Advice for improving rear end ride

[tmaxx]

I have a 2003 Class C Ford E-450 29' length with two slides.
When driving, if we drive a rough road or pothole, the rear end jars so badly the kitchen doors fly open. It's pretty severe.
There are air bags on the rear and I am pretty sure it has the original shocks all around. I am wanting to improve the ride and looking for suggestions. I understand it won't ride like a car. I am looking at Bilstein HD shocks for the rear, but I am concerned they may be too stiff and will cause more of a rough ride. Would new shocks help dampen the rough roads? Will the Bilstein HD help with this?
Thank you.

[Capt Steve]

Your 17/18 year old original shocks are all but useless. I put HD Bilstein's on my 2012 E-350 24' Class C at 33,000 miles and was amazed at the immediate improvement in the ride and at 66,000 miles they still perform like new. There was no downside to the Bilstein's, the ride and handling will only improve... dramatically. Replace all four shocks.

What psi are your air bags set at? When towing or running heavy I inflate my Air lift 5,000 airbags to 50 psi which brings the rear end back to dead level. Per Air Lift's recommendations I run them at 25 psi when running light/not towing to maintain the integrity of the bags {never run with them uninflated}.

[Bill Gail]

Originally Posted by Capt Steve

Your 17/18 year old original shocks are all but useless. I put HD Bilstein's on my 2012 E-350 24' Class C at 33,000 miles and was amazed at the immediate improvement in the ride and at 66,000 miles they still perform like new. There was no downside to the Bilstein's, the ride and handling will only improve... dramatically. Replace all four shocks.

What psi are your air bags set at? When towing or running heavy I inflate my Air lift 5,000 airbags to 50 psi which brings the rear end back to dead level. Per Air Lift's recommendations I run them at 25 psi when running light/not towing to maintain the integrity of the bags {never run with them uninflated}.

X2 everything Capt Steve said.

[Ron Dittmer]

I installed the heavy duty Bilstein shocks and am very pleased.
CLICK HERE FOR DETAILS AND SOME GOOD PICTURES.

But......

If you have the extra money, consider the Koni-FSD shocks. They will soften all the tiny road imperfections that would otherwise be felt more severely.

About air bags.....We had them on our first motorhome SEEN HERE to help with the handling because there were no aftermarket offerings to improve handling in some other fashion. One thing I quickly learned about air bags. The higher the PSI, the more harsh the ride. Most or all air bags systems require a minimum amount of air to prevent damage. I would not add much more than the minimum unless it helps tremendously in managing a handling issue.

There is one more thing you can do without additional cost, but you will need to weigh your rig fully loaded during a trip. Many truck stops have weigh scales. Weigh each axle independently with everyone in their normal seating position. Divide your rear axle weigh by 4 (for 4 tires) then use the PSI chart for your particular rear tires. Over-inflating your tires will unnecessarily make a rougher ride.

For our current motorhome built on a 2007 Ford E350 chassis, I managed to soften the ride up front in an interesting manner. CLICK HERE TO READ ALL ABOUT IT WITH MANY PICTURES.

[Isaac-1]

Step one is weigh the coach, preferable 4 corner weight, though axle weight will do, (you can get axle weight for about $10 at any CAT scale found at many truck stops, just pull onto the weigh bridge, push the call button, when asked for truck number make up something, I use 24, go in and pay, they will give you a print out with axle weights) also many places will weigh you for free, dump stations, landscape bulk material sales, bulk fertilizer sellers, etc, then consult a tire inflation chart like https://www.rvtirepressure.com/asset..._Inflation.pdf and inflate the tires to the correct pressure. One of the big causes of this problem is over inflated tires.

[Fiesta48]

I just got down under my E-350 to check to see hard it would be to put on Koni's in the rear.
Looked at the leaf springs. There are 9 leaves on each side on the 350, a 450 probably has more.
No way shocks are going to reduce hard riding with that many springs. They are 1/4 to 3/8" steel each.
Don't waste your money buying new shocks.
I am going to reduce tire pressure but keep weights in line/with in limits.

[R Cabesa]

Originally Posted by Fiesta48

I just got down under my E-350 to check to see hard it would be to put on Koni's in the rear.
Looked at the leaf springs. There are 9 leaves on each side on the 350, a 450 probably has more.
No way shocks are going to reduce hard riding with that many springs. They are 1/4 to 3/8" steel each.
Don't waste your money buying new shocks.
I am going to reduce tire pressure but keep weights in line/with in limits.

Don't believe this one.


17 year old truck, buy new shocks FIRST and then go from there.

[CRV2]

New shocks definitely are very helpful. With a lot of weight, you have to have heavy duty springs, the forces that move those springs are very powerful therefore that action can be hard on factory shocks and cause them to lose their ability to do their job sooner than you may realize. I did a lot of reading on whether to go with Koni FSD or Bilsteins, what I found was that most people report the Koni's are better on the smoother highways but get a bit harsh on the rougher highways, on the other hand the Bilsteins provide a better ride on the rougher highways but not as soft of a ride on the smoother highways. In any case, that was just what I have read through many comments and users, I went with the Bilsteins and I can say for sure the ride is better than the OEM shocks for sure. I suspect you can't go wrong with Koni's or Bilsteins, I didn't see the point in paying a bit more for the Koni's though, as most of the interstates and highways I travel are a bit rough to say the least, likely where you travel as well. ~CA

[S.LANGE]

I have a 2007, 26ft Lexington GTS with dual slides on the driver's side, 40K+ miles.
We too found the jarring and jolting from the rear and its effect on the coach to be concerning and nerve-wracking, especially on sections of I-40 on a cross country trip.

