No, I don't have an owners manual to look it up. I did a search all over the internet and this site, and can't find out how much my truck can tow, the one in my sig. Cna somebody please help me?
Also, I have been thinking about changing to a solid front alxe. If I do, would it be worth it to change to a 4.10 gearing for towing? Or would that not help much?
Thanks for the help.

 

Your tow capacity for bumper pull trailer should be somewhere around 5000-5500 lbs. If you put 4.10 gears the rating goes up about another 1500 lbs. The 351 engines didn't get very high tow ratings and your 3.55 axle doesn't help matters any.

When I looked mine up I was very disappointed: '92 F350 CrewCab LongBed 4x4 351/C6/3.55 gears GVWR 9200 lbs, GCWR 11,500 lbs minus average truck weight of 6500 lbs (more if loaded) = 5000 lbs. The actual tow rating was more but they arrived at that figure with a lighter actual truck weight. With 4.10 gears in same truck tow rating was 7200 lbs bumper pull, 7700 lbs 5th wheel, GCWR went up to about 13,000, maybe 13,500 lbs, so say about 6500 to 7000 lbs actual towing capacity. I have towed 7500 lbs with it and the chassis handled it beautifully but it was ssllloooowww going up hills and pulling from a dead stop. Next week the truck goes in for a gear change to 4.56 and that should give the beast a much needed kick in the pants.

If you're going to larger tires with that solid axle swap, remember that you need to go lower than 4.10 (4.56 or more depending on tire size difference) in order to get an actual effective 4.10 ratio and corresponding towing performance. 4.56 w/ 33" tires will give me an effective ratio of about 4.30, a little lower than 4.10 but that's ok, I'll take the extra torque and live with the loss of high freeway cruising speed.

 

I don't have the tow guide for the year 1990 but I do have the 1991 which should be the same or pretty darn close. From The Ford Towing Guide, 1991, for your truck, max trailer weight is 6700 lbs. Going to the 4.10 gears makes it 8200 lbs.

 

Thanks for the info guys. I would stay with my current tire size, as any higher and I would need a ladder to get in my truck. OR a trampoline. Are gear changes something a weekend mechanic can handle, or another one of those best left to the professionals jobs? Besides the safety issues with over towing my GCWR, what would take to hurting? I'd guess my diff overheating. But would synth diff oil help?

The short term reason for the questions is that I have a job in about 3 weeks which I need to get a little over 6000 lbs of fence material to a job, on my dad's 14' dual axle trialer, which he's guessing in at 4000 lbs. I have to go about 25 miles, with hills and all. I'll need to hook up an electric brake controller. I have no problem with splitting the load down the middle. It's between my truck and my dad's dump, '71 GMC reg cab dually( all under bed, 4 spd w/granny. Belive it's got a 350, not sure what gearing. We've never towed with the truck, only know it can handle 4000 lbs in the back without breaking a sweat. Dad says it's got elec brake hookup, but there is no box in the dash. I'd rather take my truck because it's mien, so I'm more comfortable driving it, but only if it can handle the load. Thanks again.

 

If all you're going is 25 miles, I wouldn't worry about it. Just take it easy with it.

A gear change isnt really something you want to tackle if you don't know how to do it and dont have the special tools to do it with. Best to let the pros do that.

 

I figured it would be a PITA for me. And I'll definately take it easy with the load. Thanks SoCal.