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NFW Ecobox donor cases

Mattygwheeler

Mattygwheeler

Well-known member
Joined
May 21, 2020
Member Number
1036
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220
I am setting up a NWF ECO box and Dana 300 for my wife's jeep. Where is everyone sourcing 6 pinion planetary gear sets from? Both the jeep and dodge 241 donor cases I have are 3 pinion gear sets. I could buy new i guess but the defeats the ECO part of the doubler.

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fwiw in about 1995/1994 they changed the pitch/cut of the gears so if you have a pre95 input you need pre95 planetary, post95 input needs post 95 planetary

Because of differences in the cut of the gear, as a general rule; one should not interchange pre-'95 gears with post-'94 gears. These years are not hard and fast delineations. If one is not absolutely certain, disassembly and inspection is required.
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I sourced my parts from EBAY. A seller was pretty much parting out a Chevy 241. I bought a case half to get the ring gear and a 6 pinion planetary. This was cheaper than finding a complete 241c.
 
I tripped over my 241 in the grass at the junk yard and was able to walk out with it for $75. I went and pulled a second one to have as a backup for parts that I still have laying under my work bench. they can be had for next to nothing if you search around
 
BTW, you can take 2 3-pinions and make a 6-pinion if they have the holes machined. Just swap the pinions and gears from one into the other if they are the same gear cut.
 
Anyone successfully put one together? $1100 for an ecobox looks more appealing than $900 Jb gears

Tip, tricks, or reviews?
 
TRINDU said:
Anyone successfully put one together? $1100 for an ecobox looks more appealing than $900 Jb gears

Tip, tricks, or reviews?
Click to expand...
I've had one in my buggy for a few years now built with an np231 C HD...6 pinion from a s10 blazer. I used a hack saw to cut the housing and then a chisel to split the case to get the sun gear out. You need a press to install the sun gear in the new housing. The gearing is good, but with 4 to 1 t case gears I don't run both in low. It's too low. 2.72 to 1 is good for hill climbs and sand dunes, 4 to 1 is good for the rocks.
 
DesertCJ said:
I've had one in my buggy for a few years now built with an np231 C HD...6 pinion from a s10 blazer. I used a hack saw to cut the housing and then a chisel to split the case to get the sun gear out. You need a press to install the sun gear in the new housing.
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I thought about scavenging a tcase, but it looks like I can buy the parts new, sell the tcase and come out even.

DesertCJ said:
The gearing is good, but with 4 to 1 t case gears I don't run both in low. It's too low. 2.72 to 1 is good for hill climbs and sand dunes, 4 to 1 is good for the rocks.
Click to expand...

I was looking at the ecobox-i for a dana 300, supposedly shorter than a np231j with sye. The ~2-300 at that point seems like a fair trade over 4:1 gears, especially when it comes out to 66:1 vs 115:1. I'm also a believer of 4:1 cracking the cases.

thanks for the feedback, need to send nwf an email as well.
 
Is the 6 pinion really necessary in a mild rig? I think they push for 6 pinion in the guys running V8s. But a 4cyl or 4.0 jeep is probably not going to hurt it?
 
Chevy 241's have reliably had 6 pinion planetaries for me. That '94-'95 changeover Rockyota mentions is crucial. They went from a pretty blunt straight faced tooth cut to a nice involute profile. You can still mesh them together, but they will be angry.

As far as 6 pinions being necessary, TBH I haven't personally seen the 3 pinions to be much of a failure point even in built rigs, but I still try to get 6 pinions for tcase builds when I can for the peace of mind. I wouldn't be afraid of romping on 3 pinions though if that's what ya got.
 
I ran a 3 pinion setup in a buggy with a stock H0 5.0. Broke a T18 output shaft and a stock d300 output shaft over the years but I didn't have any problems with the 3 pinion planetary. I went 6 on my current rig just because. I have the eco box i and yes it's short and sweet. You don't need 4 to 1 gears with a crawl box....I never use both in low.
 
