Fredvon4,

My truck has the following after market items. I am curious as to why you dislike the Gear Vendors. That is my favorite add on that I would not want to be without and really helps in the hills with the 1/2 gear up or down.

1999 Ford F350XLT, White, CC, SB, SRW, 2WD, V-10, Auto, 4.30 LS Rear End, Borla headers, downpipe & exhaust, K&N Filter, 265-75-R16'S, Towing&Camper Package, Stabilizer Bars, BF Goodrich Velvet-Ride Shackles, Power Programer, Gear Vendors Under/Overdrive, Line-X Bed, Amsoil Synthetic Oil in everything, By-Pass Oil Filter System.

Thanks, LIKENIT

 

Re the gear vendors.... I know of a few units that do not like compression loads and grenade leaving you stranded on the down side of the mountain....do a google search and see what pops up in RV forums.... I can not remember which units were prone to this dynamic but one of them is big trouble for mountain towing..... most of the time folks set them up to add a second OD and do not us it as a reduction spliter.... if you have used that brand in the past and know well how it works and how to use it ....go for it...

you asked earlier this "If the H.P. starts declining slightly after it's peak of 4,000 & torque has declined down to 150 lb ft at 4500, why would increasing rpm create more power."

The amount of HP and torque (TQ) to move any load at a speed is really relevant to the TQ curve as you are asking but you have to remember that with the gears you get to MULTIPLY those raw numbers

at 1:1 and 4500rpm your curve says 150ft pounds (at the fly wheel)

times 4.30:1 will give your axle 645 Ft pounds of TQ applied to the center of the tire... from there the math gets weird factoring the vector angles to arrive at the rolling force to the ground...

Now at that point if you shift to a lower gear and stay at 4500 rpm you multiply the new gear factor in ---------let's just say the next gear lower is 2:1 ratio... you just doubled the 645 force to 1290ft pounds to the wheel a 100% GAIN....

Now assume the TQ curve falls off like you see on the chart to 100 foot pounds around 4700 rpm... your lower gear still is multiplying it at a higher ratio then it is loosing from motor power loss...

By the time you are down to 2nd or 1st gear and 5200 max rpm you are still applying more torque to the wheel even with the top rpm power loss

Of course you already know this.... your mods are about as good as can be done to the 99 2v V10... your gears and tires are as optimum as can be....

your next level includes a 2005 or up 3v V10 or a super charger.... lowers gears are not going to do you much better then what you have

Your big F350 is a great truck but I need to tell you that the 21k+ tow load is too much for the size brakes on you 99... so make sure the trailer brakes are always working perfectly....

too fast, down hill ...off camber... and faded out pads does not make for a happy ending... be carefull brother......

wisdom and experiance here...not a safety **** but just a been there done that observation......

 

Fredvon 4,

Thanks again. You sure sound like you know your stuff. I'm very impressed and appreciate your taking the time to explain this. I am aware of not using Gear Vendors to hold back a load going down hill. There literature that came with the unit warned of that & to stay in the factory gears.
I am also well aware of exceding my weight limits by about 1500 lbs right now. I told my wife when she said this was the trailer she wanted that we might need a new truck also. As protection for problems, I added hydraulic disc brakes as one of my trailer options. Those are really something. I can't believe the difference they make. I can feel the trailer slowing the truck down.
I'm a very careful driver and always keep a good distance between myself and the vehicle in front of us. I don't tow over 60 other than when gaining momentum downhill as I approach a hill and prepare for downhill grades by getting into second or low as I start my drop. As I start picking up speed, I brake relatively hard to slow down and get off the brakes to allow cooling between braking. At the present time, we travel pretty much North & South between Mn & TX with the seasons. I will need to experiment on some steeper grades before I consider the Mountain Country and will most likely not go there until we have a new truck.
I don't buy until I have the cash for the purchase, so it may take another 1-2 years before I can upgrade trucks and head for the mountains.

LIKENIT

 

Gearing even lower would help. There are some guys on hear that have 4:56's.

If you truck is a dedicated tow rig you may even want to go lower.

Sounds like you need a F-450 to F-550. Or maybe even a F-650 there are nice.

