Detroit DT12 Verses Allison 4000 8 Speeds - Mike Mas

[MemByTheMile]

And for those of us with older coaches, who always wondered if we should have gotten a 12 speed, now we can rest easier knowing it wouldn’t really help us when at highway speeds.
Other possible outcome, if enough people ask for it, could Renegade be convinced to bring back the Allison or make it an option?

[lslblues]

As I said in a prior post, the gear spacing is a little different and I do wish my Allison was geared closer to DT12.

It's Freightliners decision not to make any Cascadias with Allison. It has to do with greenhouse gas emissions scoring. They basically get penalized for putting an automatic transmission in a HD truck.

[lslblues]

Originally Posted by Idleup

Thanks or the reply - however Renegade can't order a Freightliner chassis without Fuel Sense nor has any authority to change transmission algorithms especially when it comes to fuel usage. The trucking industry works on fuel mileage and Fuel Sense provides 6-10% increase in mileage.

Mike - here's the build sheet from a 2025... Fuel Sense can be disabled and Renegade orders them without it.

[Idleup]

Thanks for the replies guys - While I have no knowledge if other coaches have Fuel Sense or not However, that's exactly what Renegade told me when I bought my Verona. Woody said they order the chassis with Fuel Sense was disabled. Anyhow, my coach was horrible it had less acceleration than a 6.7 Valencia. On every start it would over-shift and fall flat on its face shifting to 3rd when it needed 2nd and 4th when it needed 3rd. In fact it was so bad I quit using drive all together and shifted manually, which I do most of the time anyhow.

After crying like a baby for months to everyone I knew, finally a builder friend who also designs Cummins tunes, told me where to bring the coach, the tech immediately told me Fuel Sense was indeed Active. He also said it was in fact mandatory on L9's. With our coaches being so light, the TCM thinks it bob-tailing and begins over-shifting.

Anyhow in 15 minutes he unhooked the computer and said lets go for a ride, I instantly freaked out, It was like I was driving a different rig. My Verona 34 was a true rocket ship.

Regards - Mike

[Idleup]

Originally Posted by lslblues

Mike - here's the build sheet from a 2025... Fuel Sense can be disabled and Renegade orders them without it.

Thanks does your spec sheet show its a 5th generation Allison like mine? Unlike yours, there is no mention of Fuel Sense on my build sheet. Is yours a 25. Here's the key below!

"Load Based Shift Scheduling (LBSS) performance as the automatic selection between economy and performance shift schedules"

It appears as Fuel Sense is now replaced with 5th generation improvements where the TCM now self-adapts to loading to decide shift points. Here's a paragraph from Allison.

Embedded in the 5th Generation control module is a new inclinometer, which enhances vehicle productivity and efficiency in stop-start operations. The inclinometer’s precision and responsiveness improve Load Based Shift Scheduling (LBSS) performance as the automatic selection between economy and performance shift schedules is faster and more accurate, resulting in further reductions in fuel consumption.

This new generation of electronic controls provides two additional acceleration levels, enhancing Vehicle Acceleration Control (VAC) to allow for an even greater ability to improve fuel economy by controlling engine fueling and moderating aggressive driving practices.

[lslblues]

Yes the build sheet shows 5th Gen transmission. LBSS pre-dates fuel sense. There are press releases on that from back in 2008. The article you quote is from 2012.

Originally Posted by Idleup

Thanks does your spec sheet show its a 5th generation Allison like mine? Unlike yours, there is no mention of Fuel Sense on my build sheet. Is yours a 25. Here's the key below!

[/I]

[Doug M.]

There is a reason (or maybe several) why OTR trucks rarely use Allisons; they are more commonly seen in dump trucks and other vocational uses. At upper levels of weight, which most RVers won't see, the additional gears add a lot of flexibility with closer ratios.

