Trailblazer 4 wheel drive has a rough switch from 2 wheel to 4 wheel drive.?

Answer 1

The switch from 2 wheel to 4 wheel should be almost unnoticeable for the most part. I am not sure what model year your TB is, but mine is a 2002 which is the first or second year of the bodystyle change. I know Chevy had a trailblazer model before this change (old bodystyle) and if you have that style, the 4 wheel drive system may be different. If you have a 2002 or later model, the 4 wheel drive system is the same as mine and I the only thing I notice when I switch to 4 wheel drive is a slight, and I mean very slight squeel (almost like an electric motor running). I can't even hear it if it is too windy out or the radio is audible. I definitely don't feel it switch though.

Another possible scenario is that your rear wheels are spinning faster than your front wheels when you engange 4 wheel drive (switching while spinning tires in the snow, switching while already offroad, etc). This would cause the front wheels to suddenly accelerate from there original speed to match the speed of the rear wheels (again the rear wheels would have to be spinning faster for some reason or another). This can be felt while driving in the A4WD mode. While on a slippery surface like snow, mud, or wet pavement, switch to A4WD and accelerate enough to generate rear wheel spin. Once this occurs, you will feel a jolt which is caused by the front wheels being engaged. If this is what it feels like when switching your 4 wheel drive system, I suggest you try switching while not in motion.

If the switch feels more like a grind or a "clunk", I would get it checked out immediately!! Tralblazers often have problems with the differentials, especially the front one. I had taken mine in for service just before winter to get them checked out and my front diff had lost almost 1/3 of its fluid since I had it serviced the winter before. If you have not checked this fluid since purchase, I highly suggest you do so. If the switching process has a clunking sound or feel it may be due to a loose part in the drivetrain. There is a lot of power being transfered when you switch from 2 to 4 wheel and if a mount is broken or there is any play in the gearing of the system, you while undoubtedly hear a clunk. It may also be caused by the gear itself being engaged. If the gears are not properly synchronized while switching, they will not make a smooth transition from 2 to 4 wheel. To demonstrate this, spread your fingers on both hands slightly and point your fingers at each other with your palms facing you. Now move your hands closer together until your fingers begin to slide in between one another. This is what a synchronized gear would do when it is engaging. Now move one hand up or down so that your fingertips will touch slightly before sliding in between each other. When you move your hands closer together, the tips of your fingers touch and this is the same concept with an unsynchronized gear.

It may just be that your TB is getting older and worn out. In which case, the rough switching is nothing to be too concerned of. If it is brand new, it could be a serious problem. Either way, you should get it checked just to make sure it is nothing debilitating.