P285/60R18's and wierd TOD Operation

[VR4-Quest]

Got my P285/60R18 Nitto Terra Grapplers installed last week, they are pretty awesome, looks are 10 times better and the handling feels about the same as the 255/60R18's I had before, and I push my VX hard. Ride is a little harsher but is expected since the air volume is greater (pnuematic stiffness overrides the extra section height benefits). I was concerned about being that wide on a narrow 7" rim, that handling would really tank, but its great. And just a bit noiser.

Anyway, my TOD is now acting wierd. From a start, wet or dry, the TOD goes to full (3) leds then back to none, then back to (3) at least once or twice while accelerating. This is only around 0 - 20 mph and at part (halfway) throttle. Anything less and its the normal 1 led, anything more and it might spike to 3 then back to 2 as normal under full throttle (unless its really slick of course). I can physically feel the power going to the front and then all back as it cycles. At anything above 20 mph its good. I have no check TOD light flashing, I do have a TOD cutoff switch installed, but this just started with the tire change. Is the larger OD of the tires thowing off the TOD? Is there a way to reset the TOD or read codes? Is anyone else experiencing this with there larger Nittos?

Thanks!

[Mr. I-MAN]

There is more voids in the tread. This is good for off-road and wet pavement . However the more voids in the tread pattern the less tread contact with the road. So there is a little bit more slippage when you first accelerate. I noticed the same thing with my Nittos. Other than that these tires rock off-road , on road at high speeds and at stopping on wet or icy pavement.

[rocket man]

Hi Vr-4

I have the same set up 285's 7 in. rims Terra Grapplers...I have not noticed any difference with the TOD..I did drop the tire pressure (34lbs.) to soften that somewhat stiff ride...

:D Very Very Very pleased with this tire/rim combination..I have had many people ask me about this tire...They seem to ignore the car and oggle over the tire:confused: Go figure

[nocturnalVX]

No worries. I don't have the NITTO tires, but I've been having the same action due to switching to Pro Comp ATs. I could get the TOD meter to fully light up under hard acceleration on dry pavement even with the stock tires, and now it flickers every time I start to accelerate. The TOD system is adjusting for slipage as it's supposed to. I like watching the guage flicker like that... a reminder (as if I need one) of how wicked cool the VX is. Good times!

[VCAMILO]

;Db; I was just thinking the same thing. Same Tires on stock rims. Would TOD could something to wear out faster because of this issue with bigger tires w/less surface?

[VR4-Quest]

OK, I can understand that, I notice now when I punch it from a start, I get all three leds easier since the tires have more void and slip, but this cycling up to three and then back down to 0, repeatedly, only at part throttle doesnt seem right. I cant get it to do it in reverse at all, only forward. Again, slight throttle and all is normal with 1 led, and then full throttle resutls in three then two and holds till I let off. And this cycling is at half throttle and low spee only in first gear, the the shift to second and its gone. Still need help, can i read TOD codes or something?

[t2p]

could the tires be 'mis-matched' ......... ??? ...... same sized tires, but the size is actually different ....... enough that is is driving the TOD computer crazy ............
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maybe a sensor needs to be replaced or cleaned .... has some magnetic particles stuck to it .............
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......... could it be that when you 'punch' it, the TOD computer reads this and instantly sends the signal to send (more) power to the front wheels ........
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I don't know - I never 'punched' my VX from a dead stop .........

(hmmm, that's funny ........ I must be getting old ...... anyway, I get visions of the engine torqueing (rocking) on the motor mounts when I 'punch' it ....... and I don't believe there are flexible joints in/betwee/whatever the exhaust manifolds, so I will probably refrain from this .... I'm not up for replacing or repairing exhaust system components) ..........
.

[jim.LR>AR]

since reading this I've noticed mine does the same thing. From a dead stop the tod will light up to three and back to one and back to three and then back.. quickly. I can't feel any slipping of the back tires . It used to light up with the stock tires .but seems to jump up and down now. Where it used to be up to three for longer time.

[VR4-Quest]

Jim, what tires are you running. Sounds exactly the same as what mine is doing. I would love to have my old tire around to convince myself its just the tires and nothing wrong with the TOD.

[rocket man]

Okay...now I figured out what the heck y'all were talking about.

The "TOD" display is showing you a full load on full throttle situations..with these tires... right?...Well they also do this same thing with the stock skins too...they always have...you probably just never noticed it..

This system is designed to sense traction coificients between front and rear tires. On pavement these conditions that go on between the front and rear wheels is subtle. To artificially exagerate this dynamic..just take your VX off road and challenge a very sttep hill and at slow enough speed that you can watch the interaction of an AWD system on the TOD meter. You will notice , by the seat of your butt, as the rear wheels jsut start to spin the "TOD" will load up to meet the increased demand.

It is not magic...it is not even reallly very novel. It simply applies power to the front differencial when "it" thinks it needs it..Think of it as an ABS system in reverse..

As the rear wheels start to spin( as in rapid acceleration) the TOD transfers this torque to the front wheels..these transfers are split second events. Thus, that's why it is hard for us all, except under the slipperest conditions to "light up" all four wheels with this car. BUT, the TOD meter, if you will, senses all this and automatically gets those front tires into the act...

