• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Atlas?

Mark USN

New Member
Joined
Nov 18, 2013
Messages
13
Loc.
Duluth
Guys,
I bought a 76 for my retirement present from the military a few years ago. It had a frame off restoration pretty much new everything that’s the good. The bad is the guy used a 350 yes a Chevy. Before you bash me I used tha as a major bargaining point and got a smoking good deal. Back to the good I have a fresh full roller 351w bored 40 over AFR heads, upgraded piston the list goes on.
Will my Dana 20 be able to handle the extra hp and torque, with only 33’s and stock axles pretty much street use. Should I spend the extra dime on a atlas transfer case? I also have a 4R70w that I want to install. I already purchased rebuilt Dana 20 that still in the box because at one time I was going to use a stock 302.
By the way I won’t even open my hood in public until I get my 351w installed.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
The 20 can be strong enough, won't saw that it will be.

Figuring that you won't need an adaptor if you start with a 4WD 4R70W (you can order it to bolt up) you can put that money toward the Atlas. Makes it more affordable.

Big fly in the room is you have a rebuilt Dana 20 sitting on the floor. Hopefully you can sell that for not too much of a loss.

No sense in adding in driveline costs, you are going to need some no matter what you do.

Yes, overkill for a street rig on 33s. But you can always go wheeling, play in the sand, and you know that the output isn't going to snap off. The Atlas will always have value as well.
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
Street use?

Either keep the Dana 20 or swap in an NP205.

The only advantage an Atlas has is in hardcore rock crawling.
The major disadvantage for you would be the additional cost, more than $2000 over the NP205.
 

Local Boy

Full Member
Joined
May 23, 2016
Messages
191
Loc.
Mililani, Hawaii
I fought the urge to up-grade to an Atlas because of the cost involved...Kept talking myself out of it and kept rebuilding my Dana 20 (several times)...because I would rationalize that I just had a mildly built 302 with a 4 speed top loader... Honestly, I do drive this thing hard...very hard.... Fully locked at both ends...with 35's... The Dana 20 just couldn't take it...

Once I up-graded to a stroked 351 w, no way I was going to put a 20 behind it...

I like Overkill ... do it once (spend big $$$$ on the Atlas)... and nail down the throttle all day long...

We are all different in how we drive our broncos...only you can decide...

Just speaking for myself... and how hard I'm on it (think wheel stands)... Peace of mind = Priceless

Good Luck...

Aloha
 
Last edited:

sanndmann3

Bronco Guru
Joined
Jun 13, 2007
Messages
1,774
You won't regret it. I've trashed 3 20's before switching up to a 205. Low range spur gears in the Dana are just not stout enough if you hammer it hard...
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
What you need to ask yourself is:
'How often will you use low range on the street?'

The NP205 is stronger than the Atlas.
The only failing the NP205 has is a 1.96 low range.

But again for street use how low do you need?
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,614
You will grenade a lot of puny 28 spline axles...

I've posted many times to similar Q's about the D20 dependability. I did't destroy any D20's until I want with a doubler, taller tires and lower gear ratios also...prior to that, I think I twisted 7 or 8, 28 spline 9" axles on the street. Mostly with the fun HP289 with a toploader.

Anyway, you will eventually eat an output shaft but buy a spare...but before you do my $ is on twisting off several stock axle shafts...

I sold my Atlas (which was also behind a doubler) and put a 205 behind my doubler.

Good luck!
 
Last edited:
OP
OP
M

Mark USN

New Member
Joined
Nov 18, 2013
Messages
13
Loc.
Duluth
The plan is to upgrade my axels to 31, my understanding is they will fit in my axel housing with 411 gears. I wanted to go to 427 but I may have to use 411.
NP205 to a 4R70W do I need a adapter, or will it bolt up?
Thanks.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
A Ford NP205 will bolt to a 4WD/AWD version of the 4R70W without any adaptors.
But you will have to grind clearance into the transmission tail piece for the shift rail clearance.
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
A Ford NP205 will bolt to a 4WD/AWD version of the 4R70W without any adaptors.
But you will have to grind clearance into the transmission tail piece for the shift rail clearance.

Like this:
 

Attachments

  • 4R70W notched for NP205.jpg
    4R70W notched for NP205.jpg
    108.2 KB · Views: 56

NC-Fordguy

Bronco Guru
Joined
Jan 30, 2006
Messages
1,317
Loc.
Bethel/Greenville NC
I broke two dana 20 rear output shafts after installing a low gear set. Debated about the atlas. Installed a hardened out put shaft and an anti wrap bar.

No issues since.

If I had to do it again I'd gone the atlas route. I find the 205 low range unsatisfactory.
 
Top