Traction Control

[quadcam Junior Member Find all posts View Profile Close quadcam]

quadcam, what advantage does ARB air lockers have over traction control or vice versa?

In the situation where the front right wheel and the rear left wheel is off the ground, will the traction control still enable the vehicle to advance ahead? Or is lockers the solution for this situation?

Cheers

wengnuts, the main advantage of a mechanical diff lock (be it an air locker / detroit locker / overseas toyota diff lock) over traction control is that it can transfer all the engine torque to one wheel if necessary (assuming you have also locked the centre diff). The traction control is unlikely to be able to achieve this because the brakes clamping on a spinning wheel is in effect doing the same as the clutch plates in a LSD (but probably better due to mechanical advantage).

If you have TC with diagonal wheels off the ground i would expect it to drive if you are crossing something flat like a culvert but probably not if you are turning up an embankment.

Where the TC struggles is where there is an impediment to progress in addition to no grip on a wheel or wheels. For example you are pulling a trailer or you have a wheel off the ground and the other one is up against a rock or ledge. The amount of brake clamp will determine how much torque the wheel on the ground gets. If the loaded wheel needs more torque to make it turn than the brake can clamp on the opposite wheel then all that will happen is the spinning wheel will keep spinning. This is because open diffs, by the nature of their design, share torque equally. That is why in a 2wd with open diff and one wheel on a slippery surface you don't go anywhere. It only takes a little bit of engine torque to spin the no grip wheel, so that is same torque the wheel with grip gets, but it is not enough to drive it. (If you can put more weight on the no grip wheel and improve its coefficient of friction with the surface so that it needs more torque to make it spin then you might get enough torque to make the other wheel with grip drive the car)

The main advantages of TC over a manual locker are that TC is automatic and works on all surfaces and won't cause as much side slip. If you are on wet uphill bitumen and nail the accelerator to do a tight turn into a gap in the traffic the inside front wheel normally spins (80/100 series land cruiser without visco centre diff or series 1 discoverys) and you won't go far. TC will act on the slip straight away but that is not a scenario you would ever consider locking a diff lock for because it will drive you off the road as soon as the surface grip improved.

If you are side-on to a slope a locked diff will cause that axle to slide down the slope if there is any wheel spin as both wheels will spin where as TC should just stop the upper wheel from spinning (or at least not let the lower side wheel spin as much).

Also with TC you probably won't bust as many things mechanically in the drive line as you potentially could with a locker (especially a manual locker engaged when it shouldn't be) because, as previously stated, the TC probably can't transfer all the engine torque x 1st gear x low range x diff ratio to a wheel with grip like a locker can.

[Fazza Senior Member Find all posts View Profile Close Fazza]

quadcam,

You have done a good job there. "Very well explained."

Fazza.

[joedan Junior Member Find all posts View Profile Close joedan]

Thanks Quadcam.

I remember reading an article comparing the Jeep's Quadra Drive system (with e-diffs) with the Prado A-trac (Traction Control) system.

They were saying that while the Jeep's self locking e-diffs on the front, centre and rear can transfer 100% torque to any wheel, the Prado Traction Control system can only transfer a max of 50% torque to any wheel.

[Guest Close Guest]

wengnuts, the main advantage of a mechanical diff lock (be it an air locker / detroit locker / overseas toyota diff lock) over traction control is that it can transfer all the engine torque to one wheel if necessary (assuming you have also locked the centre diff).

This doesnt make a lot of sense?

A Locker mechanical or otherwise is just that "Locked" Meaning each side wheel (or all 4 if F/R fitted) are locked together.

How can only one wheel take all the torque if it is locked? Torque will be applied evenly thru the entire driveline.
Even wheels that are off the ground or "bogged" will still take a substantial amount of the power applied to it.

Traction control on the other hand can pulse the wheels to apply more power to one (or more) wheels.

What most people forget is TC needs momentum to work efficiently.
Lockers can be used at much slower speeds to achieve same (or more) traction, thus avoiding bogs and also saving the tracks from deterioration.

[quadcam Junior Member Find all posts View Profile Close quadcam]

TP, what I was trying to say was if you have only 1 wheel remaining with traction (because others are either off the ground or are on no-grip surfaces) then the locking diff can transfer all the engine torque to that wheel that has the grip.