When I ordered our Western Star 47X for our conversion, I specced the DT Vocational (there is a heavy haul version and an OTR spec, too; the highway spec is what you would find in the 57X and Cascadia). I wanted everything in the drivetrain to be Detroit for ease of service, etc. Most of my early experience in trucks was in Macks, and they advertised making trucks that were all Mack (engine, transmission, rears). (I can say I am old without being explicit - I was grandfathered on my CDL and never let it slide.) The last one I drove had a 9 speed and no engine brake. I have no idea why the dealer ordered it that way - clown shoes to the moon. The 10 speed behind the V8 was adequate; I rarely got below 10th at 80K and even on some pretty steep grades such as the big hill west of Spfld MA on the pike or Sideling Hill on the PA Pike; 65 on such hills was easy and I had to Jake to avoid getting stopped going UP.. Even with the relatively broad range of the 6 cylinder 350, the 9 speed was crummy - it needed the splits of a 13 speed. I had seriously considered speccing an 18 speed, but the splits it provides are really for 80K road trucks, not an RV that might hit 50K with a car trailer. The DT12V has 3 modes (economy, performance, and off road, plus a rock free feature) and so far economy has been ample. I would never consider an Allison under any foreseeable use because 6 (or 8) means the shifts are too far apart for climbing or descending. The DT12, and also the Fullers, are Automated Manuals; they have a clutch not a torque converter, but two pedals as the clutch is computer controlled. Modern engines are designed for lower operating ranges; when I drove a 14 liter Cummins, the operating range was 1600-2100; the range on my platform is roughly 900 RPM (peak torque, crudely speaking) to 1300 in economy mode. 65 is 1200. All indications are that we will get far better mileage than a typical class A due to be aerodynamics and specification of the power train. You do you, but I am pretty sure that anyone driving a vehicle in which the AMT is available will find it better in every way.

Big trucking companies have done lot of work to improve milage in their road trucks. Some of them actually measure to .001 mpg because it makes a difference in a big fleet. I have not heard of or seen Allison transmissions because they simply cannot do what is needed. I've been out of the industry for a while, but still have family and other sources that keep me somewhat informed. I may not be completely up to speed, but I'm close.

[Idleup]

Originally Posted by Doug M.

There is a reason (or maybe several) why OTR trucks rarely use Allisons; they are more commonly seen in dump trucks and other vocational uses. At upper levels of weight, which most RVers won't see, the additional gears add a lot of flexibility with closer ratios.

When I ordered our Western Star 47X for our conversion, I specced the DT Vocational (there is a heavy haul version and an OTR spec, too; the highway spec is what you would find in the 57X and Cascadia). I wanted everything in the drivetrain to be Detroit for ease of service, etc. Most of my early experience in trucks was in Macks, and they advertised making trucks that were all Mack (engine, transmission, rears). (I can say I am old without being explicit - I was grandfathered on my CDL and never let it slide.) The last one I drove had a 9 speed and no engine brake. I have no idea why the dealer ordered it that way - clown shoes to the moon. The 10 speed behind the V8 was adequate; I rarely got below 10th at 80K and even on some pretty steep grades such as the big hill west of Spfld MA on the pike or Sideling Hill on the PA Pike; 65 on such hills was easy and I had to Jake to avoid getting stopped going UP.. Even with the relatively broad range of the 6 cylinder 350, the 9 speed was crummy - it needed the splits of a 13 speed. I had seriously considered speccing an 18 speed, but the splits it provides are really for 80K road trucks, not an RV that might hit 50K with a car trailer. The DT12V has 3 modes (economy, performance, and off road, plus a rock free feature) and so far economy has been ample. I would never consider an Allison under any foreseeable use because 6 (or 8) means the shifts are too far apart for climbing or descending. The DT12, and also the Fullers, are Automated Manuals; they have a clutch not a torque converter, but two pedals as the clutch is computer controlled. Modern engines are designed for lower operating ranges; when I drove a 14 liter Cummins, the operating range was 1600-2100; the range on my platform is roughly 900 RPM (peak torque, crudely speaking) to 1300 in economy mode. 65 is 1200. All indications are that we will get far better mileage than a typical class A due to be aerodynamics and specification of the power train. You do you, but I am pretty sure that anyone driving a vehicle in which the AMT is available will find it better in every way.

Big trucking companies have done lot of work to improve mileage in their road trucks. Some of them actually measure to .001 mpg because it makes a difference in a big fleet. I have not heard of or seen Allison transmissions because they simply cannot do what is needed. I've been out of the industry for a while, but still have family and other sources that keep me somewhat informed. I may not be completely up to speed, but I'm close.

Doug thanks for your detailed reply and thoughts on transmission choices. I agree with you 100%, In fact, I would be just as happy with a DT12 as I am with my A-4000. If I was running the roads like I did for years, I wouldn't even be considering an Allison.

The Allison 4000 works great for Renegade for two main reasons, first, 85% of all Renegade owners are not truckers, they just put it in drive and push the pedal to the floor regardless of terrain and fortunately the Detroit's big torque tolerates their mistakes. Secondly, the 4000 works great because Renegades are so light, so light in fact, the TCM thinks its bob-tailing empty, which is another reason it over-shifts too early.

