F350 SRW Enough Truck

[bjkb1f]

Hi all. I currently tow a 7k lb TT with an F150 and we’re thinking about upgrading to a fifth wheel. Looking at the Sabre 37FLL - link with specs below.

This is totally new to me and I don’t want a dually or a diesel. So, my question is would a 2021 F350 gas/SRW be enough to tow this camper for 8-10 trips a year mostly within 3 hours of home? It would be extremely rare that we would be in any mountains.

Our TT is currently about 1,000 lbs more than dry weight, so assume we add a bit more than that to the new 5’er. I don’t think we’d get anywhere near the 2900 lb CCC. I’d assume pin weight would be 3k at the most.

Sabre 37FLL

[mkirsch]

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?

[Cummins12V98]

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.

[4x4ord]

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.

[MFL]

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

[LanceRKeys]

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.

[bjkb1f]

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.

[Devo_the_dog]

BB_TX wrote:
Us diesel guys tend to think there is no other option than a diesel for towing. But there are a lot of other guys out there towing with gassers and are perfectly happy with them. :Z

I agree.

I used to tow with my Ford V10. Actually, I used to only tow with Fords and GMs, all gas engines. I ordered a new Ram HO diesel and after towing off and on for the last 1 1/2 years, I understand the advantages. It's not a big deal though. Fuel mileage is only a little better. You don't slow down going uphill or while in a headwind. And, this truck is quiet. The cost wasn't a big deal for me but the dealerships and manufacture really sucks. Good luck getting repairs done, even if it's recall work. Dodge owners are totally brainwashed. LOL.

I'm switching back to towing with my 2005 Ford V10. It's much more reliable and if I purchase a new truck, I'm getting a Ford with the 7.3.

[Cummins12V98]

" 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.

[valhalla360]

BB_TX wrote:
Us diesel guys tend to think there is no other option than a diesel for towing. But there are a lot of other guys out there towing with gassers and are perfectly happy with them. :Z

I've had both gas and diesel. I have a Ford V10 currently but we are down around 7,500lb with the current rig.

Same truck towing a 12,000lb 5er and it did it but every overpass it would downshift. Never overheated or felt we couldn't make it up the next hill but you really felt it as testing the limits.

The 7.3 might do a little better but 14-15k, I would be looking for a diesel.

[memtb]

Just finished a 9 day, 5050 mile trip ( long story) , with many high winds (some were cross-winds), towing a 20K pound 5th wheel with a SRW Ram 3500 diesel. Though, we’ve added air bags, changes tires/rims to a much higher load rating......never felt as though we were in a loss of control situation! Others, the law, and your insurance may share a different view regarding your towing capabilities! 😉 memtb

[frankwp]

OP, I'm also one of those who doesn't want a dually or a diesel. 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.

An F350 with a 7.3 gas would tow very well, I think. If I were replacing the GM today, that's what I'd get.

[Grit_dog]

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?

[Grit_dog]

That size of trailer, get the 4.30 gears, don’t waiver on this. You’ll want em, period.
ANY F350 srw has the rear axle capacity to handle that pin weight, not a question, nor debate able , regardless of “options” or opinions.
Go order the color and trim level that you want. Don’t get wrapped up in the minutia that is getting brought out in this thread and every one like it.

[BB_TX]

Us diesel guys tend to think there is no other option than a diesel for towing. But there are a lot of other guys out there towing with gassers and are perfectly happy with them. :Z

[Lwiddis]

“would a 2021 F350 gas/SRW be enough to tow this camper for 8-10 trips a year...”

Yes but not 11 to 12 times per year. Seriously, either you are within weight limits or you are not whether close to home or far away.