n00b SR5 4wd Questions

[Vlaak]

I have a new 2013 SR5 4Runner which I LOVE! However, I have some questions regarding the use of my part time 4wd system on my new truck. I've done some reading and I'm worried about use of the system in a couple scenarios.

1. The manual says to exercise the system once a month by driving 10 miles in 4wd to keep everything in good shape. However, I don't have a lot of dirt roads near me so I was thinking the best thing would be to get out on a highway and do it there. But, I've read a lot of stuff saying its hard on the 4wd system to drive in 4HI on dry pavement which is what I would be doing. I wouldn't take any sharp turns on the highway obviously, but there would still be curves. Is it better to skip this task rather than do it on dry pavement? Should I go ahead and do it, but constantly shift in and out of 4HI at every curve or is it OK to take highway curves in 4HI if its just for this once a month task? Is it any better if I do it in wet rainy conditions?

2. In winter I'll be traveling over some passes and driving in the mountains on snow and ice. After recently learning a lot about how my 4wd system works I'm concerned that it might actually be less safe in 4wd on snow/ice. In snow or ice, or any low traction environment, if all 4 wheels turn at the same speed wont this mean that tires will often be slipping on the slippery surface instead of gripping? For example, when I go around a turn on snow, the inside tires will probably spin since they'll be traveling less distance than the outside tires right? Wouldn't this be a bad thing to have tires spinning on snow/ice? I've always thought 4wd would be safer on snow/ice but now I'm not so sure. I understand the benefits of getting started from a stop, but I'm mainly concerned about not losing traction, or losing control, while driving in slick conditions. So, if I'm driving on a snowy road should I stay in 2wd and only engage 4wd if I'm in deep snow, or trying to get started from a stop on a slippery road?

Above all I want to be as safe as possible in snowy conditions, but I also want to treat my truck right so it will last forever. I know this stuff has been addressed and I've read several threads here and elsewhere but I still don't feel like I have a good grasp on these questions.

Thanks guys
Marshall

 

[Vlaak]

Hoping for some help from you experts on my questions

 

[M1911]

Put it in 4WD on a straight section of highway. Mild turns are probably OK, which is what you'll be doing on the highway.

Yes, in 4WD, anytime you turn a sharp corner you will have some wheel slippage. This is one reason why I prefer the Limited's Torsen-based system in the snow.

No 4WD or AWD system is "safer" in the snow. A 4WD or AWD system only helps you go (accelerate) -- it doesn't help you turn or stop. In fact, it is very easy to get overconfident in the snow because there is little, if any, slipping when you accelerate, so you don't realize that you are going too fast until you have to turn or stop.

I do suggest using 4WD in the snow, but realize what it does and doesn't get you. Personally, I run real snow tires (not all-seasons, but honest-to-god dedicated snow tires) in the winter, because I want the best turning and stopping performance.

Every time I drive in the snow, shortly after I start driving, if there is no one around me I do a panic stop to see just how slippery it is. It often surprises me just how long the stopping distances are, even with snow tires.

 

[1engineer]

Put it in 4WD on a straight section of highway. Mild turns are probably OK, which is what you'll be doing on the highway.

Yes, in 4WD, anytime you turn a sharp corner you will have some wheel slippage. This is one reason why I prefer the Limited's Torsen-based system in the snow.

No 4WD or AWD system is "safer" in the snow. A 4WD or AWD system only helps you go (accelerate) -- it doesn't help you turn or stop. In fact, it is very easy to get overconfident in the snow because there is little, if any, slipping when you accelerate, so you don't realize that you are going to fast until you have to turn or stop.

I do suggest using 4WD in the snow, but realize what it does and doesn't get you. Personally, I run real snow tires (not all-seasons, but honest-to-god dedicated snow tires) in the winter, because I want the best turning and stopping performance.

Every time I drive in the snow, shortly after I start driving, if there is no one around me I do a panic stop to see just how slippery it is. It often surprises me just how long the stopping distances are, even with snow tires.

This^.

A few additional points and some elementary physics:
If you own a 5th gen SR5 or TE with part time 4WD, you CAN drive on dry pavement. You can even go around most highway turns with no damage or additional stress on the drive train. With that said, go easy on "parking lot" turns. You know, the 90 degree turns in a short distance like pulling into a parking space or turning at the end of the row.

