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203 TO 241 doubler?

BUDDY

BUDDY

1/2 ton status
Joined
Apr 28, 2000
Posts
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Location
Midland, TX
I have in my parts pile

NP203 range box
fitz all spacer/adapter
700r4 transmission (to be rebuilt)

I was going to put all of this in my 72 blazer in front of the np205 that it came with, with some form of doubler adapter, (NWF, ORD, etc.).

But, I bought a 1990 blazer, so i got to thinking. Could I put the 203 range box & adapter/spacer in front of the 241 t-case that resides in my new to me blazer?

My impression is that this would be a feasible swap, but I'm not familiar enough with the configuration of the OE adapter between the 700r4 & the 241. Spline-wise it should all be the same 27 splines throughout, but the bolt pattern is my big question.

Anybody know the answer?

Just thought of this (at work), & my truck is parked at home or I'd just climb underneath it to find out for myself.

Thanks,
Buddy
 
You would need some kind of adapter between the 203 and 241 which would either be a custom one off piece *or* one of the 203/205 doubler adapters may work.

And then I'd be awfully afraid of popping the 241 with twice as much torque running through it.
 
I'd be worried with anything other than a 205 as the second t-case in a fullsize. It may work if you don't combine throttle and traction too often. :D
 
bp71k5 said:
Interested to know more.

Seen this thread which may have -some- relevent info?
http://coloradok5.com/forums/showthread.php?t=247978
Click to expand...

This is the opposite of what I'm talking about, but still good info!!

I had thought about the effect on the 241 having double the power being sent to it, but I'm a pretty "grandpa" driver, even when off road. I don't have the money to be breaking my stuff.

I'd also do a SYE to the 241 & clock it so that I get myself a flat belly.

Which would bring up another project down the road, but i'll be saving for a welder for all of that.

thanks,
buddy
 
im in the midst of doing a 208/205 doubler with NO adapter.look in the thread there is pics.the slip yoke shaft of the 208 slides right in the female input on the 205.i will have to cut my 208 in half.this will elivate the chain.i would say the chain is the weak link in the case but i broke a flat bering which got into the planatery.i belive it came from my rear driveshaft not having enough compression and pushing the output shaft in the 208 deep into the case.this shoudlnt happen again.i will not get this project really rolling till next month but imma get it done.my 205 will be clocked so i will have to make a adapter for it to be clocked
 
IMO, the advantages of the 203/205 are the part availability. You already have the 203, the 205, and the fitzall spacer. The only thing you need is the doubler adaptor for which the cost and durability are well known.

Doing the second 203/241 is unknown strength and unknown cost (for an the adaptor).

But if you are a "grandpa" offroad why so much gearing anyway? :wink1:
 
BGKYK5 said:
The gearing helps with the grandpa factor. :D
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exactly. I think the term is "elegant driving"

SIDEBAR -

I once got to a hill that this guy in a bronco was hammering the crap out of & couldn't make it up. This guy had done a LOT more work on his than I had done to mine, (35's, roll cage, winch up front, that I could see). I got to him just as he was rolling back down the hill & asked him why he was having such a hard time. He said he just can't make it all the way up. The hill was pretty steep & loose, but it was just a big dirt mogul. I told him to watch me, & I walked right up it with no issue in my 31 shod, stock, open diff, carberated 72 blazer. So he came up the same way & when he got to the top I said, "See, I told you you could make it!", & he replied, yeah but it wasn't as much fun as hammering at it, to which I said, "I guess.", & kinda shrugged & went my own way.

My opinion is to try to make it through, over, or around whatever obstacle with the least amount of drama possible. It's how I live my life. It makes it easier on my drivetrain & my wife & kid don't get as riled up when there isn't a bunch of bangin' & bouncin' around.

SIDEBAR OFF -

Plus, I do have the 205, but it's part of the complete drivetrain that's in the 72, (that I'll either keep or sell complete).

So that means that I'd be in the market for a 205 to put in behind the 203 range box.

Let's try to keep this within my under $1,000.00 budget, that I never mentioned.

Full disclosure:

I got the spacer off of ebay like 2 years ago for $35.00
I got the range box for free from a guy in Canada when I lived in Buffalo, just had to buy him lunch. Super nice guy. I thought his wife was his son at first though. :crazy:

So officialy we're up to $50.00+/-

Later,
Buddy
 
I once got to a hill that this guy in a bronco was hammering the crap out of & couldn't make it up.
Click to expand...

