Uphill Shifting Question
 

I've been pulling a 5th wheel camper for about five years - this will be the first year with the Gryphon with 87 custom towing. :D I had the camper out last week to get it inspected and I live in very hilly southwestern PA. Because it is so hilly, I typically tow with O/D off. Most of my trips with the trailer are to Penn State games in Central PA, so I do not see any flat land for the 4 hour trip. I noticed when going up the hills that it was shifting directly from 3rd gear / TQ locked to second gear instead of shifting first from 3rd gear / TQ locked to 3rd gear / unlocked. Is that part of the custom tune that Bill and Cody have put together? Is that better on the tranny to shift to 2nd then shifting to 3rd gear / unlocked?:hmmm:
It seems to me that the last few years when in stock mode it would shift to 3rd gear / unlocked before shifting to 2nd and that sometimes that is all that was needed to crest the hill at 55-60 mph. But if it's better in the long run to shift to second locked or unlocked I will learn to get used to the rpm increase on these southwest PA hills.

You ask an interesting question, DWR. I also tow, and I've never noticed if my truck shifts directly from 3rd locked to 2nd. Since I don't pull as much weight as you (about 3,600#) plus the stuff in the bed and often 4 people, I tend to tow with the OD on. (I've talked about this in past posts - as long as the transmission activity is low, I leave the OD on).

But, I know the transmission will go from OD locked to OD unlocked before shifting down to 3rd. Then, it kind of seems to me that my transmission does what yours does between 3rd and 2nd, but I could be wrong. I think maybe it has a lot to do with the grade of the hill and the weight being moved though. Here in Arizona we have several hills with 7%+ grades that are 10-12 miles long. I'm always in 2nd gear going up those hills, and I try to maintain 65 mph, since they're on the Interstates, where the speed limit is 75.

- Jack

Yeah, I wll have a better idea in about a month when it hits the highway for the first time with Gryphon. When I got the trailer inspected last week I only had it on country roads where the speed limit ranges from 45-55 mph.
I really like the way it pulls and shifts from a dead start - big difference over stock. I've been driving the truck since new - and I've always listened closely to every little noise - especially when towing - so I will just re-adjust my ears when pulling hills. I imagine it is much better on the tranny to shift to 2nd and pull the hill then to try 3rd gear unlocked and have to shift to 2nd anyway. Thanks Jack
-Dale

Uphill shifting w/OD locked out
 

I also lock out the OD in hilly areas with my 06 screw 5.4 towing a 7 x 7 x 18
5000 lb toyhauler to prevent constant shifting and keep temps down. It seems to me most of the time it would downshift from 3 locked to 2 locked,....if I leave the OD engaged it will shift in and out of lockup and the trans temp goes up as does the oil temp,...BTW my flat towing temps with deep trans pan, synthetic oils, 25% antifreeze with Water Wetter, 3:55 gears, 29.4" tires are as follows:
trans(flat loaded) 150- 165 hills 192 max
CHT 200 218
EOT 204 238 max uphill 110 ambient
Coolant 205 224 max

I have 600 lb tongue weight, friction antisway, rear axle sway bar,...very stable

This is all with Bill's custom tow tune,...

cheers !

Jcperform, I am just curiosity what your fuel economy is when pulling your trailer? I am running a similar setup and am getting what I think is horrible fuel economy, I am getting <7 mpg.

To help readjust your ears you could set one of your PIDs as COMM GEAR. This is Commanded Gear and says not only which gear you are in but also the status of the torque converter.

Readjust what? :hehe: I'll have to remember this, now that I'm entering my "twilight years", when hearing, and so on, starts to decline. :geezer:

- Jack

I didn't know hearing aids had the display output for gears...hmm I better pay attention....:cheesy smile:

No, but there's and App for that. :hehe:

Habbi98

I have a2010 supercab max tow with 5.4 and 3.73 gears. Gryphon with 87 towing tune. On average I get 10mpg running 65mph. If lots of hills it gets 8.5 to 9 mpg.

stl454, that mileage looks pretty good to me. I get about 12.5 mpg pulling our 3600# HiLo telescoping trailer at 65 mph. The "telescoping" feature means it has a smaller frontal area and much less wind resistance than you would have (towing height is only 72").

