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Re: [Healeys] Transmission / Overdrive or Clutch slippage

To: healeys@autox.team.net
Subject: Re: [Healeys] Transmission / Overdrive or Clutch slippage
From: Bob Spidell <bspidell@comcast.net>
Date: Thu, 20 May 2021 15:44:11 -0700
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
References: <604018491.4470645.1621546916052.ref@mail.yahoo.com> <604018491.4470645.1621546916052@mail.yahoo.com>
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Strange case indeed. My guess--and it's only a guess--is that the cone 
clutch in the O/D is worn and slipping when the oil is hot. The cone 
clutch is a 'wet' type, and AFAIK new ones aren't available (DWM sells 
relined ones, with a core of course). When the O/D is not engaged, eight 
very strong springs hold the cone clutch together as a 'solid' unit, 
when you engage the O/D oil pressure--yours appears to be 
adequate--pushes a couple pistons that force the cone clutch apart and 
locks the sun gear, which starts overrunning of the output gearing 
(hence 'overdrive'). Since new clutches aren't available, yours may be 
original and not have sufficient material to fully engage the outer part 
(FWIW, I went through my BJ8's O/D and it still had sufficient material 
at 205K miles; I attribute this to my superior O/D operating technique ;)).

The other thing is the springs; I read somewhere--possibly in the shop 
manual--that these springs should ALWAYS be replaced when going through 
the O/D and, even though mine looked fine I bit the bullet and bought a 
new set. It's possible the springs weaken over time and become unable to 
keep the cone clutch engaged in all conditions (e.g. hot, slippery oil).

Again, this is just a semi-informed guess, but maybe someone can expand 
on it.