For over a decade, Freightliner / Allison have reverted to fuel saving protocols (Fuel Sense). As you mentioned, trucking revolves around fuel economy. Regretfully, this means over-shifts especially on Alison's 3rd and 4th gears. Even with the pedal down, they always occur too soon, leaving the engine at struggling at around 1000 rpm, below its curve, killing 5-10 seconds as you attempt to reach ramp speed to merge into dangerous 70-80 mph traffic with your rig.

Coming from old-school, my Allison's are always in manual. I occasionally move my backhoe and excavator state to state, while the Allison shifts totally different under load, it still over-shifts. What I'm saying is, while the Allison is much faster than a DT12 with two light Renegade's (as the video demonstrated if both Renegade's weighed out at 70,000 each, I would guess there would only be a few lengths difference because the Allison does not have to alter engine speed like the DT12 does to shift.

In any case when using manual, I decide when to shift rather than some pencil head sitting at desk at Allison. Thanks again!

Travel Safe - Mike

[Doug M.]

Thank you, Mike. I have been a professional nerd for most of my adult life; I actually ran the road after law school because I made more money and had a better life than I would as a baby lawyer. I was mostly a cop and a prosecutor, and although I was adequate as a trial lawyer, I mostly beat down my opponents in motion practice.

In full honesty, I did see a use today that would probably require an Alison from the highest ratings. It was very heavy haul (400K as a single unit, a million pounds as the pulling unit with another pushing) custom KW T800 for I presume to be a very specialized purpose. The tractor had a 7 speed Allison and 4 speed auxiliary box ( 2 under drives, 1 direct, 1 over). Other than one can't get a Cat road motor now, I would probably power it with a C18, which easily made from a C15 by a real mechanic, which I am not. 800 HP and some level of torque that no conventional transmission will handle, probably well over 2500 ft./lbs. None of that applies to an RV, and I cannot conceive of an RV that would be better with the Allison.

Admittedly, I have my views and biases that drive that, just as our RV is being custom built by an Expedition truck maker. We aren't social, we don't want to spend on useless luxury that we would not have at home either; we want to be functional for extended trips. No propane, all diesel electric, and lots of water.

[Idleup]

Originally Posted by Doug M.

Thank you, Mike. I have been a professional nerd for most of my adult life; I actually ran the road after law school because I made more money and had a better life than I would as a baby lawyer. I was mostly a cop and a prosecutor, and although I was adequate as a trial lawyer, I mostly beat down my opponents in motion practice.

In full honesty, I did see a use today that would probably require an Alison from the highest ratings. It was very heavy haul (400K as a single unit, a million pounds as the pulling unit with another pushing) custom KW T800 for I presume to be a very specialized purpose. The tractor had a 7 speed Allison and 4 speed auxiliary box ( 2 under drives, 1 direct, 1 over). Other than one can't get a Cat road motor now, I would probably power it with a C18, which easily made from a C15 by a real mechanic, which I am not. 800 HP and some level of torque that no conventional transmission will handle, probably well over 2500 ft./lbs. None of that applies to an RV, and I cannot conceive of an RV that would be better with the Allison.

Admittedly, I have my views and biases that drive that, just as our RV is being custom built by an Expedition truck maker. We aren't social, we don't want to spend on useless luxury that we would not have at home either; we want to be functional for extended trips. No propane, all diesel electric, and lots of water.

Doug,

Thanks for the reply - I sympathize with you, I ran Miami to La for Seminole Trucking in Miami for years, maybe that's why I like driving a RV that feels like a truck. The only thing missing is all the gears. As I mentioned in my article, I would be just as happy with a DT12 as I am with the Allison. The Auto does not bother me too much because 95% of the time, I'm in manual especially when pulling my excavator I use all 8 speeds. By the way, I noticed a lot of 8 speed disbelievers vanished when they drove their motorhome and discovered the 8 speeds are really there. Fact is, there is 400 rpm difference between 2nd gear slip and 2nd gear lock, this is a big ratio change when you consider there is only 200 rpm difference between 5th and 6th gear on an Allison.

Like you, I've owned just about everything they make, but I'm staying with Super C's. My last 5 motorhomes (4 years) were all cab and chassis. I only keep coaches for a few years, so I don't get too attached to them any longer.

