I have a 2010 e450 (V10) based little motorhome with a 4:56 rearend
Ive improved intake and exhaust flow (K&N and Banks) and Im using a SCT custom tune. The power increase exceeded expectations and its much more drivable now.

Before these mods it didnt have the power to pull minor to moderate grades in any gear higher than 3rd, so at 55mph it would downshift to 3rd and run at 5000rpm if Id let it, which i wont so I end up pushing it in the 45 - 47mph range which is still too much Engine speed for me.

Now it has the power to use what I'll call 4th (since it only uses 5 gears) on the same grades but there is no way to lock it in "that gear". So i spend a lot of time trying to feather the throttle to coax it into "that gear" and keep it there, and then slowing down when the transmission figures out what Im doing and shifts to 3rd.

The alternative is to run at under 50 mph in 3rd. Ive heard many say 5000rpm is just fine for these engines,but to me it aint. And I now have the power to pull in a higher gear (and lower rpm) if I could get the transmission to cooperate.

So Im considering a Gearvendors OD unit to split 3rd getting me close enough to 1:1 (I think it would be 1:1.19) and keep it there, and also enjoy a higher final drive splitting the highest gear (5th, 6th - whatever) for what I hope would be better fuel economy under the right road conditions.

Questions are as follows:

1. Is there any way (aftermarket, tech trick, etc) to electronically lock the 5R110 into 4th or 5th to achieve something near 1:1?

2. Will splitting 6th with a GV OD, resulting in a total 45% (double) overdrive, put excessive strain on any component in the transmission?

Im fairly certain that GV will be happy to sell me a unit for $3300, but I'm not certain it is the only solution, and Im equally uncertain that it is safe to do so.

Ideas?

PS: I get the 1-2-3-5-6 vs 1-2-3-4-6 thing - its just a little cumbersome discussing a 5 speed with six gears, so I hope I haven't muddied the waters further with my attempt

 

GV's write up discusses what you are talking about.

They say no lock into 4th, and don't offer a way to do it. You would probably have to invent a controller or reprogram the computer to make that happen.

They say no towing in double OD.

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

 

I saw that on the GV website - I was hoping one of the more advanced members of this board had come up with something or knew of something. I can see by looking at all those servos that a device could be invented, and incorporated into the harness, with a switch on the dash or something like that, but its a bit beyond my capabilities.

 

Your trouble is not really trans or gears but inadequate power. The money would be better spent on a turbo charger with an intercooler. The gear vender product has its applications but that V10 just is not up to the task normally aspirated unless you can live with going slow up hills and in high elevations. I'm surprised a V10 with 4.56 gears has that trouble. Jus how much does this little RV weigh? Is it class A type?

 

I know you say you are using a custom tune but I don't know whose it is. I would talk to Custom Dynomemeter Chassis Tuning Products and Services - 5 Star Tuning because they can adjust transmission shift points too. May be able to get into the gear you want earlier and hold it longer based on your desires.

 

Goodwrench, Ive made considerable HP gains with what Ive done so far. My seat-O-the-pants dyno says around 50. As an example, towing 5000lbs now is like how it used to run towing nothing. And learning a bit more about this transmission, down shifting to 3rd on grades is 1.00 to 1.54. That would explain the radical RPM change causing me to slow down just to keep the thing at lower RPM when it seems like it could pull in a higher gear. Applying the GV OD to 3rd would get me approximately 1.2 which is currently not an option.

The rig is a 25' "B+" and only weights 12,000 and I normally pull around 3500lbs so I think (hope) 1.2:1 would be a useful gear ratio. (This is using ATSG and Gear Vendors data)

I dont mind slowing down when necessary, but it seems like Im slowing down because Im in the wrong gear, not because of lack of power, and because that second downshift is lockable, if I had a manual OD, I could run at 1.2 instead of 1.54 dropping engine speed by around 1100 rpm.

It would be an expensive experiment and Id have to drive 55,000 in double overdrive under near perfect conditions to pay for it in fuel savings which seems a bit unrealistic. But if it saves wear and tear, and makes the thing more drivable, pulling grades at 3900 at 55mph rather than 5000, or slowing to 45 mph, it might be worth it.

VWags, Im using 5 Star's programming and it was an improvement along with the intake and exhaust, but its 3 years old and might be out of date. I'll call them and see if they have an improved program.

 

My truck has a Gearvendor but it's a manual trans. Sorry I can't help