In short its not a problem..... , enjoy these tires...they are IMHO the best

Actually, now that I think of it it is a 2 w/d system that converts to AWD as it senses conditions:cool!: Now pull that lever on the extreme right and compound low overides the TOD and it stops sensing conditions around it and its a regular 4 w/d. Remembering, of course, that the front differencial is NOT a limited slip/equal lock/ or locking axle variety. The rear diferencial IS...so..I guess you could technically call it a 3 WD plus! Oh..who gives a ship! Still a "on fire" ride with the turning radius of a atv...;)

[VR4-Quest]

No rocket man, that is not what I'm talking about. Yes, with my old tires I could get the 3 bars to light up when accelerating hard, even in the dry and especially in the wet. And yes, the new tires do the same, BUT, the new tires also light up all three bars even at half throttle in the dry, it repeatedly does 3 bars to 0 bars, 3 bars to 0 bars, etc. untill it hits second gear (it fluctuates up and down), which the VX never did before. It started with the tire change so I'm assuming it has something to do with them or is pure coincidence. It doesnt feel right at all, cause its dry pavement, I'm not accelerating hard, so there should be no slip yet its sensing it.

[jim.LR>AR]

yeah. before 3 bars would stay lit up till I was off the accelerator and back to one bar. I also noticed it will spinn the back right if I pull out quickly now when before it would never spinn. it is very brief scratch. I had this problem when the fuse was blown on the tod. but it was very extrem then.

[rocket man]

Yeah, well you guys may, indeed, have a problem. I suppose, if it is under warranty, you could take it in and have it checked out...The Nittos and the Pro-Comps have been put on by quite a few VX's owners that post on this site and I don't believe I recall any problems posted such as you report.

Presuming your tire diameters are all four the same :rolleyes: Technically, I can think of no reason these tires by themselves would cause some abberation in the TOD system. So a trip to the dealer might be in order.

FYI... I owned an auto transmission shop out here for many years and I fixed mucho 4wd systems, though never a system like this

John

[jim.LR>AR]

I think its ok....I went out on a newly cut road , Loose dirt very steep , Went up it no problem Tod would light up 3 lights and stayed up till I made it to the top. Didn't slip much. all 4 wheels pulled. No problem . It was so steep My buddy wanted to get out and just watch . He was worried about flipping it. I didn't give him time to get out...:D Locked it in to low 4wd and went through a good ditch. no prob. Seems to work fine.

[rocket man]

Good...the ole steep dirt road test always works!!:cool:

[mrtew]

So is it still doing it? I have the 285 Nittos and mine seems totally normal... the lights don't go up and down like you describe. You have check the pressure to make sure all 4 tires are equally inflated haven't you? Tire stores seem to pump them up to 'whatever' these days. Mine were all different when they were first installed.

[t2p]

hmmmm .....
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..... if it is not the pressure, I do wonder if the size of one of the tires is different than the others ......
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I would attempt to meet with a fellow VX owner and 'switch' tires - install another set of mounted tires from a VX that does not have the problem .........
.

[VR4-Quest]

Yep, still doing it. I can pretty much make it do it on command. The thing is, it takes a very specific throttle position to get it to oscillate (the TOD adjusting from 0 led bars to 3 leds. Its somewhere between half throttle and full throttle, and will continue to oscillate if I hold it in this position, only in first gear though. All other gears are fine. I do believe it has to do with speed. I tried the winter start mode, and it does the same oscillation with the same throttle input.

Might it have something to do with the TOD cutoff switch? I might disconnect it all together. I just started to notice this when I got the tires changed, but it doesnt sound like they are the problem, I did do the TOD cutoff a week or so before my tire change.

I might be taking it to the dealer (yuck)!

[t2p]

TOD Cutoff ? .......... did you mention that ........ ???
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Why do so many people .... anyone ........ want to disconnect TOD ...... ??? ........... This is a 4wd SUV .......... as my Dad would say: 'Leave the $#!@@ thing alone !!!' ......
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Maybe a tech will tell you to disconnect the battery reset the computer ....... or something like that .........
.
???

[mrtew]

I just posted above that I have the Nittos and mine doesn't do that crazy TOD thing, because I was sure that if it did I would have noticed, but today I happened to look down and DID notice it! I watched it at ever street light and it does it every time I take off from a stop. The lights bounce all the way up and down three or four times really fast. Can everyone else actually go check theirs and post whether they see anything like this or not? I was sure mine didn't do that but it does, so now I am wondering if it's normal or if I have the same problem that the original poster has, or if it's something with the tires???

[Mr. I-MAN]

I think I might have solve the mystery. The TOD has an inertia sensor box under it near the rear axle. Which has a mercury switch type set up. I noticed with the bigger tires the unsprung weight in more and the ***** end drops when I accelerate because the rear coils flex more than the front torsion bar which are stiffer. This probably fools the sensor unitl the Vx is straight and level again. Before I put the bigger tires on I noticed that on steep inclines regardless of speed 2 bars would light up on the TOD. I guess the 2" in height combined with the greater unsprung weight could be the culprit. :blab: