I have a 98 1500 with a 5.9l and it has a lot of trouble maintaining speed while in overdrive when pulling my trailer. The slightest hill or even gust of wind makes the van downshift to 3rd, so I find myself driving in 3rd almost all the time. Ive had a couple ideas on how to fix this problem, one of which was to throw a supercharger on and the other was to swap out the differential with one that had a higher ratio. I figured that a new diff would be a lot cheaper. Is this a good idea? Does anyone know what the ratio of a stock diff in a 1500 is? and does anyone have any other ideas?

 

They say you should not even tow with the overdrive engaged. The transmission is the weak link in towing, not the 5.9.

If you insist on towing in overdrive, you should make sure you have fresh ATF+4(synthetic) and an external tranny cooler, and argueably a tranny temp sensor.

A taller gear ratio will help too, as you suspect.

 

It doesn't make any sense to go to a lower gear rear-end just so you can drive in OD. Leave the rear-end alone and turn the OD off. Your engine RPMs will be roughly the same without spending all of that money to swap out the rear-end.

 

Definitely turn off OD when you tow. A saying an old tranny mechanic said to me once is "tow in drive keep your tranny alive". Works for me - when the bf towed on slight hills with OD engaged (wouldn't listen to me) he killed the OD on our '90 B250 with 5.9.

 

I've towed in OD for many years with the Ram Van 5.2L/318 B2500 with 3.92 rear. However, not going up hills nor into a strong wind. OD towing needs to be on a flat highway or a good stretch clipping along at no more than 60mph. Of course, the towing weight needs to be lighter than the norm too. For my Ram Van, 4,500lbs or lower on the flat highways allowed OD to be used.

Make sure the hubs are greased well on the trailer, the brake controller not set to extremely sensitive, and the van rear adjusters on the drums set properly without dragging. Also, keep with the 10W30 oil. I run 5W30 in the fall/winter/spring with no towing involved. Have a clean air filter and clean/new PVC.

Now, if you have ever had the tranny get too hot, I would recommend not to ever tow in OD until it was properly serviced.

I did tow with the V6 B1500 3.55 rear, but it was wimpy and my travels were limited due to the needed access to flat highways. Of course that was only an auto 3 speed.

ATF+4 will work the best as it was mentioned here.

If you take the hills, push the button to turn off the OD. While in dense traffic keep off the OD. While driving with the OD off, do not exceed 50-55mph. If you go higher, the engine gets really hot, the oil pressure rises and the rpm's rev very high.

 

Im starting to think that I might have a problem. I think "hills" was a bit of an overstatement. Now keep in mind that this is a band trying to get to each city in time to play a show, so where-as I should be doing 60mph, Im usually doing anywhere from 70mph to 80mph on the highways so my RPM's in general should be higher but regardless, the slightest incline, and when I say "gust" I mean light gust of wind, and the van downshifts. I make sure to replace the air filter, change the oil and re-pack (re-grease) the hubs on the trailer, the day before every tour. Plus I'm only pulling, im guessing a 2500-3000lbs trailer. I used to pull this exact same trailer with the exact same epuipment with my 2000 Toyota 4Runner that had a 3.4L V6 and it never had as many power issues as this van does, and the van has a 5.9L 250hp 345lb-ft V8. I went all the way across Texas with that 4Runner+Trailer and never had this problem. And its not that my van is old and weary or anything, it only has 70k miles on it and has been meticulously maintained with the paperwork to prove it. Arggg, Im sorry im ranting. Anyways... help
Oh and no I've never had an overheating transmission problem before.

 

The only question now is the rear gear set. Sounds like you have the 3.55 rear, but why mate that to the powerful 5.9L? The 3.92 rear would be ideal for your setup.

It would be interesting if you could post some details about the rear axle plate with the number of bolts. Maybe a photo here even?

 

Better gas mileage and less engine wear.

 

I was going to do the 3.92 but I just got a smokin deal on an aftermarket 4.11. Ill post the results and pics of install soon.

 

i have a b30 15 passenger for my band, so i think we probably haul a similar type of weight. Now ive used 1/2 tons for band biz, but i dont recommend it....try and find a 1 ton 15 pass from an old church. thats what we did.

anyway, we really monitor our driving. when flat we will use overdrive. but ours has a o/d on / off switch, so on hills or in town, we shut it off.

hope that helps!