Trail Gear Trail creeper 2.8/4.7 crawl box
 

So, I know of two 5th gen 4runners that have this crawl box installed (not sure which gearset they run, respectively), but trailgear doesn't list 5th gen 4runners yet, only tacoma's. I talked to trailgear a couple weeks ago and they said that 4runners haven't been tested yet, officially, but the gent i talked to was stoked to hear about the 4runner install. We agreed that if our 4runners have the same transmission/tcase, then it should be a fairly simple bolt-up. From the trailgear website:

"This adapter kit is compatible with any vehicle with a Toyota A750F Transmission and several other applications, please see the application data tab for full application information."
Some thoughts:

• The development part would be electrical connectors, any mounting/clearance issues and shifters, (possibly solved via a kit from Trailgear, eventually?)...

• along with the expected driveshaft shortening/lengthening by the installer/owner.

• One consideration is if you get to keep ATRAC/Crawl control or if that system has to be deleted?

Link: Trail-Creeper 2005-2022 Tacoma Crawl Boxes - 2.28 and 4.70 Gear Ratios


I think I LOVE the idea of a 5th gen with stock engine, transmission, tcase axles, running 33's-34's, fully armored with a 167:1 crawl ratio. Seems like it would be very effective and would allow you to creep over rocks without stressing the IFS front end or overloading your steering, etc with huge tires. I think you'd also retain a nice stock low range with the crawl box disengaged unlike some drop-in 4:1 gearsets, all while remaining completely streetable on reasonable sized tires.

1st gear, low box, high range = 3.52, 4.7:1, 1:1, 3.73's = 67.7:1
2nd gear, low box, low range = 2.04, 4.7, 2.52, 3.73's = 97.2:1
1st gear, low box, low range = 3.52, 4.7:1, 2.56:1, 3.73's = 167.8:1

Update: Marlin Crawler is currently selling fully warrantied/pre-built Tacobox that fit 4th and 5th gen 4runners (among many other applications) Very Cool!

Link: TacoBox | Marlin Crawler, Inc.

Here's one of the rigs that i'm fairly certain is running a 4.7:1 gearset in the crawlbox. (I could be wrong about that ratio) He also runs the Marlin Crawler upgrade suspension/steering setup to run 40" tires (which he's running in the video)

link: https://www.youtube.com/watch?v=jv4etlECGq0&feature=youtu.be

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I don’t see why it wouldn’t work, mechanically speaking. There will be floorboard clearance problems more then likely(probably not too bad), drive shafts and shifter locations to deal with.

Now on the electrical side…that one I have no idea. The Atrac might flip out because wheel speed versus engine speed is probably out of it’s range of operation. The rear locker should be fine. I know jeeps can’t run a 4spd Atlas t case because their computer flips out because everything is out of it’s calibration points as far as wheel speed, engine speed, etc.

Same here, no idea - i have a sneaky feeling that certain features might have to be disabled to run the crawl box, but not sure. I want to find out who did the install on the white 4runner to ask them some questions about it. Maybe a simple re-mapping of the engine and/or wheel speed sensor(s) is all that's required, meaning that if the engine is revving up to say 2500 rpm vs 1500 for normal low range operation and ATRAC/Crawl Control/Rear locker activation - it wouldn't trigger any issues.

OK, had a great conversation with the folks @ StellarBuilt who did the install on the white 4runner in the video. Some info on mods needed/no needed and approx costs

>>rear driveshaft shortened,
>>front driveshaft lengthened,
>>no underbody mods,
>>bolts right up to the A750F 5th gen 5speed auto,
>>doesn't mess with ATRAC/Crawl control,
>>requires mods to the crossmember/mounting,
>>requires mods to your skids if you have a full belly skid like i do (but mods are very doable/reasonable).
>>Cost from TrailGear is $2800-ish for the crawler box for either a 2.8:1 or a 4.7:1 ratio
>>Labor based on their rates currently is probably in the $2000-2500 range (don't quote me- completely depends on your setup/build list/specific rig)

We had a good discussion about the cost vs. benefit of this mod for a rig that isn't running 37-40" tires or isn't running the most extreme trails. The gent i talked to made it clear he wasn't trying to dissuade me, but also wanted me to consider 4.56's/4.88's as a Stage 1 mod, if I was looking for a deeper crawl ratio without the list of modifications that the crawlbox requires.

The benefit being that maybe we find the lower ratio (via diff gears only) is enough, and get to stop there with mods, for a lower price of entry. At that point, if we wanted to go deeper/lower we could still always drop a crawler box in.


Great food for thought and puts it back on our plate to decide where we want to end up capability-wise.

Crawl ratio info - so I don't have to keep hunting it down...lol
 

Stock A750F - 3.52 first gear
Stock Aisin Tcase - 2.52 low
Stock diff - 3.73

Stock crawl ratio 33:1 - which with an auto transmission we can multiply by 1.5-2.0, (i use 1.8) for a final crawl ratio of 59.4:1

Not bad. Now the same calculations with available aftermarket gearsets:

3.52 first
2.52 low
Nitro 4.56's
Crawl ratio: 40.44 x 1.8(auto) = 72.7

3.52 first
2.52 low
Nitro 4.88's
Crawl ratio: 43.28 x 1.8(auto) = 77.9


this doesn't account for tire size, and I haven't researched what it would do to overall drivability with 33's-35's, etc., nor have i looked at the total cost of a gear install w/ parts and labor.

