Regular 10km/month 4WD exercise...

I'm a new owner of a 2014 TRD/OR after having a 2004 Prerunner, so I have a few newb questions that as of yet searches having been helpful. I did however find the threads regarding OR 4WD options started by 'David K', and those were very helpful...thank you!

The manual suggests using 4WD 10km/mo for--if I remember correctly--"recirculating lubricants". 'David K' mentioned in another thread he didn't believe there'd be harm done if this was done on hard surfaces but ONLY on straight roads, or by switching into 2HI when in turns. Here in Canada, where winter lasts 8 months, where snowmobiles are king because off roaders will always find that snow drift that turns you around, many of us purchase into TRD/OR options just to guarantee we can get out of the driveway on weekday mornings. Some months that 10km of dirt just isn't available...and begs a couple questions...

Do all OR components need this kind of lubricant "exercise", or is simply switching into 4HI required?

"Use it or lose it" has been frequently seen with regard to properly engage 4LO and/or locking the rear diff ... as if components get sticky if not used frequently. What suggestions can be made?

 

I've owned 4X4 vehicles since the 1970's. It is a good idea to shift into 4X4 and drive some distance occasionally. I don't religiously drive a certain amount of miles at a specific time interval. But any time I find myself on a dirt or gravel road I shift into 4X4 for a few minutes. It may only be 1/2 mile or it could be several miles. I will also shift to lo range and lock the rear axle at times, although much less often. As long as I do that I've never had any issues. And I find myself on dirt or gravel quite often. I may miss a month occasionally, or do it several times in the same month.

We did own a 1991 Jeep Cherokee for a while that my wife mostly drove. For whatever reason it wasn't used in 4X4 for several months and wouldn't shift into 4X4 one rainy night when needed. We'd attended a rodeo, parked in a pasture, and the rodeo got rained out. The pasture got pretty muddy with hundreds of vehicles leaving in a heavy rain. We made it back to pavement, but with a lot more wheel spinning than I'd have preferred. The grease on the axle hubs had hardened from lack of use and the vacuum lines wouldn't lock the hubs. The shift lever was in 4X4, the light was on, but no power to front wheels.

I don't advise operating in 4X4 on any surface where the tires can get good traction. You can get away with it for short distances occasionally if you don't turn any corners. By short distance I'm talking about 20'-30'. You can damage internal components. You probably won't break anything immediately, but the damage is cumulative. Over a period of time expensive parts will wear out or break much sooner.

If you have snow 8 months a year and went 3-4 months without operating in 4X4 you'd probably be OK. But surely at some point during those 4 months you'd find an opportunity to drive in dirt, sand, grass, or some loose surface for at least a short distance. Sounds like an excuse to find an off road trail once or twice each summer.

 

You can drive on 4-Hi just fine on any surface; I do it every winter and I'm sure not every road I drove on has snow. I've driven on the highway at 65-70MPH on 4HI just fine; no damages, its design for it, just like driving around a 4WD vehicle.

Every month; just spend a couple of minutes in 4-Lo on a straight slow going road and your good, lock up the rear diff too while your at it.

 

People like this is why I won't buy a used 4X4. Not only are you damaging your truck, you are creating a dangerous situation. Your truck is not ALL WHEEL DRIVE, it is 4 wheel drive. It is not designed to go around corners unless at least 1 wheel can slip on the driving surface. By driving in 4X4 you're creating a situation where at least one wheel is slipping on the pavement. Not good at 65-70 mph. All wheel drive vehicles are designed to power all 4 wheels, but send different amounts of power to each and allow them to turn at different speeds. Your 4 wheel drive vehicle is designed to send 50% of the power to each axle. When cornering all 4 wheels must turn at different speeds. It is impossible to go around a corner in a 4X4 unless at least one wheel slips on the driving surface. If traction is good, you damage internal parts.

This is a photo of the inside of a transfer case. The chain sends power to the driveshaft going to the front axle. When driven on any surface where traction is good it puts strain on the chain. Over time it will stretch enough to start slipping on the gears. If cornering sharp enough you'll break the shafts the gears are on immediately.

Just because you haven't broken anything YET doesn't mean it isn't damaged.

 

so long as you do it while you are going straight on a high grip surface there is no binding as there is no difference in rotational speed of the tires at any corner....

i shift into 4hi all the time going straight up to 60mph,

That stated, yeah dont run around town with it in 4x4 unless its slippery out (read snow and ice) binding the driveline up consistently is no bueno.

 

Explain why my 2004 Tundra went over 200k miles with driving on 4x4 and no issues for all the times I've used in all winter in the many years I've owned it; Ran it on the hwy for thousands of miles with no troubles. I've owned multiple vehicles throughout the years that have yet to show any damage. Perhaps I may have gotten lucky but I'm really telling you there is no issues with driving a 4x4 vehicle in 4wd conditions on tarmac; it is clearly the same as driving a 4wd vehicle, the Open diffs allow for this variation in cornering that is fine; its not like we have locked diffs front and back that will cause issues. However I do not recommend running it in 4x4 on sharp cornering i.e turning in around parking lots.

Majority of folks up here in Alaska use 4x4 in the winter and I guarantee that the surface is not always slippery; there are lots of dry patches(sometimes for many miles) and I have yet to witness major mechanic issues on any vehicles that do run 4x4 all the time up here, I'm a local mechanic and throughout the years have not witness any issues on any customer vehicles.

I keep 4Hi on at all times in the winter; you can run into 20 or so miles of dry pavement then hit patches of ice along the way and with just having it on 2Hi you'll end up in a tail spin easily; its a matter of safety for most of us up here as road conditions can go from good to severe in minutes, these trucks do not have any traction at all in 2hi in the winter; that rear end is so light it just spin tires and going around corners or bends when its slippery causes the rear end to slide out super easy.

I went 52k miles now on my tacoma and keeping it in 4hi in the winter for 6-7 months(our winters just last that long) so far no problems.

 

It's good to know Toyota differentials will accommodate at little bit of driver indiscretion with respect to 4WD on pavement. Still...as I understand it, default modes for 4HI (VSC on/off) will as least try to not allow for slippage, ... while open differentials would.

According to David K's thread, the "VSC hold 3-5sec" (VSC off, TRAC off) opens all diffentials while in 2HI and 4HI, while open diffs are default for 4LO (unless A-TRAC previously engaged). Am I wrong to believe these modes would accommodate 4WD modes on pavement? Do I have to come to a full stop to open the differentials?

 

I switch mine in whenever I'm on gravel just to do it.

Long term 4x4 use on dry pavement is a good way to tear up your truck without need. The front diff oil is going to wear a lot faster due to the excess heat from wheel hop and bind.

 

I've had four vehicles with 4x4 and living in San Diego, it's very rare you encounter situations when you need it. On all of these trucks, I only used 4x4 a couple times a year in the local mountains during the winter. I never had a problem. My point is, im sure it's good to "exercise" the the system to keep things lubricated as stated in the manual, but I wouldn't stress it.

 

Exactly....this is the key. The only issue is when you turn and the surface is grippy. If you are going straight, there's no indifference in rotation speeds so you're just fine.

You should really learn about your vehicle because it's clear you don't understand how it works. Please see the statement above....driving in a straight line poses no issues regardless of the number of miles. Turning (sharper is worse) is where you run into issues. Ever feel like your truck is bucking or just won't move quite right when you're turning into a spot? It's because you're stupid and have it in 4WD. Read the manual and learn how it works.

 

Lets not get started with name calling;

 

I have a PreRunner and not a drivetrain expert so take it for what its worth.

The main issue with 4x4 on pavement has to do with a the tcase, not so much the diffs right? If you have open diffs, left-right relationship is irrelevant. On that note, thats why you dont want to use a locker, on pavement, while turning.

AWD has a center diff i thought, whereas 4x4 has an unforgiving tcase, isnt that what you risk damaging in 4x4 on dry pavement?

Again, no expert so correct me if im wrong.

 

That is true; AWD/4WD vehicles have a center diff that allows different wheel speeds between front/rear wheels; however I found no ill-effects driving with 4hi with a 4x4 vehicle on the highway in dry pavement; you're really not cornering sharp enough to cause damage; some folks advise against it, while I find no issues with it as I; myself have driven for thousands of miles with my tacoma and other trucks, however I only do so when I need it; winter and at times slippery conditions but not all roadways are wet or snow covered in the winter; at times your on dry pavement for quite a bit. Majority of highways are straight so no issues.

For me driving in 2Hi in the winter has its risk; I find that when your changing lanes at times the rear end will walk out on you due to the center part of the double lane highway having snow or packed ice and you'll feel it; while keeping it in 4hi, the rear end doesn't walk out so its a matter of safety for me so I don't switch out of 4hi even with going 65-70mph on the highway. Truck feels much more stable and planted on the road, that back end is so light that it'll come out easily with just a tiny bit of throttle.

 

I have always understood that the center diff is what differentiates between AWD and 4WD where AWD has one and 4WD does not (it has a transfer case instead). This is where the issues occur in that when corning the front and rear axles can have different drive shaft rotational speeds and this can cause binding within the transfer case of a 4WD vehicle and yet is perfectly fine in an AWD one because of the center differential. It is commonly advised against driving a 4WD vehicle on a high traction surface because when you do corner then a large amount of strain is placed on the transfer case (again a center differential of an AWD vehicle is made for this) and can potentially cause damage.

 

I don't understand how wheels travelling different distances cause problems in the transfer case(?) That is, it's not like the transfer case has a drive shaft going to each wheel--it only has 2 drive shafts going to 2 differentials. The differentials can either be (1) open, (2) locked or (3) controlled by either power or braking.

My last question asked was whether "open" differentials were best for exercising 4WD component lubricants (?)

 

Just curious...why get 4x4 over and over living in San Diego? Like you said you only use it 1-2 times a year. Is that the reason? I'm genuinely curious. I thought about it myself but opted for 2wd at the end of the day. I wouldn't use 4wd enough to justify the added expense/maintenance

 

We have a cabin in Big Bear. I would rather pay for the 4x4 than deal with tire chains twice a year and I justify this by knowing that I'll get quite a bit of the premium I paid back when I sell it. Plus, when it is time to sell, 4x4s go fast here. It's super easy to find a pre-runner on Craigslist, but a pristine 4x4 DCLB is fairly rare.

That's my reason for the current rig. In years past and with previous trucks, we used to take a few trips a year to Glamis where having it was a necessity.

 

The problems arise when cornering in a 4WD vehicle because each wheel will take a different path around the corner and thus have a different amount of rotation. This is where the differentials in the front and rear come in but like you said, each differential is powered by its own drive shaft. If the drive shafts from the front and rear ever turn at a different rate then it causes binding within the transfer case and can potentially cause damage.

Because the differential is a mechanical device it can be said that for a given rotation of the driveshaft there will be a set amount of tire rotation on that axle (whether all in one or divided among the two wheels attached to that axle). Because of this, if the distance traveled by the front axle is ever different than the rear axle, there will be different rotational speeds of the drive shafts and binding within the transfer case.

As for your question on whether "open" differentials were best for exercising 4wd components I would say yes but this is purely my opinion. Open differentials are best suited for normal driving and most people don't really lock their differentials unless they know they are getting into a sticky situation. As you stated in the beginning, as long as you use it every once in a while you should be fine.

Sorry to go on a tangent in your thread but it sounds like where you live you will not have any problems using the 4wd or locking diffs features just going about your daily business. It may not be the 10km/mo (which sounds like a lot btw) but a few times a year should suffice.

 

Thanks Brian for the detailed post and taking the time...appreciated!

I was quite aware of why one wheel is "differentiated" from its counterpart...I suppose my question was more about whether I was interpreting the term "open" properly in the context of 4WD. That is, to me an open differential is a normal differential, and driving a normal differential on pavement is perfectly ok in spite of it being the front or rear(?)

Because open differentials for Toyota 4WD requires the "VSC off 3-5sec" mode (VSC off, TRAC off), I also asked if I need to come to a full stop for engaging this mode(?)

 

Thats exactly what it means. All an open (or normal) differential does is allow one wheel to move at a different speed in relation to the other. Lockers and LSDs vary this relationship. For most situations you can treat 4wd and the varying differentials independently because 4wd on a high traction surface is asking for trouble no matter what differential you have. The 4wd system and varying differential states can be looked at as different accessories that can work together or independently to achieve the end goal of traction. This is why prerunners can still have a locking diff and 4WDs can still have open diffs. Just comes down the what package each person has.

Sounds like you have a correct understanding of the differentials, and you're right, driving open differentials on pavement is perfectly ok no matter if its front and/or rear. Its how these differentials are connected and given power that separates AWD from 4WD and can cause problems in certain situations.