Intermittent 4wd? (1 Viewer)

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Hendlerj

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I had the pleasure of conquering some awesome trails today, but I feel like something is wrong with my 4wd. Here are two videos. In the mud video, the front wheels don't appear to be doing anything. It looks like 4wd is inoperative. In the second video, however, it looks like the front wheels are pulling and 4wd is working. Any ideas? Can 4wd work intermittently? I was in 4 low for both videos.
 
The way the driveline works is that the wheel that has the least traction gets the most input from the driveline. Sometimes you'll see one of four wheels turning, while the other three sit still. That means that wheel has the least traction. If you have true 4WD, meaning the driveshafts in the axles are locked so that they must turn together, and the propeller shafts connected to the transfer case are also locked together, all four wheels will turn together. The 80 guys refer to these drivelines as 3x locked (locking center differential and locking axle differentials).

The 40s don't have this capability. At best a 40 is a 2WD truck. Meaning you can lock the front and rear propeller shafts in either high or low gear, and they will turn together, but the differentials in the axles will prevent the wheels on either side of either axle from turning together. This is by design. Unless you have an aftermarket locker, you can't lock the wheels on both ends of either axle to ensure they turn together. The result is that one will turn and the other sit still, if the traction (friction) they both "see" isn't the same.
 
Malleus said:
The way the driveline works is that the wheel that has the least traction gets the most input from the driveline. Sometimes you'll see one of four wheels turning, while the other three sit still. That means that wheel has the least traction. If you have true 4WD, meaning the driveshafts in the axles are locked so that they must turn together, and the propeller shafts connected to the transfer case are also locked together, all four wheels will turn together. The 80 guys refer to these drivelines as 3x locked (locking center differential and locking axle differentials).

The 40s don't have this capability. At best a 40 is a 2WD truck. Meaning you can lock the front and rear propeller shafts in either high or low gear, and they will turn together, but the differentials in the axles will prevent the wheels on either side of either axle from turning together. This is by design. Unless you have an aftermarket locker, you can't lock the wheels on both ends of either axle to ensure they turn together. The result is that one will turn and the other sit still, if the traction (friction) they both "see" isn't the same.
Click to expand...
Thank you for that explanation. In 4Low, then, should at least one front wheel have been spinning?
 
If the transfer case is locked at least one wheel on each axle has to be spinning. Principle as a axle locker. Transfer case locked both driveshaft have to turn or neither one turns. For a driveshaft to turn on a open diff one wheel has to spin. They would be no advantage of 4WD. Open diffs 4WD just change one wheel drive to two whee drive.
 
Hendlerj said:
Thank you for that explanation. In 4Low, then, should at least one front wheel have been spinning?
Click to expand...

Yes, in 4wd hi and low. In the 1st video it appears you weren't in 4wd. As mentioned, the easiest tire to spin, spins.
 
Maybe a little more info on you cruiser. It's possible to put the transfer case in low 2WD with twin stick shifters or if the OEM shifter guide has been removed it will allow 2WD low range. A intermittent vacuum shifter can cause the issue. These are because the transfer isn't lock in 4WD.
 
pb4ugo said:
Yes, in 4wd hi and low. In the 1st video it appears you weren't in 4wd. As mentioned, the easiest tire to spin, spins.
Click to expand...
Couldn't see the left front. I suspect the left front was spinning along with the right rear. If 4WD is engaged. no wheels will spin free until one front and one rear
breaks traction. In 4WD the front drive shaft and rear driveshaft are locked together. They can't rotate independently of each other. You can put the front end in the air
on jack stands and the rear on the ground and the truck will drive off the stands, the front tires rotating the exact same speed as the rear. Same scenario, the front in the air,
the rear on the ground, lift either of the rear tires and the three wheels that have no traction will spin freely, the rear remaining on the ground will just sit there. Lift either front tire and either rear at the same time and those tires will spin free and the two on the ground will do nothing.
 
I know it's hard to tell if the left frt is spinning or not. To me, it looks like it's not. The engine is reving and there's no frt tire movement. The guy taking the video mentions something about the frt, and the driver questions if the frt wheels are spinning. It also looks like the driver was reaching and moving the tcase shifter back and forth. As @Living in the Past mentioned, maybe the shifter gate has been altered.
 
Last edited:
If you have 4 jack stands consider jacking up vehicle and placing a jack stand under the axel at each corner so all 4 wheels are off the ground. Start engine and place in 4WD and let her idle. You can then walk around outside the vehicle and watch. If you firmly place your boot on one of the tires you will see that it will stop spinning but the other three wheels will continue... You can also observe shifting in and out of 4WD.
 
Personally would not recommend to someone I don't know to put a vehicle on four jack stand much less run it. No knowledge of size condition of the jack stands. Apply pressure to stop one wheel could cause it to rock just enough to tip a jack stand and now outside the vehicle and who knows what injury and damage it could cause.
 
I've got a bit of a similar issue. I can shift it into 4WD and the front driveshaft won't engage, then I can remove the rear driveshaft and drive the 40 all day long on the front driveshaft. Gonna look into the linkage at the transfer case pretty soon, as I suspect something isn't engaging at times.
 
cbmontgo said:
I've got a bit of a similar issue. I can shift it into 4WD and the front driveshaft won't engage, then I can remove the rear driveshaft and drive the 40 all day long on the front driveshaft. Gonna look into the linkage at the transfer case pretty soon, as I suspect something isn't engaging at times.
Click to expand...
It's a good learning experience to rebuild a transfer case. It's easier to imagine what can go wrong when something does. It's a pretty simple design.
Usually if a transmission or this type transfer case seems intermittent, it would be a severely worn or bent shift fork. I'd think you'd hear some grinding
of gears if the gears weren't engaging properly. Familiarizing yourself with the T-case internals can save you if your out on the trail alone
 
I did the test that some prescribed, put it against a big rock and attacked it. In 4hi and 4lo, it was throwing dirt from the front left and rear right. So it was working today. But in addition to the mud video i posted last night, there was another climb on which i don't think the front was pulling. I am going to post that following this. I definitely think I have something intermittent.
 
lcwizard said:
It's a good learning experience to rebuild a transfer case. It's easier to imagine what can go wrong when something does. It's a pretty simple design.
Usually if a transmission or this type transfer case seems intermittent, it would be a severely worn or bent shift fork. I'd think you'd hear some grinding
of gears if the gears weren't engaging properly. Familiarizing yourself with the T-case internals can save you if your out on the trail alone
Click to expand...
Thanks. Yes, it may be the next project I take on. In fact, I bought a used tranny/tcase combo recently just to learn. Guess it's about that time!
 
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