[FC] Clutch linkage - early vs. late
Kent Sullivan
kentsu at corvairkid.com
Sat Nov 12 21:43:33 EST 2005
Hi all,
"A continuing stoooorrryyy of a quack who's gone to the dogs" (I love the
Muppet Show!)
Anyway, I think the clutch linkage on my '64 Rampside is now sorted out.
Read on for the gory details...
I recently installed the used clutch rod that Clark's sent me. When the
linkage is hooked up, this rod passes through the dust shield in the middle
whereas the previous one was all the way to one side. In comparing the rods,
it looks like they started out life as the same part but the one I had been
using was bent. Maybe when the transaxle had been lowered for removal in the
past?
I also replaced the front and rear return springs. Both were wrong. The
front was also missing the spring extension and I installed one of those
too. You may recall that I also tracked down a "Z"-shaped bracket that
receives the front of the rear return spring. And I tracked down and
installed the correct dust cap. (Yay to Jeff Williams at California Corvair
Parts for having these items!)
With all of the correct parts, the shifting was still problematic. I believe
I have isolated the problem as the location of the first (front-most) clamp
that holds the clutch cable in place. This is the one with the tang that
fits into a second hole (to keep it from rotating). Basically, 1/4" or even
1/8" difference in its location with respect to the cable greatly affects
where the clutch pedal, in its travel, disengages the clutch, to the point
that one can be in a situation where the clutch is not disengaging enough to
shift smoothly or even at all!
Here's a picture of the clamp I am talking about:
http://www.corvairkid.com/articles/images/UPC_7_Section_C_Page_3.jpg
It's part #4 in the picture. I learned that I had to (a) position the clamp
as far forward on the clutch cable as possible--basically right next to the
front boot; (b) pull down on the cable behind the clamp with my left hand
when tightening the bolt to keep tension on it--and to keep the clamp
vertical; and (c) use *much* more torque on the bolt than the 75 inch pounds
max that the assembly manual specifies.
Failing to do any of these three resulted in either a clutch that did not
disengage properly immediately or one that started having problems after
just a few down-and-up cycles of the pedal. I think I have it fixed now but
I need to drive some more miles to be sure.
Has anyone on the list had similar experiences? Part of the trouble might be
that the NOS replacement clutch cables don't have this clamp. You must
transfer it from another cable, which means you have to bend it to get it
off the old cable and onto the new one, which distorts it somewhat. (Both
ends of the cable have fittings on them that are too large for the clamp to
slide over.) Thanks to Mike Weirmier for giving me the clamp! I was, of
course, missing that too!
--Kent
-----Original Message-----
From: corvanatics-bounces at corvair.org
[mailto:corvanatics-bounces at corvair.org] On Behalf Of Kent Sullivan
Sent: Wednesday, October 26, 2005 8:25 AM
To: 'The Corvanatics list'
Subject: RE: [FC] Clutch linkage - early vs. late
Hi everyone,
I spoke to Jason at Clark's. His experience is that the rods are all about
the same length. He said the 3780836 is quite rare to see and has a "funny
bend" in it plus the bell housing end is flattened in a little different
manner.
He also said that the 3786914 and 3827690 are the same visually. He wondered
if the manufacturer changed and that was the reason for the part number
difference.
So, that plus the catalog info below means that that 1961 had a unique rod
but that unique rod was not offered as a replacement part. 1962-1965 had the
same rod but the part number changed.
Can anyone shed additional light on this?
Thanks.
-----Original Message-----
From: corvanatics-bounces at corvair.org
[mailto:corvanatics-bounces at corvair.org] On Behalf Of Shaun
Sent: Sunday, October 23, 2005 10:09 AM
To: The Corvanatics list
Subject: Re: [FC] Clutch linkage - early vs. late
Hi Kent, my parts book shows:
0.787 ROD, CLUTCH FORK PULL
1 3780836 1961/R1200 - FIRST JOBS - 12-1/2 OL
1 3786914 1961/R1200 - AFTER JOBS
1962/R1200
1 3827690 1963-65/R1200
so, there's 3 different ones...
Shaun
----- Original Message -----
From: "Kent Sullivan" <kentsu at corvairkid.com>
To: "'The Corvanatics list'" <corvanatics at corvair.org>
Sent: Sunday, October 23, 2005 9:52 AM
Subject: RE: [FC] Clutch linkage - early vs. late
> Right--I am definitely aware of the through vs. under cross-member
> part. I am wondering about the pull rod that is further back from
> there--the rod with the fine-threaded end that goes into the transmission.
>
> According to the assembly manuals, the first design linkage was used
> in
'61
> and most of '62. The '62 manual shows the second design and it's a
> very
late
> change in the production year. The drawings appear to be exactly the
> same for '62 - '65 so I would be interested in details of known
> differences in the second design...
