Subject: Re: [Spridgets] Clutch Problems

From: JMFangio via Spridgets <[email-masked]>
Date: Thu, 20 Jan 2022 08:08:45 -0600

That’s a problem I too have been dealing with, right down to the description of the clutch working like a light switch!

Thanks

Hmm, do you think that it was the slightly longer push rod  or the slave cylinder??

Lester

> On Jan 18, 2022, at 3:16 PM, Michael MacLean via Spridgets <[email-masked]> wrote:
> 
> Since I did a Datsun transmission swap to my 1275 powered Bugeye I have always had a terrible clutch.  The conversion kit is from Paul A before he passed so you can get an idea of how long I have been living with this clutch.  Per Paul I used a Datsun clutch with a re-machined 1275 flywheel and th eoriginal 948 drum brake slave cylinder.  I was assured this would all work out by paul.  Well, it worked, but the the clutch pedal went from a normal pressure and travel with my 948 and smooth case trans setup to a nightmarishly hard clutch that had to be depressed all the way to the floor and grabbed immediately when it was brought up resulting in all the clutch action happening in the first few inches of travel back up from the floor.  It essentially acted more like an on and off switch than a clutch.  To facilitate this arrangement I had a combination master cylinder using the brake bore of the original 7/8" for the 4 drum brakes I retained in the car and a 3/4" re-sleeve on the clutch side for the Datsun clutch.  I thought I was stuck with this arrangement.  As some of you guys know, I have just got around to converting the front brakes to disc.  As part of this conversion I bought an AP Lockheed 3/4" double bore master cylinder.  This made no difference to the clutch effort as the clutch bore did not change.  I don't know why, but I came to the conclusion that a 1275 slave cylinder would be better for the clutch pedal effort as I now had a 1275 in the car.  As I look back on that thinking, it is rather flawed.  Yes, I had a 1275 in the Bugeye, but I had a Datsun transmission and a Datsun clutch in the car. Wouldn't that require a Datsun slave cylinder?  Well, out of my ignorance I had the 1275 1" bore slave cylinder installed in the car with a slightly longer slave pushrod and bled the clutch with a pressure bleeder.  Holy crap!  The clutch pedal is now to an almost normal amount of actuating pressure and the engagement travel is more like a normal clutch.  I am one happy camper!  Just wanted to pass this along if any of you guys with a similar setup is experiencing the same "on/off" switch syndrome with your Datsun trans conversion.
> Mike MacLean
> P.S. Just in time for spring and summer!
> ------------------------
> 
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From: Michael MacLean via Spridgets <[email-masked]>
Date: Thu, 20 Jan 2022 07:43:05 -0800

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The larger (1" bore) slave cylinder is the reason for the great
improvement.  The longer pushrod is necessary using the larger bore slave
to get the proper amount of movement required for the throw out bearing
lever.  As long as you get all the air out of this hydraulic line you will
get the benefit from this "fix".
Mike M

On Thu, Jan 20, 2022, 6:09 AM JMFangio <[email-masked]> wrote:

> That=E2=80=99s a problem I too have been dealing with, right down to the
> description of the clutch working like a light switch!
>
> Thanks
>
> > Since I did a Datsun transmission swap to my 1275 powered Bugeye I have
> always had a terrible clutch.  The conversion kit is from Paul A before h=
e
> passed so you can get an idea of how long I have been living with this
> clutch.  Per Paul I used a Datsun clutch with a re-machined 1275 flywheel
> and th eoriginal 948 drum brake slave cylinder.  I was assured this would
> all work out by paul.  Well, it worked, but the the clutch pedal went fro=
m
> a normal pressure and travel with my 948 and smooth case trans setup to a
> nightmarishly hard clutch that had to be depressed all the way to the flo=
or
> and grabbed immediately when it was brought up resulting in all the clutc=
h
> action happening in the first few inches of travel back up from the floor=
.
> It essentially acted more like an on and off switch than a clutch.  To
> facilitate this arrangement I had a combination master cylinder using the
> brake bore of the original 7/8" for the 4 drum brakes I retained in the c=
ar
> and a 3/4" re-sleeve on the clutch side for the Datsun clutch.  I thought=
 I
> was stuck with this arrangement.  As some of you guys know, I have just g=
ot
> around to converting the front brakes to disc.  As part of this conversio=
n
> I bought an AP Lockheed 3/4" double bore master cylinder.  This made no
> difference to the clutch effort as the clutch bore did not change.  I don=
't
> know why, but I came to the conclusion that a 1275 slave cylinder would b=
e
> better for the clutch pedal effort as I now had a 1275 in the car.  As I
> look back on that thinking, it is rather flawed.  Yes, I had a 1275 in th=
e
> Bugeye, but I had a Datsun transmission and a Datsun clutch in the car.
> Wouldn't that require a Datsun slave cylinder?  Well, out of my ignorance=
 I
> had the 1275 1" bore slave cylinder installed in the car with a slightly
> longer slave pushrod and bled the clutch with a pressure bleeder.  Holy
> crap!  The clutch pedal is now to an almost normal amount of actuating
> pressure and the engagement travel is more like a normal clutch.  I am on=
e
> happy camper!  Just wanted to pass this along if any of you guys with a
> similar setup is experiencing the same "on/off" switch syndrome with your
> Datsun trans conversion.
> > Mike MacLean
> > Unsubscribe/Manage:
> http://autox.team.net/mailman/options/spridgets/[email-masked]
>
>

