Jerking when I give it gas .

[stevenmichael]

No, that's not your problem. We're guessing the problem is between the engine and the wheels. And that's a guess. Isn't the drive shaft between the engine and the wheels ?

When you say the truck is jerking, are you driving straight ahead or turning (I assume it's straight ahead)? (Answer) Straight ahead except for when they put to much grease in the drive shaft and it was jerking as I was turning slightly in the parking lot making circles till the jerking went away . The jerking stopped while I was making a circle after about a 1/2 mile .

Does the truck feel like it's driving over railroad ties (moving up and down) or does it feel as though it's lunging forward, pausing, and lunging forward again? ( Answer ) Like driving over railroad ties really fast that are 2 inched apart and 1 inch off the ground . No moving up and down , just a vibration feeling . It feels like a really bad warped brake disc and you put on your breaks as your going down a steep hill going really fast . Like anti lock brakes on steroids .

Just to confirm your description of the problem, there is no noise associated with the problem, just a feeling the truck isn't moving smoothly? Yes I can hear a noise . It sounds like a hammer hitting a piece of wood really fast .

When the engine is running, but the truck is stopped (for instance, in your driveway), what lights do you see on the dash when you shift from H to L? You should see orange ABS and DIFF LOCK lights on the left side of the instrument panel, below the tachometer. You should shift the transmission into N before you do this. You can do it in P, but you will also get a red A/T P light on the right side of the instrument panel, below the speedometer, if you do. (Answer) Yes it lit up just like you said both going from N and from P with the ATP. I tried it in low and high at the bottom of the hill and pointing up hill I punched it pretty good both in Low and High and couldn't get it to make the noise or jerking action . In low gear when I punched it the engine did raise up the rpm until it sounded like it went into another gear like 2nd gear once I got going faster and once it shifted gears the rpm dropped back down . I do have the knob on the dash on the left side that has front and rear locking diff . I can't ever remember trying using this knob because I don't know when to use it and when not to use it . I would like to know more about that knob and maybe try it out . I can get on grass in my yard and drive around or I'm not to far from a gravel road . I know I'm not supposed to put it in 4x4 low or any of the other 4x4 setting on blacktop but that's about it . Could you walk me through the front and rear diff settings on that knob ? Is there a good video showing how and when you should use them ? I have a 1,000 mile loop of off road trails called the Kentucky Adventure tour that is in my back door that I'm going to take my motocycle on but also wanted to do the 4x4 trails they have mapped out on the tour as well so I need to get busy learning what gears to use .

 

[Pierce]

Do you have this switch on your dash?

And is this switch in the orientation it shows in the picture?

I hate to add speculation but it sounds like when I was a youth driving a Jeep TJ Rubicon on pavement in 4-high with my front and rear lockers engaged. Felt like more of a bucking motion.

 

[Malleus]

Do you have the original owner's manual? It should be in the glovebox. There are instructions on how to use the 4wd controls in the manual.

In a nutshell, you can use 4wd on pavement; you shouldn't turn the steering wheel any more than you have to because the wheels are locked together when the differentials are locked. You're unlikely to do any harm, especially when you're driving slowly, but it will be disconcerting.

Here's what's going on:
when the axle differential is unlocked (this is also referred to as an open differential), the wheels on either end of the axle (doesn't matter which one, they both work the same way) are allowed to turn independently. This is important because when you're driving around a turn, the outside wheel has to turn faster than the inside wheel, in order to keep up. If both wheels turned at the same rate, the outside wheel would skip along the pavement, jumping up and down. This is exactly what happens when the axle differentials are locked.

Notice I've deliberately used the term "axle differential". This is because the Land Cruiser also has a differential in the transfer case (the box on the side of the transmission). This is called the center differential, because it's between the axles. Engineers aren't very imaginative. The purpose of the center differential is the same as the axle differential, it makes the ride smoother.

