Auto LSD

This made me LOL.

And you damn sure cant deny that youre country either. Cause only us folks down south use words like HOLLER. LOL

 

I think they hire the same sumo wrestlers to write the manual as Yamaha hires to tighten crankcase drain bolts.

 

... I've spent a lot of time in south FL.

 

We don't know that (hi-lighted above in bold). He never hit the button in 4wd High while pulling the car out of the ditch. He was in the default TRAC on & VSC on mode where throttle was regulated.

He needs to do another test where he's in 4wd High, and presses the VSC button once so the TRAC Off light comes on. That's where we will see if there's any brake or throttle regulation. I'm going assume it's open diffs, with VSC on.

 

I agree, I bet it IS open diff with VSC on.

On a serious note, I think the best option for those of us with a 2012 OR is to do the locker mod. So we can lock the rear while in 4H, if we need any more traction than that, we can get 4L and use ATRAC and locker.

 

VSC depends on engine regulation, it is therefore no different than ALSD + engine regulation. That's the default mode.

The fact that there are different lights between tap and long-press in 4wd suggests that there is some actual difference between the two modes. VSC can't possibly be in effect for either mode, so the only remaining possible difference is that there is ALSD in one of them. Since long press is "fully off", it must mean that short press = ALSD.

 

There are precisely two differences between TRAC and ATRAC:
ATRAC has an electric/hydraulic brake booster,
ATRAC operates in 4L.

Quite frankly, they should eliminate the "TRAC"/"ATRAC" names, which are there strictly to add magic to the list of features and accomplish nothing but add confusion. Stick with ALSD all the way through.

The different modes should be named like this;

2H: VSC, ALSD, OPEN
4H: VSC, ALSD, OPEN
4L: OPEN, ALSD, OPEN+RLOCK, ALSD+RLOCK

After all, those are, in effect, all of the actual modes available, just written in a way that is more consistent with standard nomenclature.

 

I understand what VSC is. We're talking about traction control (TRAC/ALSD/ATRAC). VSC is a whole different system and should be left out of the conversation for the time being. It only adds confusion. Your post is evidence of that.

There is a simple difference between the two 4wd high modes (there's actually three, but I'll leave the third VSC Off one out): TRAC Off; TRAC On. The "TRAC Off" light indicates this.

If "VSC can't possibly be in effect" why isn't the VSC OFF light on?

If "ALSD is in one of them" why isn't the AutoLSD light on?

VSC is not traction control, and does not change what traction control mode you are in. It is simply on or off (under 30 mph).

 

On my '12 Sport, I can't turn off vsc (truck w. lines) and still have TRAC on in 4wd

 

This is the only proof I've seen. It doesn't mention 4wd though.



This one mentions 4wd.

 

No, VSC is the exact same system.

TRAC *is* ALSD *is* ATRAC. Effectively just different names for the same thing.

Nobody cares what you want to CALL the modes, the IMPORTANT part is what they each DO.

VSC (ALSD+engine regulation = default mode)
ALSD (like VSC without engine regulation = tap button)
OFF (open differential = hold button)

Now you want to quibble about when the thing is making use of the sideways sensor, be my guest. It quite frankly does not apply to this discussion.

Because its turned off, obviously.

Because its turned off, obviously.

VSC most definitely includes a traction control mode.

 

Nope.

Vehicle Stability Control ≠ Traction Control

I agree (being that they are traction controls), but making up different names like you do below, is not going to help anyone understand Toyota's system.

You are using my argument against me? You are right. VSC does not belong in this conversation.

You just contradicted yourself in this post.

 

VSC == NO QUESTION AT ALL == TRACTION CONTROL.

"LSD" is an industry standard LIMITED SLIP DIFFERENTIAL.

TRAC/ATRAC/whatever are extra made-up nonsense names. Understanding the system involves ignoring all the contradictions that Toyota has introduced in the names of the different modes. What they call ALSD in 2wd is *IDENTICAL* to what they call TRAC in 4wd. If that isn't confusing, I don't know what is.

MY use of VSC in this discussion is EXCLUSIVELY related to the TRACTION CONTROL features that correspond to THAT MODE.

When the vehicle is in VSC ****MODE****, it is operating ALSD with ENGINE REGULATION.

YOU are the one focused on how it responds to the yaw sensor. NOBODY CARES ABOUT THAT ASPECT OF IT.

No. A light is just a light.

You asked why the light was off. I answered: BECAUSE THE LIGHT IS OFF.

 

VSC and Traction Control seem to indeed be 2 seperate things in my experience

 

When the buttons are pressed such that VSC would operate, i.e., in "VSC MODE", will it or will it not operate ALSD+engine regulation on a slippery surface?

