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doubler "?" NP241/NVG271

bigjbear

bigjbear

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Anybody on here running a doubler with an NP203/NP241 combo? Or even a 203/208? If you are; who made it, any isssues, what extra fab work did you do, what spline count, anything I havent thought of? TIA.
 
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The things I would be worried about with that is putting that much input power into a 208 or 241. I run a 208 and run it hard in my truck. I am a fan of the aluminum low gear options but I would be concerned about the tcase taking that kind of input torque.

The 208 is either a 27 spline (TH350 or 700R4 apps) input gear or a 32 spline (TH400 and SM465 apps) input gear tcase. The output spline counts are 32 spline front and rear. The splines on the gears are like 40 spline or something huge like that.

The mainshafts don't worry me that much. It is the planetary setup, chain, and bearings that I would worry about.

My last concern would be overall length. The 208 and 241 are long cases. The 241 can be shortened with the SYE kits though.

Harley
 
Harley, didn't Dodge put an NP241 behind the Cummins around 1990? Or possibly the 241 HD that, IIRC had a wider chain? Any guess if that would have been a 23 spline input like most other Dodge stuff? If they did, I doubt my 350 could blow it apart, even doubled. I think I need to find the input torque specs for different cases again. If its too low for the 241 this might be pointless.

Great point on the legenth. I really didn't plan on using the 208, but I do have one stashed. I'm thinking a 241 w/ a sye behind a TH350/np203 range box might not be too much longer than a TH700R4/NP208. If I move the rear axel back a little that would make it even better.

Right now I'm more concerened about cracking the case on a rock than blowing it apart. Think I should be more woried about input torque cracks? How about guys, anyone blow up their 241?
 
not really a doubler per se; but i do know of a guy running a klune in front of a 208 in a dodge :cool1:
 
I don't know the specs on the 241HD that is behind Cummins but it is not the same as a normal 241 from what I have heard. I really wouldn't be worried about cracking the 208/241 case as long as it doesn't have any direct contact with solid objects. I have smacked my 208 around pretty hard with a little skinny pedal and some offroad abuse with no problems like that. I have a good skidplate though and the case can't really hit rocks or objects. If you smack an aluminum case on something halfway solid halfway hard it will almost certainly crack the case open. The cases are pretty thin cheesy cast aluminum.

The only problems I have had with my 208 sofar was some of the thrust bearings died and the planetary gear annulus bushing became to worn out. My planetary gears started to win when I was in 4x4 and would go faster then 4mph. I replaced the planeties and all was good.

I would still be very leary about the amount of input torque. I think it could be done with a good driving style and some common sense. My only question would be longevity. It may work great for a season or two but after that I would be expecting to rebuild the 208/241.

That is what is nice about the 203/205 doubler is that for the most part the cases are bulletproof and once they are in good shape and installed it is a done deal that you won't really have to mess with again anytime soon.

FYI, I am not sure if you know this or not but Northwest Fab is supposed to be coming out with the doubler you are talking about sometime in the near future.

Harley
 
Thanks for the first-hand info. Thats the kind of stuff I was looking for. I figgured if I do this I'll make x-member with a skidplate. I didn't know about NFW building one, but I figgured someone would/did.

Next "?" Anyone clock a 208/241 up flat or close to flat and then have oil issues, or other issues?
 
You're correct, I have a NP203/NP241 Adaptor kit coming out in the next few weeks, its just hard to find time to get new products fitted into the production schedule. Price is the same, 699 for the kit.

-Kyle
 
What, if any, issues have you run into with the installation? Do you need a body lift if you don't want to cut the sheet metal?
 
it largly depends on the length of the driveline, and clocking rotation the combo is set at. Some of the longer tranmissions or adaptors between the tranny and 203 push the assembly back into where the tranny tunnel starts to taper, but the physical size of the NP241 is similar to a 205, and also the 241 tapers down towards the front output, which causes less trouble on the front output side of the T case.

Floor modifications seems to differ in everyones setup, if you do have body lift I doubt you'd need to hack anything, but somtimes in the more extreme clocking positions things can get tight.
 