 

[Malleus]

So, when and how to use the 4wd system:
when is entirely up to you. Whenever you think you need it, preferably before you get stuck. Sand, snow and mud are good candidates for 4wd.

how to use it:
the transfer case is actually a transmission; it has two speeds and is a manual transmission that doesn't use a clutch. Since it doesn't have a clutch, you have to be stopped before you can shift it. Once the transfer case is shifted into low (L) gear, the center differential automatically locks, and the center diff lock light on the instrument panel is illuminated.
(There is a modification that can be made to lock the center differential when the transfer case is in high (H) gear. If this has been made, you will also have a center differential pushbutton on your dash - if you don't have one, don't worry about it)

Once the center differential is locked, you can lock either the rear axle differential, or both axle differentials, using the round selector switch on the dash (AKA the magic button). This will also turn the rear, or front and rear, axle differential lock lights on the dash. You should also be stopped when locking the axles. This gives you the possibility of more traction, since both wheels on the locked axle have to turn together, instead on spinning separately.

It's important to remember that only the wheel with traction moves the vehicle. An axle with an open differential will spin the wheel without traction and the one with traction just sits there. Since you have two drive axles, with the axles unlocked, at best you have two wheel drive. The reason for locking the center differential is to make the front and rear axles share the driving load, when the traction is less than desirable.

It's also important to know that, although you have an automatic transmission that will shift for you, the maximum speed when the transfer case is in low gear is about 30 mph (13 mph in 1st gear, 27 mph in 2nd gear). The truck will feel like it's towing a really heavy load. You should not use the low range of the transfer case on public roads when there is traffic around, because the handling and speed is greatly reduced. (Also, FWIW, 4wd does not make you invincible on ice)

Lastly, you should "exercise" the 4wd system at least monthly. This ensures that the controls work smoothly, aren't prevented form working due to dirt or mud accumulation, and that all the seals get a chance to work around the shafts they're on, so you don't get leaks before their time. I drive mine up and back the length of the driveway in 4wd (in a straight line) the first weekend of every month, whether I've used it offroad or not.

 

[stevenmichael]

I think I should add that once they put grease in the drive shaft and I was going around in the parking lot trying to get it to stop jerking I could not build up any speed at that time . It was making me go slow . Maybe 5 mph at most .

 

[stevenmichael]

So, when and how to use the 4wd system:
when is entirely up to you. Whenever you think you need it, preferably before you get stuck. Sand, snow and mud are good candidates for 4wd.

how to use it:
the transfer case is actually a transmission; it has two speeds and is a manual transmission that doesn't use a clutch. Since it doesn't have a clutch, you have to be stopped before you can shift it. Once the transfer case is shifted into low (L) gear, the center differential automatically locks, and the center diff lock light on the instrument panel is illuminated.
(There is a modification that can be made to lock the center differential when the transfer case is in high (H) gear. If this has been made, you will also have a center differential pushbutton on your dash - if you don't have one, don't worry about it) (Answer ) I have watch the videos about installing the switch in the dash but I haven't done that yet . I think there is a good step by step on here on adding it . If I remember right the wires are already back there you just find it and plug it in . If I do that center diff locking switch ,if something happens and that jerking won't stop when I'm on the interstate would this help keep me going to the next town ? I've been wanting to ad that swiitch anyways . I found this video about it . If doing this mod will help figure out why its jerking I'll order the switch and install it . I noticed in the video that he was in stopped but in D when he pushed in the switch . Did he do that correctly ? Why didn't he put it in P or N when making the change ?

Once the center differential is locked, you can lock either the rear axle differential, or both axle differentials, using the round selector switch on the dash (AKA the magic button). This will also turn the rear, or front and rear, axle differential lock lights on the dash. You should also be stopped when locking the axles. This gives you the possibility of more traction, since both wheels on the locked axle have to turn together, instead on spinning separately. (Question ) What gear should I be in once I'm in low to use the magic button D,P N ?

It's important to remember that only the wheel with traction moves the vehicle. An axle with an open differential will spin the wheel without traction and the one with traction just sits there. Since you have two drive axles, with the axles unlocked, at best you have two wheel drive. The reason for locking the center differential is to make the front and rear axles share the driving load, when the traction is less than desirable.

