5th gear nut / engine RPM questions

[Dan_69GTX]

Besides the fully splined shaft that standard transmissions sells, what do people do to fix the 5th gear nut?



The truck I bought had that problem and was fixed, by whom or how I don't know - I'm curious what options there are.



Why do people say if you fall below 1600-1700 RPM while towing that you can have more of a problem with the 5th gear nut?



Is driving around in 5th gear, empty or almost empty, around 1500 rpm not good??



Thanks!

Dan

 

[Champane Flight]

Yeap

There were several fixs for the fifth gear nut,but the splined shaft is the best. They had a new nut with a greater torque and even a pined nut.



The torque vibrations sent to the fifth gear shaft at low RPM 1800 and below seem to be the main culprit. It tends to loosen the nut up by the low frequecy vibrations.



Definitly not good for the transmission or the engine running at 1500 in fifth gear...



I keep my engine turned up where ever I go. It is better for the engine and fuel mileage. Keeps the engine from sooting up to.

 

[Dan_69GTX]

So, it doesn't hurt your mileage when you have the motor reving above 2000?



I kinda thought that would hurt it. Have you tried any tests?



Thanks!

Dan

 

[SteveH]

I only had about 10k on mine when fifth gear went out. Wasn't pulling a trailer at the time and just went on home in 4th gear. Dodge supposedly did a fix on it but I think they just put some loc-tite on the same style of nut that was originally on the spline. I pull a 31' 5th wheel and pull in 5th gear all that I possibly can. Running empty, I don't mind staying at 1500 RPMs at all, still have plenty of power, doesn't lug, and gets much better mileage than if the RPMs are above the 2000 mark.

 

[wbrown02]

Overdrive Anyone

Sounds like you pull a heavy load and like to run in 5th gear... . Have you thought of useing a Gear Vendor Overdrive..... I pull a 5th wheel with a 22' boat behind the 5th wheel never touch 5th gear while pulling above combo... . gross weight is approx. 19500 lbs..... with the 3. 54 rear end I cruise in 4th over at 1800 rpm and 60 mph... ... . empty she will do well over 100 mph..... 5th over and empty at 75 mph motor turns 1700 rpm and gets 19 mpg... ... The Gear Vendor is fun to use and works very well... ... just a thought... . Picture included... .

 

[Champane Flight]

Better

I get a solid 20-23mpg. This is keeping rpm above 1750-1800 all the time. I have always believed if you keep an engine in its peak powerband you can't go wrong. Regardless of what people say max torque on my 95 comes at 1800 to 2100 rpms. I have found that peak fuel mileage comes at 1950. I run 65 at this rpm. And pulled a high of 25. 4 with great restraint keeping my foot out of it. . With 3:54s at 55 I am taking her down to fourth. I also keep my foot on the fuel when I disengage my cruise control to keep from jerking the drivetrain.



I have 76000 miles on mine now with NO sign of any transmission problems. I am not saying it won't happen,but not so far(knock on wood). .

 

[rhoads]

milage/nut

see post on other 5th gear nut.

For mpg's stay at max 2000 --Best Under.....