Subject: Re: [Mgs] clutch release bearing

From: Max Heim via Mgs <[email-masked]>
Date: Mon, 19 Aug 2019 09:28:33 -0700

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Hose deterioration like that is not unknown.

Not sure how the clutch release bearing figures into this. IME they =
outlast the clutch disc; for example, when I recently pulled the engine =
for the first time in at least 21 years (could have been 25, I need to =
look it up), the clutch disc was down to its last millimeter of wear, =
but the flywheel surface was perfect, and the throwout bearing looked =
good enough to re-use (I didn=E2=80=99t, though).

When I read complaints about these failing, it almost always seems to be =
from people who had installed a =E2=80=9Cheavy duty=E2=80=9D clutch. I =
get the impression that people buy these with the idea that =E2=80=9Cheavy=
 duty=E2=80=9D means it will last longer. This is not the case. It =
refers to heavier clamping pressure for the purpose of handling extra =
horsepower =E2=80=94 if you don=E2=80=99t have a more powerful than =
stock engine, it is completely unnecessary and merely puts more stress =
on the other components, such as the throwout bearing.

--
Max Heim
'66 MGB

> On Aug 19, 2019, at 8:48 AM, Allen Hess via Mgs <[email-masked]> =
wrote:
>=20
> I have a 71 MGB and I=E2=80=99m wondering how many miles people are =
getting from the carbon release bearing.=20
>=20
> The original clutch was replaced at about 54,000 miles because it was =
slipping (Moss parts, 1998). Recently had very erratic clutch operation =
which I thought was going to be the release bearing or pressure plate =
diaphragm. Started with the hydraulics and found the slave cylinder =
containing what can only be the insides of the slave cylinder hose. =
After rebuilding/replacing clutch hydraulics, it seems to be okay but I =
am still not comfortable.=20
>=20
> Thanks,
> Allen
>=20
>=20
> _______________________________________________
>=20
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> Donate: http://www.team.net/donate.html
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>=20
> Archive: http://www.team.net/pipermail/mgs =
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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
class=3D"">Hose deterioration like that is not unknown.<div class=3D""><br=
 class=3D""></div><div class=3D"">Not sure how the clutch release =
bearing figures into this. IME they outlast the clutch disc; for =
example, when I recently pulled the engine for the first time in at =
least 21 years (could have been 25, I need to look it up), the clutch =
disc was down to its last millimeter of wear, but the flywheel surface =
was perfect, and the throwout bearing looked good enough to re-use (I =
didn=E2=80=99t, though).</div><div class=3D""><br class=3D""></div><div =
class=3D"">When I read complaints about these failing, it almost always =
seems to be from people who had installed a =E2=80=9Cheavy duty=E2=80=9D =
clutch. I get the impression that people buy these with the idea that =
=E2=80=9Cheavy duty=E2=80=9D means it will last longer. This is not the =
case. It refers to heavier clamping pressure for the purpose of handling =
extra horsepower =E2=80=94 if you don=E2=80=99t have a more powerful =
than stock engine, it is completely unnecessary and merely puts more =
stress on the other components, such as the throwout bearing.</div><div =
class=3D""><br class=3D""></div><div class=3D""><br class=3D""><div =
class=3D"">
<div style=3D"color: rgb(0, 0, 0); letter-spacing: normal; text-align: =
start; text-indent: 0px; text-transform: none; white-space: normal; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: =
break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;" class=3D""><div style=3D"color: rgb(0, 0, 0); =
letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
class=3D""><div style=3D"margin: 0px; font-size: 13px;" =
class=3D"">--</div><div style=3D"margin: 0px; font-size: 13px; =
min-height: 16px;" class=3D"">Max Heim</div><div style=3D"margin: 0px; =
font-size: 13px;" class=3D"">'66 MGB</div></div></div>
</div>

<br class=3D""><div><blockquote type=3D"cite" class=3D""><div =
class=3D"">On Aug 19, 2019, at 8:48 AM, Allen Hess via Mgs &lt;<a =
href=3D"mailto:[email-masked]" class=3D"">[email-masked]</a>&gt; =
wrote:</div><br class=3D"Apple-interchange-newline"><div class=3D""><div =
class=3D"">I have a 71 MGB and I=E2=80=99m wondering how many miles =
people are getting from the carbon release bearing. <br class=3D""><br =
class=3D"">The original clutch was replaced at about 54,000 miles =
because it was slipping (Moss parts, 1998). Recently had very erratic =
clutch operation which I thought was going to be the release bearing or =
pressure plate diaphragm. Started with the hydraulics and found the =
slave cylinder containing what can only be the insides of the slave =
cylinder hose. After rebuilding/replacing clutch hydraulics, it seems to =
be okay but I am still not comfortable. <br class=3D""><br =
class=3D"">Thanks,<br class=3D"">Allen<br class=3D""><br class=3D""><img =
name=3D"image1.jpeg" class=3D"" apple-inline=3D"yes" =
id=3D"57D34B72-DA79-4036-93A4-5D161D664658" =
src=3D"cid:[email-masked]"><br =
class=3D"">_______________________________________________<br =
class=3D""><br class=3D""><a href=3D"mailto:[email-masked]" =
class=3D"">[email-masked]</a><br class=3D"">Donate: =
&nbsp;$12.75<br class=3D""><br class=3D"">Archive: =
http://www.team.net/pipermail/mgs http://autox.team.net/archive<br =
class=3D""><br class=3D"">Unsubscribe: =
http://autox.team.net/mailman/options/mgs/[email-masked]<br =
class=3D""></div></div></blockquote></div><br =
class=3D""></div></body></html>=

