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Keep NP241 or....

MudFrog

MudFrog

1/2 ton status
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Feb 23, 2000
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Daleville, Va
My 700R4 is starting to get a little quezy. So I wanna go ahead and put in a TH400 or TH350, prefer the TH400 though. I was looking at Advance Adapters website and the adapter I need to go between the TH400 and NP241 is like $520. The same price for the TH350 adapter. Now is there anything special about my NP241 that I should want to keep it? Or should I just buy a differen't transfer case that will bolt right up? If I should get a differen't one what would be a good one to use?

89 K5 Silverado
http://mudfrog.coloradok5.com
 
At the moment I might be leaning to a TH350 I have heard many things about them that I like. Plus a local junkyard has several of them for $125 each. Does anybody here have a preferance? Keep in mind my 350ci is stock and when I do upgrade it I doubt it will have more than 350HP. The TH350 should be able to handle this fine. Don't you think? Going back to the Transfercase, should I pay the $520 for the adapter so I can use the NP241 or should I just get a differen't transfercase altogether? I know some of you have some answers for me so please spit them out
wink.gif
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89 K5 Silverado
http://mudfrog.coloradok5.com
 
If you swap transfercases then you will also have to get new driveshafts also. If you do swap to a case that will bolt right up to a turbo 350, it would have to be a np203 or np205. The 203 would be easy to find but you would probably want to put a part-time kit in it because it is a full-time case. The 205 is a good case for strength but its 4 low gearing isn't as good as some of the other cases. Oh yeah, weight! Your np241 has an aluminum case that is light as were the 203 and 205 are cast iron and are very HEAVY! When you figure the money for the tranny, tranny rebuild, transfercase, driveshafts and fuel costs, it would actually be better (in my opinion) to go back w/ the 700r. There are several upgrades that make these trannies good ones. Just my .02 worth!

baldbandit
 
Guess what? As long as the TH350 you find is a 4x4 version with a 27 spline output, it is a BOLT IN replacement for your 700r4. It is a shorter tranny though, so you may need a drivehsaft mod or two, but you will NOT NEED to buy any adapters, as the adapter is the same for the TH350 and 700. Just make sure the 350 is a 27 spliner. Good luck!

ken
 
Just another thing to keep in mind.........
You will lose a lot of low range gearing if you go with a different trans and/or transfer case combo.
For example the 350 and 400 have a 1st gear around 2.5:1, while the 700r4 has a 1st gear of 3.06:1........that's almost the same as the difference between 4.10 and 4.56 axle gears. For the transfer cases, the 203 and 205 only have low ranges around 2:1, while the 241 has a low range of 2.72:1......when in low range, that's like going from 4.10 to 4.88 axle gears.
Combine these together and you go form a 1st gear/low range ratio of 8.3:1 with the 700r4/241 combo vs. the 1st gear/low range ratio of only 5:1 for a 350/203 combo......that's a huge difference if you are into slow crawling.
 
It is good that you are doing a lot of research up front before starting. You may find that by the time you consider crossmember changes, driveshaft changes, crawl gear loss, overdrive loss, you might go with a beefed up 700R4 and come out way ahead. See if you can find someone with one of the seriously beefed up 700R's before you decide.
 
Deep six the junk 700. If you don't bite the bullet and do it now, you'll do it later. These trannys were not meant for anything over 1/2 ton and definitely WERE NOT meant for towing. Yeah, I know, tons of folks tow with them and have stories of them lasting x amount of miles, but go thru a few 700s at $1,000+ per rebuild and you will quickly grow weary and tired as I have of their inherent inability to last very long. Notwithstanding the "beefy rebuilds" that some shops offer, I would still not chance another 700, especially when they're over $1,000 per rebuild!!! TH400 all the way baby!!!

ken
 
I agree with Ken to a certain extent. If you are running huge tires, huge horsepower, or constantly tow or haul large loads, than don't mess with the 700r4............but I think in a moderate condition that the 700r4, properly built and kept cool, will last a long time and just as long as a th350.
Another thing to think about...........yeah, 700r4's are expensive to rebuild but a properly rebuilt one should last as long or longer than the original, and if the original one is already 10 years old that means in theory it should be another 10 years before it needs rebuilt (assuming the same amount of miles per year).
 
Hmmmm...OK, I am running a 700 (make that WAS running) in a 1990 Suburban, 6" lift, 35" BFG Muds, stock TBI 350, 4.56 gears, never towed a thing, driven exclusively by my wife who doesn't race around, and we just toasted #6 700 in 224,000 miles. NOT huge horsepower, NOT huge tires, it is geared properly for the 35" tires...but yet it still insists on blowing 700s at an average of one every 35,000 miles. To me that is an inherently BAD designed tranny. Call me crazy, but I'm going to a TH400!!!

ken
 
Just out of curiosity, how long did the original trans last? I bet it lasted a lot longer than 35,000 mile......am I right?
I not trying to get into an argument or anything, it's just that I have seen numerous posts of this board about the original 700r4 trans lasting over 100,000 miles but the rebuilt ones only last 20,000 miles.....it just makes me wonder.

Between my dad and myself, we have had 7 GM trucks ranging from a '83 S-10 to a '00 Silverado equipped with 700r4's (or 4L60E's). All of these trucks, with the exception of the '00 obviously, had over 100,000 miles on them and only 1 failure. This 1 failure occurred at about 60,000 miles and was later found to be caused by a faulty ECM which was not allowing the converter to lock up properly and therefore fried the trans. Four of these trucks were work trucks and accumulated a minimum of 120,000 miles with no apparent tranny problems when they were sold. They were NEVER serviced in any way, were driven hard, nor did they have an auxillary cooler and they regulary pulled a 17' boat on the weekends, and at least one of these (an '88 C1500) is still running around town with over 170,000 miles on the original 700r4.
My current '90 K5 is running 35" tires with 4.10 gears and has over 100,000 miles with no apparent problems.....and it has been run hard since I bought it 50,000 miles ago and goes fourwheeling at least once per month.

