but coul=
d not pull more than 4000 rpm, even downhill on a motorway. That said, refu=
elling was a little less frequent.
<div><br clear=3D"none"></div>

<div>Jonmac<br clear=3D"none"><br clear=3D"none">
<div dir=3D"ltr" id=3D"yiv9085228339AppleMailSignature">At the Battle of Wa=
terloo, 1815:
<div>Lord Uxbridge: &nbsp;=E2=80=9CBy God, Sir - I=E2=80=99ve lost my leg=
=E2=80=9D</div>

<div>Duke of Wellington: =E2=80=9CBy God, Sir - so you have!=E2=80=9D</div>

<div><br clear=3D"none"></div>
</div>

<div class=3D"yiv9085228339yqt6140383728" id=3D"yiv9085228339yqt63103">
<div dir=3D"ltr"><br clear=3D"none">On 1 Jun 2020, at 19:41, Dave MacKay &l=
t;<a rel=3D"nofollow" shape=3D"rect" ymailto=3D"mailto:dave@mdmackay.ca"; ta=
rget=3D"_blank" href=3D"mailto:dave@mdmackay.ca";>dave@mdmackay.ca</a>&gt; w=
rote:<br clear=3D"none"><br clear=3D"none"></div>
<blockquote type=3D"cite">
<div dir=3D"ltr"></div>
</blockquote></div>
</div>
</div>

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<div>
<div class=3D"yiv9085228339WordSection1">
<div class=3D"yiv9085228339MsoPlainText">&gt;Date: Sun, 31 May 2020 16:52:2=
3 -0500</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;From: bill beecher &lt;<a rel=
=3D"nofollow" shape=3D"rect" ymailto=3D"mailto:notakitcar@yahoo.com"; target=
=3D"_blank" href=3D"mailto:notakitcar@yahoo.com";>notakitcar@yahoo.com</a>&g=
t;</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;Subject: [TR] RPM speed calc</=
div>

<div class=3D"yiv9085228339MsoPlainText">&gt;&nbsp;</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;Came across this calculator wi=
th all the right input fields.&nbsp; But, I wonder how accurate it really i=
s given the following input. </div>

<div class=3D"yiv9085228339MsoPlainText">&gt;TR3 with a 3.7 rear, OD at red=
line of 5,000rpm.&nbsp; Vredestein 165R/15 tires, 25.4? diameter.&nbsp;&nbs=
p; Should be moving along at 124mph!</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;&nbsp;</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;<a rel=3D"nofollow" shape=3D"r=
ect" target=3D"_blank" href=3D"https://wahiduddin.net/calc/calc_speed_rpm.h=
tm">https://wahiduddin.net/calc/calc_speed_rpm.htm</a></div>

<div class=3D"yiv9085228339MsoPlainText">&gt;&nbsp;</div>

<div class=3D"yiv9085228339MsoPlainText">&gt;Anyone get a different answer?=
 </div>

<div class=3D"yiv9085228339MsoPlainText">&gt;Bill</div>

<div class=3D"yiv9085228339MsoNormal">&nbsp;</div>

<div class=3D"yiv9085228339MsoNormal">Here (attached) is a spreadsheet that=
 I wrote to calculate speed versus rpm given different parameters. I wrote =
it to check my speedo after I installed an HVDA transmission. If the spread=
sheet doesn=E2=80=99t make it through the list as an attachment, just e-mai=
l me directly and I=E2=80=99ll send it to you.</div>

<div class=3D"yiv9085228339MsoNormal">&nbsp;</div>

<div class=3D"yiv9085228339MsoNormal">With a standard Triumph gearbox + ove=
rdrive, and the parameters you gave, I calculate speed at 5000 rpm in top g=
ear (with overdrive) as being 124.5 mph. Note that, I think that the tire d=
iameter is 25.25=E2=80=9D, slightly less than you indicated.</div>

<div class=3D"yiv9085228339MsoNormal">&nbsp;</div>

<div class=3D"yiv9085228339MsoNormal">I hasten to add that calculating a sp=
eed and believing it=E2=80=99s achievable are two different things!</div>

<div class=3D"yiv9085228339MsoNormal">&nbsp;</div>

<div class=3D"yiv9085228339MsoNormal">Regards,</div>

<div class=3D"yiv9085228339MsoNormal">&nbsp;</div>

<div class=3D"yiv9085228339MsoNormal">Dave MacKay</div>

<div class=3D"yiv9085228339MsoNormal">1960 TR3A s/n 68639L</div>

<div class=3D"yiv9085228339MsoNormal">near Toronto, Canada</div>
</div>

<blockquote type=3D"cite">
<div dir=3D"ltr">&lt;Triumph rpm to mph.xls&gt;</div>
</blockquote><blockquote type=3D"cite">
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