3.42 ratio vs. 2.64 ratio on cascadia

Does the 3.42 have a direct trans. like the 2.64 does?

 

The 3.42 would be a overdrive trans . Would feel about the same in high gear. The 2.64 will give better mileage . Startiablity would be about the only difference . How often can you not start off in second gear?

 

Grab the transmission ID, and the VIN, cross reference them with tranny maker and truck maker, 2.64 most likely a direct drive - as said, probably better MOG, unless startability is a factor.

 

I would buy 3.42 .

 

You won't notice a difference in the hills. It is only on start up from a dead stop. Takes a tad bit more time to get up to speed with a direct and 2.64. I run heavy on some very hilly rural backroads highways from time to time using a 18 speed in front of 2.64, and I have no problem. The direct and 2.64 can edge out a 10 OD with 3.42 on fuel economy, but that is also dependent on the driver and speed you typically run.

The key is the RPM range the engine is in and the engine in question. At 65 mph, a 10 direct with 2.64 will have you turning about 1475 RPM on low pro rubber. With a 10 OD (usually something like a .73 or .74 OD) with 3.42, and you will be turning about 1400 RPM at 65. That should give you a general idea of the difference. With the DD15 and a choice between those two, I would probably go with the 3.42. For something like a Series 60 12.7, I would opt for the direct and 2.64. It is all about the engine as well as the trans and rear gear.

 

Cowpie I have a coworker who is getting ready to order a glider with a 13 speed and 2:64. Just wondering what you think of that combination. I believe it will be a C-12 with a liftable axle since we run light and come back mostly empty.

 

Well, given that the conditions are primarily light or empty, I would just go with a 10 speed direct and 2.64. The only appreciable advantage of a 13 or 18 is working grades with heavy loads and keeping the RPM's tighter. A 10 speed direct is a very solid trans, is lighter, and works great for what you are describing. Of course, if one is wanting to bust the sound barrier down the highway, a direct would have the RPM's pretty high with no where to go. Then maybe a 13 might be a good option to move on up to OD at the higher speeds.

 

Well we do have a couple runs were you have to run 68 to 70 most of the day or you'll be sleeping 1/2 hr from home but no faster than that. Thank you.