Gear ratio over drive or direct for heavy haul up to 110K?

Nick34 · Jan 12, 2019

Rontonio said: ↑

I am going to try to be helpful,

If you are moving RGN freight and are worried about fuel mileage as a primary concern in spec’ing a truck, you should re-evaluate your readiness to move forward. There is a reason people build trucks to do this type of work - they are set up to deal with issues general highway trucks are not. One is start ability and another is grade ability - so starting on an incline and maintaining traction on an incline both in pavement and off.

Yes I know that 110k gross isn’t heavy but why build a truck that will suck at design weight and not be usable at heavier weights?

I think the 5700 is absolutely the wrong choice for an RGN setup and I am a huge Western Star fan(I have one and have had more). You are going to need the ground clearance that the side skirts and aero pieces won’t allow or will get torn up. No one is impressed when a ragged out freight truck with panels cracked and duct taped shows up to load their half a million dollar injection molding machine.

You should spend time talking to successful people doing the job you are trying to do. They are all probably running mainstream solutions (15l engines 1750/1850 500/550 with 13 or 18 spd transmissions with much deeper ratios like 3.7xor 3.9x and 46k rears long slide double locking fifth wheels full lockers etc)

Western star has an engineering group that will offer solutions if you give them the information. Expected axle weights spacing number of axles terrain those kinds of parameters.

Note: I do not have a bias against automatic transmissions but remember tow trucks for oversize loads are much more complicated(generally means more expensive) when things go wrong. When I looked into automatic- I looked at Allison. My application was very different than yours and it ended up not being the correct solution but maybe in my next truck.

Lastly, money is made in the RGN world by skill, reliability and service. If you are going to get 5 mpg versus 7 mpg - you need to price your service accordingly, even as a 5 axle. If you are trying to make your money by cutting rates or accepting crappy rates - you are going to fail and hopefully fast so you don’t hurt a guy providing quality service.

I have a friend that broke down with a big stretch load that we tried to help. Needed someone to go get the load and take it a long way through expensive permit states some requiring pilot cars. We would have done it - even just breaking even. When asked what he had in it - he said he only had x in it but it paid for his bounce. Problem is it didn’t cover the costs and now he either had to come out if his pocket farther or find someone who was willing to lose money too.

I hope this helps
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Humblepie · Jan 12, 2019

062 said: ↑

Wonder what he using now to pull that setup? Oh and you’re wrong cause KR said...
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Yeah! kR is the go to authority in all things trucking. Just ask him.

Nick34 · Jan 12, 2019

Thanks for your reply . Right now I have a 2011 freightliner coronado with a dd15 505 hp 1750 torque with an 18 speed double over with 3 55 super 40s it pulles good I run all over including the mountains in British Columbia. The 2 64 ratio from what I'm told should pull about the same with a 1 to 1 ratio in top gear the only problem I'm seeing is startability from a dead stop I was Looking to see if anyone was running this combo doing heavyweight. The 2 64 is very popular for guys running under 80 000 but iv heard very little on guys running it over that. I was strongly against the auto shifts up until a fue years ago now the new ones are saving over .5 mpg so I would like to try one but it looks like I should go with the single overdrive gear to save my clutch

062 · Jan 12, 2019

My suggestion would be have a mod move this to the heavy haul section and get opinions from the guys loading heavy and wide. I don’t think you’ll like the answers you get because I seriously doubt any of them will tell you to run a setup like that. @MACK E-6 may be around to move this for you.

Ruthless · Jan 12, 2019

Nick34 said: ↑

Thanks for your reply . Right now I have a 2011 freightliner coronado with a dd15 505 hp 1750 torque with an 18 speed double over with 3 55 super 40s it pulles good I run all over including the mountains in British Columbia. The 2 64 ratio from what I'm told should pull about the same with a 1 to 1 ratio in top gear the only problem I'm seeing is startability from a dead stop I was Looking to see if anyone was running this combo doing heavyweight. The 2 64 is very popular for guys running under 80 000 but iv heard very little on guys running it over that. I was strongly against the auto shifts up until a fue years ago now the new ones are saving over .5 mpg so I would like to try one but it looks like I should go with the single overdrive gear to save my clutch
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Your idea is revolutionary: and you’ll learn VERY quickly why people hate on it. You’ll be saving tons of fuel; about that, there is no doubt.

Humblepie · Jan 12, 2019

Hard to save fuel when you are working the dog #### out of your truck

Oxbow · Jan 12, 2019

Nick34 said: ↑

Thanks for your reply . Right now I have a 2011 freightliner coronado with a dd15 505 hp 1750 torque with an 18 speed double over with 3 55 super 40s it pulles good I run all over including the mountains in British Columbia. The 2 64 ratio from what I'm told should pull about the same with a 1 to 1 ratio in top gear the only problem I'm seeing is startability from a dead stop I was Looking to see if anyone was running this combo doing heavyweight. The 2 64 is very popular for guys running under 80 000 but iv heard very little on guys running it over that. I was strongly against the auto shifts up until a fue years ago now the new ones are saving over .5 mpg so I would like to try one but it looks like I should go with the single overdrive gear to save my clutch
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Personally I would not worry about the top end for now and look at the low gear ratio.
I had an 15818 that was .86 OD. I now have an 18918B, with .73 and it has a slower low gear than the old one.

I have a spreadsheet that lists the ratios of each gear for each Eaton transmission, but I am away from the office and don't have access to it at the moment .

I only get up to around 135,000 lbs. gross. I have tall tires and 4.10s, and wouldn't want to get much taller than that.

I glide 47 · Jan 12, 2019

Nick34 said: ↑

Is yours an actual direct drive transmission or are you running an overdrive tranny in direct I was wondering if the first gear ratio might be Lower in a direct one to make up for the tall rear gear?
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10 direct 10th is the one to one gear but I don't run what you call heavy

I glide 47 · Jan 12, 2019

Don't know if 1st gear is lower than normal

snowman_w900 · Jan 12, 2019

Humblepie said: ↑

Hard to save fuel when you are working the dog #### out of your truck
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He will be saving lots of fuel because the driveline will always be tore out of it, hence the truck wont be rolling down the road burning fuel.

He will save LOTS of fuel.

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