If I pulling about 5k lbs (a car plus the trailer) can I still use OD? Say im doing 70mph pulling about 5k lbs or so.

 

no.. you'll 'search' for gears, and generate heat- and heat will munch your clutch surface like their pancakes.. play it safe- keep o/d off with anything over 1k behind you.

 

so keep the highrevs then? 70mph= like almost 4k

 

believe it or not, you're doing your tranny a favor even at that rpm.. Several times I've pulled a 5500# TT at 75~80mph for ten hours straight.. I only got about 150 miles out of a tank, but it never hiccuped once.. they drink the fuel, but they are pretty reliable all in all if you keep 'em tuned, and take required precautions..

speaking of which, and on an aside: Do you have a weight distribution system for your rig? they make a world of difference..

 

what kind of weight distribution?

 

ingenious devices that spread the weight from your rear axle to your front.. they make steering and braking easier.. and another thing, fwiw: I'll never tow over 2500# without a brake controller ever again.. the distribution hitches and a brake controller are two items you will really REALLY appreciate dude.

 

I have a brake controller and have no clue how to use it or anything, it came with the truck

 

well ive been towing all day today about 5k lbs and ive had the (OD) ON and OFF, I turn the OD OFF when I get to a hill and once im either at a downhill or straight, I just turn it back ON, but this is between 65-72 mph, was that enough to mess up the trans? or would it mess it up if I kept doing it over times? I did stop every 2 hrs regardless and truck had a chance to cool off for about 30 min

 

that trailer is big enough that electric brakes are required by law, right? if you have a seven point trailer wiring harness, it is set up for brake use..

the controller has to be set for the weight you're hauling.. buttons/settings may vary, but the concept is to find a stretch of road with your trailer behind you, and accelerate to about 20~30 mph.. then let off the accelerator and push the OS button on the controller..

the trailer's brakes should slow you down a little, but NOT lock up.. you're attempting to set the 'grab' on the trailers brakes to be self sufficient, and not relying 100% on the trucks brakes.. it will vary based on the weight of the load..

the distribution hitch plays a role in this too.. if it's set properly, the rear brakes won't carry the brunt of the braking- it will lever to the front and help control it easier..

 

do you think any damage was done, from my above message that I asked?