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Old 01-04-2022, 03:51 PM   #1
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Suspension done right from start

Lightning pickup-truck suspension shows Ford knows exactly what it takes to improve ride and handling. Itís not rocket science ó just takes a little money.

Pictures show new Lightning independent rear suspension using semi-trailing arms with coil springs. It is basic by modern car standards but far superior for ride and handling when compared to a live drive axle suspended by leaf springs; plus it retains most of the toughness required for heavy duty truck use.

For this vehicle Ford was essentially forced into using IRS due to electric drive, but the design itself can be adapted easily to standard engine-driven pickups (or larger vehicles). What I find most interesting is how well this independent semi-trailing-arm rear suspension fits with body-on-frame truck frame design.

For motorhome use, this type of suspension ďupgradeĒ would be well worth the added cost (at least to me). Question is how much would buyers be willing to pay up front so motorhomes donít ride like commercial trucks?
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Old 01-04-2022, 04:00 PM   #2
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Unless shored up by tightening everything to the nth degree, it will only add to body roll.
Irs requires low profile tires and a low butt to ground ratio.
Add the pendulum of a RV seat 5 feet off the ground and it becomes a carnival ride.


I'm a huge believer and early adaptor of irs in off road vehicles.
For exactly the opposite reason you'd want it in a tall rv:
It allows for a very dramatic sway and suspension differential.
(The 'almost as strong' is engineer speak for 'so barely adequate')

The ONLY reasons people can't handle the suspension on a rv is
1 Lack of talent(many spouses refuse to even sit in the drivers seat due to some cuteness I don't understand)
2 Their butt is 5 ft above the axle instead of almost in-line with the drive train as they're used to, and their brain can't wrap around the pendulum effect. It isn't really swaying more, you're experiencing more sway due to your butt distance from the axle center. It's the LAW.

It's 90%+ mental block.
So many people operate big trucks and RV without a second thought and without added deaths or accidents beyond normal vehicles.

So, to bring up an old thread:
Are we actually admitting that some rv drivers have less talent than the new 18 year old minimally trained interstate truck drivers? Those kids just do it.
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Old 01-04-2022, 05:35 PM   #3
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Probably lots of mods, as described above, for coil springs to work on an RV.
But (I own a business with multiple trucks) everyone on my staff will jump in the barebones Ram 1500 with coil springs before taking a loaded ford or toyota with leaf springs for a delivery.
There is no comparison in ride quality.
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Old 01-04-2022, 10:48 PM   #4
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Originally Posted by Matthew View Post
Probably lots of mods, as described above, for coil springs to work on an RV.
But (I own a business with multiple trucks) everyone on my staff will jump in the barebones Ram 1500 with coil springs before taking a loaded ford or toyota with leaf springs for a delivery.
There is no comparison in ride quality.
The current Rams (1500, 2500 and 3500. come with air suspension. The downsides of air suspension are (according to Car & Driver):
  • The initial costs of purchasing and installing an air suspension system ó air suspension can also sometimes reach three times the cost in repairs as a leaf suspension system over 10 years
  • Fuel overheads for running compressors for occasionally pumping air to the correct pressure
  • Fuel efficiency can suffer from the heavier weight of air suspension over the weight of leaf suspension
  • An air suspension systemís vulnerability to air leaks can result in malfunctions.
It has been stated before the components to make an independent front and rear air suspension coach with a front gas engine are available, that puts the cost of the components and new frame required in the $85,000 and $110,000 range in limited production. Current stripped F-53 chassis is $32,215 to about $40.000 in orders of 1,000 or more. Sorta makes Liquid Spring suspension look as the cheapest alternative to leafs.
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Old 01-05-2022, 02:27 PM   #5
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Originally Posted by Matthew View Post
Probably lots of mods, as described above, for coil springs to work on an RV.
But (I own a business with multiple trucks) everyone on my staff will jump in the barebones Ram 1500 with coil springs before taking a loaded ford or toyota with leaf springs for a delivery.
There is no comparison in ride quality.

I agree the RAM 1500 does ride pretty good (my son has one) but is it due to coil springs or due to multi-link rear suspension? Can we separate the two since they come together as a package?

In any case, I expect an independent semi-trailing arm rear suspension on electric F-150 to improve on RAMís multi-link even though both may use coil springs. Reducing unsprung weight/mass and making the two rear wheels independent when they hit bumps should help.
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Old 01-05-2022, 02:34 PM   #6
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Originally Posted by Beau388 View Post
The current Rams (1500, 2500 and 3500. come with air suspension. The downsides of air suspension are (according to Car & Driver):
  • The initial costs of purchasing and installing an air suspension system ó air suspension can also sometimes reach three times the cost in repairs as a leaf suspension system over 10 years
  • Fuel overheads for running compressors for occasionally pumping air to the correct pressure
  • Fuel efficiency can suffer from the heavier weight of air suspension over the weight of leaf suspension
  • An air suspension systemís vulnerability to air leaks can result in malfunctions.
It has been stated before the components to make an independent front and rear air suspension coach with a front gas engine are available, that puts the cost of the components and new frame required in the $85,000 and $110,000 range in limited production. Current stripped F-53 chassis is $32,215 to about $40.000 in orders of 1,000 or more. Sorta makes Liquid Spring suspension look as the cheapest alternative to leafs.