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<div dir=3D"auto">The larger (1&quot; bore) slave cylinder is the reason fo=
r the great improvement.=C2=A0 The longer pushrod is necessary using the la=
rger bore slave to get the proper amount of movement required for the throw=
 out bearing lever.=C2=A0 As long as you get all the air out of this hydrau=
lic line you will get the benefit from this &quot;fix&quot;.<div dir=3D"aut=
o">Mike M</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=
=3D"gmail_attr">On Thu, Jan 20, 2022, 6:09 AM JMFangio &lt;<a href=3D"mailt=
o:[email-masked]">[email-masked]</a>&gt; wrote:<br></div><b=
lockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px =
#ccc solid;padding-left:1ex">That=E2=80=99s a problem I too have been deali=
ng with, right down to the description of the clutch working like a light s=
witch!<br>
<br>
Thanks<br>
<br>
Hmm, do you think that it was the slightly longer push rod=C2=A0 or the sla=
ve cylinder??<br>
<br>
<br>
Lester<br>
<br>
<br>
&gt; On Jan 18, 2022, at 3:16 PM, Michael MacLean via Spridgets &lt;<a href=
=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"noreferrer">s=
[email-masked]</a>&gt; wrote:<br>
&gt; <br>
&gt; Since I did a Datsun transmission swap to my 1275 powered Bugeye I hav=
e always had a terrible clutch.=C2=A0 The conversion kit is from Paul A bef=
ore he passed so you can get an idea of how long I have been living with th=
is clutch.=C2=A0 Per Paul I used a Datsun clutch with a re-machined 1275 fl=
ywheel and th eoriginal 948 drum brake slave cylinder.=C2=A0 I was assured =
this would all work out by paul.=C2=A0 Well, it worked, but the the clutch =
pedal went from a normal pressure and travel with my 948 and smooth case tr=
ans setup to a nightmarishly hard clutch that had to be depressed all the w=
ay to the floor and grabbed immediately when it was brought up resulting in=
 all the clutch action happening in the first few inches of travel back up =
from the floor.=C2=A0 It essentially acted more like an on and off switch t=
han a clutch.=C2=A0 To facilitate this arrangement I had a combination mast=
er cylinder using the brake bore of the original 7/8&quot; for the 4 drum b=
rakes I retained in the car and a 3/4&quot; re-sleeve on the clutch side fo=
r the Datsun clutch.=C2=A0 I thought I was stuck with this arrangement.=C2=
=A0 As some of you guys know, I have just got around to converting the fron=
t brakes to disc.=C2=A0 As part of this conversion I bought an AP Lockheed =
3/4&quot; double bore master cylinder.=C2=A0 This made no difference to the=
 clutch effort as the clutch bore did not change.=C2=A0 I don&#39;t know wh=
y, but I came to the conclusion that a 1275 slave cylinder would be better =
for the clutch pedal effort as I now had a 1275 in the car.=C2=A0 As I look=
 back on that thinking, it is rather flawed.=C2=A0 Yes, I had a 1275 in the=
 Bugeye, but I had a Datsun transmission and a Datsun clutch in the car. Wo=
uldn&#39;t that require a Datsun slave cylinder?=C2=A0 Well, out of my igno=
rance I had the 1275 1&quot; bore slave cylinder installed in the car with =
a slightly longer slave pushrod and bled the clutch with a pressure bleeder=
.=C2=A0 Holy crap!=C2=A0 The clutch pedal is now to an almost normal amount=
 of actuating pressure and the engagement travel is more like a normal clut=
ch.=C2=A0 I am one happy camper!=C2=A0 Just wanted to pass this along if an=
y of you guys with a similar setup is experiencing the same &quot;on/off&qu=
ot; switch syndrome with your Datsun trans conversion.<br>
&gt; Mike MacLean<br>
&gt; P.S. Just in time for spring and summer!<br>
&gt; ------------------------<br>
&gt; <br>
&gt; <a href=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"n=
oreferrer">[email-masked]</a><br>
&gt; <br>
&gt; Donate: <a href=3D"http://www.team.net/donate.html" rel=3D"noreferrer =
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</blockquote></div>

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