Is a HD D20 output shaft needed?

[OsideDave]

Is a heavy duty D20 output shaft needed for wheelin on trails in the 4 to 4+ range? 1-5 scale. I am upgrading the C4 to an auto OD soon and will install D20 low gear set, likely terra lows, and will go from 33's to 35's? While I am upgrading the D20 gears should I go for the HD output shaft? Is this really a weak link? Although costs are important (this swap is already adding up) I would rather be safe than sorry later, especially on the trail. Thanks

 

[00gyrhed]

I guess I just don't do the hard stuff or maybe I do not like working on broken drive train parts, but I have had pretty good luck with driveline parts on all of my offroad vehicles. Then again I never use tires over 33 inches either. I generally do not spend money on upgrades until I actually break the part, and I know that the way I treat things will actually break it. Things like this break from shock loads and you will not have the same shock loads with the C-4 that someone with low geared manual will.

Since it is not hard to change the D20 output shaft later, you could just wait and see if you really ever need to.

 

[scsm76]

As mentioned it isn't difficult to add on later, but you mentioned you are swapping to an AOD so you will changing drive shafts lengths. The WH HD output is about 3/4" longer than stock, and the AA output with housing is 1.5" longer (also requires some speedo cable mods). So if you don't do it now I would at least plan for it when you change your driveshafts. The BCB 300m shaft is the same length and size as stock but is pricey if available.
I chose to put the WH one in when I built my doubler setup for piece of mind.

 

[COBlu77]

By the time you buy the Tera Low gears, HD output shaft, and adapter for AOD/4R70W, you might as well have bought an Atlas II and have a much stonger TC that will bolt directly to an AOD or 4R70W.

If you want to do it cheaply, go with an NP205. The NP205 is arguably the strongest TC you can use. My NP205 was $125 and bolted right up to my 4R70W. I originally thought the NP205 would be a short term solution until I could justify the Atlas II (driveshaft length will be close enough to use my current DS's), but I've found the NP205 with the 4R70W's lower 1st gear gets the job done on everything I've tried offroad, so far.

 

[OsideDave]

Interesting, so a Atlas or NP205 will bolt up to 4r70W? No adapter needed? What about frame mods, will either one fit between the frame rails?

What NP205 is the best for my application?

Thanks for the info, thats why I love this site!!!;D

 

[Madgyver]

Put it this way..
Do you really want to be stuck with a stock d20 output shaft broken half way into a knarly rock trail?

I didn't thing so....

I'm surprised how easy it snapped the first time it happened to me.

Dana20 rear output failure ............... click this thread for pics..

 

[COBlu77]

Interesting, so a Atlas or NP205 will bolt up to 4r70W? No adapter needed? What about frame mods, will either one fit between the frame rails?

What NP205 is the best for my application?

Thanks for the info, thats why I love this site!!!;D

Yes, either the Atlas II, NP205 (Ford version), or a STAK B box will bolt right up without any type of adapter and all will fit between the frame. Depending on your 4R70W you will need a 1" spacer for the Atlas, but the vendor I talked to included it in the price of the Atlas.

As for NP205 you would need one from a late 70's Ford truck or 78-79 Bronco. They came attached to both NP435 manual tranny's or C6's. Most I've seen have 1310 yokes (matches EB), those that have the bigger yokes can either be cheaply swapped or you can beef up your driveshafts with bigger yokes when you have them re-sized.

The downsides to the NP205 is that the low range is only 1.96:1 and the weight (135 lbs). I've found that when I get on a trail I drop it into 4L and "D" immediately and the engine and tranny run in an RPM range that keep things cool. With the 4R70W and lockers I've been able to drop it into "1" and slowly climb anything I've tried, but going down you have to get good at using the brakes without locking them up. I haven't done any super radical rock crawling, but have had no problems on 4 out of 5 rated trails. as for the weight it's similar to the STAK B box and just a little more than the Atlas II, but at least it came from the factory with a side mount to give it some frame support.

Look in my gallery for some pictures and do some searching. There are several members running NP205's.