View Full Version : Factory Tcase torque ratings

02-12-2003, 06:56 AM
I is very easy to find the factory torque ratings on the chain driven tcases, but I can not find any on the following:

Dana 20
Dana 300

Anyone have any idea's.

I am trying to skimp by on my Cherokee WT project with a Dana 20 cause it will be much, much easier and cheaper to use but the engine I will be using has a lot more torque than a AMC 360.

02-12-2003, 07:03 AM
I am worthless regarding the actual torque rating, but it's always cool to bring up the point that the original bigfoot truck ran a dana 20. So it seems like it should last you a while anyway.

02-12-2003, 11:57 AM
No one has any idea?

Do I need to just call the Dana 20 a POS to get some responses? Hey Scotty, what do you think?

Joe J-Truck
02-12-2003, 01:41 PM
I think the D20 is a tough case, and I've always heard praise to that regard. Its cast iron, steel gear driven, so it should be at least as strong as any chain drive out there! The cool thing is, if you do bust one, they're cheap and plentiful to replace!
I'd say run it until it blows (if ever). What sick torque monster engine are you planning on anyway???

02-12-2003, 09:41 PM
I am putting a mild 6.5 Turbo diesel in the Cherokee. Will have a modified injection pump and waste gate on the turbo and a couple of other mods, but definitely not a torque monster like the other engine I have. This is going to be a daily driver meant more for gas mileage than lots of HP and Torque. Stock suspension with 31's so no additional stresses.

It will have about 200HP and about 325 ft lbs at 1900 rpms.

It would be a lot easier to go with a stock T-18/D20 setep than to go with a NP435/NP205 setup. I have both, just don't want to go through the hassle and expense of machining the NP435 to fit the Ranger. The Jeep T-18 is a straight bolt in for the Ranger OD/gear splitter.

Back to the question, can anyone verify what the actual factory torque rating is for the Dana 20?
If it is like 350 ft lbs or more, I would not have a problem running the Dana 20 in this light duty street driven Cherokee.

02-12-2003, 09:55 PM
...and T18A has also nice first gear...

02-12-2003, 11:58 PM
I hope you find this info and post it. Like you, I have found the info on the aluminum chain drives, but I have never found it on the gear drive cases. I wonder if New Process rated the aluminum chain drivers in an attempt to convince people they were as strong as the gear drive cases and never felt a need to formally, or publicly, rate the gear cases.

02-13-2003, 12:41 AM
FSJeeper,a couple years ago we called AA and the guy there claimed the 205 to be rated at 900 ft/lbs input torque,and the d300 to be rated at 600 ft/lbs of input torque.

he said the atlas was somewhere between,but couldnt(or wouldnt ;) ) say exactly where. i know the atlas is regarded as pretty bulletproof,but id be willig to bet that its prolly closer to the 600 than to the 900 due to the size of the gears. as you know,the 205s innards are pretty beefy.

id think the d20 is not rated quite as high as the 300,but i betcha its input rating is still hihger than the 350 ft/lbs number that you threw out earlier.

my spicer 18 held up just fine with low gears and big tires as long as i wasnt bouncing with lots of throttle in higher gears. i think the 18/20(moreso the 18) just cant handle the sudden shocks that occur as large,heavy,quickly spining tires leave and re-contact the earth in full throttle,2nd gear climbs up steep and deeply rutted hills.

in a street driven rig with 31s or 32s i think that you would be just fine withthe d20.

on the 203,you certainly wont break the gears in the rangebox,and you prolly wont break the chain either,unless it just wears out over several years of hard use. what you will break are the spider gears,tho ive only known 1 guy to ever do that. he blew out the spider gears in a 1 ton 203 he had in a blazer :eek: of course he was kind of an idiot and was running 40 or 42" tires.

under normal circumstances a 1 ton 203 with a good chain has got to be pretty close in strength to a 205.

sorry i couldnt give any better numbers or info than that. you could put on your flame retardant suit and ask on general chit chat over at pirate 4x4 ;) after you are brutally harrassed for awhile,im sure someone there would know somethin.

ill see what i can find out. if you dig somethin up before me,let me know,as id be interested in hearing those numbers as well.

