F-250 / Super Duty / Diesel

2 speed differential?

Old Mar 7, 2006 | 12:01 PM
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2 speed differential?

Does anyone make a 2 speed rear differential for Ford trucks?
 
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Old Mar 7, 2006 | 06:40 PM
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Nope.
 
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Old Mar 7, 2006 | 11:58 PM
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I don't believe they make a two speed diff, but you might try an underdrive/overdrive unit that attaches behind the tranny. Like this one:

http://www.gearvendors.com/f2wd4s.html

There are quite a few vendors that sell similar ones.
 
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Old Mar 8, 2006 | 07:52 AM
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Originally Posted by TxDrifter
I don't believe they make a two speed diff, but you might try an underdrive/overdrive unit that attaches behind the tranny. Like this one:

http://www.gearvendors.com/f2wd4s.html

There are quite a few vendors that sell similar ones.
Thanks!

Wow, $2900?? That's quite a bit-o-moola that would probably be better spent finding a brand new manual trans.
 
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Old Mar 8, 2006 | 06:57 PM
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Are you replacing a bad transmission? If so how would a 2spd rear or an over/under drive fix anything. If you're just wanting more gears then you're SOL there too. Nobody has made anything that would work with more than 6 gears for the PSD. I'm sure you could have one made but it would be a complete one off custom job. I'd be suprised if something like that is gonna run you in the $7000 minimum range by the time you figure out exactly how to design it, source the parts, and then have it built and installed. Then on top of that you'd need new driveshafts (need those with a GV or a US Gear unit too). What is it exactly that you're trying to do?
 
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Old Mar 8, 2006 | 09:36 PM
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Originally Posted by powerstroke73
Are you replacing a bad transmission? If so how would a 2spd rear or an over/under drive fix anything. If you're just wanting more gears then you're SOL there too.
I'm actually looking for options for my 1995 F150 XL. I figured this group would know the most about 2 speed diff's.

Ideally I'm looking for a 6 speed (with a lower first gear) to mate up with the 302 V8.
 
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Old Mar 9, 2006 | 07:22 AM
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That was only one vendor. Look around a bit, some might be less expensive. I think most are over the 1500 dollar mark.
 
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Old Mar 9, 2006 | 04:53 PM
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Really the only 2 making a gear reduction box like that is US gear, which goes between the transmission and transfer case, and Gear Vendor, which goes on the ouput of the transfer case. Both are priced around $3000. You might be able to find some no name one out there for less, but I question the quality and availability. You should have mentioned what truck this was for, woulda saved some time. There has not been any 6spd trannies made to work with your 302. The one with the best highway ratios is the ZF5, but thats what you should have now anyways. If you're doing this for mileage the only options you have are to slow down and don't drive like a raging maniac, and/or a gear change. What gears do you have now? Some 3.08 gears will help mileage but kill the low end power and eliminate almost all towing and hauling capacity. 3.55 gears is a decent medium between the 2. To give you any more help we need the WHOLE story this time. What are you looking for or trying to do with the truck (mileage, low end grunt, etc). Are you driving mainly highway or offroad? Are you hauling things? How is the truck setup (4x4, lift, tire size, current gear ratio, etc)? A good view of what you're going for will help in finding the right setup.
 
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Old Mar 9, 2006 | 07:07 PM
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You can probably find one in a junk yard or on E-bay. I doubt you'll find anything under the 2.5 to 5 ton range. It will also probably be geared so low that you'd probably be better off re-gearing your axle.


For everyone else here is a small explanaion of what it is.

http://www.findarticles.com/p/articl...03/ai_n9397819

Two-Speed Axle Advice

We really enjoy this column and find it very informative. I have a 2001 Ram 2500 (Quad Cab, diesel, automatic transmission, 2WD, 3.55:1 axle ratio) and pull a Sunnybrook 29RBS trailer (dry weight 5,874 pounds, gvwr 8,600 pounds), usually to New Mexico in the summer.

I am considering changing my 3.55 axle to a two-speed axle to give me a lower ratio for towing. I would like your advice on whether this is a good idea. I thought it would put less strain on the transmission (especially in hot New Mexico), as well as give me more torque at startup and on hills. I also wondered about possible effects on the computer module, etc. I will look forward to your comments and recommendations.

DON ABBOTT

STOW, OHIO

Two-speed axles are designed for medium-duty trucks with dual rear wheels (not the singles your truck has) and they're designed to work with manual gearboxes so you can de-clutch on shifts to keep them from grinding. They have completely different wheel-mounting flanges, bolt patterns, U-joint flanges, spring mountings, shock-absorber mounts and brakes. Most also require a parking-brake assembly mounted on the back of the transmission. It would also drive the computer crazy. As a result, you'd have to revamp your whole truck. Your best bet is a two-speed auxiliary transmission with underdrive, or get rid of the automatic tranny and get a truck with a manual six-speed. - KF.


Here is one from International.
http://www.internationaldelivers.com...pecbyspec4.asp

Two-speed rear axles allow a shiftable axle ratio for extra reduction. However, today’s transmissions offer a wider range of gear ratios, making 2-speed rear axles often an unnecessary expense that adds potential maintenance problems. Consult your dealer to determine if a two-speed axle is necessary for your application.
 
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Old Mar 9, 2006 | 07:50 PM
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Originally Posted by powerstroke73
What gears do you have now? Some 3.08 gears will help mileage but kill the low end power and eliminate almost all towing and hauling capacity. 3.55 gears is a decent medium between the 2. To give you any more help we need the WHOLE story this time. What are you looking for or trying to do with the truck (mileage, low end grunt, etc). Are you driving mainly highway or offroad? Are you hauling things? How is the truck setup (4x4, lift, tire size, current gear ratio, etc)? A good view of what you're going for will help in finding the right setup.
I'm looking for a lower first gear for lower-speed mild-offroading and stop and go traffic creeping. There's a slight possibility of light towing (ATV in a trailer, motorcycle in a trailer, etc). Changing the final drive ratios of the front and rear will be nearing $1k (including labor) which is why I'm searching for options like a 6 speed or a 2 speed rear diff.

It's a 4x4 stock tire size, stock suspension, stock everything.
 
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Old Mar 10, 2006 | 05:57 PM
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You can always use 4lo for crawling, thats what its there for. It can be used on the street, just leave your hubs unlocked and you've got 2lo. For a swap you can always put in an NP435 trans. That has your granny first gear, but has no OD so any and all highway driving is gonna suck. You could always run a 435 and a US Gear unit. What I don't understand is that you're saying how you think $1000 for new gears is expensive. The price is about right and is actually pretty good for both axles. Usually its $700/axle ballpark. To be flat out honest thats your cheapest option. A 435 isn't going to do what you want by itself. There is no such axle that does what you want, and a 2.5 or 5 ton rear just isn't going to fit without alot of work and will be more than $1000 by the time its done. You wanna play you gotta pay. You could always setup your gears yourself if you wanted to. It'll save about half the cost, but you'll need a few special tools and some mechanical sense. I'm doing that on my wheeler truck. New full spools for a D44 and 9" with 5.38 gears and full install kits for both is only $600. To have a shop do it is easily that much money again. Depending on what gears you go to it might be cheaper because you wouldn't need a new carrier.
 
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Old Mar 11, 2006 | 10:56 AM
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I didn't say $1k was expensive, I was saying it was a motivating factor for checking out all my options.

Also, 2 lo isn't an option since traffic speeds up so quickly and erratically. I'm looking for a gear for creeping, not low speed rock crawling type stuff.
 
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