doubler vs D300 4.1 kit? options/input please

marty79

marty79

Well-Known Member
Joined
Nov 24, 2013
Location
Newton, NC
I'm still unsure of transfer case setup for my new build...2001 ford 5.0 and 4r70w transmission.
There's the 231/231 doubler kit for $475 which is "weaker" but gets that 7:39.1 stupid low ....hooweii (lol)
There's the 203/205 Doubler kit for $770 which gets you tons of strength and a 4:1.1 ratios low crawl.....meh
There's the D300 to a 4r70s with the 4:0.1 low range kit for $729 to get the same gearing from single case...meh
I'm trying to plan this out and narrowing down to these last few options to get the best bang for my bucks...
(I'm more than aware of the "weakness" of the 231 doubler but I also know if you put about 5 extra mounts on the darn thing, should hold up. (my current setup has total of 12 mounts between front and rear case (yeah pain in the ass but it's held up great).
***I'm more interested in the 203/205 doubler information on what ford NP203 and NP205 I would need to get as this point I'm 90% leaning in that direction for pure brute force of no holding back throttle on this V8 build and want as much of a bulletproof drivetrain as possible on 40s. thanks in advance
 
Personally I wouldn't do a d300. They aren't bad, but don't like to hold up to alot of beating, unless you dump a ton into it.

If you go 5.13/5.38 in your axles, you won't need a deep gears in the case.

The Ford 203 should bolt up to your trans. I believe the doubler you choose will dictate which 205 you need.

There are also 241/205 doublers, or used to be. You can also do a 1356/205 doubler cheap if you have the length.
 
I have the 203/205 dodge ford version. I'd go NWF Black box 205 personally. It's what I will eventually do. I know of a few guys that ran a D300. Every one of them broke stuff and ended up dumping more mony into them. One friend broke his D300 behind a 4.0 3 times.....
 
paradisePWoffrd said:
You can also do a 1356/205 doubler cheap if you have the length.
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I will be 116/117" wheelbase max so I'll have the length but NWF isn't done with their kit for the 1356 doubler yet.. or are you talking about making one.

And scrap the D300, that's out the window since 2 of you already dogged it on top of other reviews.
 
ghost said:
I'd go NWF Black box
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That's a little too pricey since I'm going fox air shocks front and rear and everything else will be "fancier " stuff so I have a total budget in mind including bumping the 5.0 from 222hp to roughly 285-300hp
 
Someone has couple GM np203s in the for sale ad on here for $100...you guys know if those are 31 spline input for my ford transmission
 
Get an Atlas and be done, lighter and stronger and easier to service. But I know you will say it costs too much.
Second option would be black box to 205 like mentioned.
Stop being a cheap ass and put together a good combination.
 
marty79 said:
Someone has couple GM np203s in the for sale ad on here for $100...you guys know if those are 31 spline input for my ford transmission
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No, but I have a 31 spline input I would let go if you can figure out if they will mate to your trans.

Duane
 
Stuntman Autoworks said:
Stop being a cheap ass and put together a good combination.
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Cmon now this build wont be cheap relatively speaking compared to any and all other builds I've done. I'm just not an atlas fan for the price, just being honest. My current crawler has 5.08.1 crawl ratio for $140 total so why pay 2400, just saying. Plus shifting reviews on em isn't that great either.
 
CLRracer said:
No, but I have a 31 spline input I would let go if you can figure out if they will mate to your trans.

Duane
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Just the input or the whole case
 
You should probably swap in an NP435 with the 6.68:1 first gear, a 7.39:1 231 doubler, and Rockwells with 7.17:1 ratio so that its low enough for you. That'll give you a very useful 354:1 crawl ratio. So at 1000rpm just off of idle, your tires will turn about 3 times per minute. So with 40" tires, that's about 10ft per rev or 30ft per minute. Yee haw!

:dumbass:
 
jeepinmatt said:
You should probably swap in an NP435 with the 6.68:1 first gear, a 7.39:1 231 doubler, and Rockwells with 7.17:1 ratio so that its low enough for you. That'll give you a very useful 354:1 crawl ratio. So at 1000rpm just off of idle, your tires will turn about 3 times per minute. So with 40" tires, that's about 10ft per rev or 30ft per minute. Yee haw!

:dumbass:
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Hey hey I like my crawler gearing but this build I want both high speed fun and low crawling
 
Being that low sounds very boring.

Iā€™ll be in Harlan again shortly and this time of year is always wet. Being super low is great some times, but wheel speed is usually needed to sling the mud out and/or be able to bump it over something.

When I ran the 37ā€ sticky Treps I did wish I had 4:1 cause I had so much traction the slower control would have been nice. But itā€™s a toss up, so both options are perfect. Iā€™d go with the Black Box
 
NWF Ecobox + 205

1:1
1.96:1
2.72:1
5.33:1


eco%20wb%20blend.jpg
 
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To actually beat on a 300, you are going to be in it for $1300-$1700 depending on what you pay for the case and how many bearings you replace. Thatā€™s for 4:1s, HD outputs f/r and rebuilding it plus whatever shifter setup and mounts.

Then you still run the risk of splitting the case and have it pop out of gear on deceleration in low range.

231 suck bc of the chain and splitting the case in half when you climb the chain under high load and high torque.

203/205 is practically bulletproof but also weighs a ton.

241/205 is probably best option bc of the ratio splits, saves weight, and relatively minimal upfront cost compared to other options.

All of the doubler options are pretty long and can make the rear d/s short and the front super long, when you push the engine back for front diff clearance and better weight distribution. Often requires a carrier bearing on the front shaft for skid and bell housing clearance.

Atlas is obviously THE solution as they donā€™t lose their value and it will generally outlast everything else around it. Only $500-$1000 more than a built d300
 
Mac5005 said:
203/205 is practically bulletproof but also weighs a ton.
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Pretty sure I'm going this route, weight has never bothered me on my build
 
Are you going to have room under the body for a 203/205 combo? They're huge
Do you need VSS signal with your transmission? If so, better consider that and what case(s) have that provision for one.

I am about to have a D300 with 4:1, 32 spline outputs, cable shifters, the whole enchilada, for sale soon. You would just need a 31 spline input for it. Food for thought.
 
Jody Treadway said:
Are you going to have room under the body for a 203/205 combo? They're huge
Do you need VSS signal with your transmission? If so, better consider that and what case(s) have that provision for one.

I am about to have a D300 with 4:1, 32 spline outputs, cable shifters, the whole enchilada, for sale soon. You would just need a 31 spline input for it. Food for thought.
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Mine has vss in the rear end so working on figuring that out also. Price on your d300 since its already built up thanks
 
$1400 firm for the 300
JB conversions HD front output, Advance Adapters HD rear output, 4:1 ratio, cable shifters, etc.
Took it out of an XJ to swap in a 4 speed Atlas. He needed the added length of the 4 speed for front driveshaft angle.
I will personally tear it down and reseal it/inspect it prior to sale.
 
Jody Treadway said:
$1400 firm for the 300
JB conversions HD front output, Advance Adapters HD rear output, 4:1 ratio, cable shifters, etc.
Took it out of an XJ to swap in a 4 speed Atlas. He needed the added length of the 4 speed for front driveshaft angle.
I will personally tear it down and reseal it/inspect it prior to sale.
Click to expand...
Is it flipped? How hard is it to flip these? I think @hurt4x4 was looking for one.
 
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