4x4 / Off-Road TechThis section contains all discussion related to taking the FJ Cruiser in Off-Road situations, 4x4 applications and any armor modifications.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
My head just exploded. But I like gross, gooey things, so thanks!
I'm going to try everything out on dirt this weekend, just to experience what actually happens. I'm also looking forward to getting into a big, snow-filled parking lot this winter to see how best to control the FJ by way of the vsc system in 2wd versus non-vsc in 4H. Curious to see what happens when driving fast in snow, turning and powering out.
Can't imagine the 2wd will be better, since the front end will push, but I'll have to see for myself. In 4H, you should be able to add traction by applying power to 4 wheels and affecting steering under power. With no power to the front wheels, if you start to push, the traction and anti-skid mechanisms would theoretically allow rolling to the front wheels and brake the rears until such time as the fronts regain traction and a turn can be executed. The problem in this scenario is that it takes time+distance to get the fronts steering properly and not pushing. In 4WD in my past vehicles, I was able to power through turns on snow, and the time/distance for turn execution was minimized, making excellent use of front wheel steering (as opposed to rear wheel throttle steering (directional change with increased power-on slip angles).
So, I fully expect to have better control of direction in 4H on snow at or above 50mph. Could I be wrong with this specific vehicle? Certainly. Should I be traveling on snow above 50mph? No comment. But I have and will continue to do so. Carefully, of course.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Quote:
Super D previously said:
So, I fully expect to have better control of direction in 4H on snow at or above 50mph. Could I be wrong with this specific vehicle? Certainly. Should I be traveling on snow above 50mph? No comment. But I have and will continue to do so. Carefully, of course.
No electronic system in the world is going to overcome the physics of available traction vs vehicle mass/momentum....."better control" is a relative term
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Quote:
RoverGGM previously said:
No electronic system in the world is going to overcome the physics of available traction vs vehicle mass/momentum....."better control" is a relative term
So true. Looking forward to feeling out this FJ, seeing how it handles different situations. I'm sure it has much more performance potential than I do at this point in time.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
ROTFLMAO!
Quote:
Ridge111 previously said:
Yes, great summary, BUT, there's still no real significant difference in any of the control systems (diff lock excluded). TRAC, ATRAC, and VSC all use the brakes to control wheelspin. So what if one only works in 2wd and one only works in 4lo, or if you have to push a switch to make you think you're stimulating the magic traction fairies, it's still performing the same function. The only difference is the computer programming logic involved.
"TRAC - If the system detects wheel spin, it adds brakes to increase traction."
"ATRAC - detects wheel slippage and adds brakes accordingly to give added traction"
"ALSD - uses the traction control system (TRAC) to control engine performance AND braking when one of the rear wheels begins to spin (or slip). "
"VSC - prevent the vehicle from skidding when cornering on a slippery road surface or operating steering wheel abruptly"
Does anyone see any real difference here? I just want someone to admit that it is one system that performs these functions. It's all the same computer, the same abs sensors, the same brakes. The abs sensors are used to detect wheel slippage, and then the brakes are applied individually as needed. The ALSD says it also controls engine performance, though I don't see why that function would be labeled ALSD, as it really should be part of TRAC. And then VSC is to prevent doing 360s around a corner, as opposed to the other systems that are designed for assistance with forward acceleration. BUT, even the VSC is detecting a loss of traction and applying brakes to individual wheels.
"RRDIFF - for use only when wheel spinning (as oppose to wheel slipping)"
There is no difference in slipping and spinning, so long as you're referring to forward acceleration (as opposed to braking). And how could one wheel ever spin anyway, with TRAC always active?
"Hit the Auto LSD to get added traction in the rear wheels."
So the TRAC only gives you a little extra traction, but ALSD applies the brakes a little harder? I don't get it.
"Hit ATRAC switch for added traction."
Again, added traction?
