Any thoughts on how to calculate towing capacity of an F100? I know there are a million variables: engine size, rear-end ratio, cooling system etc. Assuming a decent 351 Windsor, C-6 auto, 3.50 trac-loc diff, 4-core radiator, well connected receiver hitch, what else should I worry about? How does vehicle weight affect towing capacity?

Thanks in advance for any advice.
John

 

How much do you want to tow? Use a class IV hitch if towing over 5K#. I would not suggest using a homemade hitch if towing a large trailer, it may handle the weight, but would fail a DOT highway inspection (I know several people who have been ticketed for equipment violations when revenue happy local constablery set up roadblock inspections down the road from race tracks on race day) and/or make life he!! if you ever had an accident while towing, no matter if the hitch was involved the insurance cos and court sharks will look for any reason to blame you, if the hitch does not have a DOT rating sticker on it. Trailer tongue weight also affects towing capacity. Too much tongue weight can make the front end of the truck dangerously light and easily hydroplaned. I highly reccomend using a weight equalizing hitch if towing a heavy trailer. They are not very expensive (check hitch sellers on ebay for some of the best prices) and get a sway reducer while there if towing a large vehicle or enclosed trailer with a lot of side wind resistance. Your truck should easily handle 10K# but you may want to add an aux tranny cooler especially if your tranny came from a passenger car, just be sure it is well in the airstream not tucked up away where it gets no airflow.

 

I thought the legalities of GVWR were a little more particular. I, for one, have heard of a horror story of fatality accident involving over weight towing and vehicular manslaughter conviction. I'd take the time to visit a local qualified, knowlegeable person whether a person who sells trucks, trailers, and equipment, or the local authority to learn the particulars in my own state or any state I planned to traverse. I know Colorado for one has very strict regulations concerning suspension alterations, among a slew of other vehicular modifications.
the way it's been explained to me, GVWR is simply the maximum your entire rig can weigh, including curb weight of tow vehicle, trailer and its contents, you and any passengers, your luggage, the flashlight in your glove box and the big gulp you got at the gas station. Take a glance at a late model 1/2 ton truck and its easy to see to remain "legal" you don't get to pull very much. That is, if I'm not way misinformed.
JML

 

Technically speaking, the maximum weight of your truck, regardless of modifications, is the GVWR listed on the door plate.

As for towing/ hauling capacities, that's the GVWR minus the physical weight of your truck loaded to go, fueled up, with tools, cooler, you, whatever else in it. If the GVWR of your truck is 10,000 pounds (just as an example) and your truck, ready to go weighs 8,000 pounds (again, just an example) you have a legal truck payload of 2,000 pounds. That can either be hauled in the bed, or as trailer tongue weight. That's the legal definition as explained to me by a family member who's an attorney.

However, the DOT is a different story. Driving an antique half ton truck, I'd be amazed if you ever get hassled by them. They don't care about the GVWR on the door tag, they look at your actual weight and your license plate weights. For example: If your truck has regular passenger car tags, they probably have a legal weight limit of 8,000 pounds. If your truck and trailer, loaded physically weigh 10,000 pounds, you get a ticket for being overloaded by 2,000 pounds. It doesn't matter what your GVWR is, or towing capacity. To be letter by letter legal, your truck should have tags sufficient for whatever weight you intend to haul with it. In most states, the 'weighted' tags are commercial plates. Yes, super technically, grandma and grandpa towing their RV with regular plates on their pickup are illegally overloaded. However, unless you look commercial, you won't get hassled, and driving a antique truck usually doesn't look commercial.

When I had my PowerStroke, I was busted by the DOT for hauling metal culverts. I owned the truck and trailer, and I had purchased the culverts for private use on my property. However, since it looked commercial, I got pulled over and spot weighed with a portable scale. The entire rig with me in it hit just under 18,000 pounds and I was tagged for 26,000. No ticket. However, my '56 has regular passenger tags on it. The truck weighs about 5600, and I've hauled an estimated 14,000 pound load (farm tractor, implements, and trailer weight) with it once or twice. Aside from being a little bit of a scary ride, it's technically by the book overloaded.

