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school me on t-cases

73redblaze

73redblaze

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This is what I know: that np 208 is an aluminum case, chain drive and np 203 are heavy as hell, cast iron, also chain driven, and I know np205s are better because they are gear drivin. What I want to know: why do people mate np 203 to np 205 instead of a np208? Can you mate a np205 to a np208 what would be advantages and disadvantages?
 
i definitley am interested to anyone who knows the reason for this because i already have a mated to a th400. Any reason i couldnt use a custom machined adapter to mate it to a 205? everything is already 32 spline unlike a 203. Im guessing the issue is just durability, But i think short of smacking it on rocks which is easily avoidable with rock guards a 208 would hold up just fine :dunno:
 
where could we get said adapter? and if you make one mark me down for one
 
73redblaze said:
where could we get said adapter? and if you make one mark me down for one
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Im related and associated with some very experienced machinist, not talking about scott btw lol

Also i couldnt find a blow up diagram of a np208 online to figure out if splitting it in 2 like a 203 was possible so i pulled out my chilton manual and found the 208 overhaul section and i qoute
''the np208 is a part-time unit with a two piece aluminum housing. On the front case half the front output shaft,front input shaft, four wheel drive indicator switch and shift lever assembly are located. On the rear case half, the rear output shaft,bearing retainer and drain and fill plugs are located.''

Im kinda excited about this now, Is the np208 so weak that only using the front portion would be risky?
 
obijuan said:
Front digs and super short overall length.
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I thought front digs were done with a triple stick by putting the front case in low range,the 205's rear axle shifter in neutral and the 205's front axle shifter in low range? How would a 208 affect this? Also super short overall length is desirable for a short wheel base buggy im planning on?

edit: i understand what you mean about front digs, I compared the front case section of a 203 and 208 in my chilton book and found the 208 front section has the front drive shaft output where the 203 only has its range box in the front piece of the case. Is it possible to not use that 208s front driveshaft output and use the 205's front driveshaft instead or would the 203's front drive shaft input get in the way during extreme flex?
 
You need to check some google images of a 208 to understand that it is constructed entirely differently than a 203. The 203 has a reduction box for lo and high range that unbolts from the rest of the case. Not so with the 208.

What you guys are looking to do is already being done using a NP241 planetary set and a custom machined housing. Northwest Fabworks calls it their "Black Box.

Read more here: http://www.northwestfab.com/blackbox.html

Rene
 
tRustyK5 said:
You need to check some google images of a 208 to understand that it is constructed entirely differently than a 203. The 203 has a reduction box for lo and high range that unbolts from the rest of the case. Not so with the 208.
Looks like im back with a aftermarket case or a unicorn np203 if im going to use my th400 :( . Well it was a fun research opportunity

What you guys are looking to do is already being done using a NP241 planetary set and a custom machined housing. Northwest Fabworks calls it their "Black Box.

Read more here: http://www.northwestfab.com/blackbox.html

Rene
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...
 
Rene beat me two it. The 241s and 208s use a planetary set to get gears down. The planetary is VERY beef but the aluminum case and chain are not. Dont get me wrong they arent bad cases, especially the 241 with a fix yoke.

There are guys that have done 241s to 205s I believe. The reason for not using a 241 as the out put case in a double is again because the chain is a negative.
 
What's wrong with running the 203? It's a pretty strong case even though lots of guys hate on em. Rebuild, part time kit, twin stick it and enjoy.

Rene
 
tRustyK5 said:
What's wrong with running the 203? It's a pretty strong case even though lots of guys hate on em. Rebuild, part time kit, twin stick it and enjoy.

Rene
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mating it to my th400 is a huge expensive PIA. Blazinuk makes a very good argument for using a built to the hilt th350 for competitive use and the th350/203 combo is easily found everywhere all day for cheap.
 
73redblaze said:
This is what I know: that np 208 is an aluminum case, chain drive and np 203 are heavy as hell, cast iron, also chain driven, and I know np205s are better because they are gear drivin. What I want to know: why do people mate np 203 to np 205 instead of a np208? Can you mate a np205 to a np208 what would be advantages and disadvantages?
Click to expand...

Because the 208 isn't as stout and it's far from easy to do.

I made my own a while back using a 241, it was a TON of work. I like the gearing (though double low is more than enough, I hardly use it), though it will never be as strong as a 203 gear box.

Thread here.

Quick breakdown:

203/205: 2:1 and 4:1 options, easy to do with off the shelf parts, bulletproof, plug and play

208(241)/205: 2:1, ~2.7:1, ~5.4:1, much more difficult (required cutting the case half, welding aluminum, etc), lighter, definitely not as strong, parts are practically impossible to find (I made my own adapter because the 241 plate wasn't available by anyone and I had to make a dozen calls to even buy the shaft, the only guy that makes this stuff is terrible with customer service).


So there is a niche for the 208/241 doubler stuff, we've talked about building the kits because there is some demand for them and they have some advantages. They aren't ever going to be as stout or easy as a 203/205 but they do have deeper/more gearing options and the kit would probably cost less than our current doubler.

In all likelyhood the final product would use the 241, just about everything about it is stronger than the 208, including the gearset.
 
gotblazers said:
i definitley am interested to anyone who knows the reason for this because i already have a mated to a th400. Any reason i couldnt use a custom machined adapter to mate it to a 205? everything is already 32 spline unlike a 203. Im guessing the issue is just durability, But i think short of smacking it on rocks which is easily avoidable with rock guards a 208 would hold up just fine :dunno:
Click to expand...

You can get just a 205 behind that trans relatively easy, if that's what you want.

Unlike the 203, the gearbox isn't a convenient deal to just unbolt. The 208/241 gearset require a custom box (like the black box) or make your own from the stock housing (fabrication, welding aluminum, etc required).

As far as durability, the aluminum case is plenty strong in torsion. The problem as far as breaking them (not the entire t-case, just the 208/241 doubler portion) is either from weight hanging off of them (weight not being supported correctly) or from the front driveshaft binding (even a good front driveshaft won't want to slip when power is being transmitted through it and it won't want to slip, hence the strut rods on auto trans equipped trucks to prevent the tailhousing of the trans from breaking).

I have a fair amount of faith in mine, but it's in a 4300 lb truck with two crossmembers etc. Fingers crossed, so far so good.

Just like a 205, you'd never have to worry about breaking the 203 box.
 
sweetk30 said:
why is this ? thay come from the factory with this combo. just got to find it. :whistle:

oh ya and you noobs need to search. :eek1:
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yea, good luck finding that factory option, Itd be easier to find a k5 with factory power mirrors :rolleyes:. On ck5 and the local wheeling club where people specialize in this bull**** i got ONE HIT from a guy in texas who never responded again. Im getting an atlas, or i might do the custom 208/205 thing just for the fun of it and itd be cheap as fock to do. Just gotta find someone to help me weld aluminum and cut out a custom adaptor :whistle:.
 
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