Question re automatics-"part-time"4wd (1 Viewer)

[TLCgrappler]

In reading the manual and the PRduct reference guide on the FJCruiserowners site, I am a little uncertain about something.

From Page 9(and 8) of the Product reference guide

http://www.fjcruiserownersgroup.com/toyotadocs/2007FJCruiserPRG.pdf

I can now see more clearly the differences in drivetrain between the manual and my automatic. The auto system is found also on the Taco and the TUndra, and the manual system is found on the 4runner v8.

MY question. The PRG suggest that you NOT use 4wd on dry pavement, and says you may cause driveline damage (because of the lack of a center differential in the automatic version). The FJ manual doesn't mention this that I remember, but says to prefer the 2wd mode but to drive in 4wd once a month or so to stir up the lubricants and excercise the gearing, I believe.

Is this the way Taca and Tundra owners with automatic transmissions run their trucks?? Never in 4wd unless you're stuck somewhere??

And what about switching to 4wd on the highway when its wet? is that generally safe for the drivetrain, or not?

This is not a big deal one way or the other, but I sure as heck don't want to screw up the driveline components by driving in 4H around town if that's likely to do it.

 

[Rusty Phillips]

dont do it - you will break stuff!!

http://www.4x4abc.com/4WD101/driveline-bind.html

not only that, but a full time 4x4 with CD locked or a part time 4x4 with the front axle locked in will have BIG TIME UNDERSTEER

understeer with low traction = bad

ever drive in a light snow and see all of the SUV's upside down or backwards off the side of the road?

 

[Tim Scully]

Correct me if I am wrong but the FJ manual is a full time 4wd system which is always engaged. You can't put the manual FJ into 2wd(unless it is a 2wd version).

As for driving on pavement in 4wd, you can break anthing you want to. If you lock the center diff and drive on the pavement in circles you will break stuff. If you are on pavement in a low traction state, i.e. snow, ice, wet roads, you shouldn't have an issue.

 

[firetruck41]

Correct me if I am wrong but the FJ manual is a full time 4wd system which is always engaged. You can't put the manual FJ into 2wd(unless it is a 2wd version).

As for driving on pavement in 4wd, you can break anthing you want to. If you lock the center diff and drive on the pavement in circles you will break stuff. If you are on pavement in a low traction state, i.e. snow, ice, wet roads, you shouldn't have an issue.

You are right, but he is asking about his qutomatic.

TLC Grappler- Do not drive your automatic in 4x4 on high traction surfaces (IE> dry pavement), it will cause driveline bind, then one of two things will happen 1) Wheel slip (ok), or 2) something in the driveline (CV, drive shaft, hub, etc) will break. The same rule applies for any conventional 4x4, or a center diff locked AWD/full time 4wd vehicle.

 

[Jetboy]

This is crazy talk, it's not the best on the vehicle in terms of wear and tear to run on dry pavement in 4 hi, but it shouldn't damage the vehicle. You should be able to drive in 4hi all you want. the only ill effects will be shorter tire life and a little odd feel in tight corners.

If the drive train isn't strong enough to be in 4hi on pavement there is no way in hell i'd trust it on the trails, or even the mall parking lot. I've had 4 toyota minis and run them all in 4hi at times on the highway, just like every other part time 4x4 on the road. If the road manners were that bad or it wasn't intended they wouldn't give you the option of 4 HI! they would only allow 4low. I have driven every 4x4 I've ever had in 4x4 at highway speeds on pavement. All with part time TC's= locked CD. these include toyota trucks, landcruisers, suburbans, and full size chevies. It may cause some additional wear, but it better not break anything. It is actually barely noticable as long as the tires on the front are the same size as those on the back. I can take my fj40 locked differentials front and rear and put it in 4lo and drive in circles on pavement. the tires will scrub, but nothing will break.

 

[Rusty Phillips]

jetboy

you are never allowed to borrow my truck again

dont even ask

rusty



from the link I provided above - a jeep TC that ran ~150 miles in 4hi on the interstate

 

[TLCgrappler]

Well, I thought I had posted in between this but I must not have hit the post button.

After my question above, I went to a Tacoma/Tundra site and found a long thread dealing with this. It basically hits the same points as above, and several people note that they don't worry about it very much, with others disagreeing about its importance.

My concern came from the fact that the manual doesn't quite give you the same impression of damage danger as the product guide does. The owners guide notes you get the least wear in 2 wheel mode, and say to use 4H for "normal driving on wet, icy, or snow covered roads".

The product guide for the salesmen says operating in 4wd on dry hard surfaces "lowers fuel economy and can cause drivetrain binding and damage to components". [not true of the 6 speed manual transmission model since it has a center differential]