I'm not sure but I think all np241s might be 6 pinion? Most 231's are 3 pinion except for 231 C HD. There's a whole bunch of others that I don't know much about or if they're even close to the same. NP242, NP271, NP272
 
One thing I can note on that topic, is at this point the more I discover the more ambiguous it all gets. I've learned it's a topic where blanket statements just don't work. There are like 6 versions of each the 231/241/242 that I know about across the decades. Some change planetaries, some change chain width, some change rear output diameter, and some even flip flop between the light duty few-bolt case bodies and the later more beefy cases with higher bolt counts. So the make and model makes all the difference, and the case number doesn't mean as much as it should
 
YotaAtieToo said:
Is the 6 pinion really necessary in a mild rig? I think they push for 6 pinion in the guys running V8s. But a 4cyl or 4.0 jeep is probably not going to hurt it?
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I’ve contemplated this, and figured if I’m going to do it I might as well go 6 gear since you can’t pull the 3 gear out once it’s in to upgrade later… just future proof it.
Although a 3 gear would be easier because I have this Jeep 231 just sitting here waiting to sacrifice it’s input shaft.

I’m sure it’s going to be fun since my 231 input shaft donor is a 95… so it sounds like it’s a toss up whether I need the square cut or round cut planetary from a 241

It’s also interesting those of you saying you don’t use the double low. I’m running 4.88s and it just didn’t quite seem worth it to do all the work for “just” 75:1 in the end
 
Can anyone post the ecobox-I instructions? The NWF website only has the standard ecobox instructions posted.

I just want to see what the difference in assembly is if any
 
fl0w3n said:
I’ve contemplated this, and figured if I’m going to do it I might as well go 6 gear since you can’t pull the 3 gear out once it’s in to upgrade later… just future proof it.
Although a 3 gear would be easier because I have this Jeep 231 just sitting here waiting to sacrifice it’s input shaft.

I’m sure it’s going to be fun since my 231 input shaft donor is a 95… so it sounds like it’s a toss up whether I need the square cut or round cut planetary from a 241

It’s also interesting those of you saying you don’t use the double low. I’m running 4.88s and it just didn’t quite seem worth it to do all the work for “just” 75:1 in the end
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I get it, I'd be looking for a 6 gear donor also.

Crawl ratio is so subjective. Some guys are happy with a 2:1 tcase and others need 11:1.

Are you manual or auto? Either way, 2.7x2.6 gets you 7:1 which is pretty damn respectable for anything with more tq than a samurai. :laughing:
 
That "might as well" attitude is how I feel also. The 6 gear are plentiful enough that it's hard to say no if you can conveniently access them. Funny enough I have a 3 pinion 231 planetary in front of my own Ford 205 right now and it's performed just fine.. Granted the planetary bushings in it are toast and it's been noisy from day 1 due to its previous life (regret using well used parts in that specific scenario) so I'll be tearing it down and most likely putting a 6 planet in "while I'm in there".

There are 3 pinion and 6 pinion planetary sets on both sides of the gear cut change so I wouldn't necessarily say if you build it with 3 pinions now you'll be stuck with that forever, but you definitely have to make sure all 3 gears (outer, planetaries, inner) are on the same side of the break, whichever generation you chose.

When it comes to crawl ratio, it's definitely a case by case thing. And a huge part of it is engine displacement and rotating mass. Automatics definitely don't need as much ratio due to the slip of the converter, and V8's with heavy flywheels can wheel well below 1k rpms. My main experience is my jeep with a 4.7 v8 that I wheeled for years as an auto and then manual swapped with a 40+ lb flywheel. I was able to wheel it on 36"s with a sub-50:1 crawl ratio for years with a bit of clutch slipping, but the engine momentum gave me tons of leeway. I finally did the 231/205 and ended up around 95:1, but tbh I rarely use double low. Most of the time I'm either in the 1.96:1 of the 205, or the 2.72:1 of the 231. A small 4banger link a sami or yota is a completely different game though
 
YotaAtieToo said:
I get it, I'd be looking for a 6 gear donor also.

Crawl ratio is so subjective. Some guys are happy with a 2:1 tcase and others need 11:1.

Are you manual or auto? Either way, 2.7x2.6 gets you 7:1 which is pretty damn respectable for anything with more tq than a samurai. :laughing:
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I’m probably doing the tcase surgery at the JY too, should save a couple hundred bucks Vs taking the whole case.

Right now I’m auto with stock 2.7 case and 4.88s. I’ll be swapping to manual / ecobox / 4:1 d300 so low low would be 3.83 / 2.72 / 4 but the idea with the manual is im thinking I can grab 2nd or 3rd. Effectively 200:1, 123:1, 75:1 with just the push of the clutch. We will see how it actually works out.
 
