Safety Tip ?
 

I cut this from one of the wonderful emails we all get. Seems bs to me.
How can your speed increase if wheels have no traction? :mg:

NEVER DRIVE IN THE RAIN WITH YOUR CRUISE CONTROL ON. She had thought she
was being cautious by setting the cruise control and
maintaining a safe consistent speed in the rain.

But the highway patrolman told her that if the
cruise control is on and your car begins to hydroplane --
when your tires lose contact with the pavement, your
car will accelerate to a higher rate of speed and you
take off like an airplane. She told the patrolman that
was exactly what had occurred.

The highway patrol estimated her car was actually
traveling through the air at 10 to 15 miles per hour
faster than the speed set on the cruise control.

I think the idea is that the wheels start spinning real fast when they have no traction, and then when they gain traction the car lurches forward. Sounds reasonable, but I'm no expert.

I don't buy it.

There is feedback from the speedo to maintain the proper speed. As soon as the car got traction again, the cruise control would go back to normal.

It doesn't sound right. The wheels would be spinning at the same speed whether there was traction or not, right?
Hmm.....

Actually, wouldn't the cruise control just turn itself off? I know it does if you apply more gas to accelerate. Is cruise control dependent on the gas pedal or brakes being hit or is it how fast the wheels are spinning? I know if I have cruise control on and I start climbing a steep grade in my little 4 banger, the cruise control turns itself off without my doing anything. :confused:

Your cruise control is defective if it's doing that. It should adjust for increases and decreases in grade, up to a point. If you're going up the side of a fucking mountain, your speed should be below the 45 mph required for cruise control and you shouldn't have it on anyway ... if you're going up and down hills, the vehicle should compensate.

Now, as far as cruise control in the rain ... you're still in control of the vehicle when it's activated. It is not autopilot. As soon as a problem is identified by the driver, ANY of the appropriate corrective measures take over from the cruise control ... braking shuts it down totally, and after accellerating, it automatically would drop back to the set speed, unless the driver brakes or deactivates it. I don't see a problem as far as maintaining control.

Obviously, you have never driven in Colorado. Both I-25 and I-70 have stretches that go over passes or up steep grades where the posted speed limit is anywhere from 55mph to 75mph. There is one very long, steep grade on I-25 between the towns of Pueblo and Walsenberg where I have learned its pointless to try to keep the cruise control on. It turns itself off everytime, and I don't think it does this because its defective. My car has a manual transmission, if that makes any diff.

If you need to gear down to ascend the hill, you shouldn't use cruise control.

OK Professional opinion here.

Do NOT use your cruise in the rain. You can easily hydroplane and when you do, the car will slow down a bit. That's exactly the wrong time to apply power, which is just what the CC will do, causing you to spin out and lose control. I do not use my CC in the rain, snow or heavy traffic and neither should anyone else. It probably tells you that in your owners manual.

Mountains are a different story as my CC is a bit different than yours. If your actual speed drops more than ten mph or so from your set speed, the CC will drop offline to allow you to take more appropriate action, such as gearing down. My truck will NOT drop offline however. It keeps the power on no matter how much I slow down so that when I crest the hill, I can go right back up to my set speed again. Just in time for the next hill. ETC.

And just for your information, the cruise control unit takes it's data from vacuum and magnetic sensors, not the speedometer. Go to How Stuff Works website to see more info. I'd include the link but Quick Reply doesn't let me, and I'm too lazy to type in the proper codes.

Brian

Brian just paste it in. It'll link.

If the driven tires lose traction they will speed up. When they do the traction control will slow the engine down. It's reading the speed of the wheels(driveshaft) not the road speed. :eyebrow:

If you have traction control that is.

People.

You use cruise control when you want to pay less attention to your driving, yes? Then please, for pity's sake, when it's raining, turn off the cruise control, and pay attention.

I don't need to enforce this rule--Darwin has described the penalty for failure.

Brian. Is your truck an automatic or do you just lug it down till it stops moving?
It's been years since I drove. 10,11, 13, 15, 4x4, 4x5s ETC. speed transmissions. But sadly no CC. So I guess I'm not up to snuff or understanding what you're saying.

Drove the last car 3 years and 3 months on the current one. Both came with cruise control. Don't know if either one worked. :headshake

I have a Cat C15 and a E-F 9 speed Top 2 trans.

I don't do lugging as that spikes my exhaust temps and melts the turbocharger.

What happens is this: I'm cruising at 65 in nine @ 1400rpm. I hit a long hill and the rpms drop even with the cruise trying to compensate. When I get down to 1150 rpm, the trans automatically goes to 8. I hate that. Mostly because I should shift to 7 when I hit 1100 or so. Eighth gear is a formality but once in a while it's all I need to get over a hill.

Anyway, that's all the automatic there is...the rest is all on me and I've had to go down as far as 5 @ 1500 to get a heavy trailer up a steep hill, such as Donner Pass or Cabbage Hill. Poking along at 25 mph in the far right lane is hard but I've learned to get along over there since I also have a neutered truck.

Brian

Post #16 is why I love the cellar.

What? That was standard trucker talk. We always mention rpms along with the gear when discussing our trucks since it is possible to do, say, 55 in gears 7-8-9 with different rpm ranges depending on personal preference/load demands. When I'm light or empty, I usually go for high gears and low rpms but the opposite if heavy or going uphill.

Kids these days don't know how to drive stick. :-)

In the Cardinal, I cruise at 2,000 ft MSL at 2,200 rpm and 23"hg manifold pressure. :-) To climb, it's "25 squared": 2,500rpm and 25"hg.

Takeoff power is "balls to the wall" though...never know when you might need a little extra.

See that is what I mean, on the cellar you don't have to contend with the blank looks, and the rest of us can read and learn!

I mean it, that's why I love it here.

That and the sarcasm. <––– being sincere there.

I'm not going to say a word.http://www.cellar.org/images/smilies/rolleyes.gif

I would never use cruise control in rain. I also understand about downshifting and getting out of cruise constrol on steep grades. I just wondered if the cruise control wouldn't turn itself off in the situation described in the OP. I guess not if the car has an automatic transmission.

I actually use cruise control when I want to pay MORE attention to my driving, not less. I'll put it on when going down a stretch of the interstate, especially after dark, where I don't have to be glancing down and checking my speedometer for my lead foot tendencies and can instead concentrate on the road.

The Pueblo-Walsenburg stretch of I-25 is annoying because the change in grade is gradual but steady. The first couple of times I drove it in my current car, it seemed like I should be able to make it in 5th gear just fine, but the laws of gravity and a four cylinder engine would always catch up with me near the exit for the bustling metropolis of Rye. I have resigned my self to just down shifting to 4th (and out of cruise control) when I reach a certain spot near the beginning of the long, slow climb.

It'll slow down real fast when you hit the telephone pole.

I meant to say cruise control. :redface: Cruise control uses the driveshaft speed whereas traction control uses wheel speed..... and most people don't have that anyway.

I forgot the link
 

Here is the link for how a cruise control works.