Tech Question - What is the grinding-clicking noise you hear when A-TRAC is active ?

[logic2]

Does anyone know exactly what causes the grinding-clicking noise you hear whenever A-TRAC is engaged and is actively controlling wheel spin ?

Does this noise happen by design, letting you know it's active ?

Is it just a by-product of the ABS system, and if so, what is actually happening to make the click/grinding sound?

Is it in any way destructive or should it be a cause for concern during extended use of this system ?

Thanks

 

[saskdiesel]

Some of the noise comes from the brake servo motor, some comes from the brakes, like ABS.
I believe that the the rest of the noise comes from the tranny/t-case as it loads and unloads during the operation of the a-trac system.
I dont think it would hurt anything for the short time that it's used.

 

[uzj100]

See above.

uzj100

 

[roosterdo]

It is the sound of it working

 

[k_os]

yeppp like he said when I first used A-TRAC i thought I had fxxxed up my Tranny but then it drove nice on the highway so I was like wtf?

It's like a grinding/clicking ABS noise.. not pretty but hey it's the way ti works

 

[VoltsAndBolts]

A-Trac & Roof Rack...

I got my FJC on 4-7-06 and haven’t even tried out the A-Trac. Well at least when I do now I won’t freak when I hear it do its thing…

Has anyone noticed a rattling sound from the roof rack at highway speeds? I can’t find anything loose but at 65-80 there it is…. Wonder if it’s air turbulence through the rack flexing the roof sheet metal?

 

[woody]

Has anyone noticed a rattling sound from the roof rack at highway speeds? I can’t find anything loose but at 65-80 there it is…. Wonder if it’s air turbulence through the rack flexing the roof sheet metal?

https://forum.ih8mud.com/showthread.php?t=86180&highlight=rack+rattle

welcome

 

[VoltsAndBolts]

Thanks for pointing me over there Woody.

 

[jerdog]

A-TRAC works by sensing free spinning and activating the brake for that one wheel, pushing torque across the axle to the other tire with traction. It then pulses the brake on and off to monitor when the wheel regains traction (i.e., stops free spinning), and this happens several times a second. This is opposite ABS, which is activated by and monitors for non-spinning wheels when braking. It sounds like clicking and grinding, but it's not. Hummer optimized this technology in the H1.

 

[1911]

Has anyone noticed a rattling sound from the roof rack at highway speeds? I can’t find anything loose but at 65-80 there it is…. Wonder if it’s air turbulence through the rack flexing the roof sheet metal?

 

[WyoCruiser]

Thanks 1911, it's time we all acknowledged the true source of rack rattle.