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porterzcustomz
Bone Stock
Posts:15
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| 09/16/2007 4:29 PM |
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| What is the difference between different GM transfer cases? Like for example a 208 vs a 241 or 205? Is one better then the other besides the years that they were used? I had a 241 and I had to change to a 208 to go with my SM465. Are they geared different from each other? If you had a 2wd with same rearend gears and tranny vs a 4wd with same tranny and rearend gears would they share the same overall ratio or not? |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 09/16/2007 5:09 PM |
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Here's a quick overview...
The NP241 transfer case is a chain driven unit in an aluminum case used in 1987 and up in Jeeps, and 1988 and up Chevy and GMC trucks. The GM version comes in drivers and pa$$enger drop versions. The K series trucks use a drivers drop version. This transfer case is also used in Dodge trucks and Ramchargers after 1988. These transfer cases are part time 4WD (Shift positions 4HI - 2HI - N - 4L). They have a relatively thin aluminum housing. They are 1:1 direct drive in high range, and use planetary reduction gears for low range with a ratio of 2.72:1
The NP 231 series transfer case became standard in Jeep, Dodge, and Chevrolet applications. These transfer cases are part time 4WD (Shift positions 4HI - 2HI - N - 4L). They have a relatively thin aluminum housing. They are 1:1 direct drive in high range, and use planetary reduction gears for low range with a ratio of 2.72:1
The NP208 transfer case is also a chain driven transfer case in an aluminum case used in 1988+ Chevy and GMC trucks. The NP208 has a high range of 1.00:1 and a low range of 2.61:1
The NP205 transfer case is a heavy duty gear driven transfer case in a cast iron case. The low range is 1.96:1 and it was used from 1971 until 1980 in Blazers and full size pickups. The transfer case has a poor low range, but may be useful in situations where strength is more important than crawl ratio.
The NP203 transfer case is a chain driven transfer case in a cast iron case used. It is a heavy duty case with a 2:00:1 low range with a set of differentials for full time use. It was used from 1971 until 1980 in various Chevy pickups. It's also a heavy sucker that doesn't have a very deep low-range, so it's not a popular swap. The NP203 has a high range of 1.00:1 and a low range of 2.01:1.
Hope that helps. |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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SnoMan
Lift & Lockers
Posts:943
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| 09/16/2007 6:37 PM |
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quote:
Originally posted by webby4x4
The NP208 transfer case is also a chain driven transfer case in an aluminum case used in 1988+ Chevy and GMC trucks. The NP208 has a high range of 1.00:1 and a low range of 2.61:1
Ir was used from 81 to 87 in 1/2 and 3/4 ton P/U and blazers and burbs and used thru to 91 in old style blazers and burbs. One tons 81 thru 87 used 205
quote:
Originally posted by webby4x4
The NP205 transfer case is a heavy duty gear driven transfer case in a cast iron case. The low range is 1.96:1 and it was used from 1971 until 1980 in Blazers and full size pickups. The transfer case has a poor low range, but may be useful in situations where strength is more important than crawl ratio.
I had a 67 that had a 205 in it from factory. 67 was first year for that Tcase mounting style too. From 73 to 79 is was used in 1/2 and 3/4 ton trucks with manual trannies. (2 ton had it regardless of tranny) 1980 saw a 205 spec'd to use ATF fluid and a few cases were made that were aluminum to reduce weight for MPG.
quote:
Originally posted by webby4x4
The NP203 transfer case is a chain driven transfer case in a cast iron case used. It is a heavy duty case with a 2:00:1 low range with a set of differentials for full time use. It was used from 1971 until 1980 in various Chevy pickups. It's also a heavy sucker that doesn't have a very deep low-range, so it's not a popular swap. The NP203 has a high range of 1.00:1 and a low range of 2.01:1.
203 was used in GM trucks with automatics from 73 to 79 (though a few made it out with 205's and automatic) and as before, 1 ton used 205 regardless of tranny. Dodge used 203 exclusively from 73 to 79 and invented that bastard hubless bearing to go with it. |
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porterzcustomz
Bone Stock
Posts:15
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| 09/17/2007 7:53 AM |
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| So back to my original question, why did they change them, is the newer ones suppose to be better or are they all basically of equal value? Reason im asking is I had to switch my 241 to a 208 and wanted to know besides the way they mount if there is an advantage to one or the other. |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 09/17/2007 10:05 AM |
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Well... each one evolved for a variety of reasons, I'm sure. Cost savings, weight savings, full-time vs. part-time 4WD, different vehicles, etc. That question is kind of like asking why engines change, or why body styles change - they change for a variety of reasons (some good, some not so good).
