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I have a Zf5 manual from a 460 big block in my 97 F350 with the 7.3 diesel. I have 4.10 ring and pinion gears and I went to 35" tires, so even with the 7.3 running out of RPM with the 35's I get a decent highway gear (like 2200 rpm at 65 mph)
The nice thing about a 5 speed manual behind a diesel is you can shift when you want to....
I WISH I had more OD...for long runs (Like from Colorado to Idaho) I am sitting at 3000 rpm for hours at a time...something the 7.3 does not mind, but it would be nice to have a gear splitter or aftermarket overdrive so I could do 75-80 mph and get my rpm down to like 1800...but that's a big chunk of $$$$
You know this but a lot of people don't... IF you are looking to increase the tire size on your Rig, you first need to determine what you are going to do with the Rig and what rpm range is right for the engine you have; once you can figure that out, then you can look at tire size vs rpm and determine the best gear ratio.
The best of both worlds would be a low cost Gear Splitter for smaller truck, I like that... Go through the gears, then go through them again, sounds like good driving !
With a Diesel, you need to understand that rpm's are limited BUT you have torque to carry you through, so you can go long on the gear, or other words... a higher gear ration and if it is a 4x then a good gear range in the T-Case helps off road or pulling.
That's one thing I like about the Atlas-II/4.3, a nice low gear once you are at the off road site AND I can drive in 2x front or rear, so I can tow in 2x Low... but that's another story.
I digress, IF I had a Diesel, I think a nice Allision 6 six automatic would be nice, but there are others, and I would need to find out about them before going further. I was told that with the R2.8L-Cummins, the low range of the NV4500 wouldn't work as well as some autos..., i.e. too much gear I guess.
Cost of the automatics is another thing... way too high for new stuff, rebuilt, I am not sure.
Thanks for this thread and the info put here, good stuff to think on !
IMHO... if you are running the 4BT, the NP435 Trans, and the NP205 T/C, you should think a higher gear ratio, 4.10's or in that range... !?!
Again, off-road the T/C makes up for the higher gear ratio but on the Hy-Way/The Interstate/The FREEWAY, low gears don't work, and the Fuel Consumption with suffer too.
You guys have me thinking Diesel AGAIN !
For the time being, https://ford-rangers.com/view_post.php?post_id=14291 i'm pretty confident still applies for my needs.. The time for me to start taking this 4BTA down to the bare block is a couple years away now. Too many irons in the fire and I'm behind 3 maybe 4 months now on my goal of getting things done in time of Overland Expo West as it is. It was going to be a 3 vehicle display and now its a final 2 vehicle display.
As for the Cummins 4BT swap, my initial comments were based off of what others have been successful at and in use. Keeping in mind these arent based upon the stock fuel pump, turbo, governor valve-train, or power stats at all. Raising the HP & Tq for that matter will also change the behavior of how the trans and gearing work. I remember the premise also of Tq is what gets you down the track (street), Hp is how far down the track (street) it will get you.
Also, under new information and research; the Ford ZF5 Transmission will likely become mated to the 4BTa and NP205 Transfer case, NOT a NP435.
Shown below are some numbers based upon just transmissions and on 4.56 gearing. (i'll be doing 4.10 among other gears to get closer to what I want. Although I am not totally concerned about top end speeds, I don't want to be limited to 62 MPH either. If I can get what I want out of the setup, still touch near 90-105 MPH IF I HAD TO STRETCH OUT THE LEGS.. I'm happy with that. I have other vehicles for speed or towing. If I have to regear or build a custom axle(s) at some point among prepare for other concerns. It won't be a Ford Ranger anymore, it'll be just a Ranger Body on a custom chassis. Whole other issue which leads me into a 3rd project design I dont want to start on yet.
As much as I will go out of my way to indulge some criticisms or a LOL.. I'm really about building a poor-mans, capable, ALL-Terrain, type vehicle with some serious tricked out features wrapped in modern day MULTI-functionality & Purpose.., minus the .50 cal mount and turret, (Mini-guns are so much more the rage.. lmao jk). Ill get the other charts up soon.. its way late now.
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