Wheels that are off the ground effectively don't need any power to turn them (only bearing losses and brake drag) meaning that the other wheel on the locked axle is going to receive virtually all the drive torque being delivered through the locked diff.

TC doesn't need momentum to work, but your statement that momentum is required for proper operation is really because TC generally can't provide as much drive as a locker and any momentum assists the TC. Also while lockers may stop track deterioration in some cases they also contribute to it if they are locked when they aren't needed.

[Justo Advanced Member Find all posts View Profile Close Justo]

Mate... I think you would be surprised at traction control versus locked diff..!!
Credit where its due I have no doubt whatsoever that diff lockers are the ultimate in traction assistance however I would say TC would get you at least 95% of places that lockers would. You can't directly compare them.! :roll:

Read the reviews from guys that have them and have compared against lockers it will provide a more accurate comparison than someone that has never driven one.! Try a search here on Pradopoint, there are other reports of the comparison.
Personally I think the TC is brilliant and unless you are doing absolute hardcore 4wding on a regular basis I simply couldn't justify the addition cost for the little extra traction.!! Just my 2 cents.. 8)

[joedan Junior Member Find all posts View Profile Close joedan]

Some more commentry / info...

http://www.toyota-4runner.org/showthrea ... genumber=1


ATRAC is there to PREVENT loss of torque to the wheel with traction.

For example, if one wheel (in mud) is spinning on an axle, then the other wheel (on dry land) LOSES it's torque because power is routed to the wheel with least resistance (the one in mud). So, power is being transferred to wheel in mud. Now, with ATRAC, the ABS sensors will sense this slippage and apply the brake to the spinning wheel. It will apply the brake UNTIL the two wheels are spinning at the same speed (in theory)...that is, it will apply the brake to slow the spinning wheel to the same speed as the wheel that is on dry land. By doing this, it tricks the differential into thinking that the slipping wheel is also on dry land...thus, preventing all power from going to the slipping wheel. It evens out the torque distribution to both wheels. This prevents the wheel with traction (on dry land) from losing torque. Thus, it will have power to move your truck forward.

Does ATRAC really allow for 50% split?? Well, in theory, yes. However, in real life, i would say that it helps prevent torque from TOTALLY going to the spinning/slipping wheel. However, because of the stress on the brakes (brakes have to go against the power flow...aka HEAT LOSS) AND powertrain (remember, ATRAC can be quite sudden in it's operation), i doubt it. I would say that it is somewhere less than 50%. That is, ATRAC will prevent most of the torque from going to the slipping wheel. So, the wheel with traction will receive less than 50% of torque, but enough to keep your 4runner moving forward.

Thus, this is the role of ATRAC...it prevents the loss of torque from the wheel with traction...to allow that wheel to get enough power to move your 4runner forward.

This is why the 4runner has big brakes with multi-pistons and 4-channels. You need good brakes in a vehicle with ATRAC for effective ATRAC operation. In addition, 4runner powertrain needs to be beefy to take the stress of ATRAC.

How good is ATRAC?? It is as good as any limited-slip differentials (LSD) on the market. It will only lose to a true locker over rocky terrain, hill climbs, and deep mud. But then again, it is less stressful on the axles than a locker in most circumstances.

With ATRAC, it's like having LSD on the front AND rear axles. With the center diff locked, the 4runner is quite capable! ATRAC is such an elegant and simple design...no extra stuff...it just uses the existing technology (4-channel ABS, ABS sensors, etc.) to create a LSD.

Hope this makes sense...and sorry about the length.

[quadcam Junior Member Find all posts View Profile Close quadcam]

Mate... I think you would be surprised at traction control versus locked diff..!!
Credit where its due I have no doubt whatsoever that diff lockers are the ultimate in traction assistance however I would say TC would get you at least 95% of places that lockers would. You can't directly compare them.! :roll:

Justo, I wasn't trying to pan TC, I have driven with it and the current systems are very good. In the vid on the 1st page a non-TC prado wouldn't go where that one did and even a non-TC with 1 locker would probably struggle. The TC would probably be like having a 75% locker effect in both axles. That will get you much further than one lsd. And, like you say there is a fair cost involved to improve on that.

The thing that concerns me is the reliability of the sensors, solenoids etc in harsh environments and how you are going to get out of somewhere tricky if it fails.

