covered in this article -
accelerator cable is routed from the accelerator pedal through
the floor pan, then into a flexible guide tube near the transaxle,
and finally through a tube in the fan housing to the carburetor,
where it attaches to a lever arm that in turn attaches to the
throttle valve inside the carburetor. In the top of the lever
arm there is a screw that rests on a stepped cam. This cam is
attached to the upper butterfly valve in the carburetor, the
choke, which we will discuss later.
Accelerator Cable Replacement
Dave found that one of the reasons his car was
not idling as is should was that the accelerator cable connection
under the accelerator pedal was not attached correctly. "A very
poor design," he thought at first. He bent the metal piece of
the end of the cable around so that it could not come loose
or get twisted around improperly. Then he was able to adjust
the cable properly at the carburetor end.
time later Dave's accelerator broke while he was driving home
from work, right behind the metal fitting that he had previously
bent around to make it fit properly. Dave then examined the
fitting on the new cable properly and had a learning experience!
:-) The proper attachment of the fitting on the forward end
of the accelerator cable is shown in the following picture -
Correct Attachment of the
poking around behind the fan shroud from the left side, Dave
found the copper guide tube coming through the fan shroud but
NOT going through the hole in the firewall. So he jockeyed it
into position and I had his son hold it in place while he pulled
the old cable out from the front. Dave discovered that was was
frayed down to two strands about two inches from the front end.
his son held the copper guide tube in place, Dave started snaking
the new cable towards the back, greasing it as he went. It got
right to the hole in the firewall and hung up. So Dave crawled
under the car and jerked the flexible tube out (he wasn't going
to replace it, but when he found the fitting on the rear end
missing he changed his mind). Getting the cable into the tube
and the tube in place was fiddly, Dave found but not so much
so as guiding the end of the cable out of the flexible tube,
through the hole in the firewall, and into the copper tube that
goes through the fan shroud.
this process Dave found that something was interfering with
the accelerator tube just forward of the firewall. He crammed
a piece of stiff wire through while his son was watching from
underneath -- he found the interference to be the new tranny
rubber he had installed. So Dave cut a little notch in the rubber
to accommodate the cable and reinstalled the cable with no problems.
came adjustment time. First Dave adjusted the cable exactly
according to the specification -- accelerator pedal all the
way to the floor, throttle lever wide open, 1mm clearance between
the lever and the carburetor body. No problem -- except adjusted
that way the throttle lever wouldn't return all the way to the
cam and the throttle valve inside the carburetor was open too
much -- thus high idle, just like before when the throttle valve
was sticking. Dave decided that wouldn't do and readjusted the
accelerator cable as Rob suggested -- throttle lever against
the cam, cable pulled back as tightly as possible (finger tight).
With it adjusted that way Dave was able to proceed with the
expressed concern about the interface point between the rear
end of the flexible tube and the copper guide tube as it pokes
forward through the firewall. The fitting on the end of the
flexible tube is flared, and the two just rest together, or
so it would appear. Manipulating that interface is all by greasy
feel, with your arm bent around at a very awkward angle. It's
almost impossible to see it -- it's right on top of the tranny
a couple of inches above and toward the center from the clutch
adjustment nut. The copper guide tube wiggles around in the
fan shroud and comes out of the hole in the firewall very easily.
The rubber screw-in grommet type thing on the rear as it comes
out of the fan shroud is deteriorated and not doing much to
hold the tube in place.
responded - So which way did the cable move when you tried it
my 'quick' way? Did it project further to the rear of the car,
or less? If too much further to the rear of the car (more cable
through the fixing nut on the accelerator arm) it might result
in overstretch of the cable on full throttle, and would be pulling
hard on the accelerator arm. If less cable now pokes through
the fixing nut, it means that at full pedal movement you'll
have a 'not quite' vertical throttle butterfly maybe lose a
few revs at the top end.
response to Rob - The accelerator cable was further "in" when
adjusted your way. The other way it was further "out" and the
idle screw (which I knew to be set correctly) would not return
to the lowest step on the cam. So setting it your way works
much better. Haven't noticed the loss of a few rev's at the
you see in any of your catalogs one of those screwy little rubber
grommets that goes on the rear end of the copper guide tube,
between it and the fan shroud, please let me know. That would
hold the tube properly in the hole in the firewall.