[ February 13, 2003, 07:54 AM: Message edited by: scotty ]

02-13-2003, 02:16 AM

I find it interesting you can find torque ratings all day long for the chain driven cases and not gear driven ones.

If the Dana 20 is close to 600lbs, I am definitely going to run it. A lot easier and cheaper.

Peter Matusov
02-13-2003, 02:59 AM

the numbers seem low to me.
the t-case has to hold up against torque of the engine times gear reduction in the first gear (or first gear and torque converter for automatics).
Given with the fact that a Dana 20 is perfectly safe behind a Buick 350 and TH400, I'd put the input torque number to 1800-2000 lb-ft.
In reality, it must be much higher. It is a stronger case than a BW QT - which, in its turn, can stand up to a built 454 and TH400 (for about 60kmi).


02-13-2003, 03:27 AM
The D20 is a strong case, as long as you don't shock it by dropping the clutch with the engine wound up a little. The gear sets in the d20 seem to me to be just a bit on the brittle side, compared to the other cases.

Otherwise, I'd have to agree with Peter, because the multiplication factor of the tranny would put the torque at a min. of 900ft-lbs.

02-13-2003, 04:03 AM
the numbers could very well be low,the only place ive heard or seen numbers is frm that one guy at AA,so i wouldnt bet my next paycheck the info is 100% correct ;)

what are some of the numbers for the 208,231,242,etc.?

02-13-2003, 04:14 AM
I'm not totally sure, but at New Venture Gear's website www.newventuregear.com (http://www.newventuregear.com) the lowest torque rating that I saw was for the NP242 case, and that was 1486 ft-lbs. (that's max torque capacity, BTW)

They do have cases that approach the 8000 ft-lb mark, but I don't think I'd want to spend the cash to get one!! ;)

02-13-2003, 04:43 AM
The chain driven tcases are generally much stronger than the Dana 20 including the NP208 and some of them more than the NP205. Still wish I could get an exact Dana/Spicer torque rating.

Peter Matusov
02-13-2003, 08:34 AM
\quote{NP242 case, and that was 1486 ft-lbs. (that's max torque capacity, BTW)}

which makes it okay for a 4.0-powered JGC, and barely acceptable for a 5.2 or 5.9 JGC... i thought better of NP242...


02-13-2003, 11:33 AM
The following link has the torque ratings of the 231, 241, and 271. I think the 208 is actually pretty close to the 231. These are all good transfer cases especially when you consider the 241HD holds up well behind the cummins diesel rigs. The 242 is simply an electronic shift, full time/part time version of the 241. I wouldn't call it inadequate behind any fsj power plant.


[ February 13, 2003, 06:39 PM: Message edited by: TexasJ10 ]

02-13-2003, 11:33 AM
Run the Dana 20 if it is the easiest / least expensive for you. Look at all the Chevy powered CJ's that are out there running them with no problems.
My last CJ had a 375 horse vette engine with a Ford T-18 and a Dana 20 t-case and 4.10 axle gears and 33's. I beat the crap out of that thing, 4hi, 4lo, 2wd on the street I was always WFO. Never did I Break the T-case. Now driveshafts, axleshafts, lug studs, that's a whole different story.......

Good Luck,

02-13-2003, 11:43 AM
Peter, the 242HD, the one that lives behind the V8's in the Grand Cherokee's is rated around 2300+, I think.

02-13-2003, 12:06 PM
I checked around today and the general consensus is that the 70's model FSJ D20's come in around 600 ft lbs. No one could actually quote a source for that information. I did find out something interesting though, the 70's FSJ Dana 20 behind a turbo 400 has a 32 spline input shaft. Not bad. Too bad they did not carry it all the way through.

I think I am just going to do a rebuild and do the Novak idler shaft conversion and carry a spare rear output like my friend Scotty does. tongue.gif

02-13-2003, 12:42 PM
it looks like everyone but me can find the torque specs on the chain cases... anyone know them off the top of their head ?

02-13-2003, 01:03 PM
Stolen, check the link in my previous post and lindels link to new venture gear