4wd at speed - noisy?

Hey Folks,

Had a question about my 4 wheel drive at higher speeds.

I got caught out in a snowstorm the other day. On a small backroad highway, asphalt but it was quite slippery and snowy and I got caught up in a pretty bad fishtail. The only thing that stopped me from spinning out was hitting the 4wd button just in time to go 4 hi. Everything straightened up and crisis averted. However I tried to continue the drive in 4 hi, but seemed like it was running quite loud. So far I've only used the 4wd on poor backroads at slow speeds, so not sure what I should expect from highway speeds, 55-65mph ish. It seemed like there was a lot more engine noise like higher rpms, even though the tac looked normal.

Normal for extra engine noise in 4wd? I get the impression it may not be the best idea to run 4hi at those speeds, and I should definitely engage and disengage at lower speeds. The engine sounded particularly loud around 50mph (80km) and would get quieter above and below.

New tires are coming to replace my bananna peels, but just wondering what standard practice is for driving in 4wd on snowy asphalt.

Thanks.

 

When engaging 4WD you want to make sure that you do not have wheel slippage or spinning before engaging. I know in a moment of panic its human nature to do anything that may help an emergency situation, but when you engage while things are slipping you essentially put a shock load on the drive train when the front diff engages and grabs traction. Which in turn can cause damage. I doubt you did any damage for you would probably be having more symptoms then just noise. Probably wouldn't hurt to pull the plug on the front diff and possibly the transfer case to inspect and fill with new. I do know when im in 4WD and i go to accelerate from a stop i notice a bit more noise. The noise is engine rpm related and not speed related... sorta like a harmonic vibration.

As far as engaging and disengaging i do believe as long as your under 45mph you can engage 4wd, disengaging can be done at any speed, but if you need to be using 4WD while driving i wouldn't be doing 55+ mph.

 

1st gens have push-button 4WD?

 

Yep, manual shift to Low range but we have a button on the side of the range shifter for 4x4.

 

Learn something new every day. Thought it was strictly a stick-shift T-case like the FJ Cruiser.

Then probably no damage for BackCountry's driveline. If 4WD engaged, it meant the ECU determined via the various sensors that the parts lined up and matched in speed.

 

Should not go over 55mph in 4WD anyway. IIR it is in the owners manual.

 

My 4x4 will not engage at speeds faster than 65 MPH, it just beeps.

 

Except on 95-00 models, they were all true manual t-cases. My truck kinda disappointed me when I got it, I was expecting full time manual t-case too, but it works I suppose.

 

Believe it says to engage it under 50mph, go as fast as you want when it's engaged.

 

No such thing in the owner's manual. http://www.toyota.com/t3Portal/document/om/OM35766U/xhtml/OM35766U_OM0005.html?locale=en

Page 134:

If you don't have the push-button, the speed to shift from H2 to H4 is limited to 80 km/h (50 mph).

In both cases, once engaged, top speed for in H4 is the top speed of the truck.

 

I stand corrected sir.

 

^Now find a dry lake bed or racetrack and try to hit top speed in H4.

Be sure to follow the owner's manual and inflate the tires by extra 3 psi for extended operations above 100 mph.

 

Thanks for the info folks. Slipping into some Discoverer AT/3s this week, so hopefully that will help the situation and I can save the 4wd for off-road and otherwise slow driving situations.

The pushbutton 4H is pretty nice. Most of the time it's quite responsive and silent engaging. Disengaging sometimes takes a little while followed by the classic loud thump.

 

Before you disengage it, make sure your tires are straight in a line, blip the throttle, then when the engine comes down in RPM about halfway, hit the button, it should disengage smoothly that way. I do that and never have problems with clunky disengagement.

 

Thanks for the tip, will give that a try next time.

It sounds like taking the load off the engine is key. Seems to me some of the times it's taken a while to disengage, I have been straight, but on a hill or accelerating from a stop.

 

I have a '04 3.4 double SR5 TRD with just the standard "J" 4WD engagement. No button...

 

My 4x4 engaging was always silent up until I got my frame replaced a couple of years ago. Ever since then, when I put it in 4 hi, I hear a faint whistling noise almost like bearings spinning. I had Toyota look at it a couple of different times when it was in shop for other items. They said everything checked out ok. So now I just live with it, it is still very, very faint.