Traction control on a gravel road

We live on a gravel road that has a fairly steep grade, but apparently not as steep as the road you were on. I'm anxious to see how the stock tires will do this winter. I'm not expecting miracles, but I've also got a 4WD truck for snowy weather.. B)

 

<div class='quotetop'>QUOTE(qbee42 @ Oct 23 2006, 11:27 PM) [snapback]337168[/snapback]</div>

The problem does not lie with the tires, but with the anti-slip control of the Prius, which you can't turn off. For regular travel on steep gravel roads use another car.

 

I've learned there are places I just don't go with my Prius. The gravel drive leading down into the soccer field where my son plays for one. It's so steep and the crest where it meets the road is so abrubt, even 4wd's spin wildly and some even bottom out.

I tried it once (ok twice). Spin, anti-slip, clunk, sweat, curse - etc.

The only thing I can suggest is, try to find the patch of ground on the outside of the drive which doesn't have mud or gravel to get the best traction. Also, my guess is tires which offer better traction would help but I'll bet the they'd do the opposite for your mileage. It's a trade off.

I solved my problem by parking along the road and walking down to the fields while the other parents ruin their cars.

 

If you're really desperate to get up the hill, you might try backing up. The driving wheels will be in the back for more traction. I also find myself wondering/hoping that maybe the traction control doesn't work in reverse...?

I think the traction control feature is my least favorite about the whole car, and I REALLY wish I could turn it off.

I'm scared to do any electronic hacks to my car...with the exception of that one!

 

<div class='quotetop'>QUOTE(Pinto Girl @ Oct 24 2006, 02:28 PM) [snapback]337456[/snapback]</div>

I thought there was a magic sequence of operations you could do to turn it off, but put yourself at risk of snapping a u-joint or something from the electric motor torque. My last car had a button for this, it's a feature I miss sometimes.

 

<div class='quotetop'>QUOTE(qbee42 @ Oct 24 2006, 01:46 PM) [snapback]337480[/snapback]</div>

I remember going up a steep road with rough gravel in northern VA. It was a FWD vehicle, no traction control, and I was spinning the wheels and kicking out rocks for a good distance but I made it up by keeping a constant pressure on the gas and not over-spinning. Then I had to come down the same way and that got me really nervous - if I was spinning out going up, what would keep me from skidding going down? Then I'd have no control over running into a tree. But I kept it in low gear (stick shift) and didn't have any problems, luckily enough.

Sorry, no advice. Just brought up a memory.

If it's winter, you could bring chains along and put them on the tires before going up, but I'm not sure they do much for gravel. Might be worth a try though, and you only have them when needed, unlike beefier tires.

 

A couple of comments:

Re: backing up

The Prius runs totally on electric power when reversing. There is no contribution of torque from the ICE in reverse. If the grade is steep, you will have less power available to get up the hill.

Re: traction control

The reason it can't be turned off (I have heard) is because the MG1 would be at risk for overspinning, which could cause its catastrophic failure. So Toyota engineers made sure the TC can't be disabled at any speed, under any condition.

 

The prius runs totally on electric when reversing? I don't think so. I've gunned the pedal on reverse and the gas engine turned on for a few seconds. Has anyone else experienced what i've gone thru? Try it out... pedal to the metal on reverse.

As far as answering the original question, I hate this full time traction control but hey it keeps me from creating a big fat invoice on transmission repairs.
I always believed that this full time traction control is not there for your protection, but for the car's protection.

 

<div class='quotetop'>QUOTE(silentak1 @ Oct 24 2006, 08:40 PM) [snapback]337794[/snapback]</div>

It seems amazing, but think about it.

The ICE drives the wheels through the planetary gearset. The ICE only rotates one direction -- the crankshaft never turns backwards (of course). There is no place in the planetary gearset to reverse that direction of torque from the ICE! The ONLY way you can back up is by using MG2 which is attached to the ring gear and drives the wheels directly.

Check out John's excellent site, or Graham's site. They have great technical explanations for how the HSD system works. It's how I learned about this issue. For example, look at the bottom of this page on Graham's site: http://www.ecrostech.com/prius/original/Un...gOnAsIDrive.htm

 

I routinely back out of my garage to a turn-around about 100 feet away. So what some are saying here is that even though the ICE is running (it always starts at about 5 seconds after I press power), it's not contributing anything to reverse movement?

I will say this, at the end of my backup, there is a pretty decent hill. As I go up the hill in reverse, there doesn't seem like there's very much power. I've never looked at the MFD to see where the power is distributed.

 

<div class='quotetop'>QUOTE(dreichla @ Oct 25 2006, 06:18 AM) [snapback]337865[/snapback]</div>

All power is through the motors when in reverse. Much of that comes from the engine when it is running which is why the engine will start if you press the accelerator enough.

The battery alone can not supply as much power as the motor can use, so the engine and generator can help it.

There is no direct mechanal path to the wheels in reverse from engine to wheels because there is no reverse gear.

 

The ICE supplies power to MG1 which then supplies power to MG2 so you don't run out of battery power when backing up. Be aware, the full HP of the car is only needed to go fast. How many of you go 100 MPH in reverse? You only need 15 HP or so to back up, even up a hill. I'll bet you could even "chirp" the tires in reverse, if you were silly enough to try it. I suspect the system will limit reverse speed anyway, to protect the MGs.

 

Wow, cool, I didn't know this! Thank you.

 

I have a very steep gravel road to my house. That is why I bought upgraded tires when I bought my Prius. Although the traction control kicks in, I get to the top every time with very little trouble. Definitely get rid of the stock tires and do some research on this site for recommendations.

 

<div class='quotetop'>QUOTE(silentak1 @ Oct 24 2006, 11:40 PM) [snapback]337794[/snapback]</div>

But is the engine being used to propel the vehicle, or charge the battery/run accessories? I have the backup camera so I can't see the vehicle display when in reverse.

P.S.
Or I could just go ahead and read the rest of the posts before I write my own and save myself the trouble ...

 

<div class='quotetop'>QUOTE(dreichla @ Oct 25 2006, 05:18 AM) [snapback]337865[/snapback]</div>

The engine always kicks in 5 (or is it 7) seconds after you turn the car on. It does this to warm up the ICE to the temperature where it will operate at best efficiency and lowest emissions. Try backing up when the engine is warm, the ICE shouldn't kick in except to recharge the batteries. (I back my car into the garage when I get home, altho it's not a fair test because I don't gun it when squeezing into my spot in the garage).

 

Ummm.....so I thought that getting a Prius with VSC and TRAC was a good thing. Now when I am visiting the family summer house in WV (thats West Virginia for the nonlocals) I can't go up or down the back roads. And I might even have to back up the roads. I just spent the past month bragging to my relatives and friends about backup cameras, mpg, and a bunch of other stuff so how is it going to look if I have to back up a hill?? :angry: