86toyoturbo

Hi all, I searched the forum but couldn't find anything similar to what's going on with my toyota. I recently bought a 1986 toyota pickup 2.4 turbo 4x4, 5 speed. I was off roading for the first time and decided to enage 4x4. I have manual locking hubs which I locked and then put it in 4h. I felt the transfer case click into 4x4 but no power to the front wheels. The drive shafts coming from the transfer case to the front diff is moving when it's in 4h and 4l. My locking hubs do lock because when they are locked the cv shafts move and when unlocked they don't. There is no noise (clunking, scraping, etc) coming from the front diff or transfer case. Also I don't know if there is suppose to be a 4x4 light on the dash or not but there is no light that comes on the dash. Any info is greatly appreciated.

josh21

Well I'm not completely sure about this year truck but my brother had a 94 t100 and when he shifted into 4wd no light came on (supposed to come on as soon as you move the shifter) but the front driveshaft would spin like your saying. It ended up being some solenoids that are located in the engine bay above the passenger wheel well I think they were red and green colored. Your truck may not even have these but I'd figured I'd tell you just incase it does.

86toyoturbo

Thanks for the reply, I just checked and I do not have those solenoids.

RJR

Best way to troubleshoot this sort of problem is to jack up both front wheels and start turning things by hand to see what's connected (or not) to what. Shouldn't take too long to see where the disconnect is.

The '94 has a disconnect on the driver's side of the front diff which can cause your symptoms, but your 86 shouldn't have that.

86toyoturbo

I put the truck on a lift and put in 4wd first gear with hubs locked. The passenger side rear and passenger side front spun and the driver side rear spun but would stop if touched. The front driver side didn't spin. I took the locking hub apart and cleaned the mucky grease off and it slid locked and unlocked easly, It still didn't spin when tested. I then tool the truck on a mud road in 4x4 and was doing burnouts and the fronts didn't spin like the backs. It seemed as though the fronts didn't breaking free at all. Is this how this year's 4x4 works or should all 4 tires spin? Everything is original on my trucks drivetrain.

RJR

What did the drive shafts do when you turned the wheels? With the truck in 4wd and engine off, neither drive shaft should turn. The wheels on the same axle should turn in opposite directions if you have open diffs.

If you have an automatic locker on an axle, you shouldn't be able to easily turn either wheel. It generally takes some finagling and significant effort to activate the ratchet and turn one of the wheels.

These trucks have no center differential, so if you spin the rear wheels on a muddy road, at least one of the fronts should spin as well. If not something is not connected properly.

86toyoturbo

I went to my neighbors shop to put it on the lift so I only had a few minutes. I just locked the hubs and put it in 4h and both rear and just front passenger side wheel were turning but both wheels on the passenger side wheels were spinning faster than the driver rear. The driver front didn't spin at all. If I lock my hubs and keep it in 2wd both front axles spin. I had a friend look at the truck while I was on the dirt and he said the fronts didn't break free but the rear did. The truck diff has the factory open diffs so I know the wheel with least resistance will break free. I'm just going to wait until it snows and see if any of the fronts break free. I know it's hard to help diagnose without looking in person and appreciate the help. I picked the truck up with 240k miles for $1200 and it lived most it's life in AZ so underneath is super clean and just has a rust spot on the side of the bed. I rather not dump a bunch of money into it because It runs and drives great in 2wd but I would love to have the 4x4 work for our NY winter up here.

RJR

With open diffs, it's not unusual for wheels on different sides to spin at different speeds if all wheels are off the ground. Depends on relative friction of the various wheel bearings and brakes.

The behavior you describe is very indicative of a disengaged ADD system(automatic differential disconnect), which is a sliding collar on the driver's side of the front diff which locks or unlocks the CV axle to the diff output. When it is unlocked, the open diff spins freely internally and no power will be transmitted to the front wheels regardless of transfer case or hub settings.