Is it safe to assume the new versoin will be clockable in the same maner as your others? Exactly which 241 will mate to the adaptor? Will need a factory adaptor to mount the 241 to your adaptor? If I would be better off calling, just say so :cool1: TIA.
 
The adaptor kit would be just as clockable, and would not require a factory adaptor.

Currently 32 spline as thats the shaft I have on the shelf, but I will get 27 spline versions going as soon as we can.
 
My concerns would be the same as everyone above. Keep in mind that the 241's in a cummins (or any other heavy truck) are built to be run in big heavy trucks with lots of torque with small tires and in rear wheel drive most of the time. The 241 explosion stories I've heard have been in heavier vehicles with bigger tires but NOT the bigger motors. It's the front drive that's a problem, not the durability in rear wheel drive. Especially if you go to a D60 so the axle doesn't break and protect the cases when you use it hard.
I usually try to fudge on the side of "not having to mess with it again" which would bring you to my recommendation of running a 205. After 4 years of pounding and having a little too much mud and water in my 205, we replaced the idler bearings and changed the oil.

For a Doubler kit, you would just use our standard adapter for a round pattern 205 and bolt it up. For rotations we'd probably just dot the extra holes so you could drill whatever set you wanted so the flange doesn't look like swiss cheese. Otherwise it's standard off the shelf stuff.
 
Stephen, This would be going into the "standard" 1 ton-ish K5. Most of the body tub is there, no doors, top or tailgate, though. Probably around 6k being pushed by around 250HP. Riding on 39s. Think that's too much for the 241???
 
The NP241, I agree might not be the best bet for those who put their rigs through serious abuse in the worst of conditions, but the key advantage is allowing a customer to use their current case without having to hunt down a female input version NP205. The NP241 has it upsides and downsides, the options simply need to be weighed.

For those who do go the NP241 route and want to swap out for a NP205 at a later date, they only need to change 1 of the 3 adaptor plates to go to a round or figure 8 NP205.
 
I think 4WOR's new buildup is a Chevy with a 203 that they're going to put a 241 behind... check out the mag this month for the initial story and then stay tuned.
 
I personally believe the 241 is a great t-case. If it was the choice for 1 ton trucks made by GM and Dodge, put behind both diesels and big blocks, then I think it will withstand more abuse than most people give it credit. It also has the planentaries that Klune uses to build their stuff. Must be some stregnth to it.

Now IF it does break, take the input shaft from the 241 and install it in any other late model tougher case like the NV261 or NV271. The NV271 out of a Pooper Duty is what 4WOR is using. I think the NV241 is a better fit for it's wider aftermarket parts like the SYE kits, etc.

I've got a late model K5 that already has a beefed 700R4 and 27 spline input NV241 if anyone *cough*NWFab*cough* needs destruction testing done on an NP203 doubler setup.
Travis
 
Funny thing is I don't have an NP241. I've ga two 203s, a 205, a208 and even a 207 from an S-10, but no 241. That is why I've got so many "?" about it. I'm not sure about demensions or anything. The reason I was thinking about not using my NP205 is because its a "figure 8", 27spline, w/ a slip-yoke output. I'm not sure its even worth messing with the mods to make it work :confused:

I just thought of something, I bet my Yukon uses a 241. Output would be on the wrong side, though...
 
If you need dimensions just measure up the 208 that you have. It is basically an identical case with all the same dimensions. It is just a little older and slightly weaker version of the 241. The 241 has the option of the readily available SYE kits that the 208's don't have.

Harley
 
thanks Harley, that will make the thought process work better. I'm even less sure about doing this now, though.
 
I think you're pushing it for 241 durability. I know it's a pain doing the mods to the 205 but it's worth it. When we started with the GEN2 Doublers we made a concious decision to make everyone use the female input gears knowing it was a pain in the butt to do but the upside is you don't have to worry about breaking a very important part of your drivetrain and we don't have to worry about you breaking a part with our name on it. Unfortunately we're not talking about a front axleshaft that's easy to change on the trail and/or easy to limp out on. If you crap a t-case, you're done.

But 241's are light, you could carry a spare. Except then you might as well have a 205 since the weight would be lower.....
 
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