Bob


On 5/20/2021 2:41 PM, Rafael Abugattas via Healeys wrote:
>
> Hi all,
>
> Last year I requested your help regarding a strange overdrive or 
> slippage problem I have in my 1962 Tricarb BT7.
>
> I received very valuable comments and suggestions but sadly the 
> problem persists: Overdrive would not activate under any circumstances 
> and when the engine / transmission is warm and we engage reverse, the 
> engine revs but the car won´t move.
>
> There is slippage somewhere in the transmission / clutch or overdrive. 
> When the car is cold, reverse engages without any issues. This only 
> happens in reverse gear after the car has been driven a few miles and 
> the engine and transmission are warm. Forward gears engage all the 
> time without any issues.
>
> The car has been recently restored. Before the restoration the 
> overdrive was operational. Now itâ??s not.
>
> The transmission and overdrive have been taken apart and assembled 
> twice looking for something visually wrong. Everything seemed to be OK.
>
> The clutch and plate were also removed for inspection. The clutch was 
> recently redone, adjusted and tested.
>
> A friend suggested we should verify the oil pressure on the overdrive. 
> On this link you will find a couple of videos of a test we have 
> recently done with a manometer installed on the overdrive to check the 
> oil pressure at different RPM´s.
>
> https://www.dropbox.com/sh/t5p8kqz6v6yduyt/AADizyVMyBKPozy284B-udA4a?dl=0 
> <https://www.dropbox.com/sh/t5p8kqz6v6yduyt/AADizyVMyBKPozy284B-udA4a?dl=0>
>
> The pressure on 3rd and 4th gears goes up to 400 psi and drops as it 
> goes to lower gears. At idle is between 150 to 200 psi
>
> In forward gears the car runs fine; the problem that we need to solve 
> is that the overdrive would not activate(even though it is connected 
> and everything seems visually OK) and the slippage we have when 
> engaging reverse (the car won´t move) when the engine / transmission 
> is warm.
>
> We are located in Lima â?? Peru and as you may imagine, there are not 
> many experts in this particular area of expertise.
>
> Any thoughts or suggestions from you collective knowledge and wisdom 
> on how to proceed will be much appreciated.
>
> Thanks in advance!
>
> Rafael
>
>
>
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    Strange case indeed. My guess--and it's only a guess--is that the
    cone clutch in the O/D is worn and slipping when the oil is hot. The
    cone clutch is a 'wet' type, and AFAIK new ones aren't available
    (DWM sells relined ones, with a core of course). When the O/D is not
    engaged, eight very strong springs hold the cone clutch together as
    a 'solid' unit, when you engage the O/D oil pressure--yours appears
    to be adequate--pushes a couple pistons that force the cone clutch
    apart and locks the sun gear, which starts overrunning of the output
    gearing (hence 'overdrive'). Since new clutches aren't available,
    yours may be original and not have sufficient material to fully
    engage the outer part (FWIW, I went through my BJ8's O/D and it
    still had sufficient material at 205K miles; I attribute this to my
    superior O/D operating technique ;)).<br>
    <br>
    The other thing is the springs; I read somewhere--possibly in the
    shop manual--that these springs should ALWAYS be replaced when going
    through the O/D and, even though mine looked fine I bit the bullet
    and bought a new set. It's possible the springs weaken over time and
    become unable to keep the cone clutch engaged in all conditions
    (e.g. hot, slippery oil).<br>
     <br>
    Again, this is just a semi-informed guess, but maybe someone can
    expand on it.<br>
    <br>
    Bob<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 5/20/2021 2:41 PM, Rafael Abugattas
      via Healeys wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:604018491.4470645.1621546916052@mail.yahoo.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div class="yahoo-style-wrap" style="font-family:Helvetica Neue,
        Helvetica, Arial, sans-serif;font-size:13px;">
        <div dir="ltr" data-setdir="false">
          <div>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">Hi
                all,</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">Last
                year I requested
                your help regarding a strange overdrive or slippage
                problem I have in my 1962
                Tricarb BT7. </span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">I
                received very
                valuable comments and suggestions but sadly the problem
                persists: Overdrive
                would not activate under any circumstances and when the
                engine / transmission
                is warm and we engage reverse, the engine revs but the
                car won´t move. </span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">There
                is slippage
                somewhere in the transmission / clutch or overdrive.
                When the car is cold,
                reverse engages without any issues. This only happens in
                reverse gear after the
                car has been driven a few miles and the engine and
                transmission are warm.
                Forward gears engage all the time without any issues.</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">The
                car has been
                recently restored. Before the restoration the overdrive
                was operational. Now
                itâ??s not. </span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">The
                transmission and
                overdrive have been taken apart and assembled twice
                looking for something
                visually wrong. Everything seemed to be OK.</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">The
                clutch and plate
                were also removed for inspection. The clutch was
                recently redone, adjusted and
                tested.</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">A
                friend suggested we
                should verify the oil pressure on the overdrive. On this
                link you will find a
                couple of videos of a test we have recently done with a
                manometer installed on
                the overdrive to check the oil pressure at different
                RPM´s. </span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif"><a
href="https://www.dropbox.com/sh/t5p8kqz6v6yduyt/AADizyVMyBKPozy284B-udA4a?dl=0";
                  rel="nofollow" target="_blank" 
moz-do-not-send="true">https://www.dropbox.com/sh/t5p8kqz6v6yduyt/AADizyVMyBKPozy284B-udA4a?dl=0</a></span></p>
            <p class="ydpfe39e09bMsoNormal"><span>The pressure on 3rd
                and 4th gears goes up
                to 400 psi and drops as it goes to lower gears. At idle
                is between 150 to 200
                psi</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">In
                forward gears the
                car runs fine; the problem that we need to solve is that
                the overdrive would not
                activate(even though it is connected and everything
                seems visually OK) and the
                slippage we have when engaging reverse (the car won´t
                move) when the engine /
                transmission is warm.</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">We
                are located in
                Lima â?? Peru and as you may imagine, there are not many
                experts in this
                particular area of expertise.</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">Any
                thoughts or suggestions
                from you collective knowledge and wisdom on how to
                proceed will be much
                appreciated. </span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background:white"><span
                
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">Thanks
                in advance!</span></p>
            <p class="ydpfe39e09bxyiv3660242746msonormal"
              style="background: white; orphans: 2; widows: 2;
              text-decoration-style: initial; text-decoration-color:
              initial; word-spacing: 0px;"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;mso-ansi-language:ES-MX"
                lang="ES-MX">Rafael</span></p>
            <p class="ydpfe39e09bMsoNormal"> </p>
          </div>
          <br>
        </div>
      </div>
      <br>
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