KONI FSD shock absorbers went on first and were an improvement over what appeared to be original OEM shocks but I wanted further improvements. I have no idea what other brands nor their products would do besides certainly better than worn out stock OEM.

Next, the ride was further improved with addition of SUMOSPRINGS but not without a challenge at the rear.
The 'for the front' SOLO product was their "-40" which is the softest of the 3 strengths offered (-40, -47, -54). I loved the change at the front.

It was initially recommended I install the 'for the rear' Maxim product in the medium "-47" strength which I was very enthusiastic about doing based on the ride improvement at the front. But the rear's ride was worsened with the "-47" medium strength insert negating the KONI's positive input. With my motorhome's reaction to the "-47" inserts, SuperSteer and SUMOSPRING engineers both suggested I switch out the "-47" inserts with "-40" strength which I did. Much, much better and added to the improvement the KONI FSD's added. The coach rides much softer and best of all, quieter. Don't get me wrong, those roadway imperfections are still there, and sometimes colliding with 4 tires carrying 9450 lbs and you know it, but they don't produce nearly the same 'shock' as they used to.
I'm hoping the coach will even suffer less very rapid horizontal racking back and forth after I have the Trac Bar installed. Not rolling sway but lateral movement.

My coach's rear weighs in at 8380lbs with no cargo, 3/4 full gasoline and 2/3 full propane, no water (fresh, black, or gray) and it's maximum allowable is 9450lbs on the rear axle. It has spent its entire life (before and with us) near or over max weight when traveling. I have no idea how good or bad the springs might be - and I've discovered, nor do the "experts" in Phoenix I've tried asking. It's a work in progress and in time I'll find the answers.

Your coach has it own weights and measures and will respond to your inputs. I wish you well in finding what works best in your case.

[Ron Dittmer]

Interesting comment there S.LANGE. Though your rear axle is heavily weighted during trips, you still get a terribly rough ride in back.

I assume you are inflating your 4 rear tires to 80 psi.

[Richie]

Check what Entegra has done to improve the ride on their Class C's. I have an Entegra Esteem 29V and love the ride and handling. The only thing I did was have the front end aligned. It ride like a dream and handles great. Check it out.

[S.LANGE]

Originally Posted by Ron Dittmer

Interesting comment there S.LANGE. Though your rear axle is heavily weighted during trips, you still get a terribly rough ride in back.

I assume you are inflating your 4 rear tires to 80 psi.

Close. Cold set to 83 psi, which I know is 3 lbs above the sidewall's "Max" of 80. Being a bit paranoid due to tire problems experienced on our one and only long trip, I've wanted a margin in the pressure setting but I'll re-focus on the 80 psi. Yesterday a trusted Porsche mechanic I know suggested I might be stretching the tires, especially as heat and pressure increase during long distance use. But there are no trips planned until I get this vehicle dialed in for safety and stability. It does get exercised 15-20 miles every few weeks per the tire installer's admonishment that not doing so is detrimental to the tires. So rear ride will be even softer but I'll still be concerned about no margin of safety with all the components at the rear being max'd out on weight. We will travel with some fresh water, clothing, some cargo, etc. - all behind the rear axle and closing in on the max 9450 lbs allowed on that axle.

Front's are 65 psi.

[Bobby F]

We spent some time years back trying to dial in some 350 and 450 extended-frame cargo trucks so that we didn't jar the heck out of show dolphins in transport tanks.

I can tell you that, if it's that big bang that you get at expansion joints and cracks that's causing your worst issues, the best shock is one that's unbolted and unconnected and dangling. Shocks can only add to the bang. So, as a trade-off, you look for shocks that have the least resistance in the first movement. Which means you're always choosing between stability and harshness, because the most resistive shock is the most stable one.

Those four huge hard tires pumped up to 80 in a line across the rear do more to make the bang than anything. Anything you can do to soften those tires will help. Newer tires with more rubber help. Dropping the pressure helps immensely - but you already know what you trade off for that.

It's all a trade-off. What makes for stability and tire life is also what makes for bang. So you find a compromise tire pressure that you can live with.

[SergioP]

Originally Posted by Bobby F

We spent some time years back trying to dial in some 350 and 450 extended-frame cargo trucks so that we didn't jar the heck out of show dolphins in transport tanks.

I can tell you that, if it's that big bang that you get at expansion joints and cracks that's causing your worst issues, the best shock is one that's unbolted and unconnected and dangling. Shocks can only add to the bang. So, as a trade-off, you look for shocks that have the least resistance in the first movement. Which means you're always choosing between stability and harshness, because the most resistive shock is the most stable one.

Those four huge hard tires pumped up to 80 in a line across the rear do more to make the bang than anything. Anything you can do to soften those tires will help. Newer tires with more rubber help. Dropping the pressure helps immensely - but you already know what you trade off for that.

It's all a trade-off. What makes for stability and tire life is also what makes for bang. So you find a compromise tire pressure that you can live with.

There is a big difference in ride quality between max(80) air pressure and the recommended pressure for the load the tire manufacturer says.

Seems like every RV response differently to suspension mods. Also everyone feels the ride differently too. So I guess it’s trial and error til you get the ride good enough to one’s liking. Of course it will never be car like but banging and thumping down the road is no fun either.