As I'm looking for a R151 and tcase combo, I'm thinking ahead to figure out whether to do a 4.7 swap in one tcase or add a 2nd tcase (with 4.7s, keep the stock gear in the other tcase).

With gas prices continuing to go up, I need to ask (no, google didn't help, sorry!).

1. What's should I expect my MPG to drop by going to dual tcases? (pretend all other things being equal)

2. If I do duals, and do one 4.7, I assume I should put the 4.7 in the back case to reduce the # of parts all that torque will go through? Or?

According to this thread, just a 4.7 might be way too slow on the trail in Low. Maybe. I'll just shift back and forth a lot.
https://www.yotatech.com/forums/f105...e-gears-56775/

Thanks!

 

In my opinion, you never really need to go lower than 100:1 final crawl ratio. With dual stock cases, 3.93 1st gear, and 5.29 axle gears that puts you at a final crawl ratio of 108:1. This is what I run, and it has never left me wanting anything lower. I also love the 2wd low range option, or double low if you install a twin stick on your main (rear) case. Gas mileage shouldn't change because high range remains 1:1. Get ready for a full weekend project. 2 drive shafts, interior mods, possibly removing rear heat if it's a 4runner, and a big bad skid plate cross member. You should also beef up your motor mounts. I broke 3 in the last 2 trail runs, but my multiple flops might have also contributed to that.

 

Thanks for the tip on the mounts and crawl ratio, that's great. I probably would have forgotten about the mounts and learned the hard way too!

I figure mpg will change because I'm spinning more parts. Kinda like why a 4wd gets lower mileage than a 2wd (plus more wind resistance, but they make locking hubs for a reason).

 

By the time you are running dual cases, I'd have to assume that you already have a lift, bigger tires, heavy bumpers, roll cage, etc, so mpg is not of too much concern at that point. What's one more little bit of resistance?

 

Man just wants to know what he's jumping into...

Eric

 

I don't see the point in dual cases. I have an atlas II transfer case built by advanced adapters with the 4.7 gears. That combined with my 4.88's gives me a 90:1 crawl ratio in 4-low. I don't think you would ever want to move slower than that on the trail, my friends are all jealous of how slow i crawl. As for going to slow on the trail, if your trying to go faster than 3rd or 4th with the 4.7's your probably gonna end up breaking something...

 

g_cali, there are multiple reasons to choose duals over single 4.70. Better drive line angles, the potential to have the same length drive shafts front and rear so that you only have to carry 1 back up shaft, slightly lower than a single 4.70 case, 2wd low range, 2wd double low range with a twin stick, 20 forward and 4 reverse gears, you retain stock 2.28 low range, and 5.20 crawl range options, and probably more that I just can't seem to come up with. I do use my entire range of gears, and compared to my friend who I almost always wheel with who has a single 4.70 case, there is an advantage on the side of 2 stock cases. It's more than just the overall lowest crawl ratio.

 

Well it looks like i stand corrected. But im just sayin, you have your duals, i have my single atlas with 4.7's and my truck will crawl over anything yours will. An i spent less money...

 

Ive got twins with 4.7:1 gearing and I love it...I can put it in super low and climb rocks without ever touching the gas pedal (5spd). And I love having 2 wheel high and low also...And like stated above..I carry one spare drive shaft for the front or the rear. Ill never go back to a single case...


and it doesnt seem to phase the MPG.. and Budbuilt makes some nice cross members and skids for twins...

 

Depends on your kind of wheeling.

Ftoy type stuff, no need for dual cases as one case with 4.7 gears is plenty low and doesn't take up all the extra space on the underside.

Typical wheeler, dual cases is nice but still not necessary.

Daily driver, I wouldn't do either.

Do a twin stick with 4.7 gears as it makes shifting from 2WD to 4WD and offers other options that are beneficial.

