Does the Seneca have enough power

[vanovafan]

Absolutely what I was looking for. I have a freightliner RV (non-Jayco) with 250 hp. 22.5's stick shift with 6speed and 6th is overdrive. 5th is 1:1. And get this, a 3.90:1 rear axle. It's crazy but the truck will pull a trailer up a long hill but it really struggles. Based on everything you supplied, my truck needs 4.56:1 to be equal to your truck that even has more HP. I was already going in the 4.56:1 direction and your numbers just confirmed it for me. Thank you very much

Bill

[Robbbyr]

Originally Posted by vanovafan

Absolutely what I was looking for. I have a freightliner RV (non-Jayco) with 250 hp. 22.5's stick shift with 6speed and 6th is overdrive. 5th is 1:1. And get this, a 3.90:1 rear axle. It's crazy but the truck will pull a trailer up a long hill but it really struggles. Based on everything you supplied, my truck needs 4.56:1 to be equal to your truck that even has more HP. I was already going in the 4.56:1 direction and your numbers just confirmed it for me. Thank you very much

Bill

Just checked my Allison specs, 5th gear is 0.74:1, 6th is 0.64:1 on my rig.

[vanovafan]

Does your truck run approximately 1930 rpms at 70 miles per hour. Something close to that?

Bill

[vanovafan]

My rig has a 6 speed manual where 5th is 1:1 and 6th is .78 overdrive reduction. I have found a competent Mechanic that will change the gears. If I go to 4.56 gearing I will be turning 2093 rpms at 70 miles per hour. But if I go to 4.30:1 gearing, I will be turning 1974 rpms at 70 miles per hour.

anyone got any thoughts on which one to use. My truck is only 35 feet long, weighs 23,700 fully loaded and I usually pull a car trailer that is around 7,500 lbs fully loaded. So total weight is 31,200 lbs. any thoughts?

[Robbbyr]

Originally Posted by vanovafan

Does your truck run approximately 1930 rpms at 70 miles per hour. Something close to that?

Bill

Sorry for the response delay, this was a Seneca travel day.

70 mph is 1975 RPM on my ScanGauge in 6th gear in my rig.

[Superseneca]

Interesting read. My duramax / allison combo has a tune and I am extremely happy with it. Been thru Vail co. A few times. No complaints. Ive noticed the tranmission temp craps up when driving very slow especially on upward grades. Thinking this is the converter generating all the heat not the transmission. Once I get moving over 40 mph. Temp goes back to normal. I'm towing a trailer with my hd and jeep, can cruise at 65mph no issues. Enjoy the trip.

[barryfriedman]

Maybe I am confused but my 2020 Entegra Accolade with the Allison 3000 allows me to press the "Mode" button and then the "-" to force it into a lower gear which it seems to stay in until I press the"+" button. Is this not over-riding the overdrive function?

Barry

[RVermont]

Pre 2018 m2 units had allison 2500 transmissions with dash mounted shifter.

[david a judd]

Originally Posted by seneca37rb15

pretty much did what everyone said. The cruise sets on 68 to 70. Just seemed like on very slight grades I was to the floor trying to keep it at 55. I always dropped it out of overdrive when my speed got below 55. Altitude shouldn't affect the diesel like it does a gas. Just curious if my experience was the same as others.

Take a class on how to drive a diesel. You SQUEEZE the throttle, not MASH it to the floor. That just causes a downshift and slows you down. Keep slowly adding throttle as you climb the hill. Don't worry about lugging the engine, the computer will downshift at the optimum time.

[Bewildered]

Originally Posted by seneca37rb15

pretty much did what everyone said. The cruise sets on 68 to 70. Just seemed like on very slight grades I was to the floor trying to keep it at 55. I always dropped it out of overdrive when my speed got below 55. Altitude shouldn't affect the diesel like it does a gas. Just curious if my experience was the same as others.

I was wondering if this was just me but I guess not. Good to know. We were towing a Jeep Gladiator and had the same results. I don't exceed 65 but that is a preference. My wife is shocked when I take it up to 66 mph.

On some grades I-25 headed south I was only going 40 to 50 mph.

[Robbbyr]

Originally Posted by Bewildered

I was wondering if this was just me but I guess not. Good to know. We were towing a Jeep Gladiator and had the same results. I don't exceed 65 but that is a preference. My wife is shocked when I take it up to 66 mph.

On some grades I-25 headed south I was only going 40 to 50 mph.

This is the same issue I faced prior to my power upgrade and transmission reprogramming. With those symptoms I would be willing to bet your transmission was (mistakenly) programmed with the "Ultra Economy" shift schedule like mine was. Cummins even had a Service Bulletin for customers complaining of a lack of power when it was essentially a shifting issue. While I did have my power uprated to 360 hp and 800 lb/ft torque, and reprogramming the transmission to change it to a performance shift schedule made as much or even more of a difference in how my unit performs. It is especially noticeable at highway speeds where I not the slug going up the grades.

Initially I was worried increased power might affect transmission longevity, but Allison assured me its "Shift Energy Management" programming will still function to momentarily reduce engine torque while the transmission shifts. Allison was fine with the power uprate and told me the typical service and mileage we put on a RV we should never have a problem.

[Midnightmoon]

Originally Posted by david a judd

Take a class on how to drive a diesel. You SQUEEZE the throttle, not MASH it to the floor. That just causes a downshift and slows you down. Keep slowly adding throttle as you climb the hill. Don't worry about lugging the engine, the computer will downshift at the optimum time.

