Why are my tires spinning when off-road? (2 Viewers)

[HomersCanyonero]

Re: a-trac 101

That's a great article on A-TRAC for the 100 series that mentions a few interesting facts:

1. A-TRAC on the early years of the 100s uses the first generation software which can only monitor and manage 2 wheels as opposed to 3 wheels with later software upgrades.

2. A-TRAC is limited to 8-13 seconds of constant operation. After that the system will sound beeps (3 seconds to shutting down) and you will need to wait for the system to cool down.

3. When it comes to throttle input, 1,200RPM-2,200RPM is the sweet spot.

Question: I wonder what version of the A-TRAC software is on the 2003 GX470. Does it monitor and manage 3 wheels or only 2 wheels?

I'm still trying to process that write-up on ATRAC and I will need to experiment more while offroad to see how it works for me.

 

[JLee]

We have ATRAC II+.

Understanding & Using ATRAC II+ - Toyota 120 Platforms Forum

 

[HomersCanyonero]

I'm reviving this thread to provide an update on this particular thread. First, in the video where my wheels are spinning, I was in "Lo" and CDL locked but my transmission was not in "1st" gear. I know this because my shifter is broken and it won't stay in "L" unless I hold it in place.

Second, at that time, I didn't know that my transmission selection also made a difference. I had been wheeling in "D" or "2" most of the time even though I would lock the center and shift my transfer case into "Lo".

I've wheeled many times after learning these two important facts and I can report that my wheel spinning is very limited nowadays. I've also learned to pick better lines to keep the GX470 wheels on the ground as much as possible. I go in "Lo", CDL locked, and hold the shifter in "L" when approaching rocky and steep uphill, downhill, or rutted sections of the trail. This has reduced my wheel spin significantly.

Anyways, I just wanted to say that I'm much more satisfied with the offroad performance of the GX470 than when I first bought it.

 

[GXO]

If the shift track is intact you can replace the pin and get it to live in L. If not, new shift assembly will fix it.

 

[ChaseTruck]

So, from the cheap seats: in the video it looked to me that lower tire pressure would have been helpful.
Last week we went out to an afternoon trail ride, and I'm like "for this thing I'm too lazy to air down". And then, having forgotten about that little tidbit, I wondered why my truck (not a GX, mind you) was behaving in strange (to-me) ways on the only hill climb along the way...

 

[HomersCanyonero]

You are right that I was not aired down on the video. That was previously mentioned too, so in my last run I did air down from 40 to 25 psi. Airing down does make a difference too.

For a mild lift like mine (like 2” to 2.5” lifted), i wish i had KDSS to get better articulation and keep the tires on the ground more solidly.

I’ve seen videos whereby the kdss gx470 gets about 2” more of articulation and keeps the tires on the ground more solidly.

So far, I’ve been good in the medium difficult trails. I don’t go rock climbing on purpose. I just like to explore and run into bad roads I try to avoid the known black diamond trails!

When my rear air bags go bad, I’m going to convert to coils. I’m still researching if long travel shocks and variable spring coils will improve articulation in the rear and serve my mild build needs.

Anyways, I digress.

 

[whereischadjones]

I'm buying a 470 for my wife/daughter to fight over this week. I am used to solid axled ARB front/rear on my 80, so I'm a newbie on this platform. The CDL light came on when engaged during test drive on dirt today, and I was able to engage 4-low. I did not feel any satisfying "thunks" as the center diff lock engaged and then no "herky-jerky" feeling in subsequent turns. I'm guessing that this means these rigs don't have locking diffs front or rear? How can I tell if things are engaging? I'm worried this pavement queen may have never been in 4 low and that the lights come on, but it's actually seized up and not working. It just doesn't feel like it's in 4WD. I think it's because of what I'm used to. Thanks in advance. I'm headed back to FAQ to read about which rigs have KDSS now...

 

[HomersCanyonero]

Everything you state is normal. The center diff lock is only for the center to distribute the power 50/50 to the front and rear. There are no front or rear lockers. You won't feel any different in 4Lo with CDL on the GX470 nor the FZJ80. Just the transfer case is on low.

 

[Skyyks]

ATRAC can be tricked when overheated (3 beeps to shut down) by backing up 6” or so and go at it again.
Sound advice so far on keeping it slow and steady and let ATRAC do the work.

 

[GXO]

Full time life! No front or rear lockers. Try getting it to spin a tire and keep it at 1500 rpm and just let it spin and ATRAC will kick in. Trick is to not hop, just use the brake to keep it steady and slight throttle up to 2000 rpm and no more and it will just make a bunch of noises and magically move forward.

