2019 F350 4x4 custom HPI flatbed/AT Atlas topper

[RAM5500 CAMPERTHING]

Show me your mathmagician to calculate that you'd be running at 1750ish RPM "sweet jelly spot" with 4.89s and 40"s. Pics or it didn't happen.

Sure thing. ?????

Spicer Transmission Ratio RPM Calculator

Use the Spicer Transmission Ratio RPM Calculator to determine your engine’s RPM based on the transmission gear ratio, tire height, MPH, and ring and pinion gear ratio.

spicerparts.com

 

[mk216v]

Sure thing. ?????

Spicer Transmission Ratio RPM Calculator

Use the Spicer Transmission Ratio RPM Calculator to determine your engine’s RPM based on the transmission gear ratio, tire height, MPH, and ring and pinion gear ratio.

spicerparts.com

View attachment 606819

Thanks duder. That's a handy calculator.

To help others, here are ratios for the 6R140 TorqShift Ford 6spd;
This unit has a total of six forward gears with the ratios as follows: 1st gear 3.974:1, 2nd gear 2.318:1, 3rd gear 1.516:1, 4th gear 1.149:1, 5th gear 0.858:1, 6th gear 0.674:1.

Here we go...

A. STOCK (33s)
Ring & pinion gear ratio; 4.30
Tire height (in.); 33"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 59.3

Ring & pinion gear ratio; 4.30
Tire height (in.); 33"
Engine RPM; 1650
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.92


B. 35s
Ring & pinion gear ratio; 4.30
Tire height (in.); 35"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 62.9

Ring & pinion gear ratio; 4.30
Tire height (in.); 35"
Engine RPM; 1550
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.71


C. 37s
Ring & pinion gear ratio; 4.30
Tire height (in.); 37"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 66.49

Ring & pinion gear ratio; 4.30
Tire height (in.); 37"
Engine RPM; 1450
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.09


Thoughts Kevbo, others?

 

[RAM5500 CAMPERTHING]

Thanks duder. That's a handy calculator.

To help others, here are ratios for the 6R140 TorqShift Ford 6spd;
This unit has a total of six forward gears with the ratios as follows: 1st gear 3.974:1, 2nd gear 2.318:1, 3rd gear 1.516:1, 4th gear 1.149:1, 5th gear 0.858:1, 6th gear 0.674:1.

Here we go...

A. STOCK (33s)
Ring & pinion gear ratio; 4.30
Tire height (in.); 33"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 59.3

Ring & pinion gear ratio; 4.30
Tire height (in.); 33"
Engine RPM; 1650
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.92


B. 35s
Ring & pinion gear ratio; 4.30
Tire height (in.); 35"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 62.9

Ring & pinion gear ratio; 4.30
Tire height (in.); 35"
Engine RPM; 1550
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.71


C. 37s
Ring & pinion gear ratio; 4.30
Tire height (in.); 37"
Engine RPM; 1750
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 66.49

Ring & pinion gear ratio; 4.30
Tire height (in.); 37"
Engine RPM; 1450
Transmission gear ratio; 0.674:1
Vehicle speed in MPH; 55.09


Thoughts Kevbo, others?

I have no feedback here, as I have no idea where the freeway RPM sweet spot is on the ford gas motors.

The sweet spot on my tundra seemed to be around 2000 for some reason

I set mine up strictly for MPGs with no regard for power or performance

You can use that calculator to enter the speeds you usually drive and it will tell your RPM, makes it a tad more understandable

 

[mk216v]

I have no feedback here, as I have no idea where the freeway RPM sweet spot is on the ford gas motors.

The sweet spot on my tundra seemed to be around 2000 for some reason

I set mine up strictly for MPGs with no regard for power or performance

You can use that calculator to enter the speeds you usually drive and it will tell your RPM, makes it a tad more understandable

I'll get it onto the highway this weekend and advise further.

I'm not sure how you got the Spicer calculator to allow you to enter MPH, it doesn't let me do that.

 

[Deleted member 9101]

View attachment 606819

I used that same calculator to talk myself out of a 3.73 gear swap in my F150...haha.

