[font size="1" color="#FF0000"]LAST EDITED ON 09-May-01 AT 11:16 PM (EST)[/font][p]My '78 F150 SuperCab doesn't have the gcwr(gross combined weight rating) listed anywhere in the door area or in the owner's manual. The max gvwr is listed at 6,050lbs. It's got a 460, 4bbl carb, a C6 auto, and a 2.75 geared nine incher out back. I'm going to change to 3.50's or 3.73's later this summer. Any ideas?
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6

 

I don't know the answer but will take an educated guestimate on this. Keep in mind I am no expert and am guestimating from experience with towing with my F250 and from reading articles etc. The answer I come up with may be WRONG, but it may get you in the ball park and at least it will give some areas to think about.

You could weigh your truck and each axle weight at a truck stop to give actual figures from which you can base better calculations. An early 90s(manual I have is 94 F Series) F150 would pull as little as 0 pounds up to about 7,000 depending on engine, tranny etc. 94 Book figures are GCWR between 9,000 and 12,000 for 2WD and between 11,500 and 12,500 for 4x4. With your engine I would lean on the high side, but with your gears you drop a lot. And since I have a 94 manual and you have a 78 all bets may be off.

The key on the F150 will be 1) Not to exceed the axle rating and 2) Not to over stress the chassis and drive train.

Without knowing more about the axle I would speculate that since the 150 is a half ton truck that, you should safely be able to carry 1,000 pounds in the bed. Keep in mind that includes fuel passengers etc, so I would guess a reasonable tongue weight to be about 500 pounds or less. From a tongue weight of 500 pounds you could expect a trailer weight of upto 5,000 pounds usually this is about a 25 foot or less, travel trailer size. Most 90s F150 max out on a trailer around 7,000 pounds. With your current gearing I wouldn't even attempt this weight. With 3.73 or higher gears, you could get closer.

The limiting factors will be the axle weight carrying capacity and basic strength, plus the chassis setup, engine and tranny are probably not a problem. Brakes, bearings, cooling system etc may be marginal. The 2.73 gearing tells me your truck was probably not designed for heavy loads and was more of a cruiser. Most of the higher load ratings on the 90s were fro gears 3.55 to 4.10.

So, you might need better cooling and a tranny cooler. Better gears are a must, maybe even a stronger axle(I don't know what the rating is on yours) ratio is not the only thing to consider on the axle. Definitely use a weight distributing hitch so that you don't over stress the rear suspension.

So in a nutshell I would say that unless you find better figures, I would approach 5,000 pounds cautiously. Like I mentioned earlier, 90s F150s are rated for ZERO upto somewhere around 7,000 pounds. You are probably somewhere in between. With better equipment, you can probably approach 7,000. Keep in mind, weight ratings should also take into account your passenger load, liquids, and junk in the bed of the truck, i. e. more junk and passengers, means lighter trailer.

NOTES ARE IN CAPS WHICH MAY SHOW MY REASONING.


Good Luck,

Jim Henderson

>
>My '78 F150 SuperCab doesn't have F150 IS A HALF TONNER SO IT WON'T PULL A LOT ON A REGULAR BASIS.
>the gcwr(gross combined weight rating)
>listed anywhere in the door
>area or in the owner's
>manual. The max gvwr is
>listed at 6,050lbs. It's got GCWR WILL BE GREATER THAN THIS FIGURE AT LEAST.
>a 460, 4bbl carb, a GOOD ENGINE, CAPABLE OF HAULING A BIG LOAD.
>C6 auto GOOD TRANNY, and a 2.75 CHEESY GEARS
>geared nine incher out back.
>I'm going to change to
>3.50's or 3.73's later this MOST TOW VEHICLES WILL USE A 4.10 BUT IT DEPENDS ON THE TRANNY GEARING.
>summer. Any ideas?
>Jason Kendrick
>1970 F100 Custom 390/C6
>1978 F150 Ranger Lariat Supercab 460/C6
>

 

Jim, Thanks for the response. It's got the heavy duty cooling system with an aftermarket tranny cooler mounted in front of the radiator, and plumbed in with the factory radiator cooler. In other words, this truck has two tranny coolers.

Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6