Legally, any modifications you make to the vehicle are 100% irrelevant. You could drop your cab on a Kenworth frame and drivetrain, then register and tag it as an F-1. Legally speaking, you are driving a 1/2 ton pickup truck. However, modifications to hitches, the suspension, etc can be brought into play in a bad, bad way should you ever be in an accident and go to court. A friend of mine was in a nasty court battle after he hit someone towing a trailer load of hay. The plaintiff's attorney argued that since he had put air helper springs on his Dodge, he had intended to overload the truck and go beyond it's designed capabilities. The insurance company wound up settling it.

However, there aren't many options for a 50 year old truck. Fortunately, there usually aren't many people who will mess with you. Here in the next month or so, I'm going to be installing a gooseneck hitch in my truck. Naturally, there aren't any bolt- in options available, especially since it has the dump bed. It's going to be custom fabricated.

As for what your truck can tow, that all depends. Are the factory springs in it? I'd say try to find out what it was rated for when it was built, then go from there. More importantly than what you can get moving is what you can handle and stop. My truck gets a 14,000 pound load moving without too awful much strain. Stopping it with 4 wheel manual drum brakes (and trailer brakes) is a scary proposition. I won't be hauling that load again until I get power brakes and maybe front discs. The F-1 is light, too. The truck has to have enough weight to keep the trailer from wagging the dog, so to speak. Dual wheels help a lot, as does a gooseneck hitch compared to a ball.

That's the legal aspect of it, hope that helps. As for as what you can physically haul, I really don't know, but I'd guess way less than 10K. Just because you can get it moving doesn't mean that the truck can handle it and stop it in a panic situation. If you're doing 50 with a load and have to swerve sharply or stop right now, you need to know for sure the truck is heavy and strong enough to do it.

Just to clarify: I am not a lawyer, nor do I play one on TV. Consult an attorney in your state/ county to get a correct answer. What I have written is not legal advice. Please do not interpret it as such. Consult a licensed attorney with any questions you may have, as I am not one.

 

BUT, he is smarter than the average Bear, BOO--BOO.

 

Sure hope you don't mean me. I'm just an old farm boy with a CDL that's been busted once or twice for being a tiny bit overloaded. Kenworth was tagged for 60K, rolled over the scale in Manchester, TN at just a bit over 72K. Wasn't my fault though, the boss told me to get all four forklifts on the truck regardless of what I had to do. Wound up leaving one lift sitting at the scalehouse so my truck was legal to leave with three, then having to go back for it.

You'd be surprised how much plain old boring looking farm trucks get pulled over, or chased down for passing the weigh stations. Heck, every once in a while the DOT officers go ride up and down the state highways that bypass the scale on the state line. Not without good reason, mind you, but I wish they'd chase down the bigrigs with broken suspension parts and leave my little pickup truck alone.

 

Towing capacity has nothing to do with GVW. My 1/2 T pickup has a GVWR of 7100# and a towing capacity of 10K#. I tow a 7500# trailer with it. I'll be towing the same rig with my 56 panel.
If you don't have commercial plates, you do not have to hit the scales.
If you are going to be doing a lot of heavy trailering, make sure your tires are up to the task, standard pass car tires aren't up to the task. It goes nearly without saying you need electric trailer brakes on any trailer > 3K # GW and a good adjustable automatic brake controller.

 

"Towing rating" has little to do with anything except marketing. What is safe to tow on the highway at highway speeds is way, way less than advertised rating. AX, if you are towing a 7500 lb trailer with a 1/2-ton, you should go to church regularly! (What 1/2-ton has a 7100 GVWR? it weighs almost 6,000 empty??)

Do a websearch on towing ratings, you'll see that the Big 3 all magically jumped their towing ratings about 25% from the late 90's to current without any apparent change in equipment... Would anyone really want to tow even 6,000 lbs with a Ranger???

Out West we see flipped vehicles and dead bodies all summer vacation season from towing mishaps with relatively light travel trailers.

 

Size of tire contact patch, brake shoe/disk contact area, brakeing force, springs - type - ratings, sway bars, towing vehicle weight, tongue weight, trailer weight, trailer center of gravity, trailer center of mass, Hitch - type-mounting, driver-expierence-common sense, oh and dont forget the angle of the dangle and the slip of the lip.