I know you didn't make this stuff up Tran, I'm not blaming you, but you have to admit it's baloney. That's why you can buy a $40 ATRAC switch to "unleash" this magic. Imagine how much money they've made by getting people to buy the upgrade package just for the ATRAC.
Customer: Why do I want this package?
Dealer: It has ATRAC!
C: It has an 8-track?!
D: No, AAAAA TRAC.
C: Aww that sucks, I have some old 8 track tapes at home that would sound great on the FJammer.
D: (fake chuckle)
C: So what is ATRAC?
D: It's a traction control system that controls wheel slippage in adverse conditions.
C: Oh. Doesn't it already have that standard?
D: No. That's TRAC.
C: So what's the difference?
D: Well, that's TRAC, this is AAAAA TRAC!
C: So the A makes it better?
D: Well it's more than just an A sir. See, it controls the wheel spin when you're in the 4wd low gear.
C: And TRAC doesn't do that?
D: Well it does, but it's different.
C: How?
D: Well, ATRAC only works in 4lo.
C: And TRAC doesn't?
D: Yes TRAC works all the time.
C: So TRAC also works in 4lo.
D: Well yes.
C: So why do I want ATRAC?
D: Because it's better.
C: And you can only get ATRAC in the 4wd? What if I wanted 2wd?
D: Well you can get Auto LSD.
C: 8 tracks, LSD, what's going on here?
D: (another fake chuckle) Not that kind of LSD sir. It stands for Limited Slip Differential.
C: What's that?
D: It's actually a simulated LSD, it uses the brakes to control wheel spin.
C: I thought that's what TRAC does.
D: It does, but TRAC is on all the time. You have to push a button to use ALSD.
C: Hmm. You people are proud of your buttons aren't you. So back to the ATRAC, how do I turn it on?
D: You push this little button right here.
C: And how can I tell it's working?
D: There's a light on the button.
C: Oh, a light. Well that's pretty cool. Alright, I'll take it. And how much extra is this package?
D: It's just a little bit more, we'll make the numbers work. Let's go sign those papers... (as they walk off into the sunset)
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
ok im still confused about this ATRAC thing. what are the actual benifits??? why not just be any normal person and float the throttle if your wheels are spinning???
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
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Wombat previously said:
ok im still confused about this ATRAC thing. what are the actual benifits??? why not just be any normal person and float the throttle if your wheels are spinning???
Because it will "float the throttle" on each wheel...one at a time depending on that individual tires grip on the surface. Manually "floating the throttle" when climbing makes you lose momentum and stop.
The benefits are that you can go when others can't and still be able to steer the vehicle. With one drive wheel (on each axle if you wish) floating in the air you can feather the throttle all you want and the airborne wheel will get the power, with ATRAC you will keep moving forward.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Quote:
Wombat previously said:
ok im still confused about this ATRAC thing. what are the actual benifits??? why not just be any normal person and float the throttle if your wheels are spinning???
If I could float the throttle independently on each wheel I would agree.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
I think several threads, including this one, should be bundled into a..."Read these BEFORE wheeling your FJ for the first time" or "Read these BEFORE asking a question that has been covered in detail by experienced FJ owners".
Once again the SEARCH feature finds the answer to my question.
I just got back from a little wheeling. Since we have had no rain, all the trails, hills and holes are dry. Not having to worry about getting stuck or sliding off a hill, I decided to see what the FJ could do in 2WD. Started my slow climb and about halfway up the hill the rear started spinning slightly. That was no surprise or nor was it anything that concerned or alarmed me. However, it was the first time I experienced what I NOW know (by SEARCHING and reading) was the Traction Control. Felt the vibration and thought something was wrong. I thought the front drive was binding or the front wheels were trying to engage into 4WD on their own. I was ready to take the FJ to dealership for it's first warranty issue. Thanx guys for putting my mind at eaze and thanx to everyone who contributed to this very informative thread. You rock !
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