Community Forums

tomg44 · 07-11-2019, 02:28 PM

We just bought our first RV 28 ft 1999 Gulf Stream Conquest Class C. Everything is great so far except rear end drags on ground when big dip in road. We attached a pair of 6 inch solid rubber wheels under the rear bumper but still get a drag. We enjoy spots that require a bit of dirt road access like forest service campgrounds, rather than KOA all the time. Do we need bigger wheels? Anyone got another suggestion?

A32Deuce · 07-11-2019, 04:05 PM

Do you have air bags on the rear? I pump mine up when I know that there are dips like that. It will still drag on the skids but not as bad.

RiverBurt · 07-11-2019, 04:34 PM

Sounds like the shocks are shot.

A32Deuce · 07-11-2019, 04:46 PM

Shocks don't support the rear, just control bounce.

RiverBurt · 07-11-2019, 05:06 PM

Quote:

Originally Posted by A32Deuce

Shocks don't support the rear, just control bounce.

Whatever you say.

arcaguy · 07-11-2019, 06:10 PM

Not trying to open a can of worms here but both Riverburt and A32Deuce may be right. In a static situation A32Deuce is correct shocks do not support any of the weight of the coach, unless they air shocks which are not too common any more. However, in a transient situation (when the suspension is moving up and down) the compression side of the shock will sometimes help keep the coach from bottoming out on a bump as it essentially makes the axle/wheel see a stiffer spring as both the shock and the spring are resisting the upward motion of the wheel. That said, the shock is likely not the issue. On a 20 year old coach it's almost a given that the springs have lost some of the "springyness", or rate as the spring guys would say. This is usually checked by measuring the ride height of the coach. Ride height is the distance from level (very level) ground to a particular point on the frame of the coach. If this measurement is less than it should be the springs either need to be re-arched or replaced, assuming the springs are leaf springs. If they are coil springs I believe replacement is the only option. You should also check to make sure the springs are not broken. This can be somewhat difficult to see on leaf springs as it usually occurs where the axle mounts to the springs. Personally I would opt for the replacement route regardless of the type of spring as you then get brand new springs and the cost isn't great. Hope this helps you out.

Soppy · 07-11-2019, 08:35 PM

I would avoid larger tires as they will affect you overall gear ratio and could cause performance problems and transmission hunting. if your suspension is in reasonable shape , you could consider adding air bags with a onboard compressor to the rear springs. That way you increase the air pressure which would raise the rear of the motorhome for "off roading" , then decrease it to minimum for highway use. Depending on the amount of overhang , an increase of 1" at the springs could raise the rear of the coach by 6" or more. Lowering the front will also raise the rear of the motorhome.

hoakken · 07-11-2019, 10:54 PM

I added air bags on my 2007 Gulfstream conquest. It made a big difference in increased height and also helped greatly with ride quality.

Ron Dittmer · 07-12-2019, 05:53 AM

Hi Tom,

You did not mention the brand and model of your chassis. Most rigs of that length in 1999 were using the Ford E350.

I would consider having a truck suspension shop with expertise, add a leaf spring or more at each rear position to permanently lift the rear to the proper height and proper support. Your rear axle is likely close to the max, or over-loaded. Get the right support back there. Your rear tires and rear axle will still be of concern, but you permanently addressed the rest.

Regarding over-loaded tires, there are a few specific RV tires rated 500 pounds (per tire) more than the others, same size and 83 PSI to get the max capability. Your steel wheels are rated at 80PSI so don't select the tires that require 90 PSI to get the increased load capability.

An extra 2000 pounds of tire load capability in back is a huge increase, great affordable insurance from a rear tire blowout on a heavily loaded rear axle.

I also agree that heavy duty shocks in back will help avoid rear-suspension-over-reaction on dips and such.