 

[mk216v]

So I got the truck out today, cruising at 55mph, with factory 4.30gears, stock 33" tires, RPM's are right about 1650rpm just like the Spicer calculator said. Engine seemed happy.
To test what 55mph would be like with 37"s, I slowed the RPM's down to 1450rpm (this was about 49mph with my stock 33"s). Engine didn't seem to be lugging at all, I felt like I was going pretty slow though (well I was--49mph). I rolled into the throttle at 1450rpm's and the truck accelerated without issue. Deeper into the throttle and then trans downshifted and the truck really took off.

Trying to imagine driving at 1450rpms with 37"s in a 55mph zone, it'd be ok. Hit a hill, then the trans may shift down for that hill; no big deal in my mind.

Going 65mph on 37"s with 4.30 R&P, engine would be at 1700rpms which is perhaps a sort of sweet spot for the engine.

All in all, at this time I don't see an issue with 37s, my 4.30gears, RPM's being too low or too high when cruising, nor issues with MPG's or lack of power.


In other project news, I taped out the service body dimensions on the garage floor. Started playing with layout.
Off to pay Hwy Products a visit next week.

Worked further on the build list, in order of priority. Thinking I'll move the Carli susp up, after I confirm F&R axle weight numbers with Dan at Carli. With a 3mo wait until the service body is complete, then another 3mo wait until the topper, and the stock F350 susp is pretty stiff (certainly now yes without anything on the rear end, but still, I won't be putting anything close to the 4860lbs payload on the rear), probably no reason to wait a year for better susp. I'll still keep the stock 18s and 33" Goodyear A/T's on, run them down, then upgrade to my 17" MR701's and 37" General Grabber X3's.

PS--updated the name of this thread.

 

[Korey H]

Thanks for subscribing you two. I'll call it a pre-retirement "just get out there willya?" rig.

Current state;
--about to finalize my options for the FWC Hawk flatbed and place the order. Current build time is 22-24wks. That puts us into almost August.
--waiting to hear back from Alum-line to get the flatbed/storage going.
--working on planning the custom changes on truck from non-sliding glass window (PS--it shattered on drive out from east when a rock flew up on the freeway and blew out the window with only about 800mi on the rig. I already had a new factory Ford rear window installed.) to aluminum pass-thru panel.
--working on planning the custom changes on FWC Hawk flatbed (details to come, can't spill the beans yet!).
--waiting for Carli to get a new '20 7.3L gas truck in to start 6.2L/7.3L gas "coils" R&D.

Can you tell me about the “aluminum pass through panel”? I’m needing to create a pass through for our new rig. Thank you

Sent from my iPhone using Tapatalk

 

[McCarthy]

@RAM5500 CAMPERTHING Will have me hung, drawn, and quartered, but i'm with you. 4.30's will be just fine.

 

[mog]

Going 65mph on 37"s with 4.30 R&P, engine would be at 1700rpms which is perhaps a sort of sweet spot for the engine.
All in all, at this time I don't see an issue with 37s, my 4.30gears, RPM's being too low or too high when cruising, nor issues with MPG's or lack of power.

My '02 F250 (crewcab-7120lbs) with the V10 like yours and 3.73s on 35"s is very happy and lops along at right around 1700 rpm at 'freeway speeds'. Zero issues and no complaints in the past 18 years.

With a 3mo wait until the service body is complete, then another 3mo wait until the topper,
PS--updated the name of this thread.

Too bad you could not find an already assembled single cab F550 with a standing height service body for less than $11k

Magic Mike Overland Interiors ® could make an awesome interior for this. He has already thought of putting a large window behind those forward upper doors.

 

[rruff]

Going 65mph on 37"s with 4.30 R&P, engine would be at 1700rpms which is perhaps a sort of sweet spot for the engine.

Looked up the ratios for my Tundra vs your Ford, and the Tundra's gears are 14-19% taller (same 4.3 final). I have 35s which gets back ~6% of that difference, but I'm still going to be in worse shape than you... though with less weight, and probably a more aero camper.

Does your truck have a shift mode that lets you select your high gear? If so you could just stick it in 5th if it's hunting, and I think you'd have zero issues.

 

[mog]

Does your truck have a shift mode that lets you select your high gear? If so you could just stick it in 5th if it's hunting, and I think you'd have zero issues.

On my C4500 my current tires (385/65R-22.5) are almost 30% larger than the stock tires (245/70R19.5) and I do just that. With 'overdrive' (Allison 1000) turned off, it 'drives' normally around town, like it had stock tires, and at freeway speeds (in overdrive), it is in the same 'sweet spot'.

 

[mk216v]

Can you tell me about the “aluminum pass through panel”? I’m needing to create a pass through for our new rig. Thank you

Sent from my iPhone using Tapatalk

Sweet Kodiak! I was just going to call on Mog(KODIAK1) to look here, but he's already arrived, so he can also advise on anything specific to your rig.

For my cab-topper pass-thru, picture the rear window of my truck as it is, like this;

Now, have a windshield company nicely remove that glass if they can (keep it for future), and instead of the glass, have an aluminum panel in its place (panel bonded to truck cab). This panel would have a crawl-thru hole cut in it. Currently I'm thinking of having AT just cut their standard cab-slider-window hole in the topper(advantage is that long term, if I sell the topper, then the new owner could just put a standard cab slider window in, making the topper more mainstream and less full custom), and then on the truck cab side we'll cut the same size hole. Now, this standard cab slider window is only about 14.5"H x 50"W, which is pretty narrow height. Thankfully I'm slim and yesterday I already tested (via CAD--cardboard aided design) if I could fit thru this pass-thru hole, and I can. So, this pass-thru will provide HVAC from the truck cab to the dogs in the topper, as well as give us an emergency truck cab access should we ever need it. There will be a bellow between truck cab and topper.
Pass thru hole (remember, no actual glass window) will be this sized footprint;

Does that make sense?

The far more comfortable-sized pass-thru would be to also cut a hole in the lower forward part of topper, and lower rear of truck cab, but since we have a factory Ford 3 person seat arrangement in the truck (middle seat is its own unit, where the seat back folds down and acts as an armrest and center console---we will be having this re-upholstered in gray S211 scheel-mann leatherette to match our front seats), so it's not like we could easily walk thru from topper to truck cab, due to this middle seat/console being in the way. Plus, have to shave some costs somewhere, and having Mario at AT cut a standard cab slider window hole in the topper is quick and easy, vs a totally custom pass-thru hole (which he'll do as well, but for more $).

 

[mk216v]

@RAM5500 CAMPERTHING Will have me hung, drawn, and quartered, but i'm with you. 4.30's will be just fine.

Glad you agree.
It's good for him to twitch sometimes.

 

[mk216v]

My '02 F250 (crewcab-7120lbs) with the V10 like yours and 3.73s on 35"s is very happy and lops along at right around 1700 rpm at 'freeway speeds'. Zero issues and no complaints in the past 18 years.

View attachment 608864



Too bad you could not find an already assembled single cab F550 with a standing height service body for less than $11k
View attachment 608865
Magic Mike Overland Interiors ® could make an awesome interior for this. He has already thought of putting a large window behind those forward upper doors.

Thanks M!
Remember mine is the 6.2L V8, not the 6.8L V10 (I had in the 2nd "Unicorn" E350.

A consideration, however overall, taller than we'd want. And that "living space" is a bit narrow.
Magic Mike Overland Interiors is one clever organization, he'd have all sorts of cool ideas for this.

 

[mk216v]

Looked up the ratios for my Tundra vs your Ford, and the Tundra's gears are 14-19% taller (same 4.3 final). I have 35s which gets back ~6% of that difference, but I'm still going to be in worse shape than you... though with less weight, and probably a more aero camper.

Does your truck have a shift mode that lets you select your high gear? If so you could just stick it in 5th if it's hunting, and I think you'd have zero issues.

What overall weight do you think you'll come in at?
Which camper?
Yes, it has a Tow/Haul button at the end of the steering-column-mounted gear shift lever, so if needed I could press that and it'd probably downshift into 5th. As well, I have an M(Manual) mode I could shift the lever into...in this mode it'll allow me to manually shift the trans using a + and - button on the shift lever. So I could do this as well if needed, but will probably just use the Town/Haul button like I've done in our '01 F350 7.3LTD and U-Haul trucks.

On my C4500 my current tires (385/65R-22.5) are almost 30% larger than the stock tires (245/70R19.5) and I do just that. With 'overdrive' (Allison 1000) turned off, it 'drives' normally around town, like it had stock tires, and at freeway speeds (in overdrive), it is in the same 'sweet spot'.
View attachment 608878

Sweet!