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From: "Osborne, Paul via Mgs" <[email-masked]>
Date: Tue, 20 Aug 2019 00:02:22 +0000

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[email-masked]

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From: Barney Gaylord via Mgs <[email-masked]>
Date: Mon, 19 Aug 2019 20:59:56 -0400

I run standard MGB clutch parts in my MGA, and I 
keep good records.  Last replaced 5/15/18 with 
5-1/2 years, 155,566 miles.  It was not worn out, 
but it was a convenient time to replace it.  I 
recon they could go 200,000 miles if you don't 
abuse them.  Just keep your foot off the clutch 
pedal when you're not shifting.  Most likely the clutch disc wears out first.

Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com

At 11:48 AM 8/19/2019, Allen Hess via Mgs wrote:
>I have a 71 MGB and I’m wondering how many 
>miles people are getting from the carbon release bearing.
>
>The original clutch was replaced at about 54,000 
>miles because it was slipping (Moss parts, 
>1998). Recently had very erratic clutch 
>operation which I thought was going to be the 
>release bearing or pressure plate diaphragm. 
>Started with the hydraulics and found the slave 
>cylinder containing what can only be the insides 
>of the slave cylinder hose. After 
>rebuilding/replacing clutch hydraulics, it seems 
>to be okay but I am still not comfortable.
>
>Thanks,
>Allen
>....
>Attachment: image11.jpg

[email-masked]

---

From: Charley Robinson via Mgs <[email-masked]>
Date: Mon, 19 Aug 2019 20:23:49 -0500

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Looks to me like you've fixed the problem, so quit worrying. :-)

CR

On 8/19/2019 10:48 AM, Allen Hess via Mgs wrote:
> I have a 71 MGB and I’m wondering how many miles people are getting from the carbon release bearing.
>
> The original clutch was replaced at about 54,000 miles because it was slipping (Moss parts, 1998). Recently had very erratic clutch operation which I thought was going to be the release bearing or pressure plate diaphragm. Started with the hydraulics and found the slave cylinder containing what can only be the insides of the slave cylinder hose. After rebuilding/replacing clutch hydraulics, it seems to be okay but I am still not comfortable.
>
> Thanks,
> Allen
>
>
>
> Unsubscribe: http://autox.team.net/mailman/options/mgs/[email-masked]

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    Looks to me like you've fixed the problem, so quit worrying. <span
      class="moz-smiley-s1"><span>:-)</span></span><br>
    <br>
    CR<br>
    <br>
    <div class="moz-cite-prefix">On 8/19/2019 10:48 AM, Allen Hess via
      Mgs wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:[email-masked]">
      <pre class="moz-quote-pre" wrap="">I have a 71 MGB and I’m wondering how many miles people are getting from the carbon release bearing. 

The original clutch was replaced at about 54,000 miles because it was slipping (Moss parts, 1998). Recently had very erratic clutch operation which I thought was going to be the release bearing or pressure plate diaphragm. Started with the hydraulics and found the slave cylinder containing what can only be the insides of the slave cylinder hose. After rebuilding/replacing clutch hydraulics, it seems to be okay but I am still not comfortable. 

Thanks,
Allen

</pre>
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      <fieldset class="mimeAttachmentHeader"></fieldset>
      <pre class="moz-quote-pre" wrap="">
</pre>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
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From: PaulHunt73 via Mgs <[email-masked]>
Date: Tue, 20 Aug 2019 08:49:56 +0100 jV/8v96/yS3/8Q2oV17yv0njNViMKu1JX5x+n9rHMqJeCzqGrOhpvuN7wU3j1xYNeevLBmT95TsIlFKOtbYuqVxd4ag9SpVR5VI=

It's a bit of a minefield with many variables.

A graphite release bearing _should_ last the life of the clutch friction 
plate, apart from my roadster described below I've never had one fail, the 
clutch has started slipping from friction plate wear before that.  But if 
the main driver rides the clutch and sits at traffic lights with the pedal 
down then its life will be reduced.

A few years ago someone started making them with the graphite ring pinned 
into the casting instead of being glued and they tended to explode in a 
short time.  Hopefully they will be out of circulation now.