While I do agree that the transmission programming should be such that it will not cause engine damage due to a lugging condition if you allow it to shift on its own, it doesn't necessarily mean that it will provide optimal shift points for performance and efficiency under loaded conditions. I have been especially disappointed in the shift logic of the Allison 2000 and 3000 series behind the Cummins ISB/ISC and Navistar DT466 in both Freighliner and International medium duty chassis. I've driven both combinations extensively and neither of them are programmed to properly shift, keeping RPM's and boost pressure up, and EGT's down.

I reserve the right to be wrong, but I was always taught that pulling grades with a load is a matter of momentum, both vehicle and driveline. From the time that I started driving commercial vehicles, I was instructed that you want to downshift at or above the torque peak of the engine, which, in the case of the ISB Cummins, ranges from 1600-1800 RPM depending on specific programming. Allowing the engine to pull below that torque peak not only drastically raises EGT's, it also lowers the potential RPM of the engine once it lands in gear after the downshift. Anticipating an upcoming grade by downshifting early, even with an automatic, keeps that RPM up, boost pressure up, driveline momentum up, and EGT's down.

Now it has been nearly 25 years since I got my CDL and it is quite possible that they now teach things differently. However, I haven't ridden with anyone who employs a different approach.

[SloPoke]

Originally Posted by Midnightmoon

Now it has been nearly 25 years since I got my CDL and it is quite possible that they now teach things differently. However, I haven't ridden with anyone who employs a different approach.

Things have changed dramatically since the 90's. Every one of our tractors and dedicated delivery trucks have an integrated ELD, Telemetry and VHC system onboard. We integrate this on a National level with every vehicle in our fleet.

This system monitors everything on the truck with GPS/cellular and connectivity to the vehicle that tells us everything within the last 3 minutes. We can look at the transmission temperature, Boost, EGT and even the pressure/temperature of tire #9. We can also modify the governed speed, engine RPM and even turn on/off the trailer lights from our computers in the office if we wanted to.... All of these are easily set / changed from a connection from RoadNet to our tractors.

We also can monitor and limit a driver from doing stupid things - without having to be there actively monitoring them - by setting limit parameters to just about anything... even make a vehicle go into limp mode if the driver goes rogue.

We have total control of the vehicle... but Seneca owners are not controlled by these systems - they need to have these settings programmed into the vehicle - be that performance shift patterns, Maximum torque or maximum HP are all programmable. At a cost to the owner.

[Midnightmoon]

Originally Posted by SloPoke

Things have changed dramatically since the 90's. Every one of our tractors and dedicated delivery trucks have an integrated ELD, Telemetry and VHC system onboard. We integrate this on a National level with every vehicle in our fleet.

Most of my driving was done well before the initial Phase 1 of the ELD implementation timeline. So, I don't have much first hand knowledge of how those systems effect the drivers over the road. I know that it has fully changed the way we used to operate.

[JFlightRisk]

[QUOTE=SloPoke;876769 All of these are easily set / changed from a connection from RoadNet to our tractors.

We also can monitor and limit a driver from doing stupid things - without having to be there actively monitoring them - by setting limit parameters to just about anything... even make a vehicle go into limp mode if the driver goes rogue.

We have total control of the vehicle... [/QUOTE]

Is this tech used by the majority of trucking companies on the road today? Just curious. It must be expensive.

[Midnightmoon]

Originally Posted by JFlightRisk

Is this tech used by the majority of trucking companies on the road today? Just curious. It must be expensive.

I don't know all of the regulations, but there must be an exemption for local and regional haulers because many of the tri-axles running out of the quarry here don't run the ELD's, at least the last time I was in one a year two ago. I thought I read somewhere where it was within 150 miles that they were not required. Again, I am just guessing. SloPoke will certainly have the answer.

[75462]

On my 2020 Seneca Allison 3000 it does this,

Transmission Mode Switch
Some vehicles are equipped with a transmission
mode switch, shown in Fig. 4.15. The transmission
mode switch is a fuel conservation option that allows
the driver to choose either performance or economy

[RyRoRyan]

For those of you reading this thread and have not done the transmission reprogram yet, I HIGHLY recommend it. It changes the way the RV performs dramatically. When the rig comes from Jayco, it is programed for ECO mode shift points. For the rigs that have the 2500 transmission, Jayco never put a mode switch in the panel, however, that transmission does have another mode that is already programed into it, but you cant access because you dont have the switch to change it. There are some threads in regards to this in the past, and there used to be a guy who worked for Cummins who would help you with the reprogram, but most Allison dealers can do it. Basically they just need to make the performance mode the default mode at startup. Once I did this, I noticed much improvement in just standard acceleration as well as holding speed on hills. It will still drop some, but it will now upshift earlier instead of holding a higher gear, slowing you down.

[SloPoke]

Originally Posted by Midnightmoon

I don't know all of the regulations, but there must be an exemption for local and regional haulers because many of the tri-axles running out of the quarry here don't run the ELD's, at least the last time I was in one a year two ago. I thought I read somewhere where it was within 150 miles that they were not required. Again, I am just guessing. SloPoke will certainly have the answer.

Many companies did not implement until the final requirement to have ELD's on December 2019. They still could use paper logs until that date. As for a rock quarry - If the vehicle does not travel over public roads, they are not required either.

Here is a link we go to for the latest on exceptions and new information on the rules: https://www.fmcsa.dot.gov/hours-serv...ogging-devices

Also note, there are minimum requirements for an ELD, What extra features I posted about RoadNet and PeopleNet are above and beyond the basic requirement of hours of duty. Not all ELD's will monitor tractor telemetry unless you pay extra for those features. . .