Hello folks. I've got a 2000 F250HD V10 4x4, manual 5 speed, reg cab, long box. Just traded campers, need more pulling power. Can't afford to trade trucks, so am looking into ways to give my truck more power. I've read the V10 forum from top to bottom, and have looked into chipping it, changing the exhaust, changing the intake and air cleaner, even looked into a super charger. There are pros and cons to all of them. I recently started reading into auxillary transmissions, specifically ones from Gear Vendors, and US Gears. The more I read about them, the better they look. I've requested info from both outfits, and am wondering if any of you folks have experiences with either of these units. If you do, would you care to share them? Pros and Cons? Is either one better suited for a manual shift rig? The Gear Vendors unit is an over-drive unit, the US Gears unit can be ordered either as an over-drive or an under-drive unit. Any advantage to one over the other?

Sorry for all the questions, I'm just trying to gather as much info as I can so I can get the best setup for my $$. Thanks in advance

Corm

 

Which way do you want to go with your gearing, up or down? That will decide whether the Under or Overdrive is for you. For more highway speed, go up. For more towing power, go down.

The Underdrive lowers all the ratios in your transmission, like a 4wd transfercase's low range gear, but not as deep. This will give you more pulling power and less speed (more engine rpms for any given vehicle speed, compared to what you have now). You can use it to split the gears or run it straight in Low or High. Running it straight in Low would be like having a lower axle ratio in the truck, say 4.30 instead of 4.10 (bigger numbers are lower ratios). I don't remember what the underdrive ratio is on the US Gear unit, so my 4.30/4.10 example is just for illustration, not an exact comparison with that unit's ratio. You can do a comparison by multiplying the uderdrive ratio by your current axle ratio to find out what the overall gearing would be with the underdrive in low.

The Gear Vendors and the Overdrive from US Gear raise the overall ratio. You would have double overdrive with the trans in 6th (assuming your truck has a ZF 6-speed) and the overdrive in high. That won't help you at all with towing, but it will give you a higher cruising speed than what you have now.

You can split gears with them too, but you already have 6 gears in the transmission and the gas engine has a wide enough powerband that it doesn't need any more gears between 1st and 6th. If you had a 3 speed auto like I have in my truck, splitting the gears would be more useful since the jumps between gears are much wider in my trans (C6).

Sounds like what you need is either an axle gear change to a lower ratio than what you have now, like 4.30 instead of 3.73, or the underdrive unit and run it with the underdrive in low when you're towing. The underdrive is a nice choice if it happens to have the ratio that you need and you have the money to spend on it (they're not cheap). Because it goes between the transmission and the transfercase, the truck will need some modification to put it in. The axle gear change is a good choice if your'e on a budget, aren't up for doing modifications to the truck and are willing to live with a compromise between speed versus power.

I had a similar situation with my truck. Here's what happened:

My truck came with a 3.55 axle ratio and that was too high (smaller numerically) than what I needed. My engine was operating below it's optimum powerband and bogging out on hills, causing me to do alot of driving in 2nd gear when towing, which I wasn't too excited about. I looked at an underdrive unit, an axle gear change, a transmission gear change (lower gears in the same tranny) and a transmission swap to a different tranny.

I also looked at power upgrades to the current engine, rebuilding it as a high performance stroker motor, swapping to a bigger motor, swapping to a diesel, and trading the truck for one better suited to towing, power- and gear-wise. For reasons that are beyond the scope of this discussion, I elected to go with gearing mods instead of motor mods.

Narrowing it down to gearing, here's what I did:

I decided that the cheapest and simplest way to get more towing power from my truck was to just change the axle ratio. I changed from 3.55 to 4.56 and it did make a huge improvement in towing power. I did lose some highway cruising speed though, since my transmission has no overdrive gear in it. The optimum thing for me would have been to change the axle ratio like I did and then either add an overdrive unit, like the Gear Vendors or US Gear Overdrive, or swap to a trans with an overdrive gear in it. I can still do that in the future, but for now I just have the axle gear change.

Since you have overdrive in your transmission, you can get away with a lower axle ratio and still have descent cruising speed. How low you can or need to go depends on what size tires you're running, how much weight you're pulling, whether you live in the mountains or the flats, and how fast you like to drive on the freeway.

The gear change was $1500 for both axles (4wd truck, professional installation, top quality parts). While the axles were apart, I also took that opportunity to put a locking differential in the rear axle, for another $300. I chose the Powertrax Lock Right and I'm very happy with it.

For comparison of cost, an over- or underdrive unit would have been about $3000-3500 installed, with driveshaft modification. Even without installation and driveshaft mod, the over- and underdrive units are about $2500 alone. A transmission swap to an E4OD, heavily built for towing, would have been probably about $2500-3000 complete and I would expect the trans rebuild alone would have been around $2000 for a top-quality job with all updated parts, since the E4OD is so problematic when used for towing without beefing it up.

