disengaging 4wd--like butter or speed bump?

[frankie stockboy]

I can’t find this topic addressed here, nor in the owner’s manual. I’m just wondering if my Tundra is acting normal or not. When I engage 4wd hi the transition is smooth. There’s no evil sounds or vibrations or whatever. When I disengage while my foot is on the accelerator though, there’s a tangible “thunk” that can be heard, too. It feels like I’ve run over one of those cables they stretch over the road to count the number of cars that drive by. If I disengage 4wd hi while coasting, it’s as smooth as when it engages. This has been from day one. Whatcha think?

[userw5]

Originally posted by frankie stockboy
If I disengage 4wd hi while coasting, it’s as smooth as when it engages.

I would do this one!

When you are on the accelerator there is pressure (for lack of a better word) to all of the drive wheels. When you are coasting that pressure is relieved and allow the system to disengage smoothly.

Jeff

[red's tundra]

I get that thump. It just feels like a bump in the road. After 38000 miles, it still works fine

[Breathing Borla]

I always let off the gas when shifting. There is much less resistence in shifting which tells me it is easier on the components.

On the 3 tacomas i had with levers your can really feel the difference. It was much easier to move the lever with your foot off the gas.

[arkie6]

Originally posted by frankie stockboy
I can’t find this topic addressed here, nor in the owner’s manual. I’m just wondering if my Tundra is acting normal or not. When I engage 4wd hi the transition is smooth. There’s no evil sounds or vibrations or whatever. When I disengage while my foot is on the accelerator though, there’s a tangible “thunk” that can be heard, too. It feels like I’ve run over one of those cables they stretch over the road to count the number of cars that drive by. If I disengage 4wd hi while coasting, it’s as smooth as when it engages. This has been from day one. Whatcha think?

That sounds normal. Quit disengaging 4WD while it is under load if you want to extend the life of the driveline components.

That thunk will be worse if you have been driving on a hard surface and making turns because the front and rear axles will have a load on them relative to each other and when the transfer case breaks the connection between the front and rear axles you will get a pretty good thump. While this likely isn't damaging anything in the near term, it is putting unnecessary stress and strain on the gears that will likely shorten their life.

I always shift the transmission into "N" when shifting into or out of 4WD HI to lessen the load on the transfer case gears during the shift. Even then, there can be some binding between the front and rear axles if you have been in 4WD on a hard surface.

[frankie stockboy]

Thanks for the info, guys. I'll heed your advice and be kinder to it.

[Snake777]

Wait a minute, by not engaging the 4WD while the "rear wheels are spinning" do you mean dont ever engage it while your moving?

[Imdone]

I think what he was trying to say was. If your rear wheels are spinning like you are stuck or one wheel is off the ground and it is in a free spin, DO NOT engage the 4wd. If all wheels are on the gound you can shift on the fly up to 40 mph. I personally wouldn't shift the T-case going any faster than 15 mph. I have not done any faster than 5 - 10 at present. Toyota card on visor I believe states 60 mph and the book says 40 mph. I don't really see any reason to shift at this speed, but then again the book also tells you to drive in 4wd in the rain. I personaly havent yet and dont plan to. The 4wd is designed to work in slip situations and needs the slip or binding can occur.

[red's tundra]

Originally posted by Imdone
I think what he was trying to say was. If your rear wheels are spinning like you are stuck or one wheel is off the ground and it is in a free spin, DO NOT engage the 4wd. If all wheels are on the gound you can shift on the fly up to 40 mph. I personally wouldn't shift the T-case going any faster than 15 mph. I have not done any faster than 5 - 10 at present. Toyota card on visor I believe states 60 mph and the book says 40 mph. I don't really see any reason to shift at this speed, but then again the book also tells you to drive in 4wd in the rain. I personaly havent yet and dont plan to. The 4wd is designed to work in slip situations and needs the slip or binding can occur.

I think it basically means if your tires aren't all spoinning at the same rate...don't engage it. I have engaged the 4wd doing 60 and it is smoother than at low speeds.

I use my 4wd quite a bit in the rain. With an open rear axle and BFG all terrains, good luck tyring to take off with even just a little throttle...your tires just spin and you go no where. In 4wd it doesn't slip a bit. Even in the rain, don't make sharp turns. Moderate turns seem to do fine (no binding) but if you try to make a U-turn, you'll know you are in 4wd.

[Imdone]

Cool Red,

Here in AZ we dont get much rain, but when it does rain the roads are slicker than cat snot on a wet car hood. I put different tires on my truck so in the rain I havent had any slippage. For the bfg rugged trails though I could see the possible need.

[BirdDog0]

Engaging 4wd, for me, has always been smooth. Sometimes a small "click" or no sound at all. I have noticed though that when disengaging, it is absolutely best to be traveling in a straight as possible line for at least 15 feet or until it unlocks. I haven't noticed any clunks at all when this happens, regardless of speed(up to 30 mph), but I do notice quite a chunk if I disengage and my front wheels are turned and tracking differently from the rear. There is a certain amount of biding when doing this. Disengaging 4WD while turning while you're binding is where you get the "clunking" sound.

Just take care when you disengage.
Happy trails!