 

[tlin]

A rear locker in a GX is a major upgrade. You still have ATRAC up front with a true locked rear. It opens up some issues with momentum and the stock R&P strength on the 8.0 rear. I blew mine up and went to 4.56s and lockers last year.

Since this thread is back up, please expand on the bolded bit above. I realize the 8" rear is a "when, not if" problem for anyone regularly wheeling but would love to better appreciate:

• what's meant by "issues with momentum"?
• does the 8" go only after repeated serious rock climbing stress or is it prone to fail even with repeated mild-to-medium general 4x4 activity?
• if considering a rear locker, what's the "preferred" route to go (cost effective, bulletproof-ish longevity)?
• whatever else you can think of to share....

Great thread, super helpful advice nested herein.

Thx!

 

[dcg141]

Anyone have experience with Truetracs in a GX? I have run them in my past rigs and really like them but that was with regular transfer cases. This my first rig with any sort of electronics in the 4WD system. This a great thread btw. Every informative.

 

[GXO]

8" rear carrier has towers on either side to establish and hold the preload. Those towers (due to design) flex under load, or over time with prolonged (mileage) use. Eventually it will back off preload to where it will allow the pinion gear and ring gear to not mesh properly and will start to wear, or even chip/fail. I had my first R&P fail on a gravel road. Second (nitro, locked) chipped in harsh offroad use. If you proactively maintain the preload in the rear (R&R) you can prevent the random failures, but in harsh use you can cause a major mismatch on preload and chip it regardless. If you "do nothing" it will eventually give out and fail with even light duty offroad use.

 

[vwynn]

Dan, you mentioned "prolonged (mileage) use" . Whats considered prolong and does that include highway miles? or prolong offroad?

 

[GXO]

No real data to really know. From what I have seen, passed 120k with no R&R on the 8" seems to put it into a vulnerable state. Wheeling with nothing done to the diff when getting over 120k seems to put it in a critical state. This is all just "me thinking" based on watching 9 years of posts.

 

[whereischadjones]

@Vlad thanks for the info regarding the towers on either side of the carrier. Do you have part numbers? I’m going to baseline this new to us GX (replace fluid in diffs, tcase, etc) and one reason l bought it is the washboard roads in Death Valley. We were beaten up in my FZJ80 with solid axles and I hope this GX will be better suited with IFS. Can anyone here attest to washboard performance?

 

[whereischadjones]

By the way, I decided AGAINST KDSS even though it seems to be great. I just don't like technology that is difficult to repair, bypass or upgrade. So, there is a low mile, clean carfax mica blue sport model in Sacramento on Craigslist if anyone is interested. I've driven it.

 

[Dharma Dude]

No real data to really know. From what I have seen, passed 120k with no R&R on the 8" seems to put it into a vulnerable state. Wheeling with nothing done to the diff when getting over 120k seems to put it in a critical state. This is all just "me thinking" based on watching 9 years of posts.

I think you're saying that you have to open up the diffs every once in awhile and reset the preloads. Would installing air lockers involve resetting the preloads? Sorry if that's a dumb question. I just had lockers put in about 15K ago. So maybe I'm good for another 100K miles. I also dont' wheel as hard as you do.

 

[little_joe]

I think you're saying that you have to open up the diffs every once in awhile and reset the preloads. Would installing air lockers involve resetting the preloads? Sorry if that's a dumb question. I just had lockers put in about 15K ago. So maybe I'm good for another 100K miles. I also dont' wheel as hard as you do.

The air locker is a replacement carrier for your stock open diff carrier, which requires a full tear-down of the diff. Upon reassembly, your gear pattern has to be set and checked on the bench, which includes setting the preload.

There has been chatter about the crush sleeve customarily used in setting preload is to blame for this "issue," and use of a solid spacer + shims is alleged to mitigate the potential problem.

 

[GXO]

The air locker is a replacement carrier for your stock open diff carrier, which requires a full tear-down of the diff. Upon reassembly, your gear pattern has to be set and checked on the bench, which includes setting the preload.

There has been chatter about the crush sleeve customarily used in setting preload is to blame for this "issue," and use of a solid spacer + shims is alleged to mitigate the potential problem.

I put 4.56 gears in my old 8". Solid spacer. ARB. It failed. I saw the pattern and torque specs myself and they were perfect. I was on gold bar rim so I think I simply flexed the towers in the carrier so much it chipped the ring gear, but there it is. Light wheeling, light weight...I think preload and solid spacers are goodness. HEAVY? I would do something regardless.