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.
This could not have been any clearer
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Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
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)
This post reminds me of that Abbot and Costello Skit "Who's on First? What's on Second? . . ." Hahah!
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
OK, as pointed out VSC will save your ass in adverse road conditions at speed. I get it. However having an automatic I know that shifting into 4 wheel drive will turn VSC off. What do the folks that have manual transmissions do because their rigs are 4 wheel drives all the time? Does this mean that they do not have VSC?
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Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Quote:
ropedrag previously said:
OK, as pointed out VSC will save your ass in adverse road conditions at speed. I get it. However having an automatic I know that shifting into 4 wheel drive will turn VSC off. What do the folks that have manual transmissions do because their rigs are 4 wheel drives all the time? Does this mean that they do not have VSC?
Nope, MT's have VSC in 4Hi (not in 4Lo, and not in 4Hi with rear locked). Why VSC in 4Hi on MT and not Auto? Well... I'd like to know that too.
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Quote:
phillirw previously said:
Nope, MT's have VSC in 4Hi (not in 4Lo, and not in 4Hi with rear locked). Why VSC in 4Hi on MT and not Auto? Well... I'd like to know that too.
Ron
When I shift into 4Hi (auto trans) my VSC off light comes on so I do not have VSC in any 4 wheel drive scenario.
Interesting.
Please clarify, when you drive around town, normal to the store, etc... you are running in 4Hi with the MT? And you are saying that you get the rear locker in 4Hi as well?!?
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When people I dont know come up to me and tell me motorcycling is dangerous I tell them so is talking to strangers!
Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Both the MT and AT lose the VSC function when the center differential is locked. Actually the AT has a direct drive (so not really locking the center) that engages at the front axle differential when 4H selected. The front drive shaft turns all the time.
MT has VSC when transfer is in H, but not HL or LL.
AT has VSC when transfer is in 2H, but not 4H or 4L.
The VSC function might be dangerous if it tries to control a skid when the center differential is locked. Both axles are turning at the same rpm, but a turning track of all wheels will have the front wheels (total of left and right) traveling further than the rear wheels (total of left and right)
The reason that VSC works when the MT is in 4WD (Transfer H), is because the Torsen function of "H" is a limited slip differential, permitting the front and rear axles to rotate at a different rpm if need be.
See chart in thumbnail
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Re: Making sense of TRAC, Auto LSD, ATRAC, VSC, & Rear Diff lock.
Linear Mode
