So it begins... NP241/NP205 doubler

[Doug Krebs]

Both cases are apart...

I've got Tate's enourmous tranny over here to measure the 31 spline shaft...


First an adapter plate has to be made to bolt the 241 to the 205. This should be easy enough. Bring both cases up to the machine shop and use the digital readout on the mill to get the bolt hole patterns and to ensure the input and outputs are concentric.

Next I need to respline and cut the 241 shaft. I plan to leave it full length and turn the part I need to spline to the right OD, then I'll cut it to lenght. My thought behind this is it's already center drilled so it "should" be concentric in the lathe.

The only glitch I didn't forsee until tonight is one of the 205 range shifters will hit the 241 case. Regular doublers solve this buy moving the 203 box out ~2 inches from what I can see. However, there is nothing but empty space in this part of the 241. From my 5 minutes of looking at it tonight I think I'm just going to cut this part of the case out and tig weld in a concaved piece of aluminum.



So thats the doubler part... then I get to do it all over again between the tranny and the 241. There are stock adapters to do this, however they are around 8"s from what I remember. I have one in the blazer and I really don't want that long ass setup. My entire doubler setup should be the same length as whats in the blazer.

So my plan is to take a 2wd SM465 and then machine it from 35 splines to 27 splines. Then make another adapter...


P.S. Anyone have a parts washer I can borrow? I'm going to but one as soon as they go on sale at harbor freight. Maybe I'll take the 205 **** up to the car wash and blast it, the inside is kinda gunky...

[fbronco86]

Go to a pressure wash place and clean them up.

[Graystroke]

educate me why a 205 to a 241?

[stx4wheeler]

doug i have sent you pm's you got any answers to them. pm me back gracias frick

[Doug Krebs]

educate me why a 205 to a 241?

In order... SM465 to the planetary front housing of a 241 to an entire 205.

Reasons?

If I'm going to make my own adapters and shafts for a some kinda of doubler I might as well do what I want.

The 241 is much lighter than an NP203 and offers better gearing than an 203. 2.72 compared to 2.0 I believe

I paid $150 for the 241 which was too much, but I wanted in short notice. I paid $60 for the 205. Everything else should be either free or very cheap. This will take me a while to do, but I'll learn **** along the way.

We had a thread going on lonestar4x4 but I guess it grenaded. I first saw this setup using a 208 a couple years ago. A guy in finland sent me the CAD files...

MadRooster4wd is the first one to actually produce a similar setup. He's using a 231 which is essentially the same as a 241 minus 3 planetary gears and mating it to a dana 300. It's a little easier as the range selectors are on the rear of the case.

Link to madroosters setup...

[robertf03]

hmm, never thought about using the dro on a lathe and a tap to copy patterns before, should work out great.

so how big is tate's tranny's shaft?

[Doug Krebs]

so how big is tate's tranny's shaft?

Jesus his shaft is huge! It's a ***** to pick up yourself, and my 6" calipers wouldn't fit it

[KrazyKarl02]

Jesus his shaft is huge!

Stop your gonna make Mike jealous....

[jerryg79]

Stop your gonna make Mike jealous....

crooked > huge

[Jackasic]

this is interesting Krebs, I have a spare 241 so this may be the route I go.

[Doug Krebs]

this is interesting Krebs, I have a spare 241 so this may be the route I go.

I'm going to take the 241 case up to work today and get the bolt patterns recorded...

Once I figure out whats going to be done for 205's range selector clearance I'll start splining the intermediate shaft.

[agjohn02]

If I'm going to make my own adapters and shafts for a some kinda of doubler I might as well do what I want.

have you ever built shafts?

ive done several and turns out it works better if you cut to size +.050" or so, then heat treat, then finish machine and cut the splines.

[Doug Krebs]

have you ever built shafts?

ive done several and turns out it works better if you cut to size +.050" or so, then heat treat, then finish machine and cut the splines.

I'm using the original shaft... From what i've heard, when moser does a shaft, they don't anneal, they turn down to size, spline and they are done. They don't heat treat again. I'm going to leave it oversized, and take a hardness test.

I guess their thinking is the dimensions of the previously machined part will change...

I'll see how this works, I'll probably build another one out of 4340 sometime in the future.

[agjohn02]

i do it that way to keep from burning up tools as fast and can cut faster. i started doing this way when i had to turn 4" material down to 1" due to a flange on one end of the shaft.. this way i can cut it down most of the way without it being as hard. i leave the extra material so i can take care of the size change after heat treat. when your done, its heat reated and the correct size.

[Doug Krebs]

Hmmmm... just stuck the shaft in the lathe, it's harder than piss. I need to see if jim has labs today so i can get a hardness test...

Going to have to check on a 1.75 Diameter X 10" long piece of 4340... Maybe they have one laying around the ME shop. I'm thinking it may be easier to start with a new piece of material and go that route.