Accelerator Cable Adjustment
Dave posed the
following question to the RAMVA Newsgroup - My car is a '73
Super Beetle. My question has to do with the accelerator pedal
and cable. If the throttle lever is adjusted per spec, the cable
sticks out way further (towards the back) than it should (the
hold down bolt is actually on the cable). The accelerator pedal
has very little travel, and when I pull it back I find that
the arm with the wheel on it (accelerator cable attached) wiggles
about an inch back and forth (front to back). Intuition tells
me that this arm (Bentley calls it a "connecting lever") should
be held completely back (no pressure on the pedal) by a spring
or something and should only move forward when the pedal is
depressed. I guess the throttle lever return spring should do
this, but in mine there is about an inch of free play.
bottom line is I can't adjust the cable properly, the throttle
lever will not return completely to the cam, and thus I can't
adjust the throttle screw or the idle. And the car runs like,
well, dog do do.
and see if you have the correct cable installed first. Or,
the cable may be old and possibly.
of thoughts -- Look under the pedal pedal for dirt/fluff etc.
which might be catching the cable or pedal at that end. Sometimes
some dirt gets caught under the bottom end ('floor' end) of
the rubber cover on the accelerator pedal, which rubs on the
floor (on mine anyway). Dirt under here tends to push the
accelerator on. A squirt of WD40 etc on the shaft/bushing
and little roller (I presume you have one) under the pedal
helps to keep it loose too. Have you made sure the cable is
not pulled too tight? I set mine by loosening the lock nut
on the carby end, and while holding the throttle arm against
the lowest step on the cam, just tugging the cable rearwards
with fingers only (not pliers/multigrips) until it's snug
-- but not tight through the throttle arm connector. This
means there should be little on no play in the accelerator
pedal, but not so tight that the throttle is held open on
cable end at the carburetor should fasten on the steel end
piece, not on the cable itself. Could it be stretched, or
even frayed cable (inside the cable tube)? Could it be hooked
on wrong at the pedal end?
experience - This afternoon I took my 8mm box end wrench out
to the car, parked at the curb in front of the house. I opened
the engine lid and applied the wrench to the bolt that holds
the accelerator cable into the throttle lever assembly. Then
I loosened it up, held the throttle lever against the lowest
part of the cam, and gave a pull on the accelerator cable. I
found a problem -- the metal thing on the end of the cable pulled
about 1/4-inch past the hold down bolt. I think we've got a
stretched cable -- next on the shopping list. I tightened the
bolt down on the wire -- not the best thing to do, but it will
HAVE to do until I can get the cable replaced. I understand
that's quite a chore.
I went in and washed my hands and then fired her up. There is
lots more pedal, and a MARKED improvement in the way it runs.
Still hesitates a little on acceleration, but orders of magnitude
better than the way is was running this morning. Now I need
to check to see if the throttle lever is returning properly.
- My concern is that there is very little "travel" in the accelerator
pedal -- the distance between no applied pressure and floor-boarded
is very short. I think I need to get a buddy to help me with
this, and I need to get in there under the steering wheel and
take a look at what's going on. Something is definitely not
as it should be. I like to be able to "feel" the accelerator
responded - Hmmm... Sounds a little odd. When you floor the
accelerator pedal lever does the throttle arm move all the way?
(Put a brick on the accelerator pedal to hold it down if you
haven't got a second person to look). You might need to remove
the throttle spring if you can't find a big enough brick to
hold the throttle down.
the cable has become partially unhooked or somesuch. It definitely
sounds out of whack.
experience - I pulled the cable back pretty hard with my channel
locks before tightening the bolt that holds it in place -- I've
probably snugged it up too tight. You said to just pull it back
finger tight, as I recall.
responded - It certainly shouldn't need a hard tug -- it should
slip both ways through the cable channel quite easily.
continued - The only hard thing about taking the carburetor
off is getting that blasted accelerator cable adjusted properly.
I'm never sure that I've got it right. Your method (hold it
finger tight and tighten it down) seems to work best, but there's
still no gap between the arm and the stop as there is supposed
responded - Then if you floor it hard, you'd be putting strain
on the throttle arm. I guess you'll just have to loosen it a
bit until you get a bit of free play.
continued - I can't loosen it too much -- there's only about
1/8th inch of the end of the cable sticking out beyond the connection
on the bottom of the throttle arm. I am going to loosen it just
a tad more, though.
responded - That seems a little odd too -- mine pokes through
the clamp about 1/2 way, so there's plenty of adjustment either
Fan Housing Guide Tube
Dave's experience - Regarding the tube that passes through the
fan housing -- this tube just sits
loose in the fan housing at a slight downwards angle (rear up,
front down), and has a flange on the rear side which stops it
falling into the shroud. This tube allows a degree of engine
rotation under acceleration, etc. without kinking/pulling the
cable. The hole in the FRONT of the fan shroud is a bit enlarged
to allow this movement.
would be a devil of a job to thread the cable through the shroud
without this metal sleeve, and it could then bind on the shroud
- Somebody told me a while back that I would have to get the
guide tube welded back in place. How about if I position it
properly and then put a bead of JB Weld around it to hold it
firmly to the fan housing? I fear that our accelerator cable
is going through the fan shroud bare and that it's rubbing against
the metal edge and wearing, thus the lengthening that we seem
to be experiencing.
continued - Earlier I asked about the accelerator cable tube
and thought maybe I should "JB Weld" it to the fan housing.
With the carburetor off I had a better look, and of course you're
right -- the hole it comes through is enlarged specifically
so the tube can move. Ours has a rubber spiral type plug that
surrounds the tube and is supposed to screw into the hole, except
our plug is old and in very poor shape. I've never seen either
the tube or the plug for sale anywhere -- have you? The tube
is so loose that it's sticking out of the fan housing towards
the back! Could it be that it's just pulled back part way out
of the fan housing and maybe can be slipped back into place
responded - The sheath has a close fitting hole in the rear
of the shroud, and a slightly elongated hole in the front of
the shroud. It should be possible to just 'fiddle' it into the
front hole, so it slides forward and sits flush against the
rear (carby side) of the shroud. The front hole is elongated
slightly to allow the cable itself to align the sheath when
it's pulled (the throttle is worked). With the sheath too far
to the rear, the cable could be rubbing on the front side of
the shroud edge, especially as it now has the weight of the
sheath (the bit inside the shroud) pulling it down.
you welded (JB or metal) it in, it would lose it's capacity
to self-align, which is happening all the time as the engine
flexes (rotates) on it's mounts. So welding is not a good idea
-- it would create a real rubbing area at the front edge of
ingenious design again.
not sure if your sheath is different to mine, you have the doghouse
cooler on the front of the shroud. But I suspect it's the same
-- that the spot on the shroud where the cable comes through
is probably 'flush', just to the right of the doghouse 'bulge'.
If there is a difference, maybe you need a longer sheath? But
I doubt it.
continued - I was out fussing around the engine this afternoon,
tightening bolts in the tin and just generally cleaning. I noticed
something interesting -- the bell shaped fitting on the rear
end of the accelerator cable tube isn't sticking through the
front of that piece on the engine that sticks up (whaddya call
it!?). It's just resting on the other side, dropped down a little
by gravity. I tried to pull it through, but its too big around.
This fitting must come off so you can slip it through the hole
from the rear and then reattached it to the tube. If so, I've
never seen a procedure that makes this clear. Can you help me
responded - I have a single tube-shaped piece with an expanded
(your bell shaped?) end which slides through the shroud from
the rear of the engine, and pokes through the front of the shroud.
The hole in the front of the shroud is slightly elongated so
when the cable is under tension, the tube can align itself straight
along the cable. It's only the expanded end which prevents it
falling through/into the shroud.
continued - I'm a bit baffled by the accelerator cable guide
tube. The cable is running through okay, but there is a definite
mismatch at the firewall. And its so awkward trying to work
back there. I'm going to reach in with my long channel locks
and see if I can get a good grip on the guide tube and push
it into the hole and mate it with the cable tube on the other
side. It's hard because the guide tube moves so freely through
the fan shroud. I think there's supposed to be a rubber grommet
or something on the rear end of it that holds it in place; our's
is missing (of course) and I've never seen anything like that
in any of the catalogs.
response - There's no grommet (and never was) on mine. The hole
on the front side of the fan shroud is (on mine) slightly elongated
so the cable can line up straight from gearbox end to carby
end, with the tube being "supported" at that point (front of
fan shroud) by the cable. Makes for a small waste of cooling
air I guess, but there is definitely no grommet.
continued - The guide tube goes through the fan shroud and then
through the firewall, protruding about half an inch forward
of the firewall. The bell-shaped end of the accelerator cable
tube is supposed to slip over the protruding end of the guide
tube, but I'm having a devil of a time getting it to do so without
pushing the guide tube back through the firewall. I think I
need an assistant to hold the guide tube firmly in place against
the rear of the fan shroud whilst I reach up over the tranny
and slip the bell-shaped end of the flexible tube over the other
end of the guide tube (if that makes any sense at all! :-)
going to detach the accelerator cable and pull it forward through
the firewall, then I'm going to wrap several layers of black
plastic electrical tape around the rear end of the guide tube
and "screw" it into the hole in the fan shroud as tightly as
responded - That might work. Certainly worth a try, and easily
reversible if it doesn't help.
In January 2005 Dave replaced
his Bocar 34PICT/3 carburetor with a Pierburg model. Just on
accounta 'cuz, Dave also replaced the barrel clamp at the base
of the accelerator throttle arm, the clamp that connects the
accelerator cable to the throttle arm. Dave found that the fit
was a little tight, so Dave got out his "persuader" and gently
tapped the barrel clamp into the throttle lever. Mistake! The
barrel clamp must turn freely in the throttle lever, otherwise
it will kink the accelerator cable and cause the engine to run
at very high rpm. Dave prized the barrel clamp out of the throttle
lever and reverted to the old one, which is slightly smaller
in diameter and turns freely. Dave made sure with a healthy
squirt of WD40! :-)
used to connect the heater cables
to the heater box lever
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