Strong Resistance after Backing with 4WD Engaged

Heavy Resistance after Backing with 4WD Engaged
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This resistance I speak of will occur whether in 4-Hi or Lo. To release the clutch in reverse while 4WD is engaged, the vehicle backs seemingly without trouble. The countering of the vehicle's rearward motion occurs instantaneous to the clutch disengaging. This resistance is strong, as if the brake pedal was depressed.

So after backing using 4WD, depressing the clutch pedal brings the vehicle dead to a halt. Vehicle will not coast backwards, not if 4WD is engaged, following a backing maneuver. Shifting out of 4WD is then cumbersome in a sense, but eventually cooperates - to what extent I'm not sure. It does sometimes feel as if an actuator failed to function properly.

But why doesn't my vehicle want to roll backwards when,
A: 4WD is engaged &,
B: The clutch is disengaged?
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All-in-All, to me it's an indication of a less-than-happy drivetrain, that's just shy of 300k miles.

I welcome insight from all!
...or most rather. All responses, however are appreciated.

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Just to confirm, you have no issues going forward in 4wd?

And you have no issues forward or reverse in 2wd?

Only reverse in 4wd?

 

If you happen to have tires of a different size front and rear or even one set worn out and one new front or rear this could load up the drivetrain because of tires turning at different speeds mayb?? If this is the case do not engage 4x4 while moving I have heard of this causing major damage if the tires have good traction.

 

When you say following a backing maneuver, are you talking about, for instance, backing out of a parking spot? Or turning while backing up? If you turn at all with 4wd engaged, you create what I believe is called driveline windup. It's a difference in rotational speed between the front and rear driveshaft's that causes stress on your drivelines and transfer case. Basically, your front and rear drivelines are fighting each other, one wants to pull forward, the other wants to back up. I suggest you put it in 4wd, do not turn, and backup in a straight line. See if the issue persists.

 

David,

That above statement is a smart one. From Andy's description of the problem, it sounds like it is probably more than just driveline windup since it happens when the clutch is disengaged. Andy's problem definitely has me stumped.




Andy,

My family has the exact same rig as you. The only difference is that our truck is a couple of years newer. I am sure you already know this so please excuse the redundancy. We only use the four wheel drive system on our old Tacoma on dirt roads or snow. Even on logging roads, the majority of time it is in two wheel drive; four wheel drive only gets engaged when it needs to be. Another thing to remember is to backup a good distance in a straight line when engaging or disengaging four wheel drive. It always goes in and out of four wheel drive much smoother if you do this.

Good Luck,
Paul

 

Hey Paul, no offence intended, but driveline windup won't go away with clutch engagement (or disengagement) since its basically a battle of the drivelines. The only thing to relieve windup is to disengage an axle. That being said, it could also be an issue with the front axle...

I just didn't want to scare anyone with possibilities before I knew it wasn't something simple that had to do with someone new to 4WD

 

Hey David,

Thank you for educating me on the subject of driveline windup. Four wheel drive technology has always fascinated me. You are indeed correct about the clutch engagement and disengagement being irrelevant when it comes to driveline windup, and please correct me if I am wrong. Power from the engine is transferred to the transmission via the spinning of the crank shaft. In the case of first generation Tacomas, the transmission is not directly connected to the rear or front drive shafts. First generation Tacomas have a transfer case at the rear end of the transmission which directly connects to the rear and front drive shafts at the user's discretion, which is where driveline windup occurs when the front and rear wheels are unable to break their tires loose. Four wheel drive being engaged on a dry surface, would be a prime example of this.

Thanks again,
Paul

 

Paul

Please forgive me if I sound a little preachy, just trying to give my knowledge as best I can.

The crankshaft is the part of the engine that harnesses all the power that the engine produces from firing it's cylinders. The crankshaft (in a manual transmission) is directly connected to a flywheel (basically large rotor like in your disc brakes). The clutch plate (which is basically a collection of brake pads) mechanically links that flywheel to the input shaft of the transmission. Assuming you're in gear, the power flows through your input shaft, to your countershaft, then to the output shaft (this is where gear reduction, direct drive, or overdrive is obtained by selecting different gears). Once out of the transmission, it flows (on a 4wd vehicle) to a transfer case. In four wheel drive, a chain inside the transfer case transfers power to your front drive shaft via an internal shaft inside the transfer case. Power is also applied to the rear driveshaft. There is also the option for gear reduction using a planetary gearset inside the transfer case (low range). Then from the drivelines, power flows to your axles.

