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Suspension advice for F250 6.7


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#11 bwag

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Posted 09 July 2020 - 02:55 AM

bwag

 

 

We see a lot of trucks come through here.

 

I have seen a lot of lifted trucks with campers on them.

 

Seems like the lifted trucks also sag (squat) more with a camper on, than a truck with stock ride height.

 

A fully loaded Hawk, on a stock Ford F-250, CrewCab, Short Bed Diesel will most likely squat.

 

Especially if you lift the front.

 

Adding set of Firestone Ride-Rite Air Bags might be a good idea to keep the truck level and looking good when the camper is on.

 

We bagged all of our trucks here, even the lifted trucks. Has been working out great.

 

Hope this helps.

Thanks Stan, I appreciate your input, you likely have seen more suspension setups related to Four Wheel Camper's than anyone else.   I'm going to have the Firestone Air bags installed at the same time I do the lift.  


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#12 bwag

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Posted 09 July 2020 - 03:02 AM

SuperDutyFWC, thanks for your input! After making a phone call to another reputable shop and Stan providing his input, I'm going to do the air bags.  What I like is that I can air them down when the camper is off the truck and get the normal driving characteristics out of the truck.  

 

I did run old man emu add a leaf's on my Tacoma along with firestone airbags.  I only drove it unloaded (no camper) for a week then had my Swift on full time.  I do remember the rear of my truck was raised by the springs and it was a noticeable stiffer ride.  I don't doubt the information you provided but can only pull from my experience.  

 

The above being said, it's not an apples to apples comparison, a Tacoma with a payload of 1200 pounds is not an F250 Superduty 6.7 with a camper package.  There's no doubt I was pushing the Tacoma at it's limit and beyond at times which was a known factor prior to my purchase.  The F250 6.7 although having a less of a payload than an F250 gasser, is leaps and bounds above my Tacoma.  I suspect the airbags won't be doing near the work on the F250 6.7 as they did on the Tacoma.  


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#13 mrpeepers74

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Posted 09 July 2020 - 05:50 AM

so im curious how air bags affect the suspension in rear.

 

I have a dana 80 on older ram 2500 with camper leafs.  it still squats some with the airbags inflated.  grandby mounted on flatbed.

 

so, with stock suspension, do you feel airbags make it bouncy or dampen the load on forest roads?

 

might be an amateur question, but i really dont understand how air bags affect ride quality with leafs.


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#14 SuperDutyFWC

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Posted 09 July 2020 - 03:13 PM

Air doesn't compress very well, so you put a balloon between your frame and axle (spring) and adjust the amount of air in that rubber balloon to keep the frame from moving.  You can increase the (air) pressure in the balloon and make it as hard as you want.  The harder it is, the less your bed will move (squat).  So, you put a load in the bed and increase the pressure until you have the ride height (or lack of sag) that you want.


Edited by SuperDutyFWC, 09 July 2020 - 03:16 PM.

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#15 bwag

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Posted 09 July 2020 - 04:11 PM

so im curious how air bags affect the suspension in rear.

 

I have a dana 80 on older ram 2500 with camper leafs.  it still squats some with the airbags inflated.  grandby mounted on flatbed.

 

so, with stock suspension, do you feel airbags make it bouncy or dampen the load on forest roads?

 

might be an amateur question, but i really dont understand how air bags affect ride quality with leafs.

 

I can only speak for my Tacoma, but the Firestone bags inflated to 40psi would easily put a forward rake in my truck when I was headed for a trip.  When the camper was dry I'd run about 15psi, I had Dakar OME add a leaf heavy duty springs in the rear along with fox suspension.  I never took the camper off and the ride was fine going down the road, what I didn't like was the bounce over something like a speed bump or the sway if taken at an angle, dirt roads with some pot holes were fine bigger bumps not so much in terms of bounce.

 

My F250 has a camper package so it has an additional leaf spring in the rear as well as sway bar and some stuff up front.  The load on this truck compared to my Tacoma is significantly less in terms of payload/GVWR to camper ratio, my hope is there will be less bounce/sway, if not then I'll have to look at other options.  