 

I'm very glad Fred has stuck around all these years

 

[QUOTE=LIKENIT]I am curious as to why you dislike the Gear Vendors. That is my favorite add on that I would not want to be without and really helps in the hills with the 1/2 gear up or down./QUOTE]

Now you got me curious. I though the GV or US Gear units gave you an overdrive or and underdrive unit. Does yours do both? What do you mean by 1/2 gear up or down?

I also thing a 4.30 rear axle with an overdrive auxilary tranny would be sweet. I have 3.73 gears so a double overdrive would be too steep.

BTW, I understand the US Gear unit is okay to use for engine braking.

 

Sport45,

The Gear Vendors is a true Under/Overdrive http://gearvendors.com/
where the U.S. Gear based on my understanding is one or the other that you decide on when you purchase. I don't think you can split gears, because you can not shift on the go. I may be wrong, but that is what I recall when researching it in 99.
With my 99 3 speed w/overdrive, I have 8 gear selections on the fly and it can be operated in a manual or auto mode.
When towing, I use the manual mode. If I was starting from a dead stop to go up a grade, I would activate the Gear Vendors by selecting manual operation & stepping on a switch on the floor, like a dimmer switch us "Old Foggies" grew up using to dim our lights. I would select low gear and start out. Gear vendors will auto select 1/2 over 1st gear half way to 2nd gear & shift up. The next step is for me to select 2nd gear on my tranny, let it shift and then hit the floor switch to disengage gear vendors and go to direct 2nd gear. As I build up rpm's to the point I want to shift up, I hit the floor button and go to 1/2 gear over 2nd. I then repeat the process used earlier to 3rd and then 1/2 over 3rd, then to overdrive. If I was pulling a steep grade I would probably have stopped in 2nd or 1/2 over 2nd. If finished climbing I would continue on 4R100 overdrive and if on the level with a good tail wind or a gradual downhill, I would then go to over/overdrive.
At 70 in 4R100 overdrive I'm turning about 2400 rpm and when I go to over/overdrive, I drop down to about 1900.
The only time I would be going 70 would be with just my truck, I try to stay around 60 when towing. With the 4.30 rear, I can get into over/overdrive with a tailwind in the flat or whenever I'm going downhill slightly. If I am cruising along and approach a grade, I just manually walk it on down as I choose. It is easier shifting down than up. Going up takes a little practice. Again, for the "Old Foggies" on here, it's a little like "double clutching" in the olden days.
In auto mode, I just select auto and it starts out and shifts into all the regular 4R100 gears until it hits about 47 mph, at which time it shifts into gear vendors and auto shifts when needed
When Gear Vendors are added to motorhomes, they usually lock out the over/overdrive to prevent the driver from damaging the tranny pulling to much in overdrive. With a 3.73 rear, I don't know what they would recommend. I had a private party the Gear Vendors recommended install mine, as I was not near the factory. They are very particular about the person installing the units. The guy that did mine said he would not lock out over/over in mine because of my 4.30 rear and using as our get around vehicle when parked.
I love this thing and would definitely put another one on any new truck I purchase. It not only allows you to be geared correctly for the job, but is fun to drive. I have always had sticks in my cars and enjoy being in control of the auto trans some.

LIKENIT

 

Unless I'm missing something, you are describing an auxilliary overdrive. For your application it works just like a two speed rear axle with ratios of 4.30 and about 3.55. I think that is pretty much ideal. If you had an underdrive feature you'd be able to select a low-low gear as well. It doesn't sound like the GV does that. (I don't know of any auxilliary trannys that do that.)

Thanks for the great description of how it works and the report of your findings.

 

Sport45,

You are probably right in describing it like a 2 speed rear axel. I understood the US Gear to be either an under in all gears or an over, but it's been awhile. I really don't need a lower gear with the 4.30 in my application. I do wish I had a lower gear in reverse. That would be nice, but I don't want to go to a 4x4 to get it. That would be my only reason for a 4x4 with my use.

LIKENIT

 

Sport45,

You are probably right in describing it like a 2 speed rear axel. I understood the US Gear to be either an under in all gears or an over, but it's been awhile. I really don't need a lower gear with the 4.30 in my application. I do wish I had a lower gear in reverse. That would be nice, but I don't want to go to a 4x4 to get it. That would be my only reason for a 4x4 with my use for the 2 speed transfer case.

LIKENIT