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231 Doubler

Hogback Fabrication

Hogback Fabrication

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I am thinking about gathering parts for a 231/205 doubler and have a bunch of questions for you guys:

The trans will be a 32 spline SM465. A 32 spline NP241 input gear like this (at the bottom) should fit into the HD231 planetaries, corrrect (supposedly the same as 241 planetaries)?

If I get a late style 465/205 adapter and use the factory 32 spline output on the 465 will the 231 bolt up to it (i.e. they both use a 6 bolt circle, is the pattern the same between the 205 and 231)?

I have a 31 spline input gear from a Ford case that I intend to use for the input on the 205. Can the 231 planetaries have a 32 spline input and a 31 spline output? I don't know how many of you know how planetary gearsets work but you can see the shafts for the doubler here and here is a teardown of a 231. I'm thinking the internal splines are the same for all of the input gears.


Yes, I realize I could call d&d machine or mad rooster and potentially get answers (though they both can be tough to get ahold of) but this seems like tech that hasn't been covered on this site yet and this information might help other people. If nobody knows I will post the info back here when I find it.





Reasons why I'm thinking about a 231/205 doubler rather than a 203/205 doubler:


The adapter and shaft are $3-400 cheaper
~40 lbs. lighter than 203/205 doubler
Low range in a 231 is 2.72:1 so you can use 2:1, 2.72:1 or 5.44:1 rather than just 2:1 or 4:1


The downfalls are that you have to weld aluminum to finish the adapter (I have a friend who is a good aluminum welder) and that its weaker than a 203 range box.

I'm not really afraid of breaking the gears in the HD231 (which uses the same planetaries as the 241) as the weak point in 231's/208's/241's is the lower part of the case and the chain (which I wouldn't be using).
 
bronc3buster842001 said:
I had both a hd231c and 241 apart a couple weeks ago and the inputs or the planteries were not the same.
Click to expand...

Its likely that the input spline counts were different but as I understand it the planetaries are the same. The non-hd planeteries are smaller.

This thread and this thread both say that the HD231 and 241 use the same planetary gearset. I can't say for certain because I've only messed with 231's before, which is why I asked.
 
IIRC 231s have 3 planet gears and 241s have 6. That may only apply to heep 231s though. :confused: But they are aparently interchangable.
 
BGKYK5 said:
IIRC 231s have 3 planet gears and 241s have 6. That may only apply to heep 231s though. :confused: But they are aparently interchangable.
Click to expand...

HD231's (primarily GM applications like S-10's) have the same 6 gear planetary setup as the 241 (supposedly) and regular 231's (primarily found in Jeeps) have the smaller planetary gearset (I'm not sure how many planet gears they have, it could be 3 like you said).
 
bronc3buster842001 said:
The 231 i had was from an s10 and it was smaller than the 241.
Click to expand...

No question the case is smaller, did you actually pull the planetary gearsets and compare them? If so, are you sure the 231 is actually an HD model? There seem to be lots of people that are sure that the 241 and 231HD planetaries are identical (everything else about the 231 is smaller).
 
are you going to use duffy's (aka: D.D. machine) kit? if so, good luck getting ahold of him. I have left three voicemails, two e-mails, and i cant pm him over on pirate. I was looking at getting a 241 doubler kit, but i maybe changing routes since it is impossible to get a hold of the guy
 
He is really hard to get ahold of. I tried leaving vmails and got no return calls. I started calling a different times and finally started getting in touch with him. I think the best time to call is before 8:30 or after 5:ish his time.
 
yea, i've read over on piarte that it was pretty tough, but damn, i didnt think it would be like pulling teeth.. thanks for the heads up on the times. Hopefully i can get one of these kits asap..
 
Just keep trying. It's hard dealing with customer service like his, but when that's the only kit available, what do you do? You think the guy would hire someone to answer his phone.
 
DPI said:
He is really hard to get ahold of. I tried leaving vmails and got no return calls. I started calling a different times and finally started getting in touch with him. I think the best time to call is before 8:30 or after 5:ish his time.
Click to expand...

Which is why I asked the question here :deal:

That and it makes the tech more public and might help other people avoid this hassle :D
 
If you do it, post up lots of pics. The guys on pirate aren't so good about that. Does DD Machine even make the 241 doubler anymore?
 
BGKYK5 said:
Does DD Machine even make the 241 doubler anymore?
Click to expand...

He said he wasn't going to make anymore because the 231 doubler is so much more popular (smaller/lighter package with the same strength). I don't know if he actually makes them anymore, you could always try calling him
 
the 231c "non HD" uses a 3 planet set, the "HD" uses the same 6 planet set as the 241. the hd's only came behind 4.3's and obviously 88+. pre 98 s10 cases are 5 bolt, not 6 and they all come stock with 27 spline inputs. i would like to think the 32 spline input gear would fit in the 231 case, but i dont know if the seal will fit, etc. i have a 231HD/241 doubler from d&d sitting in the garage, it replaced the non hd 231c that came out of my 89 s10. also, 231s are all manual shift, the electric shift s10's have 233 t-cases.

this combo nets me 135:1 with a 5 speed.

you can see from the pic this has the 6 planet gear set, its a 231HD.
PIC_0278.sized.jpg
 
also, the main part of the case on the 231 and 241 are the same size, the 241 just has a longer front output section, larger rear slip yoke, etc. if you put them just behind each other, they are the same dimensions.
PIC_0500.sized.jpg
 
one last thing, i looked into this swap quite a bit back before i decided to use the 241 as my rear case. the shafts, adapter plate that d&d has will not clear the inside shift rail on a 205 without modding it. the shaft is too short to add a spacer, so you are stuck with either shifting the 205 from the back side (dont know how thats done so dont ask), or clearancing the clocking ring (possibly the adapter plate too) for the shift rail. other than that, d&d made 31 spline shafts for them (same shaft as the 241 kits), and mine uses the 6 round pattern for the rear case (i think it fits the ford round pattern too).
 
Masiony said:
the 231c "non HD" uses a 3 planet set, the "HD" uses the same 6 planet set as the 241. the hd's only came behind 4.3's and obviously 88+. pre 98 s10 cases are 5 bolt, not 6 and they all come stock with 27 spline inputs. i would like to think the 32 spline input gear would fit in the 231 case, but i dont know if the seal will fit, etc. i have a 231HD/241 doubler from d&d sitting in the garage, it replaced the non hd 231c that came out of my 89 s10. also, 231s are all manual shift, the electric shift s10's have 233 t-cases.

this combo nets me 135:1 with a 5 speed.

you can see from the pic this has the 6 planet gear set, its a 231HD.
Click to expand...


Sweet, that's a lot of the info I was looking for :bow:
 
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