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Discussion Starter #1
Interesting tidbit I read on another forum. What do you guys think? Also just to point out I have the VSC, I like it and I want it in the fj......but I want a locker too!



Thai said:
There is one disappointment with both H3 and FJ Cruiser. Apparently, when you engage LO-range and the rear locker in the H3, traction control is disabled completely. Therefore, the front axle is completely open. I had initially hoped that the front axle would still have traction control because this would provide awesome traction (rear locker + ATRAC in front).

With the FJ, apparently, you have to choose between ATRAC/VSC or rear locker...NOT both! This sucks IMO. I guess that this is the same for Tacoma. To make across the Rubicon trail, Toyota engineers apparently had to modify the FJ to have both ATRAC and rear locker working together. This apparently will not make it to production.:(
Very interesting!

Sooo....the fj didn't make it across the Rubicon in "stock" form
 

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I'd like to see some references. According to Toyota, there were modifications made to the production car AFTER Rubicon, leading me to believe that ATRAC disabling was a pre-Rubicon thing and that after they made it work the right way.

I highly doubt Toyota would make such a big deal about a stock FJ doing the Rubicon and then pulling a fast one on us.

- LC
 

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Discussion Starter #5
Lost Cosmonaut said:
I'd like to see some references. According to Toyota, there were modifications made to the production car AFTER Rubicon, leading me to believe that ATRAC disabling was a pre-Rubicon thing and that after they made it work the right way.

I highly doubt Toyota would make such a big deal about a stock FJ doing the Rubicon and then pulling a fast one on us.

- LC
They didn't disable the ATRAC for Rubicon, they used both the ATRAC and the rear locker. The ATRAC addressed the front axle and the rear locker the rear axle. The issue is that apparantly Toyota won't offer these in combination, which is how they had it set up for the Rubicon.

If you just get the rear locker the front axle is open.
 

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Yes but if we knew how they did it, then perhaps we could replicate the system as the condition warrants.
 

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ToyBox said:
They didn't disable the ATRAC for Rubicon, they used both the ATRAC and the rear locker. The ATRAC addressed the front axle and the rear locker the rear axle. The issue is that apparantly Toyota won't offer these in combination, which is how they had it set up for the Rubicon.

If you just get the rear locker the front axle is open.
No that's not what I'm saying. I'm saying that this information about ATRAC being disabled with the rear-locker was what Toyota was planning to do before they ran Rubicon but they decided to change that before running it and that it will make it to production.

Who knows.

- LC
 

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Discussion Starter #8
Lost Cosmonaut said:
No that's not what I'm saying. I'm saying that this information about ATRAC being disabled with the rear-locker was what Toyota was planning to do before they ran Rubicon but they decided to change that before running it and that it will make it to production.

Who knows.

- LC
Okay, I see. Well I hope they make them work together in 4Lo for the production trucks.
 

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What doesn't make sense is why the trac would have to be disabled when the rear is locked. This is the way I look at it (and I'm no toy tech by any standard)...

open front/rear - trac works fine as it'll detect slippage on all 4 wheels.
open front/ rear locked - shouldn't the trac work fine as it should only detect slippage on the front wheels? I mean rear locked means no slipping what so ever..

The reason why I look at it this way is becase I have the 03 4runner w/ the ARB rear locker. I've used the 4runner w/o the rear locker and w it and both times the trac system still worked. But then again I'm using an aftermarket rear locker so that could be it as it's bypassing the trac ecu.

With that said, why Toyota would want to disable trac when the rear locker is engaged? it just doesn't add up. Anyone with an 05 taco confirm the rear locker capabilities w/ the trac engaged? I haven't really seen many taco's on the local trails here so I can't confirm this so this would be the easiest way to confirm this as it's going to be exactly what the Taco currently has. (well w/o the full time but you get what I mean).
 

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Good Times said:
What doesn't make sense is why the trac would have to be disabled when the rear is locked. This is the way I look at it (and I'm no toy tech by any standard)...
That would be my question too: why disable it when rear is locked ???

BTW, Awsome 4runner, Lance!
 

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Will someone please revisit this thread and let us (me anyway) know what the FJ does and doesn't offer now that the vehicle is in production and being sold?

Thanks
 

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OK, I took the FJ over a trail yesterday in Big Bear Ca called the John Bull Trail
it is a black diamond rated trail that will get front wheels off the ground
I did it with Stock tires, aired down to 10 PSI
Locked rear and no ATRAC, The FJ did it quite well, I had to roll a few rocks, take a few different lines than I am used to, and take my time, but the FJ is proving to me more and more that it is quite a capable vehicle.
I have taken the CON 3 different times in Jeeps, twice in a 65 CJ an once in a more modern TJ, MY advice for going up the trail in the FJC, get plenty of Armor, you are going get knocked around a bit. get used to that wheel in the air feeling, you do not have SFA articulation, have a winch, you will need it.
go out and get a good set of offroad tires for the trip, I might suggest a set of bias ply Maxis Creepy crawlers
Besides that, if you do not mind a few dents, go for it
 

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ToyBox said:
Interesting tidbit I read on another forum. What do you guys think? Also just to point out I have the VSC, I like it and I want it in the fj......but I want a locker too!