Well I wouldn't call that grandpa, that's be more like "cool uncle". Grandpa would just take the freeway and not bother going up any dirt hills. :)

I do have the 205, but it's part of the complete drivetrain that's in the 72, (that I'll either keep or sell complete).
Click to expand...

Is the rest of the drivetrain worth anything out there? With a th350 (or even the sm465), the 205 to th350 adaptor is probably the most valuable component and even then not -that- valuable. Unless there's sentimental value, I'd guess you get more money by separating them.

If you really want the gearing, you have all the parts now and for another $770+shipping+shifters, you're all done.
 
A 203/241 has several concerns in my mind. The obvious one has been mentioned which is putting twice the torque into a 241. The second which is even more of an issue is driveshaft lengths. A K5 with a 241 has about a 30" rear driveshaft. Add a range box infront of that and now you are looking at a driveshaft in the 20" range. An SYE will gain you some back but your still talking about a short rear driveshaft. Also by the time you pay for an SYE and clocking ring you can almost pay for a doubler adapter. The other concern could also be the length of the front driveshaft. Even clocked up flat you will still have a very long front driveshaft and would probably have to make it a 2 piece driveshaft to keep from hitting it on everything offroad. More cost, more headache.

Harley
 
I have thought about the driveshaft length & I think that I could get by with a 20-24" driveshaft in the rear & I wouldn't actually mind having a carrier bearing/2 piece driveshaft up front if needed.

The thing about this whole setup is that I don't necessarily lose anything should it not work out. I would then need to get the np205 to go behind the adapter, which we all know works quite well.

I've been told that the "strength" issue isn't really an issue, (of course that was from somebody trying to make me a customer, so I'll take it with a grain of salt). The 241's will handle a good amount of torque & as long as I keep an eye on the chain, it should be fine. The thing that is usually problematic with them is the thin aluminum casing. I think I can work around that issue as well with a well designed skidplate/crossmember.

It'll be a long process, but as it progresses, I'll keep this thread updated. Right now I just want to get it out on some trails & have fun with it.

Later,
Buddy
 
BUDDY said:
I think I can work around that issue as well with a well designed skidplate/crossmember.
Click to expand...

The problem isn't so much with contact with rocks, you can break any case/adapter that way. If your t-case is contacting rocks you should expect something to break regardless of your setup.


BUDDY said:
I've been told that the "strength" issue isn't really an issue, (of course that was from somebody trying to make me a customer, so I'll take it with a grain of salt). The 241's will handle a good amount of torque & as long as I keep an eye on the chain, it should be fine. The thing that is usually problematic with them is the thin aluminum casing. I think I can work around that issue as well with a well designed skidplate/crossmember.
Click to expand...

The 241 isn't super weak but its nowhere near the strength of a 205. The chain and housing are big weak points. I've personally seen a few broken 208's and one broken 241, its VERY easy to find tons and tons of threads on broken 241's on the internet.

I thought about just putting an SYE 241 in my buggy; it would have good gearing and its light, cheap and easy but I would always worry about breaking it. And, to me, its not worth burning a couple hundred dollars worth of diesel to get to the trail and break. I still went the cheap way with my 241/205 doubler and its much more stout than a 241.


And, like I mentioned earlier, you'd need a way to mount the 203 to the 241 which I believe would use an identical adapter as the 203/205 round pattern adapter. That adapter/shaft combo runs ~$700-900, a 205 only runs ~$100 usually.


So why even consider a 241 behind any reduction box?
 
The money you will spend to make a 203/241 work will be the same or more then what you will spend to get a 203/205 or 241/205 to work and you will still be weaker in the long run and have more goofy driveshaft issues.

FYI, a 203 will not bolt to a 700R4. A 208/241 trans has a 1" longer mainshaft then a 203 trans does. There is also no "stock" adapter that will bolt a 203 rangebox to a 241. If you are hell bent on a 203/241 your best option is to use a 203 rangebox with a doubler adapter then a 241 with a Super Short SYE kit on it. This might make it short enough to run moderate length driveshafts and not have to run a 2pc front shaft.

The con's to this is you will not be twin stick capable on the 241, the weak aluminum case and chain of the 241, the possible cost to put a 203 mainshaft in a 700R4, and the costs will be high.

The pro's will be a better lowrange and different gear options in the cases which IMO is very desireable. I think this same option could be attained with better useability and strength by doing a 241/205 though. It gives you the best of both worlds and can be done as cheaply or cheaper then a 203/241.
 
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