I'm sure there are exceptions, but with my personal experience I have some respect for the durability of this trans. I just can't see how you can only get 35,000 miles out of a properly built 700r4 that is not used hard.
 
Hey ya'll!
Well from the start I have been against the 700R4, my old scotsdale had one and I wen't through 4 in a year and a half at $1,000 a pop. I do not want this to be the case with the blazer. I had 35" tires on my old truck and I plan on running 35" here before too long on the blazer. Oh yea. The scotsdale had a stock 305 when I wen't through my first 3 tranny's and I put in a mildly built 350 then when my fourth one went I just up and sold the thing. I have 3.42 gears right now and I'd like to have a tranny that I could run with 3.42 with 35" tires untill I get the money for a axle upgrade. I don't want to worry about a new tranny every 4 months. Especially since every shop around here only has a 3 month warranty. I know a lot of you will say save the money till you can do it all the way you want it. I can't do that cause I'll end up blowing the money on something else if I try. I have thought about the low end range, but around here there isn't a whole heck of a lot of rock climbing or anything like that. However I would like to keep the NP241. So you sat a 27 spline TH350 out of a 4x4 will bolt right up, although I will need to exted the driveshaft!?! Sounds good to me. I don't guess a TH400 will bolt right up?? Thanks for the help ya'll.

89 K5 Silverado
http://mudfrog.coloradok5.com
 
I think the problem with 700R4s is that nobody knows how to rebuild them right. The later stock ones are OK and usually last about 80-100K before a rebuild. I'd keep the NP 241, they are not as strong as a 205 or 203, but still hard to break, and I've never heard of anyone blowing their t-case, just keep it full of lube.

90K5
 
So will I have any trouble anywhere else while putting in a TH350? Not sure of the name of it but what about the linkage for the gear selector (ex. P-R-N-D-1-2). Will that be compatible with the TH350?

89 K5 Silverado
http://mudfrog.coloradok5.com
 
This is a great thread, I think most of us at one point or another will be in this same situation, what to do for a tranny when it comes to rebuild time. All tranny's have their pros and cons, man - what to do
smile.gif
. I still don't know why my 700r4/np241 combo hasn't gave out yet with 175,000 original miles. When it does give out I am thinking about the 400/205 combo or maybe a doubler. I think a Jet or Art Carr 700r4 would be fine but I still would not put one in a Suburban. Has anyone heard of a Jet or Art Carr 700 going out? or do most people who have them rebuilt just get it done at the corner Amoco station?
The 241 is a good tcase but not worth spending $520 for an adapter, if you want to loose the overdrive go with the 400/205 combo and forget it's there.
Also, things to think about (I am in the same boat or will be) are gear ratio's, if you loose the overdrive you may want taller gears for the highway or you could go with a doubler so you can still have a low crawl ratio.
Lot's to ponder, lets hear more input!!!

Steve
gears.gif

1990 K5 with stuff
 
I have had good luck with TH350 transmissions. I had one behind my mildly built 454 with 38" Super Swampers with 3.73 gears. My brother currently has a 84 Blazer with a TH350 behind a BUILT 402. No problems as of yet. So I will stick with the TH350 or 400 when I get my 74 built up.

Communication Breakdown
74 Blazer
Zeppelin
 
Im in the same boat guys. I've got the 700/241. But after all my research, I think it will be best and easiest to get a 400/208 combo. As the 208 and 241 are almost identical and I think this is a more common combo, at least from what I've heard. I think I can get the set here in NAshville for around $500. And then all I need to do is move the crossmember, different dipstick and get the driveshaft worked. I am also running 3.42's and going to 33's after January so I'm planning on having all this with 3.73's. I don't do alot of low low rolling so this combo should work good enough to get me to my camping sites and to sling mud. The only problem my dear friends is MONEY.
Someone please let me know if I'm mistaken on the combo info. I've read so much stuff It's hard me to keep up with it all.

Don't you buy no ugly truck!
 
As for the gear selctor indicator thingy in the dash...I am pondering this too with the install of a 3 speed auto from the 700r4. I believe that you just need to get that indicator thing from a 3 speed auto equipped truck at a junk yard, and bolt it in place of the 4 speed version indicator. They bolt to the dash assembly. If you think about it, and have seen one work, it is merely an indicator...the detents you feel when shifting are in the tranny, not in the indicator. Swap indicators and you should be fine.

ken
 
You might think about just getting a floor shifter, from what I understand the Art Carr gate shifter is bullet proof, they are used in a lot of racing applications.

Steve
gears.gif

1990 K5 with stuff
 
Good points Steve.........

Let me throw another monkey wrench into the thinking.......how about (since we are already thinking of spending around $1500 for a trans) a (forgive me if I get this wrong) 4L80E - isn't this basically a Turbo 400 with overdrive???? With all the talk about 700R4's on this site, you would think someone had either considered this, done this, or couldn't do this.........how about it, guys?

I too have this bridge to cross soon...........would love to have the capability to run an overdrive tranny with 35" MT/R tires (love those things) and 4.56 or 4.88 gearing and run down the freeway at 2000 rpm. My T350 is perfect and has never given me any problem in front of my NP203 but the overdrive is tempting, as is the low first gear.



<font color=black>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;http://www.blazzinor.coloradok5.com
 
I hear yah. I have thought about the 4L80E. But those things are like $2,500 dollars and you'll have to play with all the computer controlled crap.

Don't you buy no ugly truck!
 
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