Very interesting!

Sooo....the fj didn't make it across the Rubicon in "stock" form
you cant have a locker and VSC/ATRAC- a locker locks the diff- the VSC/ATRAC is just the opposite- and actually can apply brakes to one wheel- not too good when your locked!
 

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First, a locker is compatible with ATRAC. A few people have added ARB rear locker to 4runners and Land Cruisers/LX470. No issues.

I finally understand the reasoning after much thought...

OK, ATRAC was modified by Toyota specifically for FJC...to make it more aggressive in off-roading. So, in Toyota's eyes (and for most obstacles), this new version of ATRAC is more than capable.

ATRAC clearly suffers in sand and deep mud where the braking action of it can kill/slow your momentum. Remember, Toyota has apparently made ATRAC on FJC aggressive enough to handle rock crawling...which means that this aggressiveness (frequent braking/pulsing of spinning wheels) can kill your momentum in deep mud or sand. So, if you got the ATRAC option, then you simply turn if OFF and run through it with open differentials. If you got the rear locker, then you turn it ON in these muddy conditions. Remember, unlike 4runners/TLC, there is an OFF button for ATRAC (very cool). Actually, you have to turn ON ATRAC for it to work, but you get my point.

If you rock crawl, then the FJC's ATRAC system should be aggressive enough over most rocky terrain. In this type of terrain (rocks), having both helps. But how many FJC owners will see a severe enough terrain to require both systems?? Not many.

If Toyota offered both systems together, then how many people will know how to use it appropriately?? How many will complain to Toyota why their FJC got stuck in deep snow or mud?? Or how many people will complain about the complexity of the 4wd system?? (aka "too many modes and buttons to press")

This may be the reason why Hummer chose to "dummified" H2's 4wd system when they build the H3. H2 can run rear locker and front ATRAC together.

I have no idea if what i wrote above makes any sense to other people...so excuse my post if it doesn't. Gotta go and eat dinner....
 

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Lost Cosmonaut said:
I'd like to see some references. According to Toyota, there were modifications made to the production car AFTER Rubicon, leading me to believe that ATRAC disabling was a pre-Rubicon thing and that after they made it work the right way.

I highly doubt Toyota would make such a big deal about a stock FJ doing the Rubicon and then pulling a fast one on us.

- LC
Here is the link:

http://forum.ih8mud.com/showthread.php?t=73121

It is a credible rumor...however, read the thread and decide on your own:

Read the post by "4WD Toyota Owner Magazine"

"Yes, they ran the whole trail from start to finish. Only thing they changed was the tires, and fiddled with the electronics so that A-TRAC worked with the locking rear diff. Normally it's one or the other, not both together. The rock sliders are in fact OEM, and the rig's frame is built for them specifically."
 

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Thanks Thai. Your post make very good sense to me. I have questioned the wisdom of having ATRAC and a rear locker engaged at the same time. You so ably put it into a very well worded explanation.

I know there will be someone that tries the dual system hack, but your explanation fits what I have been thinking perfectly. Also, the person performing the hack will need to reprogram the ECU for the ATRAC to function on the front wheels only, when the rear locker is engaged.
 

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I dont think any reprogramming will be required, as the ATrac works with each axle independantly... meaning it will sense NO difference in rear wheel speed with the diff locked, and therefor will not try to apply braking.
 

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Thai said:
First, a locker is compatible with ATRAC. A few people have added ARB rear locker to 4runners and Land Cruisers/LX470. No issues.

I finally understand the reasoning after much thought...

OK, ATRAC was modified by Toyota specifically for FJC...to make it more aggressive in off-roading. So, in Toyota's eyes (and for most obstacles), this new version of ATRAC is more than capable. ..
Nishimura-San said:
"Negotiating a tough trail is hard enough without your rig having a mind of its own. Locked differentials work great in a straight line, but can leave something to be desired when you start tracking off an embankment, or down a slope you're traversing. In situations like this, Active Traction Control is your best friend; it keeps the diffs open and helps you stay on course."
(Akio Nishimura, Chief Engineer)


Thai,
First you say that the locker is compatible with ATRAC because it was done on Landcruisers and four runners, but then you say ATRAC was modified for FJC- so how do you know this modified version of ATRAC can be run with a locker. Also- just because folks added rear lockers to ATRAC vehicles (mechanically disabling ATRAC in the rear if it was there to begin with) doesnt mean its the right thing to do. You talk about how it is "aggressive" what the heck is that supposed to mean? Please explain how ATRAC is aggressive- and how adding a locker can simultaniously work with ATRAC. My uderstanding of it differs from yours and would like to see what you mean.
 

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lllateralus said:
I dont think any reprogramming will be required, as the ATrac works with each axle independantly... meaning it will sense NO difference in rear wheel speed with the diff locked, and therefor will not try to apply braking.
That makes sense- thank you!
But what about with center diff locked?
 
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