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Changing to a driver's side drop

four_by_ken

four_by_ken

1/2 ton status
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Just starting on some real planning to get the 406 Mogs under my Blazer.

Currently running a TH350 with a 203/205 doubler.

I have finally convinced myself to sell the 203/205 to make this work since I need to go to a driver's side drop.

What are my options?

I would like to stick with a 3 speed option, but I think costs is going to drive me in another direction. I Would love an Atlas or Stak solution, but they are expensive.

I could go with a divorced t-case from a Ford, but I am not sure I want to go with a divorced because of driveline length issues.

So, what are your thoughts? I am not set on sticking with the TH350, but that is the plan for now.

:crazy:
 
I think it might be possible to use a Chevy 203 range box with a Ford (drivers side drop) 205. I know I've seen people doing it on Pirate. I don't know if the adapter would have to be changed or redrilled.

Another option would be to use a drivers drop case out of a 88+ truck.

EDIT: I looked on ORD's website, they do have this option avalible.
http://offroaddesign.com/catalog/CustomDoubler.htm
 
toomany said:
I think it might be possible to use a Chevy 203 range box with a Ford (drivers side drop) 205. I know I've seen people doing it on Pirate. I don't know if the adapter would have to be changed or redrilled.

Another option would be to use a drivers drop case out of a 88+ truck.

EDIT: I looked on ORD's website, they do have this option avalible.
http://offroaddesign.com/catalog/CustomDoubler.htm
Click to expand...

Yes, I could redo the doubler and go with a Ford 205. But, I am not sure I want to spend the money for a doubler again. I think I would need to change my 203 also because of input or output shaft problems with the Ford 205.

If I skipped the doubler, I dont think a Ford 205 will mate up to a GM trans though.

Will the 88+ t cases work with a TH350 or TH400? What is the 88+ equivalent to a 205? I am not very up on the 'newer' stuff.
 
You could offset the cost of the new adapter by selling your old one. I'm sure finding the correct input gear for the 203 would be fairly easy. Maybe ORD could source one for you.

As far as I know, a Ford t-case will not bolt up to a GM trans without a custom adapter.

The 88+ t-cases (241?) should be able to be adapted to a Th350. As they came behind 700r4's, and you need the Th350/205 adapter for a 700r4/205 combo. No reason it shouldn't work the other way. May need a new input gear though, I don't know the spline counts. They may have even come behind a Th400, but I doubt that since Suburbans switched to 4l80's (I think) in the later years.

I don't know what the 88+ equivalent to a 205 would be. My guess would be a chain driven aluminum case though.
 
There's no reason to change the input/output on your 203, just tell the company you get your doubler from that you need an intermediate shaft for the chev203/ford205 combo
 
In order to use a doubler you would need the driver drop version doubler adapter and a Ford t-case and you couldswap the chevy 205 input into the ford case. Unfortunately when you buy a new doubler it comes complete so at that point you just order one for a GM 203/Ford 205 then sell your current douber.
 
four_by_ken i am looking for a doubler for 203 to 205 gm setup. drop me a pm or let me know. i might buy yours if the deal is right and brand i want.
 
You can mount a Ford to a GM tranny. I used a Ford 205 with the short 32 spline input, 208/241 adaptor, and a 2" thick spacer. The holes don't line up perfectly, but you could elongate 2 of the holes to line up. Had to notch the adaptor for the shift rails, not hard to do. Advance Adaptors sells a kit for 700 to Ford 205, includes an adaptor and a spud shaft, can't put a 27 spline input in a big bearing case.

somewhere I have pics of the 400/Ferd 205....
 
I understand the desire for a multispeed t-case, but wouldn't the gearing in the 'mog axles make up for a lot of the low range that may be lost for giving up the doubler? (assuming the 'mogs have somewhere around 7.56:1 gearing, versus the lowest available of 5.38 for the 60/14 bolt combo.......correct me if I'm wrong).

The NP241 t-case is the only driver's side drop t-case I can think of used in the '88-up trucks that should be a relatively easy bolt-in. There were some larger t-cases later on but I'm think they might not physically fit between the frame rails of a K5, but not 100% sure. The nice thing about the 241 is the 2.72:1 low range, when combined with a presumed 7.56 axle gear and TH400 nets a 51:1 crawl ratio. Comparatively a TH400/doubler/5.38 axles gives 53:1, and I doubt that difference would even be noticable.
 
Mog axles are 6.x:1. So, not THAT low, but still pretty low. The majority of what I run is mud... deep mud. So, I have to keep the wheel speed up. But, if I can still get that creepy crawly gear without too much trouble, I would like to do it. If I have to make a choice between the two... I want the gearing for the mud. For 75% or more of my wheeling... the double low with my current setup would not be used. I think I am talking myself out of a doubler with the mogs more and more each time I think about it.
 
I run all the time with 78Buford with a moderate but torquey (500 ft-lbs.) big block on 42's with only a 19:1 crawl ratio (auto trans). We have lots of mudholes and muddy hills and rocks on the trails around here also, and I've never seen him NOT be able to hit 4,000+ rpm if needed in any condition. On the other hand the engine has enough grunt to do moderate rock-crawling (trails like Widowmaker in Slade/Natural Bridge, and Harlan except for the super hard-core/technical rocks...and he doesn't run those for other reasons besides the gearing).

Assuming a TH400 and 205 combo (worst combined gear ratio possible), any axle in the 6.xx:1 range would give you a substantially lower crawling gear.
 
I am not really concerned about being able to hit the RPMs. I think my 468 will work out nicely for that. But, just because I am hitting 4500RPMS... that doesnt necessarily mean I will have the wheel speed I want for the bogs. See where my concern is?
 
throttleissues said:
Have you seen the way this guy did his doubler? He used the 203 part backward to give him highway gears with mog axles. Pretty innovative.:D
http://www.bc4x4.com/fv/2002/hulk/
Click to expand...

That is pretty cool.

But, I dont think I will need highway speends. :wink1:

I just have to be able to really spin them when there is 40+ inches of thick slop. Gotta clean out the treads.
 
four_by_ken said:
I am not really concerned about being able to hit the RPMs. I think my 468 will work out nicely for that. But, just because I am hitting 4500RPMS... that doesnt necessarily mean I will have the wheel speed I want for the bogs. See where my concern is?
Click to expand...

Use the next higher gear in the trans! Assuming a TH400/205 combo with 'mog axles, 2nd gear low range is about the same as 19:1 but you still have 1st gear for crawling.
 
6.2Blazer said:
Use the next higher gear in the trans! Assuming a TH400/205 combo with 'mog axles, 2nd gear low range is about the same as 19:1 but you still have 1st gear for crawling.
Click to expand...

Yeah, I guess thats true. I dont have a manual valve body in the trans... but that can be changed.
 
four_by_ken said:
Yeah, I guess thats true. I dont have a manual valve body in the trans... but that can be changed.
Click to expand...

I don't have a manual valve body either, but it's pretty easy to get second gear. In low range my completely stock 700r4 will upshift to, and hold, 2nd gear at like 5 mph under light throttle. Once it shifts to 2nd I can then hit the gas.
 
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