Turn Off TRAC/VSC Systems And Keep Them Off

But in general, I find it difficult to believe one size different tire would cause problems on a short trip to a tire store.
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Push me over that edge LWN so that I can finally get these installed. :banana: I cannot wait. BTW, I sent you another PM back. Can you check it out?
 
LWN said:
I can't remember the last time I had to run a spare - onboard plugs & a portable compresser always did the job for me. But in general, I find it difficult to believe one size different tire would cause problems on a short trip to a tire store.
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In the past and on other current vehicles it wouldn't have. But on ones with VSC and TRAC, or other computer controlled traction system it can. maybe not with a 265 and 275 as harper as said, but put a donut on your rear end and see what happens.
 
mgrande said:
Well I guess they changed the VSC for the 4runners then. But I'd look into the LSD still. For tacoma's they actually only work in 2wd. Once you put it in 4HI you loose the LSD, but TRAC still works, which is similar to an LSD as they are both brake controlled. The whole TRAC/VSC/LSD/ATRAC system can be confusing at first. You should run same size spare so you dont activate them unintentionally and heat your brakes up. I'll post a link explaining the whole system if you guys want, but keep in mind its for 09+ tacoma's so I'm not quite sure how much applys to you, but I would assume most does.
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You're not referring to the mechanical LSD right? But rather the "auto LSD" which uses the ABS system to simulate a LSD.

2005-08 Tacomas depending on option packages had the mechanical LSD. The 2009+ has "auto LSD" that only works in 2WD and upto 55mph.
 
7harper said:
It takes more then one upsizing of tire like alot of truck,suv owners do when they buy new tires to set off LSD.
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Totally agree. And I'd be amazed if even 285 did anything. If you do the math on Toyota's owner's manual, same side rotation pattern that includes the spare (and I assume is the same in the 5th gen manual), you end up with about a 1/4 inch tire diameter difference near the end of tread life on one side of the vehicle, so apparently Toyota fully allows that much difference for fairly long term use.

As for the differential, it would seem that official manufacturers recommendations for the use of donut spares (whatever they are) would provide a good model for comparison. Whatever mileage is allowed for a donut spare could obviously be multiplied by quite a lot when using a slightly smaller spare in the 4runner that would be nearly identical in comparison to a donut.
 
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Uneek said:
You're not referring to the mechanical LSD right? But rather the "auto LSD" which uses the ABS system to simulate a LSD.

2005-08 Tacomas depending on option packages had the mechanical LSD. The 2009+ has "auto LSD" that only works in 2WD and upto 55mph.
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Yeah the auto LSD that uses the ABS. But I guess they changed a whole lot with the 4runners so it really matter.
 
However, once you accelerate past 30mph the vsc will come back on again as a safety feature.
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Toyota and my user manual are correct. Just tested this on my 2010 4Runner TE. If you disable both TRAC and VSC by holding your VSC button in for 3-seconds, it DOES NOT come back on even at highway speeds. It only comes back on if you manually turn it on or, turn off and restart your vehicle.
 
ftlee20723 said:
Toyota and my user manual are correct. Just tested this on my 2010 4Runner TE. If you disable both TRAC and VSC by holding your VSC button in for 3-seconds, it DOES NOT come back on even at highway speeds. It only comes back on if you manually turn it on or, turn off and restart your vehicle.
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Yeah, I said that must be new. I'm not here to argue guys. Do what ever you want.
 
Lsd....

From what reading and research I have done the 4WD versions do NOT have a LSD in the rear, only the 2WD versions have that. *See Toyota's web site for what is std for quick ref.*

Both 2WD & 4WD have VSC & TRAC (4WD also has A-TRAC only in 4L)

1st off I was surprised (before I purchased) to find out that the 4WD did not have a LSD, I guess they figure with TRAC & A-TRAC they did not need to use a LSD in the 4WD models, maybe it would 'fight' A-TRAC, dont know. My old SUV was 4WD w/ LSD in the rear.

I think someone would need to call Toyota to find out what the tolerance of TRAC is, how much faster does one tire have to spin than the other to activate the system. Think about it people, when you turn around a corner, even at 30mph, your 2 rear tires are going to spinning at different rates yet TRAC does not kick on. Now the question is....is the system smart enough to sense/measure steering (knowing you are turning) sensing the differences but not activating the system because of that. Who know what would happen when the wheel is straight. I know that VSC DOES measure the position of the steering in regards to all the sensors so it knows when to activate, not a far stretch to think that it is also linked to TRAC as well.

Correct me if I am wrong here, but I beleive TRAC is also linked to the differences between front and rear wheel spin/speed. Hense when in the snow/sand (*in 2WD*) and you give it too much gas and the rears spin at the same rate the system will still activate because it knows the fronts are not, indicating an issues to the 4R and activating TRAC to cut back.

If you run a smaller spare, turn off TRAC/VSC you should not have a single problem, since these 4WD's do not have a LSD either.

Like I said, I think we would need to find out the tolerances of the system to get a full idea of whether or not the system would need to be deactivated with a small spare.
 
1st off I was surprised (before I purchased) to find out that the 4WD did not have a LSD
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I am not sure about the Limited but, I know the TE has a LSD. However, to use it you have to hit a button on the roof center console AND, your 4Runner has to be in 4WD-LOW. I am assuming that it is off the rest of the time.

