Dana 20 strength with a 203 doubler and terra low gears

[Gator809]

Right now I have my drive line on the table refreshing it. The NP435 is done, and the 203/20 is next. I am wondering about the strength on the Dana 20. I am debating getting the terra low gears so I could have 3 low ranges of 2:1, 3.15:1, an 6.30:1.

I know the rear out put needs to be upgraded, but is there anything for the front output, or is it necessary. What about the Dana 20 input shaft. Would it hold up to using the 203 in low range an the 20 in high?

The rest of the truck is 4:56 1 tons 39-42 pit bulls a semi heavy truck and a skinny petal stupid driver with a warmed over 302.

Thanks in advance

Hank

 

[Kyle.malone]

By the time you change the output of the Dana 20 and get the tera low gears, you are almost at the price of an Atlas transfer case. Sell the 203 and your at the Atlas 4 speed price.

I went through this just last year and ended up with the Atlas 4 just due to cost of the dana 20 rebuild and upgrades to it.

Just my opinion.

 

[Broncobowsher]

The D20 is generally a tough little cookie. With what you describe, that cookie will likely crumble. With a lot of torque the case splitting is likley to happen.

Atlas (4-speed even better) is a very good idea.

 

[Gator809]

The atlas cases are out for some simple reasons. By the time I rebuild my drive shafts, shifters, crossmembers and adapters to my 435. I'm well over the 3k mark even for a 2 speed atlas. Prolly over 4k for the 4 speed Not counting the time an headache of the change out. My truck is already built and setup for the 435/203/20 combo so it's staying.

Normally I drive with the dana20 in lo, and shift the 203 as needed. If the 20 can take the abuse of being in 4 hi and the 203 in low i'd regear it for a wider range of gearing options.

Thanks

Hank

 

[xcntrk]

Note the D20 4 high gears are all helical cut designed for nice and quiet operation while on the street or at higher speeds. The low gears are all straight cut designed for strength. I don't think you want to be doing a lot of heavy wheeling in the high gears, especially with a doubler in front of it putting even more torque on those gears.

 

[gravy]

I run a AOD/black box i/d20 with a very mild 5.0. Upgraded the output, been holding up good with no issues and it takes a beating. I think the tera low gears will be your week point, they seem to break a lot without the doubler. I would stick to the stock gears with the 435 granny low and 203 2.0 to 1 you should be pretty good. for the 800 you will spend on the tera low gear maybe consider more gear in the axles

 

[Kyle.malone]

Atlas 4 speed was $3300 from Wild Horses when I order mine and recieved it in Feb. of this year.

My drivline with the 4r70w just got swapped. Called WH with my dimensions and was told I was a stock driveshaft on both the front and rear except for my front went to the rear and the rear went to the front.

 

[wallaceb]

I recently installed a ZF/203/Dana 20 and have been wheelin 6 times with it. The doubler is awesome. I just wish the Dana 20 shifted as smooth as the 203.

With an NP435 and 4.56 gears, in my opinion, it would be a waste of money to put the gears in. I looked into it and decided against it. Your going to be about 130:1 without new gears correct? Any lower would make it so your lowest gear is too low and your next lowest gear isn't low enough. Just a thought.

Brad

 

[Gator809]

Gravy, I've been looking and can't really find a lot of cases of the Teralow gears breaking. Mind pointing main the direction of them so I can do some reading on them. Also my axles were recently rebuilt so they're good for now.

Kyle, after I buy the atlas 4 the adapters, shifters, and cross members, and drive shafts ( my truck is stretched 12") I'm still over 3K over the Teralow gears and Hd output. I just can't justify the money.

Walaceb I'm not just looking for lower gears, I'm looking for a wider spread of gear since the doubler is 2:1 and my d20 is 2.46:1 they duplicate a lot of gears. The 3.15:1 in the transfercase would give me a lot more options.

Thanks for the input

Hank

 

[bigjhoov]

I'd look for a 203/205 doubler. They can usually be had for less than a grand. Don't know where you're at but I know of one for sale for $900 right now.

 

[Broncobowsher]

The Tera Low gear failures I found (10 years ago) were Jeep D300 4:1 gears. Completely unrelated to the ones for the Bronco. Different case, different ratio, different spacing. The only thing in common is the manufacturer of the Transfer case (Dana) and the manufacturer of the gears (Tera Low). So going off that research then Dana 60 axles are complete junk because the dana 30 tends to strip teeth of the ring gear.

Too many people have been running Tera Low gears in D20 in Broncos for a long time without problems.

But you are packing a lot of gear reduction in front of the transfer case. Good luck.

 

[gravy]

Gravy, I've been looking and can't really find a lot of cases of the Teralow gears breaking. Mind pointing main the direction of them so I can do some reading on them. Also my axles were recently rebuilt so they're good for now.

Kyle, after I buy the atlas 4 the adapters, shifters, and cross members, and drive shafts ( my truck is stretched 12") I'm still over 3K over the Teralow gears and Hd output. I just can't justify the money.

Walaceb I'm not just looking for lower gears, I'm looking for a wider spread of gear since the doubler is 2:1 and my d20 is 2.46:1 they duplicate a lot of gears. The 3.15:1 in the transfercase would give me a lot more options.

Thanks for the input

Hank

Just pointing out it will be a a week point- the idlers seem to strip teeth on some running more power, not sure if its a metal issue- some run them with no issue. I believe teraflex warranties them for life though. The reduction of the 203 will put a lot of stress on the gears. Talk to Jack O'Brian (maker of the super low gears for d20) 4.86 to 1, 4 to 1- He will give you the low down- he even has used teralows. He is the d20 guru. He kryo treats all his gears. Great guy