Forum Discussion

jackgilliat's avatar
jackgilliat
Explorer
Mar 18, 2014

Are Air Suspension Motor Homes Dangerous

I started a repair business in 1965, retired and sold in 2002. I have not repaired a motor home air suspension system since but at that time considered them to be unsafe. I hope that motor home companies will respond with detailed information about any air suspension improvements.

Please let us have a polite constructive discussion that might help us be safer.

Has anyone ever seen a 40 ft motor home with large tires on the front and smaller tires on the back. I did and asked the owner why. He said the factory recalled it because the front tires were defective.
They were replaced at no charge. I asked if the replaced tires were exactly the same as the tires still on the rear. He said yes. His motor home has two front height control valves and one rear height control valve (tripod system). I found a newer motor home the same as his and climbed under. As I expected the height control valves were two on the rear and one on the front (tripod system).

On a hot sunny day, a motor home traveling east on an asphalt highway with a 10mph wind from the south entered a right turn cloverleaf. It was towing a small vehicle with it's own braking system. The motor home was equipped with tripod air suspension, two height control valves in the front and one in the rear. At the end of the cloverleaf the traffic light turned red and while stopping, the left front tire blew. I believe it blew because of the left front height control valve causing it to carry more weight than it was designed to do, particularly in the turn and braking at the same time. Also, if the towed vehicle had an empty vacuum booster or for some other common reason was not functioning, it could have further pushed up the rear of the motor home.
  • I see you posted another entry on the same thing!

    NEVER had this happen. I see in your other entry, you talked about a long, fast turn, followed by an opposite , quick turn!

    Slow down.
  • What you say is interesting! I know some companies use 8 air bags instead of 4. So would a independent air system to each corner bag be better than the current tripod system?
  • Actually, having a three-valve setup with the front end coupled means both front tires will be evenly loaded at all times (up until suspension limits are reached) and all roll-stiffness is provided by the rear-axle and the rear tires take those loads. That is assuming only the front air-springs are coupled, and none of the other mechanical components.

    In reality however, the front springs are probably coupled by a sway-bar, or in the newest high-end coaches they use hydraulic accumulators with PWM valves to have semi-active roll-control. These systems will return some of roll-moments to the front axle, however it wouldn't be any different than a conventional steel-sprung front axle.

    The more likely cause for tire blow-outs on larger coaches is simply tire overloading. Some of the bigger coaches exceed even federal highway bridge-formula limits.
  • jackgilliat wrote:
    I hope that motor home companies will respond with detailed information about any air suspension improvements.


    This is a community website whose target audience is the end user. Your request should be directed to the various manufacturers rather than the end user. The forum rules do not allow dealers or manufacturers to post here.

    "These forums are for members to members only and are family oriented. Commercial enterprises and/or their representatives are not allowed to post in these forums."

    To answer your tire question, I have never encountered this. Having said that, I don't look for it either.
  • 1. Where and what was your repair business? Did it have anything to do with Motorhome chassis service?
    2. Why do you state IYO, that Air suspensions on Motorhomes are unsafe???? I have 35 years as a professional RV service tech, and once Diesels came into large sale and production (1990 to current) I have seen no problems or heard from customers that they had any unsafe problems with their Diesel air suspension systems. This includes Freightliner/Spartan/Roadmaster/Powerglide and any other smaller makers of Diesel chassis with air suspensions. This does not mean that they never fail or have had problems, but just that they are very reliable and like anything they can break and malfunction. Doug