1-tonmudders 241/205 Doubler

[1-tonmudder]

After much deliberation and study I decided to build a 241/205 doubler instead of the traditional 203/205.My main reason for doin so was more lo-range(5.33-1) and lesss money.I'm usin the 241/205 kit from D&D machine(360-779-2500).Kit includes 241 adapter plate,indexing ring,shaft,and misc hardware. $514 shipped.

This kit is built around the round pattern 205 and a DSD 241 case that can be found in the late 80's Chevy/GMC trucks that had the SM465 4speed trans or the late 80's/early 90's model trucks with the 4L80E automatic trans.My 205 case was pulled from a 89 model 3+3 with the SM 465 trans.

I started with a teardown and inspection of things.Case was real clean inside.

 

[1-tonmudder]

That was pretty much it for the 1st day,but I did put the indexing ring on just to get an idea of how much I can clock it and I ordered some seal's for it.

 

[1-tonmudder]

This was spread out over a 2-3 day period of working on it a little at a time.I went to Napa and got a roll of cork gasket material to make my gaskets with..

After that I put the LH shift rail back in to determine where it would need cut.I cut it two inches from the end.

Since the index ring covers the hole for the shift rail you can't use it.

So I capped it with a 1-1/4 freeze plug.

 

[1-tonmudder]

I am twin sticking the 205 while it's apart so I notched the rails too.

Sice I have plugged one of the shift rails I have to run the rail out the back of the case.

So while we were at lunch one day we stopped by one of the local machine shops and picked up a scrap piece of 3/4 cold rolled rod.

I beveled both the rod and the shift rail so the weld would penetrate good.

I couldnt find a piece of angle that I didnt have to go out in the rain and cut off so I broke a piece of 16ga to lay the rod and rail in while welding.

I had the rail/rod tigged together

 

[1-tonmudder]

I spent about an hour smoothin it out to it would'nt bind when shifted.

Next on the list was to drill out the tailsection so the new shiftrail could go thru it.I used the rail print on the tailsection to go by and just center punched it and drilled it.

The rod/rail is 3/4 so I drilled it 7/8 to give it plenty of room to pass thru.This will give you an ideal of what it will look like.

I'm sure somebodies noticed how close the rail is the the speedo hookup,so to remedy that Im goin to use a Dodge 205 tailsection.The Dodge is the very same it just puts the speedo on the opposite side of the case

 

[4x4fever]

That's cool as hell steve !

 

[1-tonmudder]

The 241 I got was basically a core.It had a big hole knocked in the back 1/2 of the case from where the chain had broken.All the needed parts for the doubler were still good and for $50 I bought it.
This is all the parts from a 241 thats needed.

The kit came with no instructions at all,and there is very little info on the net about a 241/205 doubler.So with that bein said here's where I messed up.I ride with a guy who has a 231/300 doubler that was built usin D&D's kit.He said to cut the case along the casting mark.

WRONG!!! I know I should have checked before cuttin it but I didnt and it wound up bein about an 1/2 inch short in some places.So that put me to findin another case 1/2.I use to work at a trans shop and luckily enuf he had another one.I assume the 231's are cast a little different than the 241's.
I went and got another case and started over(after takin careful measurements).I used a port a band to cut it.

The kit comes with an alum slug to weld in but for some reason I didnt get one and wasnt waitin for it to get here so I used some square alum stock we had to plug the gap.The slug will need to be tapped for the bolts to seal off that end of the case.
Drake spent about 30 min weldin it up.

 

[1-tonmudder]

While he done that I made more gaskets.

I spent about 20 min with a file cleanin it up so it would seal good.

Here's what it looks like finished.

 

[1-tonmudder]

No real work done to it today,but I did get my case back from the machine shop.I had the case bored to accept a seal for the new shift rail.

 

[1-tonmudder]

That's cool as hell steve !

Thanks,I do what I can.

 

[Jeff B]

 

[Barnes 4wd]

Looks good Steve! Did you ever get your alternator charging correctly, if so what was the problem.

 

[1-tonmudder]

Yeah there was a fusible link down inside the harness that was burnt out.Took about 10 min to fix once I found it.

 

[JThomas]

awesome thread. I do worry about the gaskets between the cases and trans. I and 3 others have had the clocking rings and t cases come loose. I am thinking the gasket may compress in short time causing the bolts to become loose... even if locktite-d. I am not at all trying to rain on your parade. This is such a nice build, I don't want you to have this prob.

 

[jesster]

Good combo. Much better gearing than the standard 203/205


However, I wouldn't use the gaskets. Can't imagine that they would hold up.

 

[1-tonmudder]

Not raining on my parade at all.I understand the concern over the gaskets(and it might happen),but I have also been told that it's hard to get it sealed good,thus my plans to use gaskets.I ride with Johnny Sherman and his crew and he has the 231/300 and it leaks,and knowing Johnny I can't believe he skimped or cut corners just to get it done.
I had'nt heard anything about the bolts coming loose but anything is possible with what they get put thru.I have however read about the alum case gettin busted if not supported good.

 

[J.C.]

Great write up and pics Steve! Welcome to the low gear krawl krowd I know you'll enjoy the results! BTW, I too used a cork gasket on my 231/231 krawl box I just put in my XJ. EVERY ONE I've seen leaks and I wanted to see if this would be the fix. Between us we should get some good data.

 

[Jeep07]

Hey I'm glad that 205 worked out good for ya.

 

[Hokie_YJ]

It's Steve! This should turn the Blazer into a whole new rig. I can't wait to see it in action.

 

[1-tonmudder]

This should turn the Blazer into a whole new rig.

I hope so.I want to run the harder trails and one case with less than 2-1 reduction just don't cut it anymore.That is why I have always stayed out of the rock gardens.I had to flog it to death just to keep it movin.

 

[89wrangler]

Awsome detailed write up! Looking for the end result!

 

[rob92xj]

I've been planning on doing a 231/300 in my XJ someday I need to find a Dana 300(the closer to free the better) I have the 231 front half already.

 

[J.C.]

That is why I have always stayed out of the rock gardens.I had to flog it to death just to keep it movin.

Exactly! Now the big boy can play with the big boys

 

[1-tonmudder]

Ok so after a short hiatus I finally got back on this today.Pulled the old 400/205 out.

Since I went to a 241 case it requires a different lenth output shaft in the 400.Their are 3 different lenth's on the 400 output's and it depends on what case your runnin.They are as follows.
NP203
NP205-figure eight or racetrack pattern with the short input
NP-205,208,241-round pattern with the long input.
Since I had to change the output shaft and the 400 I was running had a ear broke off of it I elected to just completely replace the trans.I had a good lo-mileage 400 from a CUCV that originally had a 208 behind it so the 241 will be a direct bolt in.

Got the trans in and all buttoned up and started assmebling the 241.

Not a lot of progress for 8 hours work but considering all the distractions I done pretty good.

 

[1-tonmudder]

I also got these in last week.