[Justo Advanced Member Find all posts View Profile Close Justo]

I've never heard of a reliability issue myself, but of course it is electronic and electronics can fail. I have read somewhere on a US forum of the 4Runners etc overheating the system from constant use which will disengage the system until it cools sufficiently. You would have to be really thrashing the system for that to occur.
If you are seriously worried about TC failure and the cost of lockers I think a winch should be higher on your list of accessories. I know I've mentioned it before but a winch will pull you from places even lockers wont get you out of.! If money isn't an issue get both.. 8) Don't get me wrong I would love lockers, but just can't justify the extra cost for the little extra traction.!
Of course thats just my opinion, everyone is entitled to form their own opinions to suit their individual requirements.

[wengnuts Advanced Member Find all posts View Profile Close wengnuts]

Don't get me wrong I would love lockers, but just can't justify the extra cost for the little extra traction.!

That's a valid argument. However if you owned a poverty pack model (gx and gxl) without TC, then diff lockers are your only option. A GXL is probably 15k cheaper than a grande therefore spending 3k for lockers is a justifiable extra cost. As stated by many before this post, the TC is only 95% as good as a locker.

Cheers

[Justo Advanced Member Find all posts View Profile Close Justo]

I agree totally wengnuts, if lockers are the only option you have on GX & GXL models then lockers it is. It proves it pointless to compare them if it's not an option, but to your benefit, yes the lockers are no doubt the ultimate.

I think quadcam is more concerned about the event of mechanical/electronic failure of the TC than the difference in traction. Thats a valid point, but realistically the chance of failure is probably equal on either system so it's not really a justifiable reason to decide which is better or the more reliable. Someone mentioned a Discovery and warning lights..hehe need I say any more :lol: I think they are a great vehicle, and very capable but Land Rover seem to still be haunted by reliability issues. I read a report recently on the Disco 3 and they had a rear suspension airbag failure on a test vehicle.!! Thats gotta be ops:

As for the great debate on lockers/TC I think its been thrashed out enough already and as xvprado quoted, "compare apples to apples, diff locks rule, no argument, but TC does a good job".
I say it does a great job and for that I can't justify the cost of lockers. There may be some that can justify it even with TC (must have too much money..plz send some my way) and for the poverty packs that want to go further than TC, lockers are the only answer.. 8)

[Guest Close Guest]

Are you real ?

Mate... I think you would be surprised at traction control versus locked diff..!!
Credit where its due I have no doubt whatsoever that diff lockers are the ultimate in traction assistance however I would say TC would get you at least 95% of places that lockers would. You can't directly compare them.! :roll:

Justo, I wasn't trying to pan TC, I have driven with it and the current systems are very good. In the vid on the 1st page a non-TC prado wouldn't go where that one did and even a non-TC with 1 locker would probably struggle. The TC would probably be like having a 75% locker effect in both axles. That will get you much further than one lsd. And, like you say there is a fair cost involved to improve on that.

The thing that concerns me is the reliability of the sensors, solenoids etc in harsh environments and how you are going to get out of somewhere
tricky if it fails.

Are you serious ?
If your concerned about the reliability of solenoids and sensors relating to the Traction Control, you would be best to remove the engine and driveline and refit it with a Datsun 120Y running gear.
You will be safe then.
And dont forget to remove the electric windows, central door locking, cruise control, brake system etc .

[Guest Close Guest]

How many VX or Grande's has anyone heard of that have had failed traction control?
I have never seen/heard of it failing before.
Personally I would rather it than not as it offers other safety features apart from just the traction control.

[joedan Junior Member Find all posts View Profile Close joedan]

Thats right, lets not forget Hill Start Assist, Descent Control and more importantly VSC that also comes with the package.

I tested out the VSC on some gravel and sand just to see how it would go in an emergency situation on the road and I was impressed. Just a bit of added safety for the family.


Has anyone ever overheated the traction control to the point where it stopped working?

I guess that's a bad question because maybe the majority of VX and Grande sales rarely see rough terrain.

I'm an exception though, she was only days out of the showroom....

[xvprado Senior Member Find all posts View Profile Close xvprado]

I have overheated the DAC and had it shut down on a hot day and on a pretty serious hill
So I guess the TC would be in the same basket with a level of component sharing
Like all things in life...moderation is good