4 wheel drive

sr5 is strictly a commuter car. Is it ok to use 4 wheel drive in the rain or is it putting an unnecessary strain on the drivetrain

 

Part time 4wd (what you have) is generally not for rain use.

 

The SR5 has the same drivetrain as the Off Road.

 

So I should only switch to 4 wheel drive on the snow

 

I think it's ok if you don't do it often and don't make sharp turns.

 

Snow is slippery enough to allow the drivetrain to unload.

 

I take advantage of wet roads to exercise the 4WD.

 

While it doesn’t add any traction or advantage, putting it in 4H for a mile or so will hurt nothing. I have to do that with mine every so often because I don’t use

This.

 

I have done so in very heavy downpours on freeway or highway. It does help reduce hydroplaning (along with reducing speed). And the downpours are typically brief. I disengage when the rain returns to normal.

 

It would not hurt...
And it is good to put your truck in 4WD every while to keep it from seizing....
do not over speed or make sharp turns...

 

Read the manual.

 

?????

 

Snow. Loose dirt/gravel. Anywhere you could easily spin the tires by just goosing it. Any surface like that where slippage of the tires can relieve the binding that would occur if you drove in 4wd on a high-traction surface like pavement.

 

curious what you mean by over speed? After you switch to 4WD is there a speed limit to drive in 4H?

 

Technically there isn't, just maximum speeds for shifting in/out of 4WD in the manual.

So you can send it to top speed once you're in 4WD in theory, but naturally whether that's prudent is something else.

 

In a RWD vehicle, while driving, friction from the road causes the front wheels to rotate. Hydroplaning at the front wheels occurs when there’s enough water to cause the front wheels to lose contact with the pavement. When this happens, the front wheels will slow a little, allowing a ‘buildup’ of water to occur. The ability to steer accurately is reduced. With 4WD engaged, the wheels are mechanically forced to rotate, rather than depending on friction from the pavement. This reduces the likelihood of hydroplaning a little.

 

To switch to 4H you have to be under 50 MPH
To switch to 2L you have to be in neutral. and only designed to be at very low speeds.

Since both drive shafts are locked in 4H, It will be harder on the wheels on dry pavement. hence do not over speed or over corner.
Both front and rear wheels still have their own differentials..., but both drive shafts front and rear is getting 50% torque.

 

Wet roads are still considered a high friction surface and unless you have bald or super hard compound tires that allow slip do NOT put it in 4WD on wet roads. AWD is good for wet roads because all 4 wheels provide directional traction so if you find yourself in very specific circumstances you have a slight advantage. However, 4WD works against you in rain and reduces your safety. Turning (even slightly) introduces binding in the drivetrain and if you have good tires this binding will damage your transfer case. If you have bad tires they will slip reducing your traction and can cause bad things to happen. Keep 4WD for off-road or snow/ice use only. If you need (or want) 4WD for rain get a Limited.

 

Not sure that's how it works. This: "...the front wheels will slow a little, allowing a ‘buildup’ of water..." Hydroplaning is the result of the tires' inability to move the water away faster than it encounters it. No one hydroplanes at 25mph. The better the tire design and condition (at channeling water), the heavier the vehicle relative to the contact patch, the closer to 50/50 weight distribution... These are the constants. The variables are the speed of the vehicle and volume of water. Assuming the same constants and variables - FWD, AWD, RWD will hydroplane equally.

BUT, and it's a big but, AWD (almost wrote "will recover") offers the driver the ability to better recover when hydroplaning starts.

Oh... yeah, don't use 4WD in the rain. Save it for unpaved surfaces.

 

Interesting. Only know of 2 different speed limits between rotating selector vs manual selector to shift in. I believe shifting out does not have a speed limit.
I have to search to see if there is anything bad driving at high speed in 4H.

 

So you're saying it could hurt...

If you're on a proper surface to use 4H, speed isn't going to hurt the drivetrain...if it might hurt the drivetrain then you're not on a proper surface for 4wd...

meh, prudent depends on tires and driver ability, just like driving on a dry, sunny day...

 

Right. Still, I've briefly engaged 4WD under sudden, severe changes in rainfall, when I was unintentionally going too fast for this sudden cloudburst. It did help in those situations. I do not advocate driving like that for an extended period.

 

Whoops, I don’t remember if I’ve ever seen a limit on shifting-out-speed so that’s probably an error on my part.

 

Yeah no limit once in. My buddy recorded us messing around on a dry lakebed. I’m in the supercharged Taco going all the way up to the governor. 4wd is only going to give you forward traction but do nothing once you’re up to speed. It can possibly help you with engine braking on a really slippery surface.

https://youtu.be/ZHwwWX9y1uA?si=Y1I7j9meXP5naeDR

 

That looks like a fun day...!!!!!

 

Definitely good times when I used to go out. I don’t take the Runner out at all now. The Taco recording is an absolute monster now.

 

I watched that small clip from your friends youtube. That a fun truck to drive.