It's also important to know that, although you have an automatic transmission that will shift for you, the maximum speed when the transfer case is in low gear is about 30 mph (13 mph in 1st gear, 27 mph in 2nd gear). The truck will feel like it's towing a really heavy load. You should not use the low range of the transfer case on public roads when there is traffic around, because the handling and speed is greatly reduced. (Also, FWIW, 4wd does not make you invincible on ice)

Lastly, you should "exercise" the 4wd system at least monthly. This ensures that the controls work smoothly, aren't prevented form working due to dirt or mud accumulation, and that all the seals get a chance to work around the shafts they're on, so you don't get leaks before their time. I drive mine up and back the length of the driveway in 4wd (in a straight line) the first weekend of every month, whether I've used it offroad or not. (Answer ) Okay I'm going to start doing that . Thanks for the time you took to type that out . The main reason I made this post was I was afraid that jerking action would take place while I was out on the interstate and be stuck in the middle of no where . Plus I would like to keep everything working like its supposed to . I can see now how the noise and jerking could be coming from the different gears inside of any of them . I'm for sure going to have someone look at it that knows what they are doing . My daughter lives in Asheville NC . I called a garage that is there in asheville while I was there a few months back and he said he had one for a long time and he seemed to know all about them . I'll go to him the next time I go see my 4 year old grand baby .

 

[stevenmichael]

Do you have this switch on your dash?
View attachment 3342918

And is this switch in the orientation it shows in the picture?

View attachment 3342917

I hate to add speculation but it sounds like when I was a youth driving a Jeep TJ Rubicon on pavement in 4-high with my front and rear lockers engaged. Felt like more of a bucking motion. (Answer ) If the top photo is of the High center diff switch then no , not yet but I'm going to install it soon . I think in my truck the orientation would be sideways not up and down . I would say it could be a bucking motion . I do have the diff lock knob like the bottom photo . No lights are lit up on the dash and its in the Off position .

 

[stevenmichael]

Do you have the original owner's manual? It should be in the glovebox. There are instructions on how to use the 4wd controls in the manual. (Answer ) I actually have 2 1997 lexus lx450's . I gave one to my oldest daughter and I gave her the manual to keep with here . The other one was used and it didn't have the books . I will look and see if I can find it on here somewhere . But I think what you typed out for me let me know about it .

In a nutshell, you can use 4wd on pavement; you shouldn't turn the steering wheel any more than you have to because the wheels are locked together when the differentials are locked. You're unlikely to do any harm, especially when you're driving slowly, but it will be disconcerting.

Here's what's going on:
when the axle differential is unlocked (this is also referred to as an open differential), the wheels on either end of the axle (doesn't matter which one, they both work the same way) are allowed to turn independently. This is important because when you're driving around a turn, the outside wheel has to turn faster than the inside wheel, in order to keep up. If both wheels turned at the same rate, the outside wheel would skip along the pavement, jumping up and down. This is exactly what happens when the axle differentials are locked.

Notice I've deliberately used the term "axle differential". This is because the Land Cruiser also has a differential in the transfer case (the box on the side of the transmission). This is called the center differential, because it's between the axles. Engineers aren't very imaginative. The purpose of the center differential is the same as the axle differential, it makes the ride smoother.

 

[Malleus]

To answer your questions (LMK if I missed any):
1. If I remember correctly, and if I don't someone will correct me, you can engage the center diff lock at any speed below 35mph. Unlike shifting the transfer case gears, you're not moving gears from engagement to disengagement, you're just grabbing both driveshafts and holding them so that they turn at the same time.
2. You have an automatic transmission that shifts into 1st gear when you slow down and stop. So, when you're stopped, and you engage the axle locking motors, the transmission will be in 1st gear. I can't remember if the shift lock computer will allow you to engage the motor while the truck is moving, but you shouldn't do it. The gears inside the differential could be moving and if they hit the lock pin, that would be bad.
3. The axle lock doesn't care what the transmission is doing; it's just sticking a pin in the spider gears to keep them from rotating around the side gears. It does matter what the wheels are doing, because when they are spinning, so are the side gears.

this is what the inside of the differential looks like:

The transmission turns the transfer case gears, which turn the propeller shaft (AKA the driveshaft - this is what they greased for you), which turns the drive pinion, which turns the ring gear.
The ring gear is bolted to the differential case, which has the side and spider gears in it.

All of this fits inside the differential carrier you see in the center (almost) of the axle when you look under the truck.

