F350 SRW Enough Truck

4x4ord wrote:

Cummins12V98 wrote:
" I'm "getting by" with a GM 8.1 pulling a 12,000+ fifth wheel & see no need for anything more. I tow from Calgary to Radium, BC through the Rockies at least twice a year. there are sections with 8% grade & I can maintain the speed limit even on those steep grades."

NOT calling you a liar but over 20,000# up 8% grade at the speed limit I would assume around 60mph is honestly hard to believe.

Maybe 4x4ord can chime in on this.

You’re right Ron, a 20k lbs truck and rv doesn’t go up an 8% slope at 60 mph powered by a 340 hp engine. There is quite a climb coming out of Radium (this is probably the 8% grade being mentioned) but I think the speed limit might only be 90 km/hr. Even so, it takes roughly 100 hp to overcome the drag and rolling resistance of even a small 5ver at 90 km/hr. The rear wheel hp required for an 8k truck to overcome gravity while pulling a 12k trailer up an 8% grade is exactly 234.66 hp. So 335 hp is very close to the required power at the rear wheels. The 8.1 litre GM made as much as 340 peak crankshaft hp at 4200 rpm at sea level. So, maybe 260 hp rear wheel hp at 3000 ft elevation. So if the 8.1 litre had a gear to utilize 100% of hp it could pull that hill at about 42 mph.

Oops, busted! Thanks for the reality check guys. That stretch out of Radium has lots of curves, which are 60 K/hr & the rest is 80 K/hr. Going up that stretch I generally don't have a problem keeping with the speed limit, I just was forgetting the the limit was that low. BTW, the combined weight of truck & fifth wheel is just a bit over 19,000 lbs

My main point was that something like the 7.3 Ford gasser should be quite capable.

The new 6.6L chevy gasser or the 7.3L ford gasser are both potent towers. I would say anything up to 16,000 lbs and 3500-4000 hitch weight is OK to tow with these trucks. The new diesels are complex beasts that require crazy maintenance and are prone to pump, turbo, emissions etc. failures where you will either have to maintain an expensive warranty (extended) or eat up the cost - a CP4 failure on the new powerstrokes can easily cost you up to 12K to repair and ford has frequently denied these claims blaming bad fuel for the issues (it is the Bosch CP4 pump that has a problem so....).

An F-350 SRW gasser or a 3500 Chevy SRW gasser should have payloads in the 3700-4000 lbs and plenty of towing capacity.

At current gas and diesel prices assuming you tow about a 1,000 miles per month, you are looking at 80,000 miles to make up the $10K premium you pay for a diesel engine. Add to that the fact that most powerstroke people tell you to do oil changes every 5K miles ($150 at the dealer) and oil+fuel filters every 10K miles ($350 at the dealer), you are looking at extra $4,000 in maintenance over the course of the above-mentioned 80,000 miles. Did I mention lubrication additives with each diesel fuel-up? Boy, you think you are pampering a machine made out of gold! Anyway, this realistically means you will take 100,000 miles or 10 years to make up the diesel engine premium! And there are no risks of CP4, turbo, emissions etc. failures, no mystery coolant leaks...

IMHO, only people towing > 16,000 lbs and people who work out of a truck (tow things daily like tractors, heavy equipment etc. to work sites) need a diesel. The whole myth of the "reliable and runs forever diesel" was built on the pre-2004 7.3L powerstroke and pre 2004 12/24v 5.9L Cummins engines - they were easy and cheap to maintain (but then they had the same torque output as the new 7.3L ford and 6.6L chevy gassers so you weren't getting anywhere in a hurry). Today's diesel engines put out 450+ HP and 1000 ft/lbs torque and are SUPER complicated. Just open the 6.7L engine bay and then open the 7.3L gasser engine bay. You could drop a screw driver in the former and never find it again...

Grit dog wrote:

mkirsch wrote:


What's the difference? Don't know. Ford won't tell anyone.

All we know is that it is rated for 7230lbs and the others are not.