AgitatedPancake said:
That "might as well" attitude is how I feel also. The 6 gear are plentiful enough that it's hard to say no if you can conveniently access them. Funny enough I have a 3 pinion 231 planetary in front of my own Ford 205 right now and it's performed just fine.. Granted the planetary bushings in it are toast and it's been noisy from day 1 due to its previous life (regret using well used parts in that specific scenario) so I'll be tearing it down and most likely putting a 6 planet in "while I'm in there".

There are 3 pinion and 6 pinion planetary sets on both sides of the gear cut change so I wouldn't necessarily say if you build it with 3 pinions now you'll be stuck with that forever, but you definitely have to make sure all 3 gears (outer, planetaries, inner) are on the same side of the break, whichever generation you chose.

When it comes to crawl ratio, it's definitely a case by case thing. And a huge part of it is engine displacement and rotating mass. Automatics definitely don't need as much ratio due to the slip of the converter, and V8's with heavy flywheels can wheel well below 1k rpms. My main experience is my jeep with a 4.7 v8 that I wheeled for years as an auto and then manual swapped with a 40+ lb flywheel. I was able to wheel it on 36"s with a sub-50:1 crawl ratio for years with a bit of clutch slipping, but the engine momentum gave me tons of leeway. I finally did the 231/205 and ended up around 95:1, but tbh I rarely use double low. Most of the time I'm either in the 1.96:1 of the 205, or the 2.72:1 of the 231. A small 4banger link a sami or yota is a completely different game though
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Good to hear a couple people speak up that they haven’t had issue with 3 gear planetary. Worst case I have those parts already sitting in this spare 231 so it would give me everything I need without spending more on JY parts.

You seem to be implying you could change out the planetary gear from the ecobox once it’s pressed in, is that true? I assumed if you need to cut open the stock case to rob the planetary then you’re set once you press it into the ecobox.

Actually now that I look at it again, I guess you’re pressing in the sun gear (outer most ring?) and the planetary set drops in after? So as long as the sun gear has the same cut, you’re saying you can exchange a 3 and 6 gear planetary?
 
I also looked into going with a heavy weight flywheel from center force but it just wasn’t in the budget right now. I’m hoping with such deep gearing it’s going to be hard to stall… but I wouldn’t put it past myself :homer:
 
Yep you're analysis is correct - you're only pressing the outer gear into the doubler housing, which stays the same between 3 and 6 gear (as long as you're on the correct side of the gear cut for all components). The 3 and 6 gear planetaries use the same inner and outer (are they both sun gears?), just double the actual contact surface to those gears to lower contact pressure and distribute the loading.

The stall point isn't a make or break issue as we can adapt to use rigs just about anywhere on the rotating mass spectrum, but I can definitely say it's more convenient to me, there's more leeway
 
fl0w3n said:
I’m probably doing the tcase surgery at the JY too, should save a couple hundred bucks Vs taking the whole case.

Right now I’m auto with stock 2.7 case and 4.88s. I’ll be swapping to manual / ecobox / 4:1 d300 so low low would be 3.83 / 2.72 / 4 but the idea with the manual is im thinking I can grab 2nd or 3rd. Effectively 200:1, 123:1, 75:1 with just the push of the clutch. We will see how it actually works out.
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4 or 6 cyl?

With a 4cyl and manual, I like around 170:1. It's low enough that you can idle over a lot of stuff, but much lower than that and I get impatient and 2nd gear isn't quit low enough to idle.

200:1 will be nice, plus having a true 4 speed dual vs basically a 3 speed with both cases being stock.

Although if you have the 4.0, you'd probably be totally fine with both cases having stock gears. They seem to be totally happy around 100:1 or a hair lower.
 
AgitatedPancake said:
Yep you're analysis is correct - you're only pressing the outer gear into the doubler housing, which stays the same between 3 and 6 gear (as long as you're on the correct side of the gear cut for all components). The 3 and 6 gear planetaries use the same inner and outer (are they both sun gears?), just double the actual contact surface to those gears to lower contact pressure and distribute the loading.

The stall point isn't a make or break issue as we can adapt to use rigs just about anywhere on the rotating mass spectrum, but I can definitely say it's more convenient to me, there's more leeway
Click to expand...
Hmm, I actually have two 231s here… I wonder if they’re the same gear cut if I could make a 6 gear out of two? Pretty sure the planetary housing has 3 empty slots
 
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