Thanks for posting that info for us brother, Stellar is def super knowledgeable so its great to see what they had to say about it, labor prices don't seem too bad on it either, hopefully by the time my rig is ready for the low low TrailGear might have a 4runner specific kit ready :pray:

That's exactly what I'm thinking - I'd love to be able to hand an installer a vehicle-specific kit that's been tested and refined, since the biggest part of our love for our rig is how balanced/reliable it is. Rather not go the custom-one off build if TG has plans to release a T4R kit in the future. (gonna follow up with them and see if I can get more details on this)

I'm thinking we might do gears/34's this year and then maybe re-visit the crawler setup in 2023. (gotta let the piggy bank fill back up...lol)

Right on, always a smart move to stay within the budget. If you haven't already you should also check out Northwest Fab's crawl box. I here a lot of good things about their set up as well.

If I was going to do a crawlbox ,Marlin is who I would be contacting . I wheeled with him in Texas and you talk about low gearing in his old red Toyota truck.

But as stated 4:56 or 4:88 gears and a front locker would make 99% of the people happy.
I had 4:56's double locked in my last 5th with 34's and loved it.
580:1 Triple Case Demonstration in a 3rd gen 2016 Toyota Tacoma - YouTube

Downhill with NO driver in a 2016 Toyota Tacoma - YouTube

Yup Marlin Crawler is awesome too, seeing their Tacoma at King of the Hammers was super cool. The only thing about them is, correct me if I am wrong, but they no longer sell prebuilt kits anymore. Would have to buy all the parts and piece them together

I don't wanna hijack too much, but could you explain the 1.5-2.0 multiplier for an auto trans?

No worries! it's a great question. Here's what I understand about what Auto tranny's do for your crawl ratio.

in an auto tranny, the engine is turning more revolutions' than the main-shaft because of the torque converter, so the effect is that of a reduction gearset UNTIL the torque converter locks up then it's a direct 1:1 ratio (which is fine, since at higher speeds/RPM's, you'll likely do fine with a 34ish:1 crawl ratio in 4Lo.)

Up until lock-up, depending on the transmission model, most folks I've talked to agree that the reduction ratio can vary (even in the same vehicle based on throttle input/speed) from 1.5-2.0:1 (hence the 1.8:1 number I used.)

So that's why for an manual you have

trans 1st gear: ___
Tcase #1 low:2.52
crawl box(if any):__
Axle gears:3.73

and for an auto you'd have

Trans first gear:3.52
Auto reduction: 1.5-2.0
Tcase low #1:2.52
Crawler box (if any):__
Axle gears:3.73

4x4's with auto's can get away with a transmission first gear that is lower numerically/steeper than their manual tranny counterparts while acheiving the same "Effective" crawl ratio offroad.

For example the JL 8 speed first gear is 4.71:1, and the manual is 5.13:1 but both seem to achieve the same 75-85:1 crawl ratio in 4Lo.


That's what i understand and have experienced offroad. Might be that other folks on the board can delve deeper. :)

Bit of an update:

Been running our drivetrain gear ratio's through a few online calculators. What I'm coming up with is basically what others have concluded.

• 265-70/r17 tires to 285/70-r17 tires is not enough of a jump in size to warrant a gearset change all the way down to 4.56's.
  
  
• We'd really have to be running big 34's or small/medium 35's to bring our revs back to stock for highway driving.
  
  
• 4.10's would be pretty good, too, but you can't buy those from a normal aftermarket shop for a 5th gen (that I'm aware of)

To that end, we called our local 4x4 shop that's done some work for us in the past, and I think we're going to be pulling the trigger on the crawl box. Here's some thoughts about that:

• Our goal would be to maximize our crawl ratio on the trail and to leave our highway charactoristics alone. Highway manners seem fine with the 33's currently - no real change in steering, power, torque, with maaaaybe a small change in mpg's but we haven't taken a real road trip since installing them, so that data is pending.
  
  
• Should be a pretty effective sleeper setup since we'll look pretty stock with a 3" lift and 33's with an on-demand/available 150ish:1 crawl ratio.
  
  
• I'd expect to see a major upgrade to control and engine braking. (In Moab we ran out of both and stopped short of some of the harder trails because of this - had more than enough clearance, flex and grip)
  
  
• I'm thinking that our only major weakness will be ground clearance, but we are FULLY armored underneath, and should be able to minimize the effect of impacts with our Low/Low setup, traction boards or a winch, if needed.
  
  
• A final thought is that we'll leave our ATRAC and rear locker alone, because we should be able to activate ATRAC in low range at a much slower wheel speed, IF (and I have to research this) ATRAC is activated by being in a certaind RPM range. We may end up needing a front locker, but we want to do the crawl box first and then assess our need - we like not blowing out CV's and steering rack components...lol. That 8" front clamshell is a bit of a weak spot, in our opinion, so it might just stay as Toyota designed it with traction control.

So, Marlin is actually currently selling their prebuit 4.7 Tacobox that’ll fit 4th-5th gen 4runners, seemingly for a limited time per their website. Otherwise you do have to just buy their adapters and find your own parts.

Reason i know this is that we just ordered one. :) :) :)

Once i found this out I started doing a lot of reading about the history of this adapter and began watching all MarlinCrawler's videos online related to the install and operation. Biggest concerns are modifications required - which are the same as the Trail Creeper, and longevity, which with the high-quality machining, bearings and materials used, should likely be able to be measured in the 10's of thousands of miles.