I chose the least expensive method, accomplished what I wanted to accomplish, am very happy with it, and I live with the loss of top speed. I weighed all the pluses and minuses and that was the best solution for me: give up some high speed for more pulling power and spend the least amount of money. If I had another 3 Grand to put in the truck, I'd put in a Gear Vendors overdrive and be grinning from ear to ear . With the low axle ratio and the overdrive gear, I'd have the best of both worlds. Untill then, I smile happily and drive a little slower .

Anyways, hope that gives you a few ideas to kick around in your quest for the perfect Ford truck

 

SoCalDesertRider - Thanks for taking the time to respond. Much appreciated!

I've thought about changing my axle ratios (the truck came with 373s), but because it is a 4 wheel drive, the cost of doing that gets pretty expensive, and when complete, I'd have a truck that would pull better, but would use a lot more gas all the time. I'm also concerned the extra RPM's over time would shorten the life of the engine, and I plan on keeping this truck for a long while.

I live in Northern Vt - hilly country. With the 5 speed tranny I have, which gives me an overdrive, I'm leaning towards the US Gears underdrive unit. The ability to do split shifts with this unit would be very nice. Quite often I find myself in the situation where high gear is too high for a hill (when pulling my 30' fifth wheel), and 4th gear is a little too low. A '4.5 gear' would be just right. I just want to be able to keep up with traffic at interstate speeds. I hate getting stuck behind a camper that is trudging along 15 - 20 miles an hour below the speed limit, and I don't want to do that to anyone else.

Something I haven't considered is a change of the primary transmission. I didn't know something like that was possible. Do you or anyone else know if it's possible (or feasible) to exchange my 5 speed primary tranny for a 6 speed? Is there a company that sells such a thing? That might give me what I need without having to modify my rear drive shaft, which either of the auxillary transmissions would require.

Again, Thanks for your input. I really appreciate it

Corm

 

Hi Corm: I have been looking at both US Gears and Gear Vendors units for my truck (04/6.0L,3.73, 6sd, CC, 2wd) and am going to go with a Gear Vendors.
About 80% of my driving is towing. The only disadvantage of not having the underdrive, is there is no gears below 1st. I don't need that anyway. The Gear Vendors also has the advantage of 6th over when empty (close to the final drive ratio of a 3.08 rear axle, ) When towing I will have the option of 5th over (approx a 4.10 rear axle ratio) and of course 6th gear as well. In my case 5th or direct drive is the strongest gear in the transmission, so it only makes sense to be towing heavy loads in the 1-1 ratio and let the auxillary unit take the stress. Overdrive is the weakest gear in the transmission and develops more heat than direct drive. with the underdrive units you will be towing in overdrive most of the time, to maintain highway speeds. This will stress your transmission more than with the overdrive unit.
If you calculate the final drive ratios avalable to you I think you will find the Gear vendors a better choice. I have calculated the ratios for a ZF 6 sp with an overdrive ratio of .28% and a Gear Vendors with 22%

5th 3.73 1-1 ratio = 3.73 final drive
5th over = 2.91
6th = 2.68
6th over = 2.09

Final Drive ZF 6 spd manual
4.10 axle ratio = 2.95
3.08 ratio = 2.22

As you can see 5th over is similar to a 4.10 and 6th over is close to a 3.08 (3.05)
Another thing to consider with U.S. Gears is that the transfer case will have to be moved and the front drive shaft length increased.
With the range of gear ratios avalable with the Gear Vendors Overdrive and its gear splitting ability through the entire range of the transmission. If you need a higher ratio than 3.73 you still have the option of 4th over,4th, 3rd over etc. I'm not sure there are any advantages to an underdrive unit.
Hope this helps. Rember my advise and $1.50 will buy you a cup of coffee. Blair

 

X GM GUY - Thanks for the info. I appreciate your time.

I didn't realize the US Gears product would require me to move my transfer case, and lenghtening my front drive shaft as a result. I'm still waiting for my literature from them to show up. One of the reasons I was thinking about their product is the gear lower than first available with the underdrive unit. I often find myself wishing for a lower first gear when I'm backing up my trailers. My older Ford 4x4 trucks with manual hubs gave me the ability to put the transfer case in low range, without engaging the hubs. I found this ability, essentially low range 2 wheel drive, to be quite handy. I miss it on my present truck with auto hubs, although I really like the shift on the fly ability of the auto hubs. A perfect setup for me would be to have a 2 wheel drive low range option available on the SOTF dashboard switch.

I've been able to read enough about the Gear Vendors product to understand that I would only have to shorten my rear drive shaft to install that product. I like that aspect. I do like the fact that they advertise the split shifting ability of their unit. I anticipate using '4th', '4th over', and '5th' the majority of the time when I'm traveling the interstates (I have a 5 speed transmission). I wouldn't anticipate using '5th over' very much. My understanding is the US Gears product will allow split shifting, but they don't seem to advertise it to the degree that Gear Vendors does. I wonder if it works as well or as smoothly?

I'm anxious for the literature I've requested for both products to show up. I was leaning towards the US Gears product, but now I'm 'on the fence' so to speak. I really appreciate your input. Thank you.

Corm