Your truck shouldn't have had ADD, it's too early a model, but someone could have swapped in such a diff and failed to understand the implications. Check to see if there is an extension housing sticking out the driver's side of the diff about 5-6 inches.

If you do have ADD, you can permanently lock it into the engaged position by just opening up the cover and sliding the locking collar until it engages, and holding it in place with a wormdrive clamp. Google "defeating the ADD" for more detail. Since you have manual hubs, this is a perfectly valid and common mod.

Good luck!

86toyoturbo

Is that what you are talking about?

RJR

Can't see enough of it to be absolutely sure, but from what I can see you don't have the ADD system. If you had ADD the extension would be bigger, have a side cover on it, and two vacuum and one electrical connector.

Not sure where to point you next. Is your passenger side hub working properly, or is it not really locking, but dragging enough to turn the wheel under low load (wheel lifted) situations?

86toyoturbo

I looked more into the ADD like you said and I don't have it. It probably is just dragging because it would have let loose like the rear wheels if the front had power. The crazy thing is when my hubs are locked and in 2wd I hear sort of a light grinding noise but when I pop it in 4x4 the noise goes away. I would think if splines are not connected right they would make a hell of a noise when I'm in 4x4. Is it possible for the axles to pop out the diff without making any noise (I visually inspected them and they look in place and the boots are not ripped)? Also should there be a 4x4 light on my dash, I looked with a flashlight and couldn't find one. I guess my only real option is to tear down the front end and see what is going on.

RJR

I think you are getting close. My best guess is that one of your hubs is barely locking, and when in 2wd it is grinding as it tries to turn the CV shaft. When in 4wd the transfer case is already turning the CV shaft at the proper speed, and thus you hear no grinding. However, when you need real 4wd torque, it simply slips. It would grind when it is slipping, but under those circumstances you likely didn't notice because you were aggressively driving and making a lot of other noise.

Get into both your hubs and make sure they are actually working, and that the hub assembly is engaged fully with the splined end of the CV shaft.

86toyoturbo

There was a lot of mucky grease in the one I took apart. I cleaned most of it was able to push the locking ring into the hub but it is very possible that there is still too much grease in there for the spring to push it in by itself. So the greese would be able to hold it together when there is no pressure on the wheels but it wouldnt be engaged when real torque is put to the wheels. I did drive it on wet pavement in a straight line in 4h with the hubs locked and didn't hear any noises but that doesn't mean any of the locking teeth in the hubs are actually engaged.

MAINETOY

iTrader: (2)

hey just a thought,have you checked the stub shafts in the front diff to verify they aren't broken.I recall seeing this before on here.Like i said its something to rule out,if its not that and you have power to the front cv's then thougherly check the front hubs for damage.

RJR

Keep in mind there are two locking interfaces. The first is the one you have worked on, the locking mechanism itself. The second is the interface between the locking hub assembly and the splines of the CV shaft. This should always be engaged, but if the CV shaft has backed out of the hub due to a missing snap ring, it could cause a similar problem. Just something else to double check.

MAINETOY's comment is also good. Make sure the stub shafts are connected to the diff internals. With both wheels on the ground and the transfer case in 4wd, unlock one hub at a time and try to turn that corresponding CV shaft. It shouldn't turn. If it does there's a problem inside the diff.

86toyoturbo

I will check the stub shaft but if they were broken they would probably make a awful noise when 4x4 is engaged. But a good call and I will check that too.

86toyoturbo

I did replace the lower ball joint and when i did that the shaft fell out the hub but I put it back in and assemble the hub but I will check for that two on both sides.

86toyoturbo

I just put the truck in 4x4 with the hubs unlocked and realized when I replaced my ball joint and the cv shaft popped out the hub which I put back it must have popped out from the diff too. The passenger side shaft was moving all the way to the hub but the driver side cv shaft wasn't moving. Since its an open diff it probably put all the power the the driver side because it was the path of least resistance. I'll pop it back in tomorrow and see if that works. Does this sound plausible?

RJR

It does indeed. Just like having one wheel in the air.