 

 

Air doesn't compress very well, so you put a balloon between your frame and axle (spring) and adjust the amount of air in that rubber balloon to keep the frame from moving.  You can increase the (air) pressure in the balloon and make it as hard as you want.  The harder it is, the less your bed will move (squat).  So, you put a load in the bed and increase the pressure until you have the ride height (or lack of sag) that you want.

 

That's a good description.  


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#16 CoreyTrevor

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Posted 09 July 2020 - 07:27 PM

I'm curious too about the ride with airbags when loaded. Do they have a really fast rebound once compressed, that overwhelms the shocks rebound damping? I've heard that airbags have a progressive spring rate vs leaf springs or single rate coil springs that have a linear rate.

 

So the airbag ramps up in stiffness at a faster rate than the springs? Or is that not correct?

 

Is that what the bounce over speed bumps is like?


Edited by CoreyTrevor, 09 July 2020 - 07:28 PM.

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#17 SuperDutyFWC

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Posted 09 July 2020 - 08:13 PM

I can't speak to the progressiveness of air bags except to say the rubber in which they are manufactured stretches, so that it may be "progressive".  It may stretch in a progressive manner, as opposed to a linear one, but I don't know that.

 

Depending on the leaf springs, they can be multi-stage, although most probably aren't.

 

OME Dakar springs are usually dual-stage leaf packs. When unladen, the vehicle is largely riding on the primary stage.  So, around town, unloaded you have a softer ride.  Add weight and you get into the second stage that is load carrying.

 

Stock Super Duty leaf springs are dual or three-stage by the way.  The stiffest, teeth-jarring, rear leaf springs come on the diesel model.  If you have the diesel, your springs are three stage and STIFF.


Edited by SuperDutyFWC, 09 July 2020 - 08:20 PM.

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#18 ntsqd

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Posted 09 July 2020 - 08:48 PM

The biggest problem with air springs is that they are not linear in spring rate. Say it takes 500 lbs. to compress them the first inch from ride height. I linear spring with compress a further inch from a second 500 lbs. being added. With an air spring it could take 700 lbs to compress it the next inch, and 1250 lbs added for the third inch. Linearity is actually not desirable, but the rate of the rising spring rate should be low, say less than 10%

 

Where this becomes a problem is damping the suspension, particularly in rebound. Damping that worked well with a 500 lbs/in spring rate will likely be under-damped with a 1250 lbs/in spring rate.

 

My own preference is to not lift a truck carrying a camper. We fit 35's on our stock ride height Ram. At one point I had wheels with the wrong offset on the truck, and that allowed the front tires to make occasional contact where they shouldn't have. It also went down the road like a drunken sailor. Getting the right offset (i.e. back to stock) on the truck cured both problems.


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Thom

Where does that road go?

#19 CoreyTrevor

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Posted 09 July 2020 - 09:07 PM

That's what I was picturing. When the bags are really compressed they will rebound so fast that the shocks won't be able to control it.

 

A correctly designed and set up bypass shock would be a solution, being position and velocity sensitive, unlike normal shocks just being velocity sensitive.

 

That solution would get expensive just to deal with a cheap pair of airbags.


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#20 bwag

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Posted 09 July 2020 - 10:18 PM

I only drove my Tacoma 2 weeks before sliding the camper in for 2 years and not taking it off. The rear end was too stiff unloaded. With my Tacoma which had fox shocks in the rear, Dakar extra leafs and firestone bags, when the camper was on, it didn’t bounce back too fast, in fact for me I felt it was too soft. That being said, I didn’t try different air pressure settings on the bags so maybe it was related to that but I felt like I was riding on marshmallows!

I’ve read on some forums about the camper package on the F250 6.7 making the unloaded ride unpleasant, call me crazy but I think it’s great. It’s stiff but not too stiff which is how my Tacoma was unloaded.

The lift is definitely give and take, regardless of the 2.5 Carli lift I’m doing bags or some other measure we’re going to be needed bottom line is payload on a diesel isn’t the same as a gasser.

I had my tires run on my Tacoma, I dealt with it but it got old real fast! My new rims will be 9” wide with 35x12.5 tires, and a 1mm offset, I think rubbing issues on F250’s with a 2.5” lift start at the -19 or greater offset, I don’t want my wheels sticking out that far or the rub which is why I went with a +1mm offset.
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