 

Hey LiftTech, I used to haul old iron all over the US until I got caught with 222,000 on 7 axles on the 275 loop around Cincinnati, Oh, after that one I had to get legal or get a different means of making a living, heaviest load ever to be caught in southern Ohio.

 

dain homemade i thought i was the only dumb a-- to try that kinda stuff . hee hee . got caught once while local weighing 125000 in a frameless dump , the stupidist thing i ever did though was give the wrong log book to the nice dot officer that pulled me over on rt. 24 in mo.

 

Didn't want to advertise for the competition, but since you asked 2007 GMC Sierra 1500 crew cab (hence the high GVWR to allow for 5 passengers and load) with Max towing package. Has towed that trailer (24' enclosed car trailer containing 2007 Solstice and all the racing support equipment, tools, 3 sets of race tires and wheels, Generator with AC and fully wired) as far west as KS, North to MA, South to FL. I have a load equalizer hitch with sway control, 4 wheel electric brakes, the best brake controller on the market. Hardly even know the trailer is back there most of the time. My wife enjoys/prefers driving when we are towing while I navigate. I'd much rather tow my trailer than a lightweight/high side wind resistance travel trailer. They are typically top heavy and not equipped with LE hitch or sway control, some don't even have brakes. Once you get that type of trailer fishtailing in a cross wind you're in for trouble. I've never had my trailer start to sway, but if it did, a tap on the manual brake lever would bring it right back into line.

 

[QUOTE] (AX)Didn't want to advertise for the competition, but since you asked 2007 GMC Sierra 1500 crew cab (hence the high GVWR to allow for 5 passengers and load) with Max towing package. Has towed that trailer (24' enclosed car trailer containing 2007 Solstice and all the racing support equipment, tools, 3 sets of race tires and wheels, Generator with AC and fully wired) as far west as KS, North to MA, South to FL. I have a load equalizer hitch with sway control, 4 wheel electric brakes, the best brake controller on the market. Hardly even know the trailer is back there most of the time. My wife enjoys/prefers driving when we are towing while I navigate. I'd much rather tow my trailer than a lightweight/high side wind resistance travel trailer. They are typically top heavy and not equipped with LE hitch or sway control, some don't even have brakes. Once you get that type of trailer fishtailing in a cross wind you're in for trouble. I've never had my trailer start to sway, but if it did, a tap on the manual brake lever would bring it right back into line.[QUOTE]

But what we're trying to determine here in the original question is what is it safe to tow in a Vintage F100 .
From my personal experience the trailer and set up you described above would surly have the tail wagging the Dog
as it applies to the original post.

 

I don't want to rathole on your situation, but I don't think your truck is really a typical 1/2-ton truck. It sounds like you've also done more than most to have a proper set-up. I am astounded by the weight of that rig (GVWR) with a 1500 designation. Does it have a full-floating axle with 6 or 8 lug wheels? A typical 1/2-ton would not, but I wouldn't tow 7500# regularly without that.

So back to the original question, I wouldn't want to tow more than maybe 3500 - 4000 lbs at most at highway speeds with a relatively stock truck. There are a bejillion factors, but we're talking about some relatively flexible, lightweight frames, a Dana 44-like axle, and brakes that aren't super for heavy loads.

 

I am not sure how it will tow but I am setting my 49 F-1, Willard, up to tow up to 5000#. I currently tow the rig with my 2003 extended cab 4.0 automatic 4x4 Ranger.
Willard will run a Jag IFS and a 72 F100 9 inch with a 350 Vortec and AOD. I have removed a couple of rear leaves but installed air shocks. If it doesn't like the hitch weight I may have to add back in a couple of leaves.
I would prefer to tow with a heavier and longer wheelbase vehicle but do not want to routinely drive a larger gas hungry vehicle or have an extra tow only vehicle. I typically tow about 1000 miles per year.
My trailer is aluminum with an aluminum space frame with a fabric top making it an enclosed trailer however it is only enclosed the width inside the wheels which works fine for the earlier running board cars that I move with the trailer.