2013 ISX450ST Cummins information

If you go to a cummins web site "cummins engine specs and gears" they will tell you what trans will go with 2,64 and wheel size or you can call pittsburg power talk to bruce he will tell you the specs thy build gliders with direct drives and big trans

 

Back then, there was available direct drive with 13 or 18 speed. Not anymore. Probably that is what you had. Now with a double overdrive your RPM would be under 1100, or your speed 75.

 

Mr. Klaudec is right.

 

The 450 ST that was mentioned by the original poster is a 15L. I had a ISX 435 ST and it was a 15L engine also. The ST stands for Smart Torque.

 

Wrong. The 13's and 18's have direct drive.... 11 in a 13, 16 in an 18. And you can have all the torque rating you want up to 2050. For some reason, some folks can't get past the idea that you DO NOT have to use the overdrive gears in a standard double over transmission, and you never have to use the "top hole". I have an 18 speed tied to 2.64 rears. I run in direct drive (16th) at road speed. The tranny has seen 17th a couple of times when I wanted to step it up for a little bit, but it has never seen any time in 18th. The tranny stays nice and cool in direct since it is not having to turn the overdrive shafts, and it pulls hills just fine right on up to 80K gross. In 16th at 1400 RPM on 22.5 low pro rubber, I am turning 62 mph. At 1500 RPM I am running 67 mph. When I get above that, I can just move on up to the next gear.

Running in direct with 2.64's give you almost the exact same road speed as running in double over with 3.55's. Except you gain 2-3% more efficiency and don't lose some engine power turning the overdrive shafts. All of the engine power possible is making it to the axles.

And for mpg, my truck has averaged 7.6 mpg since hitting the road (hand calculated pump to pump), and has busted 8 a few time and I didn't have to drive 55 to do it.

 

The direct drive transmission use less fuel because it has less resistance, not because you do not use the overdrive gears. Period.

 

I think we are saying the same thing and coming at it from different angles. The OD creates greater resistance and has a parasitic loss of power to the rear wheels. Some, more knowledgeable than I on the technicals, say that there is anywhere between 40 and 80 hp lost just in turning the overdrives. Running in direct, even on a double over, is way more efficient and is virtually the same as a direct 10, except for the extra splits down in a 13 or 18.

 

Maybe you are right, I will go a little deeper into it. The question still, do I need the extra splits down with these new wide torque range new engines? Earlier it was a must since the max. torque range was 200-250 RPM, but now it is 400-500.

 

not sure if this helps I have a 2013 450 cummins isx in a cascadia signed papers on it with 68 miles and now have 7900 on it and lost the cummins ecm at 5k miles and now have been having to add a gallon of antifreeze and oil everyday for the past 4 days. Been to the shop 3 times already. Check engine light comes on and i lose jakes and all lights come on in the cab and cant turn them off can't regen or anything. let me say its a pain to sleep with all the interior lights on and of course there is no way to pop the domes and take them out. Also the oil and antifreeze isnt leaking anywhere so I'm assuming that its goin out the exhaust have also lost alot of power and fuel mileage dropped. I pull dry van with usually no more than 25k in the box running expedited but I have had 46k in the box before and stay away from a 10 speed I hate it and want a 13 again so bad. Well hope that helps, I'm waiting on a tow truck and trying to find a way to get my load from tn to high point nc by tomorrow now.

 

You have some serious electrical problems if your dome lights are coming on and you lost an ECM at 5k miles. Still, your Cummins story is not a surprise.