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View Full Version : Fricks turn to tear apart and not complete a Doubler



stx4wheeler
06-27-2010, 03:08 PM
Alright the other day I picked up some more transfer cases and it got me to thinking. I now have a 32 spline round gm 205, ford non slip yoke 208, and two chevy slip yoke 208's. I have seen that D&D machine makes a 241/205 doubler, and box for rocks makes a 241/300 doubler. I would like to do something like this, but with a np 208.

Here is a link to Karl's doubler thread that died and Krebs link to his plans are listed inside Karl's thread.

http://tamor.org/forums/showthread.php?t=11235

Here are some links to some 241/205 doublers the second one i really like because the guy doesn't have to shift the 205 from the rear like the first one does. I have pm'ed both of them to get the overall length from the face of the 241 mounting to the center of the rear t case output yoke.

http://www.pirate4x4.com/forum/showthread.php?t=757049

I like this one best
http://www.pirate4x4.com/forum/showthread.php?t=871556

Most of the homebrew doublers run into two problems:
1. The shaft that goes from tcase one to tcase two(ie whether to cut and reweld it of have a new one made)
2. The length of the combo forcing you to possibly use a 2 piece front d-shaft with a carrier bearing or pillow block.

Well after messing around some I found out that the chevy rear output was 32 spline just like the gm 205 I have. This is when i thought out making this work. The only problem was the output shaft was way to long, and would lead to the above 2 causes that cease homebrew doublers from ever making it past a twinkle in the owners eye.

Next I looked at the ford 208 that I bought to convert my slip yoke 208 into a fixed yoke. Its shaft was much shorter than the slip yoke. Its output shaft is also 32 spline and will fit inside the gm 205.

Picture 1 is of the ford 208 with removed tailhousing slid all the way into the gm 205. The total combo from the face of the 208 to the center of the rear yoke on the 205 is 27 1/7 inches.

Picture two is the ford 208 case and shaft, if you cut off the threaded part of the output shaft you could get the combo down to 26 1/2 inches which is only 5 inches longer than most versions of 203/205 doublers. Once an adapter was made you could run a stock ford 208 shaft and not fear shaft failure because of a homeade(welded shaft). It would also be easy to get a new shaft if it was ever to break.

Picture three is a stock chevy 208 slip yoke case next to the 208/205 combo. The slip yoke case is about 7 inches shorter than the whole doubler setup.

Picture 4 was used for me to get a rough estimate on how much longer my front d-shaft would become with the 465/208 adapter and the 208/205 doubler from the face of the trans.

The early model trans and 205 that I have in my truck now used much shorter adapters than the late model 465 that will be going in its place. From the face of the trans to the front output of the t-case my driveshaft would become 15" longer than it currently is using the doubler setup. I have plans to move my front axle another 3" when the one tons go in, but this would only hurt my huge front driveshaft. With the axle moved forward two inches my rough driveshaft length would be 48":eek:.

What I need to know is how long can my front driveshaft be and what is the max angle I can run using a 1330 chevy flange or double cardan joint? I have seen a couple two piece driveshafts made on pirate that use carrier bearings, but these complex shafts cost quite a bit in materials and parts to build which negates the fact of a cheap doubler, plus those two piece shafts look like they may be the devil incarnate!

Like most abortions that I create cost is part of the the reason I think up retarded things like this. Rough cost to do a 203/205 setup behind a 465 as follows- gm round pattern 205($300), adapter/shaft/kit($550-$650), 32 spline 203($75-$150 depending on whether you can find one that came behind a th400(32 spline or you have to buy a new input for it) for a grand total of around $1000-$1200 to get 4:1 gearing.

Cost of the frick ghetto doubler, gm round pattern 205($300), ford np 208($30), gm np 208 to get the 32 spline female input($50). Then lets say you spend $150-$200 in materials to make an adapter you are still out the door for around $600 to get 5.13 gearing. Even if you had a intermediate shaft made to the tune of around $200 to make the combo a couple inches shorter your still 2-4 hundred cheaper than the 203/205.