You do not "need" to install a manual override switch. The system works just fine as it came from the factory. As a matter of fact, if you're not going to drive offroad, on trails that are difficult, I wouldn't bother at all. It's up to you whether you want to take the time to modify the center diff lock control so that it's lockable in HI. My advice would be try to drive the truck as it came from the factory, and if you find it needs more, add more.

I am having a hard time believing too much grease in a slip joint would be the root cause of the problem you described, but I guess anything is possible.

I'm sure you can find someone in Ashevillle who's worked on a Land Cruiser once or twice. I'd be surprised if you can't find someone where you are that can do it. If all else fails, take it to the Toyota or Lexus dealership and ask them to look at it. It won't cost you a thing.

 

[stevenmichael]

To answer your questions (LMK if I missed any):
1. If I remember correctly, and if I don't someone will correct me, you can engage the center diff lock at any speed below 35mph. Unlike shifting the transfer case gears, you're not moving gears from engagement to disengagement, you're just grabbing both driveshafts and holding them so that they turn at the same time.
2. You have an automatic transmission that shifts into 1st gear when you slow down and stop. So, when you're stopped, and you engage the axle locking motors, the transmission will be in 1st gear. I can't remember if the shift lock computer will allow you to engage the motor while the truck is moving, but you shouldn't do it. The gears inside the differential could be moving and if they hit the lock pin, that would be bad.
3. The axle lock doesn't care what the transmission is doing; it's just sticking a pin in the spider gears to keep them from rotating around the side gears. It does matter what the wheels are doing, because when they are spinning, so are the side gears. (I have a question ) I'm just a little confused about what is happening when I put it in low vs high that it stays in all the time . If I'm understanding you correctly when I'm in High which in my truck is always in 4 wheel drive , all 4 wheels are turning all the time but if one wheel ,say the back left side gets lifted off the ground that wheel is going to turn and cause the opposite wheel to do nothing but the other 2 front wheels will be turning so its really a 2 wheel drive , but when I put it in Low what is changing as far as traction goes if I don't engage the lockers ? That's the part I'm not understanding . When I put it in low without using the lockers is this action somehow causing the back right rear to turn even if the left rear is still of the ground and spinning ? Or does going into low just give you more torque and it allow you to switch on the lockers either just the rear or front and rear together ? One more thing, If I do add the high center diff button ,once its installed and pushed ,will this allow me to use the front and rear diff locking knob ?

this is what the inside of the differential looks like:
View attachment 3343201
The transmission turns the transfer case gears, which turn the propeller shaft (AKA the driveshaft - this is what they greased for you), which turns the drive pinion, which turns the ring gear.
The ring gear is bolted to the differential case, which has the side and spider gears in it.
View attachment 3343209
All of this fits inside the differential carrier you see in the center (almost) of the axle when you look under the truck.

You do not "need" to install a manual override switch. The system works just fine as it came from the factory. As a matter of fact, if you're not going to drive offroad, on trails that are difficult, I wouldn't bother at all. It's up to you whether you want to take the time to modify the center diff lock control so that it's lockable in HI. My advice would be try to drive the truck as it came from the factory, and if you find it needs more, add more.

I am having a hard time believing too much grease in a slip joint would be the root cause of the problem you described, but I guess anything is possible.

I'm sure you can find someone in Ashevillle who's worked on a Land Cruiser once or twice. I'd be surprised if you can't find someone where you are that can do it. If all else fails, take it to the Toyota or Lexus dealership and ask them to look at it. It won't cost you a thing.

 

[Malleus]

Yes, you understand correctly. You really only have, at best, two wheel drive, if the axles and transfer case are unlocked. A typical road car or truck with an open, or unlocked, differential really only has one wheel drive.

The selection of gear, high or low, in the transfer case does not affect the axle differentials. If one wheel loses traction, say because it's off the ground, that wheel will spin and the other will not. That's how the differential works. It's just like the gag at the end of the movie, My Cousin Vinny. The claim was the Buick Skylark had an open differential (non locking) and couldn't make two skid marks when it left the parking lot, but the Pontiac Tempest had a limited slip differential (the road version of a locking axle for straight ahead travel) so it could spin both tires at the same time.