What makes the AXLE unsuitable? Probably nothing. Most of these axles from their respective component manufacturers are rated to 10,000lbs gross.

However, as you well know, there is more than just an axle at play here. Springs. Frame. Tires. There may or may not be differences there. Don't know. Ford still isn't talking. All we know is that they're willing to extend the warranty for 7230 if you buy the 7230 axle.

Yes, I get your "Just shove a chunk of well casing between the axle and frame, and load 'er down, it's all good!" attitude. I'd agree with you if the OP was looking at anything besides a brand new truck. When you can get the truck from the factory built for the job, why would you buy a lesser truck and immediately start putting aftermarket load assistance devices on it?

You can figure out the difference. You just have to spend a little time figuring it out. You're correct though, it is not in the axle.
But they still offer srw trucks with 17" wheels and we all know you can't buy a normal 17" tire with more than a 3200lb load rating.

My attitude is exactly opposite of what you said though (although, I'll admit to doing similar things, maybe, more than once, lol).
It is one of education and my attempt to dispell the plethora of Rvnet myths and misnomers and old "I remember when" logic.
Cheers bud!

According to Ford: “Gross Axle Weight Rating is determined by the rated capacity of the minimum component of the axle system (axle, computer-selected springs, wheels, tires) of a specific vehicle. Front and rear GAWRs will, in all cases, sum to a number equal to or greater than the GVWR for the particular vehicle. Maximum loaded vehicle (including passengers, equipment and payload) cannot exceed the GVW rating or GAWR (front or rear).”

In reality I don’t think the rated capacity of the axle is ever the minimum component of the axle system. Additionally there are times when the minimum component is simply the door sticker.

mkirsch wrote:


What's the difference? Don't know. Ford won't tell anyone.

All we know is that it is rated for 7230lbs and the others are not.

What makes the AXLE unsuitable? Probably nothing. Most of these axles from their respective component manufacturers are rated to 10,000lbs gross.

However, as you well know, there is more than just an axle at play here. Springs. Frame. Tires. There may or may not be differences there. Don't know. Ford still isn't talking. All we know is that they're willing to extend the warranty for 7230 if you buy the 7230 axle.

Yes, I get your "Just shove a chunk of well casing between the axle and frame, and load 'er down, it's all good!" attitude. I'd agree with you if the OP was looking at anything besides a brand new truck. When you can get the truck from the factory built for the job, why would you buy a lesser truck and immediately start putting aftermarket load assistance devices on it?

You can figure out the difference. You just have to spend a little time figuring it out. You're correct though, it is not in the axle.
But they still offer srw trucks with 17" wheels and we all know you can't buy a normal 17" tire with more than a 3200lb load rating.

My attitude is exactly opposite of what you said though (although, I'll admit to doing similar things, maybe, more than once, lol).
It is one of education and my attempt to dispell the plethora of Rvnet myths and misnomers and old "I remember when" logic.
Cheers bud!

Grit dog wrote:

4x4ord wrote:
I can’t imagine why anyone would buy an F350 with a gas engine .... my way of thinking is if I need more than a half ton to pull it I’m going diesel, but, yes a F350 SRW 7.3 gas would work for that trailer. You’ll want the 7230 lb rear axle.

I’ll ask a leading question, like you tend to do a lot.
What is different about the “7230 lb” rated axle from the other F350 axles? And what would make the lower rated ones or even the smaller axle in the F250s unsuitable for an up to 9000lb + rear axle load?

What's the difference? Don't know. Ford won't tell anyone.

All we know is that it is rated for 7230lbs and the others are not.

What makes the AXLE unsuitable? Probably nothing. Most of these axles from their respective component manufacturers are rated to 10,000lbs gross.

However, as you well know, there is more than just an axle at play here. Springs. Frame. Tires. There may or may not be differences there. Don't know. Ford still isn't talking. All we know is that they're willing to extend the warranty for 7230 if you buy the 7230 axle.