MOST LIKELY THIS WILL NEVER HAPPEN BECAUSE MOST TIMES WHEN YOU CHEAP OUT YOU GET WHAT YOU PAY FOR, and this will become another failed doubler thread, but I really think this is doable concept.

Any info on the driveshaft lengths and angles of what people are running or that didn't work would be great.

DRAGOONRANCH
06-28-2010, 02:51 AM
With it that long, your d-shaft lengths in the chevy will be near identical I bet.

stx4wheeler
06-28-2010, 06:54 AM
Negative my rear frame has been shortened like 18". When I put the new axles in I am gonna push the wheel base another 6-12" in the rear, even with this the front would still be about 8 inches longer.

DRAGOONRANCH
06-28-2010, 08:26 AM
Negative my rear frame has been shortened like 18". When I put the new axles in I am gonna push the wheel base another 6-12" in the rear, even with this the front would still be about 8 inches longer.

Shortened from a longbed or shortbed? What are you looking for your wheelbase to end up at?

(sorry for the thread hijack :laughing: )

stx4wheeler
06-28-2010, 09:33 AM
I don't know what it originally was. Wheelbase is like 101" now. Before this idea I was thinking 109-110" on the same length of chasis, which can be accomplished with little work by swapping springs.

With this doubler idea I would prolly add another 6-8" of frame in the rear and move the current spring hangers back to match the longer frame.

Unless I can figure out the driveshaft stuff better I may just go with my first idea and slap the 208 in there by itself, so that I can wheel sometime this century and slowly figure out the doubler stuff. With the 208 I will still be geared at 100:1.

DRAGOONRANCH
06-28-2010, 09:46 AM
Yeah 101 is short, the 110 ought to be pretty good and not having to run huge tires. I still don't think you will need to run a double d-shaft up front though. I plan to stretch the front ~8-10"s (along w/ moving the rear forward the same amount) and the shaft will still be just fine. This should get both of my shafts equal if I plan right.

stx4wheeler
06-28-2010, 09:49 AM
Damn ed are my 42" iroks considered small?:flipoff2:

DRAGOONRANCH
06-28-2010, 09:54 AM
Oops, forgot you had stepped up. :laughing:

Can't wait to wheel with ya!

stx4wheeler
06-30-2010, 01:56 PM
Alright, now that I have got quite a few measurements on long front d-shafts and doublers, now let's talk about the shafts and adapter design.

Alright, first off I'm not an engineer and don't know lots about machine work, so some of this may be stupid questions.

As far as the shaft goes I would like to run this doubler with the stock unmodified ford np 208 shaft for a couple reasons.
1. Cost
2. Having an easy way to get another shaft if it was ever to break.
Technically speaking isn't a longer shaft stronger because it will take more twist before it breaks?

The stock tailcone has a bearing to help support the rear output, do you all think that it would take some stress off the shaft if I incorporated it into my new adapter?


Next thing to be adressed is adapter material. I would like to make the adapter out of steel because I can do any welding or modifying that would need to be done myself at home without having to take it somewhere to be tig'd if it was aluminium. I know someone has everything to weld aluminium, but this is not a project that I want to be practicing my aluminium welding on. The benefits to an aluminium adapter would obviously be weight and it would be easier to drill all of my holes in.
Most doublers use aluminium adapters isn't this because of my above thoughts on it being lighter/ quicker to machine, or is there something I'm missing?

Now the easiest way to make an adapter would be build the 208 side adapter flange off of the current 4 tailhousing bolt holes like I have pictured in my first post. Most doublers like this remove the whole back half of the case and use a completly new plate flange that mimicks the bolt pattern of the case. I think this would be mainly to get the overall doubler shorter, but I could see that it might be stronger since you would be spreading out the weight of the 205 on more like 6-8 bolts instead. I'm leaning towards going this route.

stx4wheeler
07-27-2010, 10:37 AM
Frick doubler T.O.D at 1025am. :gigem:

DRAGOONRANCH
07-27-2010, 11:32 AM
wtf happened?

stx4wheeler
07-27-2010, 12:27 PM
wtf happened?


The answer lies in my build thread.:gigem: