N14 or C15 or ??? for good power and MPG?

What year is the white one pulling the low boy? Don't worry about the Jake's they don't do too much besides make noise Lol. Better than sticking your hand out the window though.

I'll agree with you they're dead from the factory but you can make em run.

https://youtube.com/shorts/guoqVaulZVk?feature=share

 

I think that truck is an ‘08 model. He had two of those detach lowboys but I bought the other from him. My FIL’s uncle(Griffin Contracting) is who owns the Mack trucks. 4 dump trucks and two road trucks. The Superliner is the only one I like. The rest are just late model plastic Macks. The engines in the newer ones, have “Renault” stamped on them.

 

Ok, sorry it took so long to get you the transmission number. I’ve been planting corn and it’s been some long hours. Here it is.

 

Mystery solved
Lmao
That ain't no 10 speed!! It's a "Performance" 9.. I got one too, but mine's rtx14609R..

Difference is your "P" has a .83 OD, my "R" is .80..

Can be shifted like a 10, but the 9 hole in low range is basically redundant to 5th..

 

When I bought the truck several years ago, the owner, which only owned it for a year or two, said it was a 10. I drove it just like a 10. After I bought it, I changed all the fluids and noticed the transmission tag and that it said it was a 9 speed. I drove it like a 9 and it definitely felt like I was skipping a gear. Not sure why it feels that way but I don’t like driving it like a 9, with a load. Maybe it’s the 12.7, maybe it’s the rears and maybe it’s both but it does not feel right skipping that hole and that said, it just doesn’t feel like a duplicate of 5th. Appreciate the info.

 

Ok, let me pic your brain some more. Can the RTX14609P, be changed to a 13 speed?

 

You know I only got a good chuckle before cause you're the only other guy on the planet with a Performance 9 besides me right? Lol

You are correct in a few ways.
- It technically does have 10 foward progressive speeds, eaton fuller just decided not to market it as such..
-And I did the math on your ghost gear. It is a better step than mine at .4 ratio taller than your 5th is. (Remember our trans are labeled like this)



My ghost gear is only .26 taller than 5th. Probably why it's unnecessary for me?


Drive that girl however she works best. Sure it ain't hurt'n a thing. I only tend to use my ghost gear in traffic when I'm too lazy to flip the range up.. lol

Our trucks are spec'd sort of similar.
Mine is
350 M11
DS404's with 3.70
low pro 24.5
similar trans, but slightly deeper OD at .80 so does 70mph at 1700

I'd much rather have your Detroit though..

This I'm not sure about?
Because we have 5 in high range instead of 4 in high range like a typical 9 speed, it would end up being a 14 speed? Or maybe a 15 speed? as I just learned all 5 down low are technically progressive ratios..

Seems it'd be pretty nice if we could. I'll ask around..

I'd like it alot better than a typical deep reduction 15, being able to split 5 on the high side would be sweet..

 

C15 is still overhead cam. Over head cam is and has always been a stronger more efficient design. Timing is everything and there is all but no deflection in an overhead cam engine. The problem isn’t overhead cam but more of a displacement issue, that said that can be overcome knowing the right people. Lower RPM doesn’t always mean less fuel or less wear. For the trouble time and money to make the swap I would stay with what you have

 

I appreciate all the helpful info. The DDEC2 has been a good engine but it don’t hold its torque quite like the red head and cat. So using that ghost gear is sometimes necessary. My RTO15613 in another truck, can also use the ghost gear(low hole, high side) in it and split it too. So, by that idea, it to has 15 speeds but 2 are duplicates. I’d really like to make the RTX14609P a 13 if possible. Thanks for taking the time.

 

What you really want is an RTO or RTX14609B use an RTO14613 main shaft as is different for the back box. Also use the 13 back box. Now you end up with an RTOO With .62 high hole but .73 12th that doesn’t turn the rear box and make heat. You also maintain a good low gear and reverse. Where as turning a regular RTO or X around speeds up the entire trans making low and retreat suck. Now there’s a bit more to it but there’s the jest. However any 13 isn’t going to do what you’re hoping. It’s more rotational mass etc. improving torque is the only help you’ll have. What I’m getting at is any hill you have to drop to the 1.1 gear position for now you will with a 13. It will climb at the same speeds same or similar ratio just a different number position