Yes, I get your "Just shove a chunk of well casing between the axle and frame, and load 'er down, it's all good!" attitude. I'd agree with you if the OP was looking at anything besides a brand new truck. When you can get the truck from the factory built for the job, why would you buy a lesser truck and immediately start putting aftermarket load assistance devices on it?

4x4ord wrote:

Cummins12V98 wrote:
" I'm "getting by" with a GM 8.1 pulling a 12,000+ fifth wheel & see no need for anything more. I tow from Calgary to Radium, BC through the Rockies at least twice a year. there are sections with 8% grade & I can maintain the speed limit even on those steep grades."

NOT calling you a liar but over 20,000# up 8% grade at the speed limit I would assume around 60mph is honestly hard to believe.

Maybe 4x4ord can chime in on this.

You’re right Ron, a 20k lbs truck and rv doesn’t go up an 8% slope at 60 mph powered by a 340 hp engine. There is quite a climb coming out of Radium (this is probably the 8% grade being mentioned) but I think the speed limit might only be 90 km/hr. Even so, it takes roughly 100 hp to overcome the drag and rolling resistance of even a small 5ver at 90 km/hr. The rear wheel hp required for an 8k truck to overcome gravity while pulling a 12k trailer up an 8% grade is exactly 234.66 hp. So 335 hp is very close to the required power at the rear wheels. The 8.1 litre GM made as much as 340 peak crankshaft hp at 4200 rpm at sea level. So, maybe 260 hp rear wheel hp at 3000 ft elevation. So if the 8.1 litre had a gear to utilize 100% of hp it could pull that hill at about 42 mph.

Thanks for the confirmation! I have no idea how you come up with these numbers but I do appreciate your skills in this arena.

What got me thinking that this was not possible was the fact I couldn't maintain 55 mph up 6% @ 20k combined with my 98 12V Cummins dyno 300 rwhp and I think it was around 750 tq.

Cummins12V98 wrote:
" I'm "getting by" with a GM 8.1 pulling a 12,000+ fifth wheel & see no need for anything more. I tow from Calgary to Radium, BC through the Rockies at least twice a year. there are sections with 8% grade & I can maintain the speed limit even on those steep grades."

NOT calling you a liar but over 20,000# up 8% grade at the speed limit I would assume around 60mph is honestly hard to believe.

Maybe 4x4ord can chime in on this.

You’re right Ron, a 20k lbs truck and rv doesn’t go up an 8% slope at 60 mph powered by a 340 hp engine. There is quite a climb coming out of Radium (this is probably the 8% grade being mentioned) but I think the speed limit might only be 90 km/hr. Even so, it takes roughly 100 hp to overcome the drag and rolling resistance of even a small 5ver at 90 km/hr. The rear wheel hp required for an 8k truck to overcome gravity while pulling a 12k trailer up an 8% grade is exactly 234.66 hp. So 335 hp is very close to the required power at the rear wheels. The 8.1 litre GM made as much as 340 peak crankshaft hp at 4200 rpm at sea level. So, maybe 260 hp rear wheel hp at 3000 ft elevation. So if the 8.1 litre had a gear to utilize 100% of hp it could pull that hill at about 42 mph.

bjkb1f wrote:
Thanks all. I would definitely be getting the 7.3. Assuming that, SRW and the highest available axle rating, what is the max GVWR and pin weight I should be looking at?

Assume Lariat trim which will take a bit from payload capacity.

Yup, gonna have to agree with Grit dog again...get the trim level you want, the small payload difference has little to do with rear axle wt, and towing a FW. Yes, do get the 4.30 gear set, since you will be ordering.

Jerry

Put me down for a 7.3/4.30 F350 as well!

Some day I’ll get to post on here what it is like going from a diesel to a gas. Not the best comparison since my truck is old and noisy.

Thanks all. I would definitely be getting the 7.3. Assuming that, SRW and the highest available axle rating, what is the max GVWR and pin weight I should be looking at?

Assume Lariat trim which will take a bit from payload capacity.