Habbi98, you didn't say what speed you tow at. If it's anything over 65 mph, your mileage is going to be KILLED due to the increased wind resistance and, you are really unsafe, since trailer tires are supposed to be kept to 65 mph max. I've learned a lot about trailer tires since getting our trailer, and I've got to say, I "baby" them now (also use the highest load range rated tires I can fit). The OEM Goodyear tires I had on the trailer both failed at 5000 miles within 2 years due to cord separation.

- Jack

Jack - the speed I tow at doesn't appear to be a factor in my MPG. I've towed it at 65-70max and at 55-60 and it appears to be the same either way. My dad has a 1500 GMC with a 5.3L and is getting 2-3mpg better when hauling this trailer in the same conditions. I have made minor performance mods (Headers, exhaust & Programmer) in an effort to increase the performance of my truck and it seems that it has hurt more than helped which is why it is frustrating to me. The truck has all kinds of Power on the Low End it's just at the Top End where is seems to be lacking the Power. I called Bill a couple of weeks ago and he said that it's possible that the tune may have had an issue with the programming so he is going to rewrite it and see if is any better. I hope it was just a programming issue because i can't afford <7mpg on a 1000mile round-trip haul.

Habbi - Thanks for clarifying. Things really get complicated when you try to compare the performance of one brand of truck to another, even doing identical tasks. I know I got better gas mileage pulling my trailer with my old, 6-cyl Nissan Frontier than I do with my F150, but I sure find pulling it a whole lot easier with the bigger vehicle. The combination of engine size, vehicle weight and gearing in the GMC may be making the difference.

If you have 3.55 gears, your truck doesn't have the factory tow package I think. So that, in combination with your tire size may make it hard for you to beat the GMC. Think of it this way: your truck might be "factory optimized" for "non-towing" driving. Yes, a programmer can help, but you may not be able to expect miracles.

Out of curiosity, what kind of highway mileage do you get when NOT towing? I currently get between 15.0-15.5 mpg. (This is on long Interstate trips.)

- Jack

Jack, What you said makes perfect sense. With that being the case i may look into a Gear Upgrade, to something that is a little more aggressive for towing. As I am not as concerned with my "Non-Towing" mileage because the main purpose of my truck is going to be hauling my camper. I have another vehicle for my daily driving. Any suggestions on Gear size? Would like to be able to run 33's and still have the towing power.

On the "non-towing" mileage i just went on a 600mile trip and was only able to get between 12-13mpg. Mileage was great with the Stock Program and factory manifolds (16-17mpg) but as soon as i replaced the cracked manifolds with the set of LT Headers it went south.

-Habbi-

Yikes! I'm not an expert in any way regarding the effects of LT headers. My understanding is that they CAN provide modest power gains, but that there are so many compromises (to make them fit into the truck) that they may not deliver all that is promised. In addition, if you're still putting the exhaust into the "Y" pipe, you're probably defeating the whole purpose of them.

Cleatius12r (Cody) and 88Racing (and of course, Bill) are much more knowledgeable in this area though. They might have some ideas.

Your mileage sounds VERY low to me though. Was that computed at fillup (miles driven/gallons added) using a correct value for tire size? Putting larger tires on and not correcting for them would reduce the odometer reading at fillup.

With 33-inch tires and towing, I think I'd use 4.10 gears. My truck has 3.75 gears and 32" tires. I think it would be "kinder" on the driveline to use the higher gear ratio if you are towing 5,000 # or so. I suspect your gas mileage would be about the same with either 3.75 or 4.10 gears though. I wouldn't go higher than 4.10. Ford has a funny way of changing the max torque output downwards if the load sensed has dropped too much.

If you have 4WD, you're going to have to change the gearing on BOTH axles. This gets a bit expensive.

- Jack

Jack - my tire size is actually smaller then factory. Factory specs are 31.5 and the tires that were on it when I bought it are only 30.6 which is what really strikes me as strange, because you'd think it would have helped on the power end of things. I am hoping that I can actually get a hold of Bill this week sometime to see if he has my tune reworked so I can get it downloaded to see if it helps correct the mileage and power issue.