When taking the motorhome on dirt, rough or rocky roads, do you recommend lifting the vehicle with the airbags?
Use caution driving lifted very far because it puts the driveline at a bad angle. Someone correct me if this is incorrect
IMO, only as a last resort.
I will extend them to slowly creep over a berm so I don't catch the front or backend, or aquahot exhaust, but that's it. If you feel you need the clearance constantly you probably don't want your coach there.
I used the bags all the time. Impossible to achieve an angle to damage the drive line by pumping the bags up. The output shaft on the transmission and the input shaft on the rear end always stay at the same angle though the rear end may be lower. Any angle above 3 degrees will put greater wear on the components over time but since this is at low speed and for a short distance, there is no problem. 4WD vehicles with or W/O lift kits, may utilize a CV joint (constant velocity) or Cardan joint rather than a conventional U joint to reduce the possibility of wear.
Watch trees close to the coach as it may lean and contact the awning, etc. Several BLM campsites we go to require traveling over the forest floor so we may use the bags on one side to keep away from limbs, etc.
Good to check joints once a year. Any red dust is a sign that the grease has gone away and you are metal to metal. Especially true if driven in the rain a lot. Red synthetic grease is the ticket here. As Brett pointed out in one post, a Zerk fitting may be installed in more than one point on a common cavity. This is so you don't have to move the vehicle to grease the U joints.
We are off the pavement all the time to reach our campsites. Have been doing this with our bus and U300 without any damage in many years. You just have to pay attention so you don't hit anything or get stuck.
Pierce
We use our coach in many places I would not recommend using. Our coaches really were designed for paved road use. That being said I routinely raise or lower to clear whatever is in the way. I'm not worried about driveline issues because I'm not moving fast enough to be a issue. BUT Its not what they were intended for. If you have exceeded the travel limits of the suspension you may never know you did. Next you know you have a damaged coach.
Sunday December 5, 2021 we were traveling North on US 287 toward Greenville, TX. As we approached Palestine, we were directed to take Loop TX 256 to bypass downtown. As we approached the intersection of TX 256 Loop and US 79, we were doing just under the 55 MPH speed limit and had a green light. A smooth 4 lane highway crossing another 4 lane hwy both with turn lanes. As we crossed US 79, it felt like we hit a speed bump. It seemed to us that the front wheels of our coach went airborne and immediately slammed back down. I am sure we stressed the air bags. Nothing broke inside or outside, we stow loose items well before we travel. I have used street view in Google Maps to examine every inch of the road surface. I did not see a dip or rise that could have caused the reaction we experienced. Neither was there a warning sign of dip or bump ahead. I am impressed with the quality of our 20 year old coach. A lessor even newer vehicle would not have faired as well. If you are driving that road, be very careful at this intersection.
I hope I am not hijacking this thread with an ON road story. Grins.