The type of spring used (leaf, coil, air) is part of suspension design, but it does not define the entire suspension. We should be careful not to lump all suspensions with similar springs together. For example, there are very different suspension types that use coil springs. The same can be said of air suspension. And while leaf springs are typically used with solid axles, occasionally we see them used with independent suspension.

I agree that independent suspension adds cost, but comparing Ford F-53 chassis to diesel pusher and associating suspension to $10,000s added cost is not right either.

The new electric Ford Lightning pickup isnít as expensive as many originally expected, so adding the independent rear suspension canít possibly have added that much cost. Same goes to electric Transit vans.

I would expect it doesnít cost Ford more than $1,000, maybe $2,000 tops, to manufacture and install the semi-trailing arm suspension compared to live axle with leaf springs.
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Old 01-14-2022, 07:17 PM   #7
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Originally Posted by ducksface View Post
Unless shored up by tightening everything to the nth degree, it will only add to body roll.
Irs requires low profile tires and a low butt to ground ratio.
Add the pendulum of a RV seat 5 feet off the ground and it becomes a carnival ride.


.....cut.....

I believe it is more about (avoiding) added costs than anything else. Most luxury diesel pushers have independent front suspensions which are often rated at up to 20,000 pounds (more than plenty strong). And while most DP and commercial buses (also IFS) lean considerably compared to autos and SUVs, drivers and passengers rarely complain. When Houston Metro buses came into Park-and-Ride lot where I picked up my wife, they did a tight 180-degree turn and would lean over 10 degrees or more. I asked my wife if it concerned her that the bus could tip over and she replied that she had not noticed anything out of the ordinary.

For a motorhome the added cost for independent rear suspension is even less justified because people ride close to front where front suspension makes biggest difference.

There have been motorhomes built with semi-trailing-arm rear suspension in the past, and most get great reviews for ride quality compared to traditional solid axles (given same time frame). Obviously solid axle trucks ride better today than 50 years ago, but I would expect similar improvement for IFS and IRS as well.

The Classic FMC motorhome used for On the Road With Charles Kuralt was a gasoline pusher with fully independent suspension. A much smaller motorhome with semi-trailing-arm IRS was the VW Vanagon. Also, Al-KO modifies (upgrades) Mercedes Sprinter chassis in Europe for motorhome use, and one of the main features is replacing Sprinter solid axle with semi-trailing-arm independent rear suspension.

Just saying I wouldnít write off IRS benefits too quickly. Even if it leaned a bit more in turns, the benefits in ride quality should be well worth it. And for what itís worth, in my opinion the biggest improvement manufacturers could make to motorhomes is to reduce their height. That would solve a lot of problems including leaning and harsher ride.
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Old 01-14-2022, 07:29 PM   #8
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My change from
IFS and coils
To
Straight axle and leafs
On my 24.1 tightened up my turning circle by about 30 inches and it rides and handles so much better.
The whole front suspension was cut out, scrapped and replaced.

I chased irs for my offroader for years.
I had the thunderbird rear end ready To go.
I truly believe in it.
My pretty radical offroader is ifs contrary to what offroader believe in. We decided that IRS in a 6,000lb 100" wheelbase top heavy offroader would make it toss itself into a ditch every chance it got.
But they now make irs jeep kits.

I ran portals on my vw sandbuggy so I could flat axle the irs and still have the ground clearance.


That silly 'vette i have is transverse leaf spring, irs, solid diff mount, solid motor and trans mounts and the headers bolted to the frame at the collectors. Nothing moves in that drivetrain but the axles(or halfshafts or whatever the kids are calling them these days,)

I'm all for irs.
I cant find advantage in a large squirmy due to height vehicle without a huge electronic assist from hydraulics,

You'll have to look it up because I might have the model wrong
Type 151 jeep.
Marine corps made, like the mighty mite.
The 181 had irs.
Them catching a bounce and flipping upside down caused the whole batch to be cut in half and scrapped.
There's a place in Oklahoma(?) Where you can you can buy both halves and weld them back together.

Yup. I had one. One of the very few uncut ones outside of Vietnam.
it sucked, I moved on.
It's the only jeep I've ever had. I didn't put 60 miles on it. That irs really really sucked.

I would buy a marine corps mule. 4wheel steering. Everyone wants too much for me to pay to use as a ranch vehicle.
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Old 01-14-2022, 08:24 PM   #9
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The first Ford Econoline vans I drove had solid axles with leaf springs front and back. They were OK but didnít drive or handle as good as my current E-Series van. Their very short wheelbase gave them great turning radius but ride was a little choppy. Fortunately, roads were all asphalt back then and a million times smoother than many Interstates today.

I test drove a new VW Vanagon decades ago, and salesman asked me to drop right-side wheels off payment at 60 MPH or so, and the handling was far better than I expected. Fast forward a decade or more and I purchased a German sedan with semi-trailing-arm independent rear suspension, and the ride and handling was much better than the Ford with solid axle and leaf springs it replaced.

Another sign of trend is that Ford eventually upgraded Expedition and Explorer large RWD SUVs to IRS, and one could argue that it forced GM to also upgrade Suburban to IRS. Now electric pickups and vans are going to IRS, in large part due to drivetrain packaging, so it will be interesting to see if IRS is offered as an option on gas-engine F-150 and Transit. I know IRS would add a little cost, but would gladly pay for upgrade if vans like Transit offered it as an option.
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