Engine/Transmission (1994 - 1998) 5 Speed transmission Question

[Mopar Man]

I have a '97 2500 with a 5 speed, 3:54 rears and 285 tires. It also has a GV o'drive, so when I pull my trailer (flat deck with tractor or old truck or??? on board), I pull in 4 OD most of the time. Why? Well is is about 150 RPM more than 5 direct at 65MPH ( and I am geared tall with the 285's and 354) and I think I am "saving" 5th gear from a premature death. Also, I like the quick down-shift from 4 OD to 4th direct. Now my question Am I doing some damage to the transmission running for hours in 4th??

 

[ata]

No you are not hurting a thing running in 4th gear all the time. If you are going to run in one gear all the time that`s the best one to run in the 5 speed. Because it`s not really a gear. The input shaft is hooked directly to the output shaft so you are not running on any gears just stright through the transmission. But I don`t know which is more spendy to fix the 5th gear nut or the Gear Vendors box.

 

[drrhoades]

Heres a guestion I have on the five speed with a 12 valve with 3. 54 gears. Is it alright to cruise around under 1600 rpms in 5th when there is no load, i. e. flat level ground and nothing in the bed or behind the truck. I was thinking that this way would be good, come to a slight grade and drop it into 4th, then back to 5th once up to speed?



Thanks

Doug

 

[JStordahl]

Drhoades: Though I'm no expert, I believe that 1600 rpms in 5th gear is not good. Go to 4th. The low rpm usage of 5th induces more vibration contributing to the dreaded 5th gear nut failure. I like to keep the engine at 1800-2000 rpm for its normal work, and this seems to be a nice sweet spot for the engine.

 

[drrhoades]

JStordahl: What about when you are just driving around town and the speed limit is 45 or 50 do you still drive in 4th. In my truck this puts you at around 1750-2000 rpm. From what I understand you get the best mileage at maximum torque and minimum horsepower. And from the the charts that I have seen this seems to be at 1600 rpm. Please note that the only thing in the truck is me and this would be on flat level ground with no acceleration or decelration. I understand about the torsionals from the engine and have seen what they can do. I am just trying to learn as much as possible about driving this truck and doing right so that I can prevent as many problems as possible.



Doug

 

[Rams-n-Hogs]

Doug,



I don't know how good it is for the transmission, but that's how I've been driving mine since it was new, and so far, it's lasted 110,000 miles. Most of that time was before I was a member of TDR, so I didn't know about it, and it wasn't BOMBed, yet. Now that I know about it, I put some money away to upgrade if it becomes necessary. Part of my quest to bulletproof my truck. Got a long way to go before I finish, though.



Jim

 

[redram]

Originally posted by drhoades

JStordahl: What about when you are just driving around town and the speed limit is 45 or 50 do you still drive in 4th. In my truck this puts you at around 1750-2000 rpm. From what I understand you get the best mileage at maximum torque and minimum horsepower. And from the the charts that I have seen this seems to be at 1600 rpm. Please note that the only thing in the truck is me and this would be on flat level ground with no acceleration or decelration. I understand about the torsionals from the engine and have seen what they can do. I am just trying to learn as much as possible about driving this truck and doing right so that I can prevent as many problems as possible.



Doug

I wouldn't be in 5th at 1600 rpm under any load, it's a fourth gear application unless you've deviated severely from stock tire diameter.



146K and no problems with 5th gear nut backing off- no idea if running higher rpms helps but I am not going to be the guinea pig on this one. You can if you want.

 

[drrhoades]

Alright well I guess due to the responses that I have gotten I will keep 5th gear for 1800 and above.

Thanks for the advice



Doug

 

[JStordahl]

Originally posted by drhoades

JStordahl: What about when you are just driving around town and the speed limit is 45 or 50 do you still drive in 4th. In my truck this puts you at around 1750-2000 rpm. From what I understand you get the best mileage at maximum torque and minimum horsepower. And from the the charts that I have seen this seems to be at 1600 rpm. Please note that the only thing in the truck is me and this would be on flat level ground with no acceleration or decelration. I understand about the torsionals from the engine and have seen what they can do. I am just trying to learn as much as possible about driving this truck and doing right so that I can prevent as many problems as possible.



Doug

Affirmative..... that is what I do when the speed limit is 45-50... . just stay in 4th gear. The engine likes 2000 rpm, and it is a nice easy range for the 6BT. Even on the interstate, 2000-2100 rpm is cruising speed with light egts and low boost... ... still get 20 mpg. I still run the stock size 245 tires. Of course with the GSK, which I really like, I can still run the rpms up if necessary. Just try various rpm speeds and use what you're comfortable with. The 6BT is a tough and forgiving animal.