Suppliers want you to buy roller bearing release bearings at extra expense 
(clutch kits normally come with the graphite type) but they have their own 
problems.  John Twist describes how they aren't the complete answer by 
demonstrating how they move in an arc as the pedal is operated and released, 
so sliding across the face of the release ring on the cover plate, which 
causes excessive wear.  Graphite bearings are designed to cope with that, 
roller bearings aren't.  Whilst what he says is true the arc they actually 
move in use is very limited, the real problem is there is nothing to 
centralise the bearing to the cover plate in the first place.  Depending on 
how far your release arm is off-centre - and I found mine a good 3/16" - as 
well as sliding back an fore all the time the load will be on one side 
significantly more than the other, something else they are not designed for 
http://www.mgb-stuff.org.uk/clutchr3a.htm#5  I've been told by someone who 
has worked on these cars for decades that "They are all like that". 
Proponents say all modern cars have roller bearings so they must be good, so 
does the MGB GT V8 and the Midget 1500, and they don't fail.  But that is 
because they have a guide tube over the first-motion shaft to keep the 
bearing centralised to the cover plate.

On the roadster I've had a graphite bearing break up because the casting 
wore through on one side, and a roller bearing get destroyed when the 
friction plate was barely half worn.  At that point I noticed how off-centre 
the release arm was, so brought it back into line.  The most immediate 
effect is the biting point is now much higher than it has ever been - almost 
too high.  It was always lower than my other cars before and extending the 
'throw' of the hydraulics made little difference.  I'm sure that is because 
before it was pushing one side of the pressure plate down less than the 
other side because of the offset.  There is a graphite bearing in now, time 
will tell.

As for the gunge, that is normal as the flex hose ages.  That will have no 
effect on release bearing wear.

PaulH.

----- Original Message ----- 
I have a 71 MGB and I’m wondering how many miles people are getting from the 
carbon release bearing.

[email-masked]

---

From: Charley Robinson via Mgs <[email-masked]>
Date: Tue, 20 Aug 2019 11:50:49 -0500

I had a roller throwout bearing in my '70 B back in the 1980's - 
1990's.  Put in new clutch parts when I rebuilt the engine.  That B was 
my daily driver for 5 yrs or so until I sold it; had no problems with it 
during that time.  My current '69 B has the stock clutch parts including 
the graphite throwout bearing (bushing).  All that went in in 1999 when 
I rebuilt the engine and installed an OD tranny.   Around 25K miles on 
the car since then, no problems with the drive train.   The worst 
beating the clutch components had to take was when I and the B got 
volunteered into a small-town parade. (Ah, the irony; a British car in 
an Independence Day parade.)  I thought I'd stick her in first gear and 
idle along.  Not!  It was like being in stop and go traffic for an 
hour.  I figure I took several years off the release bearing in that hour.

CR

On 8/20/2019 2:49 AM, PaulHunt73 via Mgs wrote:
> A graphite release bearing _should_ last the life of the clutch 
> friction plate, apart from my roadster described below I've never had 
> one fail, the clutch has started slipping from friction plate wear 
> before that.  But if the main driver rides the clutch and sits at 
> traffic lights with the pedal down then its life will be reduced.
>
> A few years ago someone started making them with the graphite ring 
> pinned into the casting instead of being glued and they tended to 
> explode in a short time.  Hopefully they will be out of circulation now.
>
> Suppliers want you to buy roller bearing release bearings at extra 
> expense (clutch kits normally come with the graphite type) but they 
> have their own problems.  John Twist describes how they aren't the 
> complete answer by demonstrating how they move in an arc as the pedal 
> is operated and released, so sliding across the face of the release 
> ring on the cover plate, which causes excessive wear.  Graphite 
> bearings are designed to cope with that, roller bearings aren't.  
> Whilst what he says is true the arc they actually move in use is very 
> limited, the real problem is there is nothing to centralise the 
> bearing to the cover plate in the first place.  Depending on how far 
> your release arm is off-centre - and I found mine a good 3/16" - as 
> significantly more than the other, something else they are not 
> designed for http://www.mgb-stuff.org.uk/clutchr3a.htm#5  I've been 
> told by someone who has worked on these cars for decades that "They 
> are all like that". Proponents say all modern cars have roller 
> bearings so they must be good, so does the MGB GT V8 and the Midget 
> 1500, and they don't fail.  But that is because they have a guide tube 
> over the first-motion shaft to keep the bearing centralised to the 
> cover plate.
>
> On the roadster I've had a graphite bearing break up because the 
> casting wore through on one side, and a roller bearing get destroyed 
> when the friction plate was barely half worn.  At that point I noticed 
> how off-centre the release arm was, so brought it back into line.  The 
> most immediate effect is the biting point is now much higher than it 
> has ever been - almost too high.  It was always lower than my other 
> cars before and extending the 'throw' of the hydraulics made little 
> difference.  I'm sure that is because before it was pushing one side 
> of the pressure plate down less than the other side because of the 
> offset.  There is a graphite bearing in now, time will tell.
>
> As for the gunge, that is normal as the flex hose ages.  That will 
> have no effect on release bearing wear.
>
> PaulH.
>
> ----- Original Message ----- I have a 71 MGB and I’m wondering how 
> many miles people are getting from the carbon release bearing.
>

[email-masked]