Whether or not yaw sensor triggers a different routine in the firmware, when it is in that MODE, it will operate ALSD+engine regulation.

For the sake of SIMPLICITY, that MODE is best referred to as "VSC", for lack of a better name.

 

Ok I'm not going to waste my time any more. We must be getting trolled. I forgot you are the same guy that is an expert on Tacoma transfer cases.

http://www.tacomaworld.com/forum/2nd-gen-tacomas/241380-twin-stick-transfer-case-3.html#post5759613

 

The operation of "VSC" (yaw sensor routine) works like this;

1) you are driving around a corner and the back end starts to kick out.
2) yaw sensor reading exceeds expected value calculated and/or wheel speed sensors inconsistent with each other.
3) selective activation of brakes and reduction in engine power output in order to match wheel speeds to the road and reduce kick out.

When you are in that same mode on a sheet of ice;
1) You step on the gas and one wheel begins spinning.
2) Wheel speed sensors inconsistent with each other.
3) selective activation of brakes and reduction in engine power output in order to match speeds of all wheels to each other.

Imagine that. Both in the yaw sensor kickout scenario and in the stuck scenario, in BOTH circumstances, it considers relative wheel speeds, reduces engine power and selectively applies brakes in order to match all of the wheel speeds together. The difference is only that in one scenario it also considers the yaw sensor. Think maybe there is less difference between these two scenarios than initial assumptions suggest?

 

Interesting

He never posted in there again

What's next ? Towing 10 000lbs without a tow package in a 4 CYL ?

 

I don't agree that ALSD is any kind of "bastardization". The system has more strengths over mechanical LSD than it has weaknesses.

It also doesn't help for clarity to limit the use of the term "LSD". There is no model of Tacoma offered with an old fashioned mechanical LSD unit any more. They were only available up to 2008 MY.

In fact, ALSD and LSD are a lot more similar than you would initially imagine. The mechanical differential used a series of friction disks (brakes) to control the motion of the two wheels relative to each other. If one started moving significantly faster than the other, the disks would engage to some degree and slow down the faster moving wheel relative to the slower moving wheel.

With ALSD, it uses the main brakes to slow down the faster moving wheel relative to the axle housing.

On a superficial level, ALSD might seem to be less efficient than a purely mechanical LSD. It might leave the impression that energy is taken away by the brakes. That, however, isn't really the case. Imagine that you're stuck with one wheel spinning and the other stationary. 100% of the energy produced by the engine is being lost in the friction between that moving wheel and the ground, yet you aren't moving. If you fully lock that spinning wheel, then 100% of that energy is directed to the opposite wheel. If you 50% lock it, 50% of the energy is directed to the opposite wheel, and 50% is lost as friction to the ground. Yes, of course a slipping brake is going to absorb some energy as heat, but the same thing is happening in a purely mechanical LSD.

So a more thorough analysis suggests that ALSD is no less efficient than a purely mechanical LSD on an energy utilization basis.

Next up is efficiency of activation. A mechanical LSD requires a certain minimum amount of slip in order to lock the plates together. ALSD also requires a certain minimum amount of slip in order to know to activate the brakes. Meaning, of course, that BOTH need to actually slip in order to respond. I don't see any advantage for either in this respect.

Up to here, everything between LSD and ALSD seems to be about equal. There are, however, some noteworthy differences;

First up is cooling. Suggestion of ALSD overheating and ceasing to react. As far as I can tell, this is predominantly affecting models with the electro-hydraulic brake boosters (ATRAC -- TRD offroad). It is the brake booster itself that overheats, rather than the brakes (which don't have temperature sensors). The models with vacuum boosters have a similar glitch, but not quite the same; loss of vacuum. The vacuum booster can only run the brakes so much before running out of vacuum.

Now obviously, a mechanical LSD won't suffer those downsides.

The big downside to a mechanical LSD is what happens when you wear out the disks. It is a bit more involved of a repair to replace worn out LSD disks than brake shoes.

ALSD has additional advantages over mechanical LSD: that it can be controlled electronically, so can relate front to rear wheel speed, and can be activated in circumstances like yaw sensor.

The biggest advantage that ALSD has over mechanical LSD is that it can operate on the FRONT in 4wd.

And last, of course, ALSD can be deactivated. Mechanical LSD cannot.

 

The big difference, though, is that people understand what LSD *means*. That is the biggest reason to hang on to that term exclusively, and drop the extras.

TRAC = ALSD,
ATRAC = ALSD with electro-hydraulic booster.

?

I, personally, prefer the acronyms to actually mean something.