The advantages of one t-case over another maybe disadvantages to another person. Take for instance a gear driven T-Case vs. a chain-driven T-case. For the hard-core off-roader, a gear driven t-case is more valuable as it's is (typically) stronger by design, but for a daily-driver, a chain-driven t-case is better because you can (in most cases) shift into 4WD at high speeds. SnoMan - before you disect everything I'm saying, I'm speaking in VERY broad terms... ;)
There isn't a huge difference between the 208 and 241. They're both cast aluminum housing t-cases, they are both chain driven, and they both have similar low-range gear ratios. I think the shift pattern is also the same, but I might be mistaken.
The 208 (I'm pretty sure) has a thicker aluminum housing on it, so that might be important for someone with a lot of horsepower, but the 241 has a deeper gear set, which is more optimal for off-roading.
Did that answer your question?
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
- - - - - - - - - - - - - - - - - - - - -
'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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SnoMan
Lift & Lockers
Posts:943
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| 09/17/2007 1:21 PM |
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quote:
Originally posted by porterzcustomz
So back to my original question, why did they change them, is the newer ones suppose to be better or are they all basically of equal value? Reason im asking is I had to switch my 241 to a 208 and wanted to know besides the way they mount if there is an advantage to one or the other.
This is easy, cost and weight (and I am not sure in what order). Also I tend to agree with Rick that the 208 has a little bit heavier case though I cannot say for sure. ALso there is 4 Tcases designs in the NP231/241 family. There was two 231's, the standard LD model and a model that basically used the stronger planetaries out of a 241. Then there was the std 241 and a HD 241 that Dodge used for a while with V10 and CTD. THe newer cases are more efficent as far as power loss through them in 2wd and 4wd and the planetary reduction units in them is more efficent than old style designs and stronger for weight and size of unit. If you take time to change the fluid in them every 15 to 20K miles and use proper axle ratios for tires and load on them, these newer Tcases can have a long service life. Tall gears with big tires and frequent use of low range to make up for it can shorten chin life in them. |
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Visit the SnoMan at
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sammy 87
Street Queen
Posts:107
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| 09/20/2007 8:01 PM |
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| I have heard bad things about the 208's in there shift mechanisim but I have been really pleased with a 208 in an 84 Ramcharger they have a really low range and even lower with a 4speed mannual tranny I have beaten the hell out of it and it still begs for more |
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ChevyMan0784
Lift & Lockers
Posts:699
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| 09/20/2007 11:25 PM |
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| Yea, I hear ya on the 208. I have abused several and never broken one. Or stretched the chain or whatever. As a matter of fact, I run one now with a THM350 374HP and 42's |
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gimmie fuel gimmie fire gimmie that which I desire-James Hetfield
*Never give an Irish man good cause for revenge.
*Guns dont kill people, but they sure help!!
*98% OF AMERICANS SAY 'OH S**t' BEFORE GOING IN THE DITCH ON A ICEY ROAD.
THE OTHER 2% ARE FROM ALASKA, AND THEY SAY, 'HOLD MY BEER AND WATCH THIS |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 09/21/2007 7:44 PM |
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| Yup - the 208 is a pretty strong unit. I've heard people talk about people that they knew, who knew a guy, who's uncle had a 208 with a stretched chain, but I've never seen or heard of it happening from the person who owned it. I think that myth is busted! :) |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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ChevyMan0784
Lift & Lockers
Posts:699
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| 09/21/2007 9:21 PM |
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| Haha, well...I did know one person who broke theirs. But it was my girlfriend at the time's. Was very wierd. It actually just stretched the chain, and fell off in the case. The rest of it was still good. Just put a new chain on it. Who knows how it slipped off, I mean... I am a$$uming that it stretched. But who knows. All I am saying, is this: A THM350 and NP208 survied 2 motors, 4 sets of blown ujoints for the drive shafts, and a couple axle shafts. Now, I am not an expert...as they like to say. But, I think these two are pretty awsome pieces of metal. |
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gimmie fuel gimmie fire gimmie that which I desire-James Hetfield
*Never give an Irish man good cause for revenge.
*Guns dont kill people, but they sure help!!
*98% OF AMERICANS SAY 'OH S**t' BEFORE GOING IN THE DITCH ON A ICEY ROAD.
THE OTHER 2% ARE FROM ALASKA, AND THEY SAY, 'HOLD MY BEER AND WATCH THIS |
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