Is Locking the Diff Bad for my T4R

[smackitsakic]

Great forum everyone, this is a super place to come for info on your 4Runner!!

One question I have - how often can a person use the diff. lock and how harmful/safe is it for the transmission?

I haven't driven with the diff. locked at all, mainly because i'm always on dry pavement. However, now that winter is approaching and the snow is falling, what is 'appropriate' to use the diff. lock? Only when the snow is so thick that you might get stuck? Only when conditions are icy and dangerous?

And, what exactly happens when you lock the diff? What does it mean?

My wife and I just purchased our first ever 4Runner about two months ago. We bought an 07 SR5 with about 40,000 miles and so far we love love love it!

 

[adkinsadam1]

Unless the snow is VERY DEEP never lock it. The full-time 4WD is better than locking the diff. because you will lose traction much easier with it locked. You also use traction control.

 

[CJ3Flyr]

Great forum everyone, this is a super place to come for info on your 4Runner!!

One question I have - how often can a person use the diff. lock and how harmful/safe is it for the transmission? The center diff lock can't hurt the transmission. It could hurt the transfer case which is a separate gearbox behind the transmission that divides/directs the power to the rear or to the front & rear.

I haven't driven with the diff. locked at all, mainly because i'm always on dry pavement. Good. Driving with the diff locked should only be done on a fairly slick surface; less traction than wet pavement. However, now that winter is approaching and the snow is falling, what is 'appropriate' to use the diff. lock? Only when the snow is so thick that you might get stuck? Only when conditions are icy and dangerous? Gets complicated quickly... In general use 4hi. It allows the stability control to help with skids etc. and it doesn't do any harm if you 'forget' and the road dries up. The VSC, Trac and ATRAC all work together and try to prevent wheelspin (even below 10-15mph). This can cause issues. When pulling onto a slick road where a little wheelspin would be ok and acceleration/power is very important the "safety/traction" systems can mess you up! They'll cut the power to the engine to combat wheelspin. The oncoming car may not be able to stop and what you really need to be able to do is get out of the way, even if it spins a bit. So when in this situation, in preparation for pulling out in traffic or in a scenario where you think you may want full power and don't mind a little tire slip lock the center diff. Locking the center diff deactivates the VSC & Trac (the power robbing part of the system). Just remember driving with the diff locked all of the time leaves those systems deactivated and it's just like driving any 'old school' 4wd (IE slick surfaces only and the vehicle won't help with skid control).

And, what exactly happens when you lock the diff? What does it mean? The differential in the middle (transfer case) no longer differentiates the power front to back. It just sends an equal 50/50. That's why it'll bind etc if you use it on dry pavement and make turns. When unlocked you drive circles all day and the driveline won't bind up. The center diff divides the torque (and driveshaft rotations) as necessary to compensate for the different distances the front & rear axle travel. It's the same concept as the rear differential it's just longitudinal with the vehicle instead of across the vehicle.

My wife and I just purchased our first ever 4Runner about two months ago. We bought an 07 SR5 with about 40,000 miles and so far we love love love it! V8 or V6?

Does that help?

 

[scottm]

Is there any other way to get full power/bypass the traction control? My Land Cruiser will spin if I give it full throttle, even with stability control & traction control. That's intended to clear the tires in mud by spinning, but also handy when trying to cross a busy highway in slush. In my whole week of 4R ownership I haven't yet run into that situation, but kinda dreading it after reading your comment. I was warned away from the '01-'02 because the traction control did this.

How quickly does pushing that switch disable traction control? If I push it and hammer the throttle to cross a highway spinning slush, and the diff locks half-way across, can it do damage?

edit: found your "vsc off mod" mention on another thread, thanks!

 

[CJ3Flyr]

Is there any other way to get full power/bypass the traction control?
How quickly does pushing that switch disable traction control? If I push it and hammer the throttle to cross a highway spinning slush, and the diff locks half-way across, can it do damage?

1) Start out with the center diff locked or do my mod and drive with it on...

2) Very quickly for my switch, 1-3 seconds (if that).

3) Doesn't sound good to me. Gears meshing at high power settings is never good:gun5:

 

[smackitsakic]

Thanks for the responses, much appreciated.

So...if I find myself in an empty, snow covered parking lot that is slick and I want full control to do some 'spinning', I can lock the diff. and it won't harm anything, or would the circular rotation grind things up?

Oh...and ours is a V6.

 

[CJ3Flyr]

Thanks for the responses, much appreciated.

So...if I find myself in an empty, snow covered parking lot that is slick and I want full control to do some 'spinning', I can lock the diff. and it won't harm anything, or would the circular rotation grind things up?

Oh...and ours is a V6.

Lock it in the snow covered parking. Make sure the cycle is complete (no beeping, no flashing lights) and have fun!:bigok:

 

[scottm]

1) Start out with the center diff locked or do my mod and drive with it on...

2) Very quickly for my switch, 1-3 seconds (if that).

3) Doesn't sound good to me. Gears meshing at high power settings is never good:gun5:

I read your mod, still not sure if I can stomp the pedal and get unfettered power to the tires. If traction control is still trying to equalize the tire speeds, but they spin, I'm ok with that. If traction control is grabbing the brakes hard to keep them from spinning, and keep me from getting out of the way of oncoming traffic, I might also want to kill the ABS.

 

[CJ3Flyr]

I read your mod, still not sure if I can stomp the pedal and get unfettered power to the tires. Most of it... The ATRAC still is active and makes an effort to provide limited-slip like performance on the front and rear axle. It, however, doesn't throttle back at all.If traction control is still trying to equalize the tire speeds, but they spin, I'm ok with that. If traction control is grabbing the brakes hard to keep them from spinning, and keep me from getting out of the way of oncoming traffic, Plenty of "go", no worries... Only a slight loss below modest throttle settings/2500RPM as the ATRAC tries to balance the right and left wheel RPM. I have done 4wd drifts and powerslides in the sand, no problemI might also want to kill the ABS.

:cheers:

 

[scottm]

:cheers:

Sounds like the mod for me, and I think I've got some relays lying around I can do some latching circuit with. Ideally, I'd like a big button on the dash I can slap when I realize I need power now. Or a button under the accelerator pedal when I stomp on it. I'll probably cheat with a simple scotch splice instead of your nice soldering job, and a Radio Shack button in one of the many switch blanks. Maybe on the console, hmm.

I just read my wife's facebook, sounds like we have snow, wish I could play in my new truck. I'm stuck in the rain in England.