*WARNING* PHYSICS CONTENT *WARNING*
Why is it not a good idea to make sharp turns on dry pavement with part time 4WD? Engaging 4WD "locks" the front and the rear wheels together, forcing them to rotate together and complete the same revolutions over distance. In adverse conditions such as dirt, gravel, mud, snow and ice the reduced availability of adhesion (mu) will allow a tire to slip on the ground with reduced stress on the drive line. On pavement, the higher coefficient of adhesion could (probably not but...) cause damage when making sharp turns.

In normal driving, no tire completes the exact same amount of revolutions. In a turn, the outside tires have to travel further than the inside radius tires because of the width of the track. In addition, the front tires travel further than the rear tires due to the length of the wheelbase. So, if you are making a sharp left turn for example, your right front tire will travel further than the other tires and the left rear will travel the shortest distance.

Here is a link for those of you who want to understand how a 4WD or an AWD works. Four-Wheel Drive vs All-Wheel-Drive: Everything You Need to Know

Hope this helps.

 

[Donkey]

This^.

A few additional points and some elementary physics:
If you own a 5th gen SR5 or TE with part time 4WD, you CAN drive on dry pavement. You can even go around most highway turns with no damage or additional stress on the drive train. With that said, go easy on "parking lot" turns. You know, the 90 degree turns in a short distance like pulling into a parking space or turning at the end of the row.

*WARNING* PHYSICS CONTENT *WARNING*
Why is it not a good idea to make sharp turns on dry pavement with part time 4WD? Engaging 4WD "locks" the front and the rear wheels together, forcing them to rotate together and complete the same revolutions over distance. In adverse conditions such as dirt, gravel, mud, snow and ice the reduced availability of adhesion (mu) will allow a tire to slip on the ground with reduced stress on the drive line. On pavement, the higher coefficient of adhesion could (probably not but...) cause damage when making sharp turns.

In normal driving, no tire completes the exact same amount of revolutions. In a turn, the outside tires have to travel further than the inside radius tires because of the width of the track. In addition, the front tires travel further than the rear tires due to the length of the wheelbase. So, if you are making a sharp left turn for example, your right front tire will travel further than the other tires and the left rear will travel the shortest distance.

Here is a link for those of you who want to understand how a 4WD or an AWD works. Four-Wheel Drive vs All-Wheel-Drive: Everything You Need to Know

Hope this helps.

This should be included in the FAQ, seems to be a popular topic.

Another way to explain how a differential works (and why you need one) is to get five or more people and have them stand in a line. Make the line turn in a circle. The people on the end are running while those in the middle are hardly moving. Everyone covers a different distance.

The NVG242 transfer case got it right.

 

[Vlaak]

Put it in 4WD on a straight section of highway. Mild turns are probably OK, which is what you'll be doing on the highway.

Yes, in 4WD, anytime you turn a sharp corner you will have some wheel slippage. This is one reason why I prefer the Limited's Torsen-based system in the snow.

No 4WD or AWD system is "safer" in the snow. A 4WD or AWD system only helps you go (accelerate) -- it doesn't help you turn or stop. In fact, it is very easy to get overconfident in the snow because there is little, if any, slipping when you accelerate, so you don't realize that you are going too fast until you have to turn or stop.

I do suggest using 4WD in the snow, but realize what it does and doesn't get you. Personally, I run real snow tires (not all-seasons, but honest-to-god dedicated snow tires) in the winter, because I want the best turning and stopping performance.

Every time I drive in the snow, shortly after I start driving, if there is no one around me I do a panic stop to see just how slippery it is. It often surprises me just how long the stopping distances are, even with snow tires.

Thanks a lot for your awesome post. I was thinking about getting snow tires also as you suggested. I anticipate that during a winter I'll drive on snow on the weekends on some trips to the mountains or over passes while visiting family and friends, so most of the time the snow tires will be on rainy Oregon roads, but not snowy roads. They'll probably wear out a bit faster in this scenario but it will be worth it for the added safety when I'm on the snow.

Thanks again!

