Official Crawlbox BS thread!

Cleans up pretty nice.

 

Hey guys, I've read most of this thread but not all and am just about to the point where I'm going to start collecting parts for my crawl box and am looking for a sanity check for my plans and have quite a few questions for yall. Apologies for the long post and tons of questions.

Current set-up:
- 98 1st gen 3.4 with J-shift, manual transmission, 4.30 gears

Plans for crawlbox:
- source a used gear driven top shift t case and steal the low range section
- trail gear adapter plates (only place I can find them available?)
- MC 4.70 23 spline XD gear kit (if this goes out of stock are trail gear gears a bad idea?)
- triple sticks - don't want to lose cup holders (radesigns or davez?)
- trail gear dual case cross member
- shorten/lengthen stock driveshafts

Questions:
- Truck is not a daily driver but I regularly do 2k+ mile trips, and after reading this thread part of me is having second thoughts on the reliability of a crawl box. Would I be better off forgoing the 4.7 gears and doing 2.28 gear for more reliability? Is it possible to ever stop all of the leaks?
- I found an 82 t case locally but according to marlin crawlers t case bible it has "noisy gears"... is this a concern? only noisy when crawl box is in low? Seems minor but I also don't want to spend 12 hours on the highway listening to gear whine.

Appreciate any help/advice you can give.

 

Gear case do "hum/whine." That's probably one reason why Toyota went with a chain case. If you're building a crawl box, go with marlin 4.7 gears over the TG. But if you want to keep it on the cheap side, just buy the 82 case, modify the rail and slap on TG adapter.

 

Have had my tg complete cases in for several years with no leaks. (My leak is from a flaw in a 2wd transmission to the cases). They do hum and put off a lot of heat though.

 

Appreciate the feedback, curious if the "noisy style" vs the "quiet run" gears in the newer cases make enough difference to worry about. Also, not too worried about going cheap (that said I also don't want to drop Atlas money), more so reliable. My biggest concern is getting stuck 20 hours from home with a stripped coupler/shaft. That's where I'm torn on whether to go with the Marlin 2.28 total spline input gear, due to less torque being transmitted through the box or just go all out on the 4.7.

That's good to hear, appreciate the feedback on the leaks. As far as the noise, I mentioned above, curious if the "noisy style" vs the "quiet run" gears in the newer cases make enough difference to worry about. If there's not much difference then I'll just turn up the radio a bit and not worry about it.

 

Gears whine and shifters rattle. I crawlbox isn't a quiet mod. I have an auto with the 2.28 total spline and it's perfect. The torque converter effectively doubles the gearing in an auto. In a manual I would go with 4.7's without question. My adapters are TG and they don't leak. Just make sure you seal them properly.

 

I got all my leaks fixed with some rubber gasket material. It has not leaked even a drop since April or March when I added the gasket.

The FJ case I'm using seems to do fine with the 4.7 gears in the crawl box, nothing to report there. I find myself using the 4.7 gears the most and coupling in compound low for tough stuff. 2.56 works great between obstacles.

I do long-haul trips of 2k+ miles as well, haven't had any issues on the highway. Once the truck gets up to speed fuel economy was pretty unaffected. I got 19.6 hwy on one tank, I was pleasantly surprised to see that. Stop and go is another animal.

I like the RADesigngs shifter but do yourself a favor and get some longer bolts for the top of the crawl box. The ones they supplied barely threaded and I pulled a thread right out of the soft aluminum crawl box housing. Longer bolts fixed the issue and the sticks are good and stable.

The gear noise is minimal. I barely hear it. I'm fairly deaf and have raging tinnitus but no one else riding in the truck has ever brought it up so I assume it's not annoying them. Gears < tires < radio lol

I can't say there is less reliability with the 4.7 gears up front. I went with the 4.7's and I'd do it again. I'd prefer the 2.56 front/4.7 rear gear combo but it is what it is and the xfer case seems to be doing fine. I avoid shock loads and high RPM as much as humanly possible though.

I had a lot of issues with leaks both between the trans and at the seams on the crawl box. Verify all the bolts are torqued proper when you get it or break the seals and redo them yourself and you should be good to go.

 

If you are a manual I’d definitely do dual cases with minimum 2.28 in both but preferably 4.7 in the rear. If you do an automatic swap, I think a single 4.7 case is perfect. Fast enough in higher gears to run between trails without having to shift into high yet more than low enough to crawl obstacles with ease.
What I’ve always read and been told was as long as the 4.7 is in the rear case, there is not much to worry about. It’s when the 4.7 is in the crawl box that is when they start breaking and people have issues.

of course a lot of this depends on whether or not your staying driver drop or going passenger drop.

 

I’ll being staying driver drop for now, SAS is a ways out for me and so I’m stuck with the 2.57 rear chain drive case.

 

Im getting close to pulling the trigger on a TG crawl box.
When you say breakage is more common with that setup, is that typically by fretting shafts/couplers & whatnot?

 

Been a while since I’ve read up on it. Thought it had something to do with the torque/more stress when 4.7 in the front. Don’t quote me on it. I’d say go with what you want and just don’t do rev limiter dumps and you’ll be fine

 

After spending a good bit of time with the Atlas now, I would agree with this point if it was an easy(er) swap. Someone really needs to make a kit to clock and regear the stock cases.

But, if you are going through all the effort of a crawl box, go all in.

 

Had a good example of how the crawl box can really help out running Wheeler Lake with @Squeaky Penguin this weekend, going up the notch obstacle in the rain. A bunch of jeeps were in front of us and we watched them spin the shit out it and bounce all over the place looking like idiots and thankfully not breaking anything to hold us up. I was next and threw er in double low and walked up it without slipping a tire hardly at all. Squeaky went next and made made it to the crux of the obstacle where just a bit more control is needed to keep from spinning a tire and slipping into the hole (he is also a manual), just a bit of spin slid him into the crack and needed to winch after anchoring his diff. Right after this wheelstand leveled out, passenger tire slid in.

 

IFS problems

 

You're not wrong, and you really can't use jeepers as a gauge for anything, but it really did showcase how well low and slow works in adverse conditions.

 

yeah i love my crawl box. I'm adding second crawl box. 6 speed transfercase---- 22-1 ratio in compound low. then because i dont have enough power in high range im going to ditch the super charge V6 and load in a LQ9 6.0 pushing just over 400 horse raw.

 

You made that obstacle look super easy.


Need to keep a closer eye out for when I can get a good deal on one.

 

Troof.

 

You have an atlas in your 04?? Pls tell me more

 

Yessir, check out the last few pages of my build, the fun starts here. https://www.tacomaworld.com/threads/wishbone-runners-build.238998/page-63#post-22400441