Cruise Control Aggressiveness

With the ultimate goal being..?

Like it!!

What would happen if a mechanical spring located on the pedal cable is reached at certain level in order to get the limit you want when the control motor pull force and the spring force get the equilibrium. The spring will not allow the control pull to continue further the limit, unlees a pedal force if the driver want can go further. A controller DC servo motor can withstand without problems been kept energized for a time.

I don't think it safe to alter your accelerator pedal or cable with anything not specifically designed for that purpose, so I will not comment on your idea. This is not an area you want to start modifying yourself.

First, I agree withe JPool and others that this is NOT a safe thing to experiment with.

In addition, I suspect that it would be illegal to do so in most places.

Finally, I don't believe that the cruise control pays any attention to the position of the accelerator pedal, at least in the vehicles I've owned. If you press the accelerator sufficiently, the engine control unit will temporarily override the cruise control, and the vehicle will go faster than the speed set at the cruise control, but letting up on the accelerator pedal will just let the car slow down to the set speed.

I currently have two vehicles with cruise control; one of them is much jerkier than the other, but I'm not about to try to change anything...

Have you had your dealer look at it?

Maybe it has a fault that needs to be fixed.

I added cruise control kits to vehicles I drove in the late 1970's and through the mid 1980's. If I recall properly, those kits provided a proportional (gain) band adjustment and a reset (integral) adjustment as screw driver 'pot' adjustments. The adjustments were color coded screws.

The reset adjustment would make the vehicle more or less sensitive to speed lost on a hill. Increasing its gain would make it add speed more quickly to compensate for lost speed, decreasing its gain would make it less sensitive.

I don't recall a rate adjustment, but there might have been one.

I'm sure that the calculation for more or less throttle is now done in one of the controllers digital controllers. Whether there's access to the PID terms nowadays, who knows?

There are aftermarket cruise control kits for a variety of vehicles. An after market vendor could answer your question about sensitivity adjustments.

The actuators used to be diaphragm driven. Those diaphragm actuators were known to fail with smaller or larger leaks over time. A small leak would de-sensitize the response.

Sorry to be negative on this one, but cruise control associated risk don't compensate for ANY added driving "comfort". Still, there's the issue that a driver unsuspected or lazy enough to use it, is on a risk category of its own anyway, and statistics won't show dramatic differences, so what the h*ll. S.M.

When the driver is not up to task, it is time to limit the driver.

I drove a rental car, Jeep Liberty maybe, that kept the speed constant, even going downhill.

If you really need to use a cruise control, the absolute best unit I have ever used was made by Dana Corp. It was aftermarket installed with a single ignition wire pickup for speed sensing and a vacuum cylinder to drive the throttle. On a 1988 Nissan 1.6liter engine it was the smoothest transition both increasing and decreasing speed and never "hammered" the throttle wide open at the base of a hill. It was also extremely sensitive to wheel slippage and would release the cruise on any wheel slippage unlike the Nissan factory cruise control which would race and slip the tires. Still your best bet is the apply manual throttle input prior to the bottom of hills before going up the next. Higher horsepower, lower geared vehicles negotiate up and down hills with far less throttle input modification but usually result in poorer fuel economy.

I agree with some of the other folks here -- if you modify your cruise control and are involved in an accident, it could result in legal problems.

I use my cruise control on the highway, but have always thought about what to do if the thing doesn't disengage (ala Toyota).

I modified the cruise control in one of my previous cars to provide either constant speed or constant throttle with a switch selection between them.

This did not affect the clutch/brake disconnect, but in constant throttle it allowed me to over-ride the throttle with my right foot when necessary and then ease back to the constant throttle position without having disconnected the cruise.

This was good on the flat or uphill, but is not recommended for downhill, then switch back to the constant speed.

My Ford does this.

You could just tie a rope to the throttle that would limit how far it could open, but that would be stupid, right?

Most cruise systems have a coast switch, that will allow your right foot to control the speed. After the hill has been crested, you can just hit the resume switch, and the original speed will be maintained again.