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Discussion Starter · #1 ·
Ok...here's the deal, I'd like to go with as high of an axle ratio as I can...but 4.56's would push rpm's on the highway a little higher than I'd like...and I'd like to go higher than that...like 4.88 or 5.13. I don't drive much on the highway, but I would like to take more trips...and, I definatly need the as much gear as I can get offroad.

That leaves an overdirve trans, unless I kept near stock gears, and went with a 4spd manual with a granny low. Trouble is...after all the researching I've done, all the options suck.

AOD-never made in a big block bell housing, and debatably flawed internals. Expensive adaptor plates make it possible, but not anytime soon.

E4OD-from what I understand, they did make it in the right bellhousing, but you'd need some sort of expensive electronic module for it. On one hand, I've heard they're essentially a c6 with an overdrive gear/on the other, I've heard that they suck, and are prone to problems. But, I think iirc that the 205 would still bolt up.

Then, there's the option of an automatic overdive unit...which seems great...drops right in place of the tail housing of the transmission from what I understand. Kinda makes your 3 speed a 6 speed...but they're probably the most expensive option out there. Has anyone gone this route?

And, is there anything I'm missing, or any other options? I wouldn't mind going to a stick shift...but it's kind of sucks to have to deal with all the clutch pedal crap. Any suggestions or corrections are greatly welcome, and appreciated. Thanks, Jared.
 

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ZF 5 speed. Available w/ bb bell housing which I'm assuming works with a 400.

1-5 & R are 5.72 2.94 1.61 1.00 0.76 R4.66

That gives you overdrive so you can run 4.88's or 5.13's with those 38's, pluss a granny low first.
 

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I don't know of any but I'm sure it can be done. The biggest problem you have is having to fabricate a hydraulic clutch system in your truck ( the ZF uses a hydraulic clutch slave cylinder). My suggestion is to find a truck with a ZF in it that is complete and look it over before and see if you'll be up to the task of converting your truck over.
 

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Hydrolic clutch isn't too complicated if you can get all the original pedal and master cyl parts off a 250 or 350. You might also want to dump that 205 for a 1356 if you want lower gearing.
 

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ZF 5 speed. Available w/ bb bell housing which I'm assuming works with a 400.

1-5 & R are 5.72 2.94 1.61 1.00 0.76 R4.66

That gives you overdrive so you can run 4.88's or 5.13's with those 38's, pluss a granny low first.
anyone do that swap in a 78/79?
I swear I have seen a thread on someone doing this swap once here on FSB ?
 

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many have done a ZF - 205 in broncos. or later model broncos. same concept, just a little different. Check out the other forums.
 

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Discussion Starter · #10 ·
Cool, thanks for all the input. I've sort of considered a doubler...but, really it's the overdrive I want. With overdrive, I'll be able to run the highway easier...otherwise...even with a doubler, I'm still looking at a 1:1 ratio in 3rd. I really like the idea of the ZF. The only part of that that I don't like, is the clutch part of it. Mine is an auto now...and, it seems like it could be a pain to rig up the pedals...any one done it? I've heard about some firewall modifications that would be necessary...which also doesn't really bother me. Out of curiosity, what kind of clutch does it take? I think I remember reading something specific on a ZF swap but I can't find it. I wonder if there'd be a way to rig up a cable clutch? I'll have to crawl under a 2/350 and take a look.

I want to go with as numerically high a ratio as I can in the rear end, while still maintaining drivabliltiy. I've thought about it...and I can settle with 4.56, which would still be doable on the highway, no problem. But, If, and when I go to 42/44's it'll be a little undergeared. If I'm gonna do this, I'm gonna do this once. I've been doing some research...and with 38's, the difference between overdrive and a 1:1 ratio is 1000 rpm at 60 mph with 4.88's. That's huge. That's part of what really has me searching for an overdrive option.

I haven't done much looking about doublers...but the part that I think about, is the rear driveshaft. mine's already fairly short, and has a pretty harsh angle. I can't see it getting better with a doubler. The good part is, it would give me the great crawl ratio i'm looking for, and would probably be just as easy, or easier that rigging up a hydraulic clutch/clutch pedal and notching the firewall.

Thanks, and as always, any and all input is most greatly appreciated. Jared.
 

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Discussion Starter · #11 ·

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Out of curiosity, what kind of clutch does it take? I think I remember reading something specific on a ZF swap but I can't find it. I wonder if there'd be a way to rig up a cable clutch? I'll have to crawl under a 2/350 and take a look.
It's an 11" clutch. The slave cyl is internal so a cable would be really complicated (and dumb considering how simple the hydro setup is). Really, once you get the clutch pedal on the firewall all you do is run one plastic hydro line down to the transmission. Not hard at all. You do give up your auto, but the alternative is...well there isn't a practical one.
 

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Discussion Starter · #13 ·
It's an 11" clutch. The slave cyl is internal so a cable would be really complicated (and dumb considering how simple the hydro setup is). Really, once you get the clutch pedal on the firewall all you do is run one plastic hydro line down to the transmission. Not hard at all. You do give up your auto, but the alternative is...well there isn't a practical one.
That's true...a hydro setup would probably be easier than retro-fitting all the mechanical shift linkage crap. I'm still kinda on the fence...but, I know I want overdrive...and this might be the easiest way. I'd kinda like to have a manual, but I don't mind the auto. There's advantages for both. I'm not going to do anything until either my transmission gives up, or maybe when I go with a 460, just swap it all over at once. If I ever go with a stick shift, I'll go with the zf, definatly.

Thanks, Jared.
 

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Another opition that I have heard of is a NP542 with od. Its like the np435 but has an od and they were used in LARGE ford f450's and such. If I can ever get my hands on one cheap I will give it a try.

As far as not having a od going with a double setup. You wont realy need it. Just leave a higher ratio in your axles, you will have the doubler for lower gears ratios when wheeling. Just a thought. Good Luck.
 

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It's an 11" clutch. The slave cyl is internal so a cable would be really complicated (and dumb considering how simple the hydro setup is). Really, once you get the clutch pedal on the firewall all you do is run one plastic hydro line down to the transmission. Not hard at all. You do give up your auto, but the alternative is...well there isn't a practical one.
Actually just finished the ZF swap on my 93, much newer but same concepts. If your looking for a BB ZF they come with an external slave cylinder. I don't know any of the specifics on the swap for your year, but I know for sure that the BB zf's were external slave cylinders only.
 
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