I have actually had the King Cruise KC-2500 kit for about two
months and pulled the cable (front to back) when I installed the cable for my
new speedometer and a tachometer. This weekend, I finally got to the point where
I had time to modify the accelerator linkage to allow the cruise control to
work.
Essentially, the throttle accelerator linkage has to be modified to allow the
cruise control to function without attempting to pull the extra load associated
with air or mechanical throttle. In my case, I have a cable driven mechanical
throttle and there was no way that the motor in the cruise control motor could
push this kind of load.
Since I did not have the original engine, this linkage had already been modified
to function with the 8V92TA engine and, although functional, it was pretty crude.
The cruise control kit came with a number of various brackets and a sliding
arm mechanism that I was finally able to modify to work OK, I hope.
The injector pump has a rotating arm which is like a bow where
the actual actuating shaft is in center with threaded bolt holes on each end.
The inside end only has one hole and this is attached to a cable that goes to
the automatic transmission. The outside end has two holes where the outside
hole was attached to a return spring and the inner hole was attached to the
throttle cable via a small ball joint on the end of the cable.
I attached the Cruise Control cable to the outside bolt together with the return
spring in order to provide maximum mechanical leverage and to avoid interference
with the accelerator linkage.
The slot in the supplied sliding bracket was intended for
1/4 in bolt and the bolt holes in actuator arm were 3/8 inch. This required
that I attach this bracket to the actuator arm and let the cable slide in the
other end somehow unless I wanted to enlarge the slot (not easy).
The accelerator cable was secured to injector pump with a homemade "U"
bolt that was in turn secured to a small piece of angle iron that had been welded
to the support plate.
The first thing I had to do was fabricate a bracket that would allow me to move
the cable back far enough to insert the new slide between the end of the cable
and the actuator. I found a 6 inch piece of scrap angle iron that I was able
to attach to the old bolt holes for the cable support. I added new holes in
this for the homemade cable clamp for accelerator cable and the new bracket
for cruise control cable.
Initially, I attempted to use the original ball joint interface on end of accelerator
cable with my new sliding mechanism but the ball joint would shift sideways
and bind every time I pushed the pump arm towards it (which is what the cruise
control will do). I finally had to make a rigid angle bracket to connect the
end of this cable to the slide and remove the ball joint. I will note here that
the parts kit was supposed to have one or two lock nuts supplied but they were
missing. I had to go buy (2) 1/4 by 20 lock nuts to stabilize the slide assembly.
My MC8 has a lamp convertor box in engine compartment that supplies 12 VDC to tow vehicle lamps and I assumed that I could attach the brake lamp input to this but I did not have a 12 VDC switched ignition source back there for the cruise control power supply. Since I did not want to leave it on permanently, I ran a wire from the switched 24 VDC ignition source in my rear junction box( terminal #6) over to the existing lamp convertor box. I then added an additional 24 VDC relay here and used the normally open contacts on it to supply 12 VDC ignition to the cruise control.
The KC-2500 requires that you activate the controller in test
mode and roll up the cable after everything is installed and wired. I hit a
major snag here simply because of the logic associated with the brake light
interface.
I assumed that I would have to disconnect the brake line to prevent my park
brake circuit from disabling the cruise control and did so.
Two hours later after I had completely checked, rechecked all of my wiring and
had just about determined that the cruise was dead, I finally grounded the park
brake input and it started working.
After some head scratching, I finally figured out why!
Since the KC-2500 is designed for a 12 VDC automotive system, they assumed that
the brake light bulbs would provide a path to ground when the brakes were not
activated and the brake light input actually has 12 VDC on it when disconnected.
In my case, I was using a relay that provided switched 12 VDC out when the brakes
were activated and no path to ground when brakes were off unless I have my tow
car hooked up. NOTE: My rear bus lamps are still
the original 24 VDC system.
My solution:
The relays used in my lamp convertor box were automotive type that are actually
single pole, double throw but only the normally open contacts were in use. I
rewired the brake relay(only) so that:
The 12 VDC tow lamp output and cruise control brake input lines are on the relay
common.
The Normally Closed contact is connected to ground.
The Normally Open contact is connected to 12 VDC.
This could create a problem for someone who does not use diodes in the Toad wiring system since it presents a short to your car brake system but I have diodes in my Saturn.
I have yet to calibrate and test the Cruise since I currently
have my air filter off but I have not tested the latest speedometer modifications
either.
6/09/2000 Update:
I found some Teflon washers for the sliding mechanism used to isolate the throttle
linkage from injector pump arm.
Boy, do these things make a difference. There is absolutely no friction in this
assembly now.
I also received my new air filter and reassembled the housing which allowed
me to start the engine again.
I Checked the Cruise fast-idle function by releasing the park brake and it works
very well.
Hopefully, the actual cruise will work OK also but I will not be checking it
until we go to Bernards Bus on June 20 to get the drive wheel brakes reworked.
6/25/2000 Update:
I had an opportunity to use the cruise control on a 270 mile trip back from
Bernards Bus in Pa.. I wanted to use it on the way up but the speedometer that
I am using to provide a signal to it was not functional
See Speedometer Saga. The unit works great and the knob that allows you
to make minor adjustments in speed is the slickest deal since high button shoes.
I was surprised at how well the coach held speed on some fairly significant
grades.
11/25/2000 Update:
One final note after some more over-the-road experience with the KC-2500.
The calibration procedures require that you set the center operation point of
the cruise by centering the knob then maintaining your coach speed at 60 MPH
while switching the on/off switch on 4 times then depressing the set button.
This all worked fine but I later descovered that my top speed available was
around 70 MPH in cruise. I called King Cruise and they told me to simply "calibrate"
it at a higer speed to get higher limit. None of this was in the manual and
I havn't had a chance to try it yet.