P.S. In case you have seen my other thread, I ordered the BFG AT 275-70-17s and will be having them installed tomorrow. :banana:
 
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westwind77 said:
From what reading and research I have done the 4WD versions do NOT have a LSD in the rear, only the 2WD versions have that. *See Toyota's web site for what is std for quick ref.*

Both 2WD & 4WD have VSC & TRAC (4WD also has A-TRAC only in 4L)

1st off I was surprised (before I purchased) to find out that the 4WD did not have a LSD, I guess they figure with TRAC & A-TRAC they did not need to use a LSD in the 4WD models, maybe it would 'fight' A-TRAC, dont know. My old SUV was 4WD w/ LSD in the rear.

I think someone would need to call Toyota to find out what the tolerance of TRAC is, how much faster does one tire have to spin than the other to activate the system. Think about it people, when you turn around a corner, even at 30mph, your 2 rear tires are going to spinning at different rates yet TRAC does not kick on. Now the question is....is the system smart enough to sense/measure steering (knowing you are turning) sensing the differences but not activating the system because of that. Who know what would happen when the wheel is straight. I know that VSC DOES measure the position of the steering in regards to all the sensors so it knows when to activate, not a far stretch to think that it is also linked to TRAC as well.

Correct me if I am wrong here, but I beleive TRAC is also linked to the differences between front and rear wheel spin/speed. Hense when in the snow/sand (*in 2WD*) and you give it too much gas and the rears spin at the same rate the system will still activate because it knows the fronts are not, indicating an issues to the 4R and activating TRAC to cut back.

If you run a smaller spare, turn off TRAC/VSC you should not have a single problem, since these 4WD's do not have a LSD either.

Like I said, I think we would need to find out the tolerances of the system to get a full idea of whether or not the system would need to be deactivated with a small spare.
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You are pretty spot on. There's no real reason to have the LSD on the 4WD models since all the 4runners come with ATRAC and TRAC. TRAC in 4HI will operate very similar to an LSD, but it takes more gas to activate it. I want to say above 3k rpm (on my tacoma anyway). In 4LO ATRAC works similar but is much more aggressive because it uses a hydraulic booster, which makes it more like having lockers front and rear. As for TRAC not turning on while taking corners fast, I'd pay attention to your dash when you try it. There is only an audible sound when VSC is activated, but for TRAC only the light will flash on real quick. And of course it will only happen if one wheel slips. You may find it coming on every time you take a particular corner in your neighborhood fast like me. Just the way the road is shaped on this one corner, all the oil and dirt seems to settle there.
 
Well , I know for a fact that running a 33 with 32.2's does'nt affect anything at all. I was test fitting the new tire today and took it for a 15-20 mile ride. Locked in 4Hi and 4LO on a straight away too....no affect. I honestly think the springs and shocks just leveled it out to compensate and made NO difference.

The BFG MT KM2, believe it or not is quieter then the BFG AT's. I'm sold and just ordered the other three.Only rubbing was on the inner mud flap knob and needs a "mud flap mod" to take care of that with minor trimming.I did "pull" my front inner fender liners about 1/2" forward instead of cutting them like the others with 33's when I put them in.No cutting,spacers or trimming at all needed without the mudflaps.

The 305's make the 275's look like bicycle tires.
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ftlee20723 said:
I am not sure about the Limited but, I know the TE has a LSD. However, to use it you have to hit a button on the roof center console AND, your 4Runner has to be in 4WD-LOW. I am assuming that it is off the rest of the time.
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Sorry, I believe you are wrong. Toyota shows your TE to NOT have a LSD. A LSD is active ALL the time at ALL speed. I believe you are talking about A-TRAC, I have the same button on the top, it only works in 4L and ALL 4WD models have this feature. LSD is only available on the 2WD as they do not have the ability to throw it in 4WD to get 'unstuck' from a patch of wet grass or ice :)
 
ftlee20723 said:
I am not sure about the Limited but, I know the TE has a LSD. However, to use it you have to hit a button on the roof center console AND, your 4Runner has to be in 4WD-LOW. I am assuming that it is off the rest of the time.
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You are confusing a Limited Slip Differential (LSD) with a Locking Differential.

Read this: Limited slip differential - Wikipedia, the free encyclopedia

And then read this: Locking differential - Wikipedia, the free encyclopedia

The 2010 4R Trail has an electric locking differential, whereby you have to push a button to turn it on. It also has "open" as in NO LSD differentials. It uses ATRAC as a "simulated" LSD to brake the spinning wheel and send the torque over to the opposite side.
 
I was hoping a final answer had come out of this, but it seems to be up in the air. Seeing this will be my daily driver for a while too, I'm just going with the 265/70 BFG AT's. Plus I can get those in a C, so that will help on the commute.
 
hoping a final answer had come out of this
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What final answer are you looking for? The TRAC/VSC systems can be turned off and they are not turned back on until you manually turn them back on or, shut-off and restart the vehicle. And, the Auto LSD is off unless you turn it on and shift into 4WD-LOW. So, running the stock spare with the BFG AT 275s is not going to be an issue.

Also, check out Harper's post. He ran one 305 tire with three 275 tires, he didn't turn off any of the traction control systems and, he didn't have any issues.

Trust me. I would not have purchased the 275s if I thought it was going to be an issue. 4 more hours until I get them installed. :guitar2:
 
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