Now I can't say for certain as I am a ford technician, but I believe all 4wd vehicles have a transfer case. My moms explorer is what ford calls auto 4wd. When a computer notices her rear tires slipping, it will engage the front driveshaft with an electronic actuator inside the transfer case. AWD systems are different and vary greatly between manufacturers. My girlfriends Subaru houses everything (transmission and transfer case, which I believe Subaru calls a center differential) inside the transmission - all one unit. Ford AWD systems have a PTU (power takeoff unit) which is kind of like a transfer case but for a front wheel drive transaxle.

Anyway I digress and realize an error i made earlier. I believe all 4WD rear wheel drive vehicles have a transfer case. I'm not sure if there has ever been a 4wd with a transaxle (front wheel drive transmission) but I'm sure someone would point out that error without this disclamer

And you are correct about driveline windup incurring stress on the transfer case and drivelines, but I believe it also affects the differentials, rear axles, and front halfshafts. Basically everything in the power flow including and after the transfer case. Drive line windup can occur anywhere you get decent / good traction. I feel it when I'm in hard dirt because my oversized, aggressive tires can get a good grab on the terrain and are not prone to slipping. When you are offroad (rocks not included) usually if you have windup, drivetrain forces a tire slip when turning, but only until there are equal forces between traction and windup pressure, so there is still windup present and when you disengage your front differential, there will be a clunk from the pressure releasing.

 

How often do you use your 4 wheel drive?

3rd gens are recommended to use it at least 10 miles every month just to keep everything lubricated.

I would think this would apply to all 4x4. If you don't use it that often it could be because of things ceasing up.

 

This applies to most 4wd vehicles, 1st gens included, to keep everything lubricated.

 

David,

When you are referring to half shafts, are you referring to the C/V independent front axles coming out of the front differential?

Thank you,
Paul

 

Yes. Commonly those axles are called halfshafts. The cv (constant velocity) joints are the rubber booted parts where they flex to accommodate for suspension movement and turning

 

Where is this recommendation?

This is the most ludicrous thing I have ever heard. For MOST people finding somewhere to drive 10miles every month year round that isn't dry grippy pavement is near impossible. I can't see that being a TOYOTA recommendation.

Now for those who have no idea whatsoever about anything mechanical this sounds like a good recommendation. The transfer case has a small pump inside to keep everything lubed regardless of what gear or mode it is in. The rear axle turns and coat everything in oil regardless of 4wd or not. The only question mark is the front differential. Depending on the system either the whole thing turns including the front driveshaft and is only disconnected at the TC or it has some sort of axle or hub disconnects. Hub disconnects do not have any parts between the hubs and the TC turn unless in 4wd. Axle disconnects have the spiders in the diff turn along with part of the half shafts.

Now to drive 10 miles on dry hard pack roads (or whatever you found) and load the whole drive line just to lube them? That's nuts. That puts more wear and tear on the driveline than any PERCIEVED lack of lube and motion. Now if you put it in 4wd once a month (in the right conditions) for a few feet just to ensure the actuators don't seize from non use I am ok with that logic.

 

I understand your surprise but it is in the owners manual. On my first gen, not only do the front hubs unlock, but there's also an electric actuator that disengages/engages the front drive shaft. So the front diff sits there not spinning when not being used. Therefore not being lubed. Can't confirm or deny the presence of the pump in the transfer case. I know most the ford ones I've see have then but I haven't torn into mine.

If you have a problem using 4wd for 10miles/month, put it on jack stands and run it in 4wd that way

 

I apologize you are correct. Page 247 of the online 3rd gen manual does in fact say drive 10 miles a month in 4wd. I still think this is ludicrous and if questioned Toyota will likely say "if possible but not nessecary". I know many people who only use 4wd maybe a dozen times in their ownership of a vehicle. I know this winter I did maybe 20 miles tops all in one trip. The rest of the time it was dry clear roads.

So I need to find and drive 10 miles of loose roads every month and drive out of my way to do so. Still not buying it.

 

Or on jack stands....

 

Sorry for the dumb question but where/how do you guys recommend driving 10 miles on dry pavement? I usually only engage mine when the situation warrants it (snow or mud) which def isn't 10 miles a month.

 

Do not operate your 4wd on dry pavement. Find somewhere to take it offroad or put it on jack stands and run it for 10 miles

 

Thanks - yeah, I don't engage 4wd on dry. Surprised at the 10 mi rec so I was wondering if there another way of getting it done. I'll do the jack stand route unless I have time to go off-road somewhere.

 

if you're interested in taking it offroad, follow the nor cal camping and wheeling thread. I did a MET trip with some of them last week. Two weeks ago we did another MET run. Two weeks before that we went snow wheeling near downieville (I believe it was called slickback ridge). Tomorrow a few of us are headed to uncle toms cabin. I believe there's a few at Hollister right now too

And where is @KetchupOnMyTaco? There's some good info I. This thread for him/her