Gcwr

[JimMoran]

I have been a member for some time but this is my first post. So lets see what happens.

We have a 1999 5. 9 liter Dodge with a GCWR of 16,00 lbs. The Rig [truck & 5th wheel] were recently weighed by RVSEF and our Combined weight was found to be 15,650 lbs. I figure this is too close. Our current Trans. axle ratio is 3. 54. I inquired about going to the 4. 10 axle ratio and was advised against it. Because of high rpm's in third, increased engine wear and reduced fuel economy.

I was also informed that my automatic transmission was doomed to failure regardless of what I did. Is there any thing I can do to prevent the failure of the transmission? We have installed a Mag-Hytec deep Pan and now use Red Line Synthetic oil. The trans. temp. has never gone over 140 deg. Thanks for your responses. Jim

 

[Casey Balvert]

Jim, I think you are fine with the axle ratio that you have for the combined weight of the rig. Not sure who gave you the bull on the 4. 10 but the fuel economy would be fine as long as your foot isn't always on the floor and engine wear isn't even a factor with a diesel that will probably last a half million mines no matter what ratio you have. Regardless, I don't think it would be worth going to the higher ratio in your particular situation. Perhaps some others can chime in on some upgrades for your automatic that will prolong its life. Good luck and safe travels.



Casey

 

[Prairie Dog]

I agree with Casey. The gearing won't make much difference and you haven't mentioned any trouble with pulling so I'd leave it alone. Yes your transmission will die someday - but they all will. Plan on rebuilding it arround 175k to keep it reliable.

If your happy with the performance of your rig then the only other thing I would suggest is a trans temp gage to head off any surprises.

 

[Fireman]

While I believe that 4. 10 is a better choice for towing with an automatic (due to the overdrives high ratio) I wouldn't swap gears. You can always tow with OD locked out. Monitor your trans temp, and change your fluid regularly and you should be able to get alot of good service from your auto.

Fireman

 

[tgrfan2]

I would not worry a bit about your truck. I was told by an "expert" on here that my truck would not make the first trip with my new fiver. Well 5K of towing, 127K on the stock transmission and a #6 plate later she is still rolling! I gross 19,760# and I would not change my gear, although I wish I had a Dana 80 instead of the 70 since I destroyed the rear end with my TT at 80K. The secret to life of any automatic is keeping the fluid cool. I use regular fluid and LubeGard. I recommend driving it like a manual which means downshifting yourself when loaded and use drive to keep the rpm up. That is why I like the 3. 54 gear. You can keep up with normal traffic in drive in tough pulling and use OD when traffic and terrain allow.

 

[DavidTD]

I agree with these guys, you shouldn't need to change gears at your weight. What you will want to do is watch what rpm you try and pull the steep grades at.



I love my 4:10's for towing but I don't like them for running empty. 70 mph = 2500 rpm with the 5 speed. But the plus to that is at 2500 rpm I am near hp peak and the truck still amazes me how well it pulls there.