2001 Sport Trac 4x4 Problem

Recent issue i'm having with using 4x4...when engaged in either 4wH or 4WL and moving over 5 mph, there is a hard jolt/thump every 10 seconds or so felt at/near the transfer case and maybe even the front axles. Also feels like after the thump/jolt the car temporarily will pull to one side, then another jolt/thump and normal, and so on. After moving the selector to 2WD, the 4WD feels engaged for about a minute, at which time there is another hard jolt/thump as it releases back to 2WD.

Any ideas where to start before i let a Ford dealer tear into it? Thanks in advance for any guidance.

Sounds like you are doing this on dry pavement and maybe have a tire with low pressure. If this is the case, it's a no no to engage 4wd on dry pavement. 4wd is meant for situations/surfaces where the tires are able to slip. On dry pavement the is no slippage and it can cause a great amount of binding in the driveline if all the wheels are not spinning at the same rate. Which they don't spin at the same speed while turning or when you have tires at different pressure levels.

THanks for the reply John...actually i have been driving in Alaska in at least 2 feet of snow and there is usually a thin layer of ice on the roads. During those rare moments the roads are dry, i don't attempt to drive in 4WD. Took it to Ford shop today. The tech said roughly the same thing in regards to the tires. He measured the tread on the front and rear...said the rear measured a "4" and the front a "12" which would cause the huge difference in wheel speed from the front and back. I don't suppose just adding air to the rear tires would make up the difference. The front tires were/are new when i bought it 6 months ago...not sure how long the back tires have been on, but look in good shape. Maybe just need two new rear tires?

I don't quite understand those measurements.

But yes tire pressure changes the circumference and the tires will roll at different speeds going straight.

Yeah, i didn't quite understand the measurements either...maybe he meant "4/32" and "12/32"...he was using a depth gauge. Anyway, i aired up the rear tires to the max (35 PSI) and dropped the front tires with more tread to 25 PSI hoping that would temporarily fix the problem. It did sort of...not as frequent of thumps. But i did plow through some snow today in 4WH keeping a speed of about 30 mph and whenever i heard the thump i felt the 4WD disengage.

These electronic transfer cases can be quite quirky. Ughhhhh. I wish I had a manual one. You can buy manual transfer cases for our trucks. Ford mostly puts them in the 4x4 Rangers and some Explorers have come with them before. I just don't think they ever put a manual transfer case in a Sport Trac. We have the Borg Warner 1354 Electronic transfer case. And the manual one is just the same model but with a shifter. A Borg Warner 1354 manual transfer case.

I have had my own bouts with mine being wacky and not working. And one time, one time, I was testing mine(I've learned to test it occasionally to keep it in working order) in 4Hi at about 35mph and it made a huge bang and jolt to the truck. I think it might have tried jumping to 4Lo when it wasn't supposed to. It only did that, that one time. As of late and now over 10 years old, it seems to work consistently when I want it to. But, one time a couple years back out on a trail, I had to jump down underneath and hit the shift motor with a tool.

Is there a max speed you can drive while in 4 wheel hi? Just wondering since I drive about 100kms on the highway pretty straight.

keggersport said:

Is there a max speed you can drive while in 4 wheel hi? Just wondering since I drive about 100kms on the highway pretty straight.

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No.

My '01 Sport had a similar problem to this. I recently put on new tires (100 miles) and it seems to have almost completely solved itself. I think that its because of binding. The thumping noises stopped and it disengages the 4WD first try now. Lets see how it does once the tread wears down, no?

Also, does anyone know of a maximum speed for 4x4 Low?

Tiron said:

Also, does anyone know of a maximum speed for 4x4 Low?

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How fast do you want to go in 4x4 low? I'm sure 40+ is obtainable, but I don't think you would want to sustain that kind of speed in 4x4 low. And remember to always be on a surface that will allow the tires to slip if there's a bind in the system.

Well since the new tires are all evenly worn (you know, at brand new 0%) I was able to drive it on pavement without any binding (I did do some low speed tests first).

I tried it this morning, some little Honda wanted to race me at a long stoplight. Put it in 4x4 Low, and watched his jaw drop as I then continued to kick his butt. He passed me later though because I couldn't go more than 45 (I stopped at 40 so I wouldn't run it at redline). I would never have done this with the old tires, or around a corner though.
Note: I took it out at the next stoplight.

So I guess thats my answer, with the 3.73 axle ratios you can get to 45 MPH in 4x4 Low (2.48).