 

[T4RT]

Thanks for the additional explanation 1engineer. I am looking at purchasing an SR5 and was afraid of the same things the OP was mentioning if I ran in 4WD on pavement. So from what you are saying, engaging 4WD in your driveway and heading to the store should be fine minus any tight turns or parallel parking?

Also thanks for the link. I will read up when I get home.

 

[Vlaak]

This^.

A few additional points and some elementary physics:
If you own a 5th gen SR5 or TE with part time 4WD, you CAN drive on dry pavement. You can even go around most highway turns with no damage or additional stress on the drive train. With that said, go easy on "parking lot" turns. You know, the 90 degree turns in a short distance like pulling into a parking space or turning at the end of the row.

*WARNING* PHYSICS CONTENT *WARNING*
Why is it not a good idea to make sharp turns on dry pavement with part time 4WD? Engaging 4WD "locks" the front and the rear wheels together, forcing them to rotate together and complete the same revolutions over distance. In adverse conditions such as dirt, gravel, mud, snow and ice the reduced availability of adhesion (mu) will allow a tire to slip on the ground with reduced stress on the drive line. On pavement, the higher coefficient of adhesion could (probably not but...) cause damage when making sharp turns.

In normal driving, no tire completes the exact same amount of revolutions. In a turn, the outside tires have to travel further than the inside radius tires because of the width of the track. In addition, the front tires travel further than the rear tires due to the length of the wheelbase. So, if you are making a sharp left turn for example, your right front tire will travel further than the other tires and the left rear will travel the shortest distance.

Here is a link for those of you who want to understand how a 4WD or an AWD works. Four-Wheel Drive vs All-Wheel-Drive: Everything You Need to Know

Hope this helps.

Great detail. Thanks a lot. I understand why sharp turns are hurtful to the system but I was very unsure about how less sharp turns (like freeway curves) would affect things. It seems like you guys agree that for short bursts like the 10 miles per month requirement, it should be ok.

Also, thanks for that link. While I read several things about this, I hadn't seen that one and it looks really useful! I have some lunchtime reading to do today

 

[T4RT]

The NVG242 transfer case got it right.

Please forgive the possibility of a Noob question , but Isn't the NVG242 transfer case in Jeeps or is it in Toyota's too?

 

[Donkey]

Please forgive the possibility of a Noob question , but Isn't the NVG242 transfer case in Jeeps or is it in Toyota's too?

Careful, jeep is a 4 letter word around here, lol.

The 242 has been used in several makes, from WJ's to Humvees. More complicated, more features, more to break - but it offers full and part time 4WD.

 

[T4RT]

Careful, jeep is a 4 letter word around here, lol.

The 242 has been used in several makes, from WJ's to Humvees. More complicated, more features, more to break - but it offers full and part time 4WD.

Thanks! I believe that is what I had in my "previous 4x4". Appreciate the tip!

 

[ant-ny]

This^.

A few additional points and some elementary physics:
If you own a 5th gen SR5 or TE with part time 4WD, you CAN drive on dry pavement. You can even go around most highway turns with no damage or additional stress on the drive train. With that said, go easy on "parking lot" turns. You know, the 90 degree turns in a short distance like pulling into a parking space or turning at the end of the row.

*WARNING* PHYSICS CONTENT *WARNING*
Why is it not a good idea to make sharp turns on dry pavement with part time 4WD? Engaging 4WD "locks" the front and the rear wheels together, forcing them to rotate together and complete the same revolutions over distance. In adverse conditions such as dirt, gravel, mud, snow and ice the reduced availability of adhesion (mu) will allow a tire to slip on the ground with reduced stress on the drive line. On pavement, the higher coefficient of adhesion could (probably not but...) cause damage when making sharp turns.

In normal driving, no tire completes the exact same amount of revolutions. In a turn, the outside tires have to travel further than the inside radius tires because of the width of the track. In addition, the front tires travel further than the rear tires due to the length of the wheelbase. So, if you are making a sharp left turn for example, your right front tire will travel further than the other tires and the left rear will travel the shortest distance.

Here is a link for those of you who want to understand how a 4WD or an AWD works. Four-Wheel Drive vs All-Wheel-Drive: Everything You Need to Know

Hope this helps.

I like the "Physics Warning" alert. That made me laugh.