That's the purpose of locking the axles and transfer case. If you lock the transfer case, but don't lock the axles, at least one wheel on both axles will drive the truck, but not necessarily all of them. If you lock the transfer case and the rear axle, both rear wheels and one of the front wheels have to drive the truck. Toyota did this so that you can have both added traction and easier steering than you would have if both axles were locked togteher.

If you lock the transfer case and both axles, you now have four wheel drive. The steering will feel heavy, or heavier than normal, because you're trying to turn both wheels and they are rotating at the same speed, which doesn't happen when the differential is unlocked.

Yes, if you install the manual center diff lock button, you will be able to use the axle locking feature, but you can use that now.

 

[stevenmichael]

Yes, you understand correctly. You really only have, at best, two wheel drive, if the axles and transfer case are unlocked. A typical road car or truck with an open, or unlocked, differential really only has one wheel drive.

The selection of gear, high or low, in the transfer case does not affect the axle differentials. If one wheel loses traction, say because it's off the ground, that wheel will spin and the other will not. That's how the differential works. It's just like the gag at the end of the movie, My Cousin Vinny. The claim was the Buick Skylark had an open differential (non locking) and couldn't make two skid marks when it left the parking lot, but the Pontiac Tempest had a limited slip differential (the road version of a locking axle for straight ahead travel) so it could spin both tires at the same time.

That's the purpose of locking the axles and transfer case. If you lock the transfer case, but don't lock the axles, at least one wheel on both axles will drive the truck, but not necessarily all of them. If you lock the transfer case and the rear axle, both rear wheels and one of the front wheels have to drive the truck. Toyota did this so that you can have both added traction and easier steering than you would have if both axles were locked togteher.

If you lock the transfer case and both axles, you now have four wheel drive. The steering will feel heavy, or heavier than normal, because you're trying to turn both wheels and they are rotating at the same speed, which doesn't happen when the differential is unlocked.

Yes, if you install the manual center diff lock button, you will be able to use the axle locking feature, but you can use that now.

Okay I think I'm getting it now . I did a few thing this weekend trying to see if I could make the truck do the jerking thing . I loaded 20 bags of marble rock to go around my deck . It was a pretty heave load . I tried punching the gas from a stop and couldn't get it to do it . My driveway has a 20 degree angle so I stopped at the bottom and punched it and no jerking or noise at all . Once I got it all unloaded I went back to the bottom of the driveway and put it in low and then I turned the knob on the dash to rear lock the dash screen showed a red 4x4 with a dot on the rear but it was flasking and never stopped flashing . I went straight up the hill and back down again a few times then I turned it to front and rest lock and a 2nd 4x4 red photo showed up with 2 dots on it and it stayed flashing the whole time also . I didn't turn the wheels at all I just went straight up and back a few times in that gear . It all seems to work because it felt different but no jerking or noises . I'm going to start doing that like you said once a month . I'm going to have it checked out by someone that knows the truck . I'll post what they tell me is going on . At least I know a lot more about how the 4x4 system works in my truck . Thanks for typing all that out .

 

[stevenmichael]

It sounds like a transfer case issue. Assuming no one has done a part time conversion, there is a viscous coupling in the case that allows slip between the front and rear
while cornering as your inside wheels travel at different speeds than the outside while in a corner. If you had a conventional part time t-case and drove on the road in 4WD
the tires would chirp through corners. If the viscous coupling is sticking or failing, that could cause issues. You could go to a flat nonpaved field and put the truck in low
range, which should lock the t-case center diff, and see if it still shudders. Find a mechanic very familiar with the Land Cruiser T-case. There are modifications you can do to
eliminate the conveniences of electronic everything, like part time kits. (Answer ) okay thanks I will take it off road and try to make it jerk in low and see what happens . Thanks . The big problem I have is I can't get it to do the jerking when I want it to no matter how much I punch it even with a load in the truck going up hill .

Contact the closest land cruiser club and get some recommendations for a mechanic. You're probably not going to be happy with the results from a local Pep Boys
or AAMCO.
I'm a west coaster so I can't say what's out in the SE with the exception of Nolan Grogan at Tilda Bogue in Mississippi, ACC in Georgia and Marshall at Trollhole in SC .