Community Forums

Thor396 · 07-11-2017, 01:23 PM

I have a Four winds 35D Wind sport. F53 chassis. Installed new Monroe shocks all around and Goodyear air bags. Air pressure 13lbs all around. 19.5 tires. Front air pressure is 85psi rears are 100psi. Just came back from a 2600 mile trip to Florida from Michigan. The road pot holes just slammed my coach. Thought it was coming apart. Anyone else having this issue? Is a Diesel with full air suspension the answer? Should I buy a boat and give up RV? How does one deal with this. I am at a loss and would welcome advice please.

Waiter21 · 07-11-2017, 01:45 PM

13 lbs in the air bags?? I run mine at 60 lbs.

Its a truck, not a bus. Here are a few things to do: If ride smoothness is worth the cost to you, then DP is a good solution

1) weight the MH and run the tires at minimum pressure for the weight

2) air bags help - run them at the high pressure

3) CHF - do the Cheap Handling Fix, front and rear.

4) front end alignment - Check the toe adjustment

gorwig · 07-12-2017, 08:45 AM

Quote:

Originally Posted by Thor396

I have a Four winds 35D Wind sport. F53 chassis. Installed new Monroe shocks all around and Goodyear air bags. Air pressure 13lbs all around. 19.5 tires. Front air pressure is 85psi rears are 100psi. Just came back from a 2600 mile trip to Florida from Michigan. The road pot holes just slammed my coach. Thought it was coming apart. Anyone else having this issue? Is a Diesel with full air suspension the answer? Should I buy a boat and give up RV? How does one deal with this. I am at a loss and would welcome advice please.

The suspension may be bottoming out when rebounding from potholes. Do you know your loaded axle weights? You may be too heavy. Probably more pressure in the air bags would help if bottoming out but you might end up with a stiffer overall ride.

Dav L · 07-12-2017, 09:13 PM

Once you cross from Ohio to Michigan, the pot holes and road section heaves are terrible. Everything south to Miami was not a problem, relatively speaking.

The Mich I75 was unbearable on our first trip. Bilstein shocks, steering damper made a big difference the second trip. Next step was Michelin steers for the third trip. This also made a big difference. Not too bad anymore.

Next step will be custom track bars. Maybe this weekend project.
Just received poly sway bar bushings. Will investigate changing the sway bar link attachment holes too.

Thor396 · 07-13-2017, 05:00 AM

I'm getting ready to have a front end alignment and new steer tires with balance done. Going with Hankook AH 11 tires. Will set tires at lowest pressure. I'm not hauling a lot. Haven't had the weight checked yet. Already have front and rear sway bars on with new bushings. Going to bump up air pressure in bags to 20/25psi and try it their.

Waiter21 · 07-13-2017, 05:35 AM

You'll need your front and rear axles weights in order to determine minimum tire pressure. You can get these at any truck scale for about $10.

20 psi in the bags sounds to low. Do you have any documentation for the bags? My bags have a warning to not operate them less than 20 as the bags can then colapse a, get caught under mounts and get holes ripped in them.

TeJay · 07-13-2017, 07:08 AM

I've followed air bag pressure suggestions on these forums for a long time. We currently do not have air bags but would like to change that soon. We had them on our 1999 Dutch Star but that was before I knew anything about iRV2 forums.

Firestone recommends to carry no less than 10 lbs in an air bags at any time. My educated guess is to experiment and determine what is best for your RV.

Doing what another poster suggests (IMHO) is just a shot in the dark. Very little chance of hitting the sweet spot on your particular coach set up.

That said every coach is different based on all the many variables that have been talked about before. Your individual loading, RV length, rear overhang (yes /no), shocks, front axle & rear axle weights, SB's, CHF, brand of tires, your current tire pressures & on and on.

Generally speaking based on 4 wheels carrying the load on the rear those bags are usually in a range of 40 to 70 lbs. The fronts are of 20 to 40 lbs.

Start low (fronts - 20, rears - 30) and go up in 5 lb increments for both axles one at a time until you're happy.

On our DS I had the on board air compressor to raise and lower pressures while moving. That's an ideal situation. That complete option these days will cost you upwards of a $1,000.

