toyo22r

Ok this may be a stupid question, but whats going on here. A-Trac only works in 4-lo. When in 4-hi a light indicates VCS is off. However, when in 4-hi and the wheels begin to spin I can here the brake circuit pulsing like the VSC is working. Is this working as it should? I am hoping someone can explain this.

Paul
toyo22r@hotmail.com
07 FJ

AppleJack

I'll give it a shot here, but I have a '05 Taco.
So VSC is activated when a lateral skid is detected. Trac is activated when the wheels spin. A-TRAC is for 4-Lo and does essentially the same thing as Trac, only it has the ability to split torque front to rear as well as side to side.
Hopefully that's not too confusing and hopefully that's accurate.

toyo22r

By Trac, i assume you mean traction control? Is this applied to only the rear wheels? I guess i am a bit confused as to the difference between traction control and A-trac.

On a side note, when this system is engaging while in 4hi i can hear it working but no indicators on the dash. When its in 2hi and i spin the rear tires in mud or snow i hear it working as well as the slip indicator flashes.

AppleJack

Trac is only applied to the rear wheels when you're in 2wd. If you're in 4wd then it is applied to all four. Trac essentially cuts the power available to a wheel that wants to freely slip and thus encourages the wheels with traction to move you forward. A-TRAC does the same thing but also can adjust how much torque to send to the front wheels. In some situations, such as climbing a ledge, it is helpful to have more torque and traction available at the front to start clawing your way up and over. This is also where it is nice to have a front locker, but lockers in the front mess with you ability to steer the vehicle and can break stuff.

Corey

iTrader: (1)

Atrac works in 4low, and is often better than using the rear E locker.
Atrac is also for the front.

Some good reading here, topic #2.
https://www.yotatech.com/forums/f135...r-facts-98707/

toyo22r

Thanks guys.. i understand now.

On a side note my OME lift and ARB bar showed up today! Cant wait to tear into it....

Corey

iTrader: (1)

Great!
They look killer on the FJs.

Mine has the OME HD up front, and the MD back aft.

toyo22r

What size tires are those Corey, 285's? I started on the front last night after work. Got the old coils off the front and stopped since i hadn't picked up the spring compressor yet. Its the easiest lift i've ever installed.

I went with the OME HDs on front and back. I tow a 5200lb ski boat alot in the summer, hopefully the back wont ride too rough w/o the weight of the trailer attached.

Corey

iTrader: (1)

Yes, those are 285x70x17s.
I have the exact same tire sized at 265x70x17 mounted to the factory wheels.

My plan was to run the smaller set during the winter ( I have always had two sets of tires) time, but I never got around to switching them.

The HDs back aft should be fine for you.
I may switch to HDs later, as I have a lot of stuff in the rear, but I have not sagged yet with the medium coils.



The trick up front too is to make sure you have the strut holder facing up like a bowl.
Many have put it on upside down, and they gain more height, but it is wrong.

Be sure to share some pics when you get it done.

DEWFPO

Trac will cut engine power along with applying certain brakes to gain traction. A-Trac (in 4Lo) does not reduce engine power, but does apply the appropriate brakes.

VSC has nothing to do with Trac and A-Trac. VSC is Vehicle Stability Control, but it still uses the brakes to control the yaw and pitch of the vehicle when it feels you are about to loose control.

I hope that makes sense.

DEWFPO