 

ill be puttin duals in my 4runner this fall. to my oppinion from seeing differnt rigs its much nicer to have duals in a 5spd than a single case.. but thast my oppinion. sure if i had a peppy v-8 and a auto with a manual valvebody id run a single case because i know the motor can pull its way through.. unlike my poor little 22re lol and besides toyota duals is pretty cheep the way i see it, if you already have a geardrive case in the rig all you need is another case.. so hunt CL or hit the junkyard and for $50-100 you got your other case. then if your not doing gears just an adaptor, and driveline mods. atlas cases are pretty sick tho, deff not gonna break on of them in a toyota unless you have one heck of a motor infront of it and some HUGE tires behind it.

 

Your Atlas cost less than dual cases? You either got it free, or don't know what duals cost.

Dual Case adapter: $295
Dual case crossmember: $175
Driveshaft work: $300
extra Tcase $100

$870 for dual cases. An Atlas is $2000 and because of the size, you'd need to rework driveshafts as well.

Also, I think you are confused about your gearing. An Atlas never came in a 4.7:1 low range.

FWIW, the Atlas is a damn nice Tcase. I miss my old one that I had in my EB. The ability to do front digs is awesome.

Having wheeled both duals with stock gearing, and duals with 4.7 in the rear, I do prefer the duals with the 4.7 in the rear. I ran the turbo R151 as well. The gearing was 244:1 in double low. While I only used it about 5% of the time, there were those situations (like in Area BFE) where I definitley needed the lower gear set. However, for 95% of my wheeling I never used the front box.

 

$529 for 4.7 gears,no driveshaft mods,crossmember ,just install gears,sounds like single case 4.70's is the cheapest easiest way to go

 

I thought the 4.7 required some machining to fit?

 

I just did the 4.7:1 install and threw in a twin stick kit, and it does require minor modification to the transfer case but nothing you'd need to outsource. The instructions provided with the kit are exceptional and provide adequate detail in the pictures to do the modifications yourself with an angle grinder. The largest section of the case will need some of the inner wall ground out as well as some shaving on the edge of the oil channel. It's just aluminum so it will be quick. Also, one of the clutch forks needs a bit of grinding to allow some clearance. I just threw it in the vice and hit it with a wiz wheel, but the angle grinder would still work fine.

As far as driveability, mpg's won't be affected since the high gear is the same and that's what you'd be running on highway. As far as the trails go, I found that i did most of the day in 2nd and 3rd, but when i needed 1st for rock crawling or slow decline on a steep drop it was amazing. This gear set is a night and day difference from stock, and it's definitely a cheaper option than going dual. I just used 1st or 2nd in high range when i needed to move quicker between trails.

All that said, I can understand why people do twin cases, and i might add a 2nd stock case one day. If you already have the low gears it's really just a matter of extra convenience to do a dual setup. It would have made more sense for me to just go stock duals this past go around, but hindsight is always 20/20. I ended up having to get my drive shafts altered because of the new suspension, and I'd also just bought a Bud's crossmember and skid plate to get clearance, so if I'd have gone dual it wouldn't have cost me extra there. But aside from the minor inconvenience of it being stupid slow when you actually want to get somewhere a little quicker, I'd recommend this setup to anyone. It's the most bang for your buck IMHO, and being able to leave in the Tuffy center console is huge!

P.S. Kudos for hopping back into a 4year old conversation like it was just yesterday!

 

Super, thanks! And thanks!

R151f should go in shortly, so this was actually super-timely. I'll start with a single w/ a 4.7, when I find some more $.

 

just because a conversation is old ,don't mean its over.....cheers

 

i did just the 4.7 kit first and hated it so i went to duals with the 4.7 in the rear and love it. 2wd low range is awesome to have .heck all those gear options are grreat to have

 

played around with my yota in the woods the other day,a few steep rooted up hills and some concrete piles and felt the single 4.70 works for me,cant beat it for around $400 with no driveshaft mods,cutting your floors ,extra shifter ,which if you have a bench seat and want to keep it your boned.I would not tell anyone that they were making a mistake if they were running low on funds and had to get the best bang for the buck.

 

its not hard to modify the bench seat ive done a few and they look great. and as for no driveshaft mod. your gonna twist them into. it will happen when you least expect it in little stuff and crawling.plus your gonna be smokin them gears on the trail.