My biggest dislike of the Explorer is the horrid 13'6" height, she's definitely top heavy. To each his own, but I don't need my RV ceiling height to match my home and neither does the old lady who can't reach the cabinits. As manufactures moved from 12' to 13'6" they pissed away past good handling it's lost forever. My Verona 34 (which I wish I kept) was 12' it handled in curves like a rock, never felt road pitch. It actually handles twice as good as the Explorer. Hey tell me more about your rig.

Ride Safe Mike

[Doug M.]

It is a Western Star 47X. Drivetrain is all Detroit (DD13 vocational motor at 450/1650 because we could not get the road spec in the 47X; DT12V; Detroit rears at 2.93, governed to 72 I think set for 65 at 1200). Air ride 40K rear tandem; 14K front. Has OnSpot auto chains and virtually everything nice inside. The body will be about 31'6; 8' inside. Trying to keep the height down to 12'6 or less.

The habitat will be custom made by an expedition truck custom maker that does some of those, and custom kitchen trucks to go overseas for World Kitchen. They have used mostly Western Star platforms except for smaller build, and we were introduced to them when we went to the WS dealer. The main reason went to the dealer was to make sure my wife could see well enough from the driver's seat to move it in a pinch, and things just progressed logically.

Custom units like that are a pain in the butt to finance even with really good credit. It will be more like a scaled up expedition rig than a traditional Super C. It will have a deb room, bathroom with shower stall and a Splendid stacker W/D, a real kitchen and enough living room for the two of us and our little (45 lb) dog. I hope to have a Boerboel or Rott after my transplant and recovery. They are useful for discouraging miscreants and a LOT calmer than Rosie. No room for other people; we are not social. No slides as they are a maintenance horror; all diesel and electric as I would not have propane under condition I can consider. Biggest alternator that DD makes (300 amp); solar of reasonable size; generator for emergencies and a big capacity custom LI batteries about 2 days running time. All appliances will be household; we did a lot of research to make those work. Dinette, recliner, couch etc.

[Idleup]

Originally Posted by Doug M.

It is a Western Star 47X. Drivetrain is all Detroit (DD13 vocational motor at 450/1650 because we could not get the road spec in the 47X; DT12V; Detroit rears at 2.93, governed to 72 I think set for 65 at 1200). Air ride 40K rear tandem; 14K front. Has OnSpot auto chains and virtually everything nice inside. The body will be about 31'6; 8' inside. Trying to keep the height down to 12'6 or less.

The habitat will be custom made by an expedition truck custom maker that does some of those, and custom kitchen trucks to go overseas for World Kitchen. They have used mostly Western Star platforms except for smaller build, and we were introduced to them when we went to the WS dealer. The main reason went to the dealer was to make sure my wife could see well enough from the driver's seat to move it in a pinch, and things just progressed logically.

Custom units like that are a pain in the butt to finance even with really good credit. It will be more like a scaled up expedition rig than a traditional Super C. It will have a deb room, bathroom with shower stall and a Splendid stacker W/D, a real kitchen and enough living room for the two of us and our little (45 lb) dog. I hope to have a Boerboel or Rott after my transplant and recovery. They are useful for discouraging miscreants and a LOT calmer than Rosie. No room for other people; we are not social. No slides as they are a maintenance horror; all diesel and electric as I would not have propane under condition I can consider. Biggest alternator that DD makes (300 amp); solar of reasonable size; generator for emergencies and a big capacity custom LI batteries about 2 days running time. All appliances will be household; we did a lot of research to make those work. Dinette, recliner, couch etc.

Wow very, very impressive rig Doug. Unlike most (myself included) who just turn the key and start driving, Looks like you spent a good time and effort planning every detail. I would love to design a coach tooth and nail like you did.

Believe me you won't regret dropping the roof as you did, it makes a major difference in handling across the board and makes no difference in the coach. My Verona was 12'2 in the rear and 12' at the nose and would not fit in the garage we just built. So, I added a bag dump in the rear and was able to get it in my 12 ft garage door opening. Oh I left out something, I had to install a hydraulic door also.

In fact, I'm hope to visit Renegade this summer to see if I can persuade them to build me another 34' Verona. I miss the ease of handling, fuel economy and performance of my past Verona 34 VQB.

Well by all means keep us posted on the development of your coach. Please post it on my Explorer review story (below) on this forum so you can share it with other Renegade owners.

Finally, may God be with you on your health issues my friend.

Best Regards Mike

Explorer In-Depth Review Link:

https://www.irv2.com/forums/f297/exp...ml#post6975109