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How to calculate my GCWR

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Ray Cecil

How to calculate my GCWR

I need a little confirmation here, and a little help finding the correct numbers.

The goal: Find Stock specifications for this truck, and determine max safe travel trailer size and weight. Then calculate max travel trailer size and weight with an upgraded dana 60 front axle, and possible f350 rear leaf upgrade. We plan to hit the road, taking my remote job with me, sometime next year or 2025 no later.

The truck:
88 F250, c6 Automatic 4wd, 7.3, 4.10 gears with gearvendors factory GVWR is 8800lbs

Front axle GAWR is 4410lbs
Rear axle GAWR is 6084

Unkowns:

How much does my truck weigh empty?

How much tongue weight can I put on the 5th wheel hitch.

How much on the bumper hitch?

How much can I tow?

Now....I'm planning to upgrade to a solid dana60 up front. Should I upgrade to higher rated f350 rear leafs at the same time? What would be the towing and tongue weight increase if I did these suspension upgrades?

I read the 1986 Towing pages in the towing section, but not sure if my 88 has a greater cap or not.

Thanks for any help.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

85lebaront2

Re: How to calculate my GCWR

Administrator

Ray, I had to actually weigh Darth to find out. His GVWR is 10,000 lbs, his empty weight (both tanks near fumes and only an aluminum camper shell on or in the truck) was 6400 lbs. That gives me a 3600 lb capacity.

Now add 38 gals of gas, weight of anyone in the cab and you would be surprised how quick you end up with 3600 lbs. Just be glad we don't have Ram trucks, guy had a big slide-in camper on a Ram 3500 dually, frame broke right at the back of the cab.

FWIW, Gary and I were comparing some specific details on BB and Darth. BB's rear GAWR is a bit less than Darth's but BB's rear springs are the same code (K) as Darth's, his axle is coded as a lower GAWR, possibly due to single vs dual rear wheels. I have only had the factory overload rear springs actually in contact with their pads when towing our 10,000 lb 5th wheel (8800 empty, 10,000 gross).

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: How to calculate my GCWR

Administrator

Ray - This is a complex area, and as Bill said one of the steps is to weigh your truck. That will let you start figuring out what the capacity is. However, if you do install a D60, and especially if you go with Superduty springs, you'll complicate things even more since the load limit of those components is higher than what you currently have.

The quote below is this post from Big Blue's Transformation thread where I was discussing the GVWR of it, especially with the D60/SD springs.

Gary Lewis wrote

As reported in New Tires For Big Blue, the new Falken A/T3W's were mounted today. WHAT A DIFFERENCE!!!! I can't say enough about how quiet and smooth they are.

I weighed the truck, and with me out of the truck and the front tank at 1/2 and the rear full plus all the recovery gear these were the readings:

Front: 3720 lbs 57%
Rear: 2840 lbs 43%
------------------------
Total: 6560 lbs

Now, if I was still running the TTB's I think I might be worried as the certification label says the front axle's GAWR is only 3850 lbs, and by the time you add a driver, passenger, and gear I'm sure we'll be way over 4000 lbs on the front axle. But we have a D60 with SuperDuty U-code springs, and this post in PowerStroke nation says the springs are good for 4800 lbs. So I'm going to assume that they are the weak link and the front axle's GAWR is actually 4800 lbs.

If that is the case we have ~1000 lbs of headroom on the front axle and 3000 lbs (5922 - 2840) in the rear. And while I don't know how to combine the front and rear GAWR's to get the GVWR, I think it is safe to say that we aren't going to overload it since we are right now at least 2000 lbs shy of the limit 8600 GVWR on the certification label.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

85lebaront2

Re: How to calculate my GCWR

Administrator

I didn't get a front/rear weight breakdown on Darth, but it also didn't cost anything (I know the people who run the local grain elevator) I can probably get front/rear as a good friend has a set of portable electronic scales that can read all or individually as desired.

One of the interesting things I found in doing some reading up on the Dodge frame issue, the 1980-1997 Ford 250/350 frames are some of the heaviest built pickup truck frames ever made, Darth's side rails are 7" high and there is a fair amount turned in top and bottom for flanges. It also explained why the F250HD and F350 seem to sit so much higher, the cabs are all the same, so the extra height and wheel clearance are due to the increased frame side height.

Our local toll facility (CBBT) has the dually trucks in a different category than single wheel, if I go through an automated lane I get pinged for a higher toll, if I go through a manned lane, the person in the booth looks at the height scale, over 7' high and dual wheels gets a higher toll, under 7' high gets the same as a car, SUV, minivan etc. This was done because there are a number of dually trucks here for hauling horse trailers, some of which are owned by CBBT employees.

Bill AKA "LOBO" Profile

Ray Cecil

Re: How to calculate my GCWR

In reply to this post by 85lebaront2

Hey, thank. I will call around and see who has a scale. I have delivered scrap metal down to a yard before, I know they have a scale, but if would require me to drive through a disgusting scrap yard with a lot of risk for flat tires and scratches on the new paint. I'm guessing the rock quarry nearby has a scale.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Ray Cecil

Re: How to calculate my GCWR

In reply to this post by Gary Lewis

Thanks for the link Gary. I'll have a read through it.

Is there a chart in the forum docs that covers bricknose tow capacities?

I really need to get a number for GCWR with my current configuration. Even if I don't weigh my truck, I can probably make an educated guess, and start getting some concrete numbers figured out.

I'll pretty much shoot for a travel trailer that my f250 could currently haul. Any upgrades to suspension would be to increase safety. I wouldn't necessarily be trying to purchase a heavier trailer or pack more useless stuff in it.

I need to finalize the trailer brake controller wiring, and do a hydroboost upgrade as well. I'm not impressed with these vacuum brakes.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Gary Lewis

Re: How to calculate my GCWR

Administrator

No, we don't have a chart on Bricknose towing capabilities. But I'd bet they don't vary much from the 1986 specs, which you can find on our page at Documentation/Specifications/Towing. But if you find a 1988 owner's manual it'll have the specs.

And I agree with your plan to just use any upgrades as a safety factor. That way you are legal because if you are in an accident and someone sues because you were overloaded the upgraded spec's won't matter. I'm sure all the court will consider is Ford's specs.

On the trailer brake controller, I have the Tekonsha 90195 P3 Electronic Brake Control and it works well. However, it does not like LED brake lights. And it, like all electronic brake controllers, is going to pulse the brakes if you put the hazard flashers on since it'll look to the controller like you are pumping the brakes.

To get around the latter you would really need a hydraulic brake controller, although the electronic ones can be fixed with a diode. But if you are going hydroboost then you could go with a master cylinder that has the extra port that could be tied into a hydraulic controller. Bill/85lebaront2 did that.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: How to calculate my GCWR

Administrator

There is one problem with using a hydraulic actuated trailer brake controller, no one even makes them anymore.

Bill AKA "LOBO" Profile