Based on the directions I installed "T" fittings and ran one line to the rears and one to the fronts. That was (hind sight) kind of dumb. If one tire hits a bump it would compress the air and send it over to the other air bag making it stiffer. That might stop some SWAY but stiffen the ride.

I began to realize the error of my/their ways and discovered that they did have a check valve available to prevent this from happening. The valves were $100 each.

I don't know if the on board air compressor allows individual bag adjustments. I don't believe the DS set up did and maybe that's why I had to install those "T's."

An easier solution is to run separate lines to each bag so they are independent. That's what I'll do and locate the valves in one spot so I can check & adjust more easily. My portable air compressor will also be close.

It has been reported by several posters that air bags do soften/cushion the F-53 ride and that's what I'm looking for. Even if it's only a 5% improvement. SWAY control is not an issue for the most part. With the air bags being independent they will/should also assist with the SWAY.

Good luck on this!!!!

PbdBlue · 07-13-2017, 07:34 AM

Quote:

Originally Posted by TeJay

Another consideration. On the DS based on the directions I installed a "T" fitting and ran one line to the rears and one to the fronts. That was (hind sight) kind of dumb. If one tire hits a bump it would compress the air and send it over to the other air bag making it stiffer.

At the time a check valve was available to prevent this from happening but the valves were, if memory didn't fail me, were $100 each. An easier solution is to run separate lines to each bag so they are independent.

Good luck on this!!!!

Bingo. You've hit on a big issue with air bags that most overlook. On my last coach I had air bags on the rear only. Initially it was set up with both sides tee'd together and connected to the dash operated compressor. The caveat with this setup is that when one side compresses (i.e when cornering, etc) the air pressure in the opposing bag will rise resulting in accentuated body roll. Not exactly a desired effect with a motorhome. I ended up re-plumbing with check valves and that reduced the effect. A bit off topic. As far as the OP is concerned the CHF, track bars, etc will not do anything to smooth the ride and in some cases make it more harsh. Tire pressure, shocks and air bags or Sumo springs will help. On the new coach I went with Sumo Solo's on all 4 corners. They helped significantly as they seem to take the harshness out of the big hits. Also 100 psi on the rear tire pressure sounds like it could be a little high. As mentioned get the rig weighed and set the tire pressures accordingly.

Dav L · 07-13-2017, 08:03 AM

When one adds air bags...that is to supplement the existing leaf spring on a Ford Chassis - right?

Knowing the highway road conditions in Mich (live there), I haven't had any issue with bottoming out. It's really many many smaller road heaves and patched pot holes that rattles your arms off.

I would think adding air pressure would make it more jarring, IF the suspension truly isn't bottoming out.

biggcrisp · 07-13-2017, 10:23 AM

Liquidsprings.com @$12,000 cash installed.

After you have them installed let us know what you think?

I have ran airbags at 32 lbs. anything over that was too harsh.

Waiter21 · 07-13-2017, 11:38 AM

Quote:

Liquidsprings.com @$12,000 cash installed.

OUCH - Thats almsot what I paid for the entire motorhome..

The more weight you can remove from the leaf springs and transfer to the airbags, the smoother the ride.

Boondockin · 07-13-2017, 11:58 AM

Quote:

Originally Posted by Waiter21

OUCH - Thats almsot what I paid for the entire motorhome..

The more weight you can remove from the leaf springs and transfer to the airbags, the smoother the ride.

What is your front axle weight and how much air pressure are you running in you front airbags?

Waiter21 · 07-13-2017, 12:51 PM

Front
5,840 lbs empty / 6.500 lbs loaded.

Rear
11,000 unloaded / 13,000 loaded

I run 85psi in all 6 tires and 60 psi in all four bags

Boondockin · 07-13-2017, 01:02 PM

Quote:

Originally Posted by Waiter21

Front
5,840 lbs empty / 6.500 lbs loaded.

Rear
11,000 unloaded / 13,000 loaded

I run 85psi in all 6 tires and 60 psi in all four bags

I accidentally put 45psi in our front bags and it was way too rough... but I also have 90psi in the tires... I need to spend some more time and get it dialed in...