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Toyota Tacoma bucks, jumps

My 2001 Tacoma drives well most of the time, but when in 4 wheel drive low range, low gear, in demanding circumstances like heavy snow, it will buck, jump, act like the clutch is alternately and rapidly grabbing and releasing (but I’m pretty sure it’s not actually that). Tires are good. Four cylinder, standard transmission. Ideas?

Did this just start happening? How many miles on your truck?

At what RPM range? If you’re trying to pull with RPMs drifting below 2000, it is probably lugging.

What does your owners manual say about 4WD?

My1979 Toyota pickup 4X4 in 4X4 would have similar symptoms. The reason, as I understand, was that in 4X4 it had nothing in the drivetrain (i.e. differential) to keep stresses from building up if there were any difference in the amount of rotation each tire had to do to travel over the intended path. The result was that a wheel/tire would slip to relieve the stress. 4WD was only for use in conditions such as snow or mud or sand that would allow this slippage.

It sounds like you are going too fast or have too much traction for 4low. There should be a max speed listed in your owners manual. It is also not usually recommended to use 4low on paved surfaces.

It’s happened since I got the truck. About 175,000 miles on the truck. Only happens under heavy load (usually in snow, so not too much traction), in low range/low gear, so quite slow speed. I know what it’s like to forget I’m in 4wd and make a turn on dry pavement! No snow yet this year, but it’s coming…

Generally, snow is not sufficient for low range and your wheels are spinning with too little traction. Low range is for deep mud and steep hills with high traction so the low gearing can turn the wheels through heavy resistance. In snow, the wheels should spinn some to free the treads where at lower speed and in low range, the drive train may react erratically. I never drive in low range in snow…that’s reserved for heavy pulling in high traction and rock areas under heavy load and for engine braking down speed inclines. Over braking with low range will cause erratic behavior in slipper conditions like ice and snow. That’s where you use higher range and just shift gears as needed.

Many people over use low range for uses it was not intended. Generally speaking heavy snow for a 4 wd truck is not depending enough on low range as the traction is not high enough. The exception would be if you had chains and very deep snow which created high traction levels. Regardless, if you are driving over 10 mph in low range, you are going way too fast !!!

The old 4WD systems, the front and rear axles are locked together…What you are feeling are the tires breaking and regaining traction which will cause all kinds of jerking and pulling especially when the front wheels are not pointed straight ahead. You have to be very careful plowing snow not to apply a lot of power when the front wheels are turned at a sharp angle or you will will blow a front drive knuckle in a heartbeat…Whatever you do, don’t be chaining up the front wheels…Put a set on the back wheels maybe, but never the front…