>
> --Kent
> -----Original Message-----
> From: corvanatics-bounces at corvair.org
> [mailto:corvanatics-bounces at corvair.org] On Behalf Of James Davis
> Sent: Sunday, October 23, 2005 9:35 AM
> To: The Corvanatics list
> Subject: RE: [FC] Clutch linkage - early vs. late
>
> The late model system has the clutch cable terminating in the cross
> member where as the early model system has the clutch cable going
> under the cross member to the idler lever. The 61 Ass'y manual,
> Section 6 sheet 21.00
shows
> the correct early arrangement. Rad is correct in that when I changed
> from
a
> 3 speed trans to a 4 speed in his Greenbrier, I used an early setup
> (the Greenbrier was purchased with a 62 car engine and 3-sp) because
> that is
what
> came on my 61 Rampside and I had a spare. Only later did I find out
> abut the much different clutch cable system of the late FC's. Of
> course the late 63's use a hybrid system, part of the new and part of
> the old. And
you
> thought all FC's were the same ;-).
> Jim Davis
>
>
>
> .At 10:36 AM 10/23/2005, you wrote:
> >Rad,
> >
> >Very interesting--thanks!
> >
> >You bring up an interesting point. The assembly manual also does not
> >make it clear how to tell the early vs. late pull rods. I *assume* I
> >have a late one since the bell crank and etc. are not on my rig--but
> >I
> don't know for sure.
> >Do you have an easy way of determining this? The rod appears to line
> >up properly with the end of the clutch cable and does not hang down
> noticeably.
> >
> >I guess I also don't know for sure whether I have a late FC release
> >fork and fork pivot ball...
> >
> >--Kent
> >-----Original Message-----
> >From: corvanatics-bounces at corvair.org
> >[mailto:corvanatics-bounces at corvair.org] On Behalf Of Rad Davis
> >Sent: Saturday, October 22, 2005 8:45 PM
> >To: The Corvanatics list
> >Subject: Re: [FC] Clutch linkage - early vs. late
> >
> >Kent,
> >
> >I have walked down that particular road:
> >
> >When my father gave me the Twinki 15 odd years ago, it was fully
> >functional, but some of the parts were an interesting mixture.
> >
> >Dad's only prior FC experience was with his '61 rampside. Lots of
> >the late-model-specific parts were missing from Twinki when he got
> >it, so he substituted the commoner early parts and some creative
> >fabrication as necessary.
> >
> >The clutch linkage was mostly early FC, with a custom pull-rod (don't
> >have my manual handy for the proper name - I mean the threaded part
> >with the clevis pin hole on the other end that goes into the
> >bellhousing) made from a straigtened car part. The return spring
> >"extension" was a piece of carefully-formed coathanger wire made to
> >match the one on the Rampside. It had the cable bracket on the
> >transmission crossmember (even though it had the correct crossmember
> >with the hole), and an NOS early pivot arm assembly he'd gotten
somewhere.
> >
> >I really didn't like the way the clutch worked. As it happened, he
> >had the wrong mixture of clutch parts resulting in a too-long clutch
> >release travel, but I didn't know that until I took everything apart
> >and measured, eventually converting to the late car/late FC clutch,
> >release fork, and fork pivot ball. I also didn't like that the
> >clutch cable and linkage stuck down so far. I had to pick shreds of
> >grass out of the assembly on more than one occasion after parking on
turf.
> >
> >I lucked into all the right linkage parts (and a bunch of other
> >detail
> >parts) on a '64 GB Deluxe Jerry McKenzie and I parted out in the mid
'90s.
> >Luckily, the parts van had almost all the odd parts the 63-65 vans
> >came with. Also luckily, Jerry had a '61, so didn't want any of
> >them. I didn't know that the Z-shaped bracket was so rare. It would
> >be trivial to reproduce. I also didn't know that the late dust cap
> >wasn't properly documented. It would indeed be a real challenge to
> >get everything together without that special tab for the cable return
> >spring. I suspect that the late dust cap could also be done as a
> >cottage reproduction given a supply of early/car dust caps.
> >
> >My best guess about the early "extension" and that funny long
> >L-bracket tab on the dust cap is that the spring was used on
> >something that was a lot more common than FC corvairs. Perhaps Chevy
> >truck clutch return springs of the era? An interchange manual of the
> >era and the spring part number might be helpful.
> >
> >As for why GM did it that way, I've always had the feeling that the
> >first design mechanism was made to minimize investment in custom parts.
> >It certainly isn't a rational design given a clean slate. The
> >transmission cross member is the same as the early car part. The
> >spring looks like it was sourced somewhere else as well. It may well
> >be that the second design was really the original design but was
> >shelved because of the retool cost of adding that hole in the
transmission
> cross member.
> >
> >-- Rad
> >
>
>
>
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