Why does the RV’s slide room ‘thunk’ every 3 to 4 seconds when it’s in motion?

Dear Dave,
My RV’s driver-side slide out has developed a profound “thunking” sound, 5 times every time it slides out at a 3- to 4-second interval, coming from the floor. When it retracts, it sounds like the floors are scraping together. After a demonstration, the mobile RV repair guys don’t know what the issue is. I do use 303 spray before use. It doesn’t seem to help. What can you tell me about this situation? —Bob, 2007 Fleetwood Flair 33

Dear Bob,
First, make sure the jacks are down and the unit is level and stabilized. If not, the chassis can twist as the unit goes in and out. That would mean the side wall twists, as well, and could bind the RV’s slide room.

303 Protectant is not a lubricant, but rather a conditioner for rubber, fiberglass and other materials. Proper lubrication depends on the type of slide mechanism. I believe your Flair uses the Power Gear mechanism, which is a rack-and-pinion type that has gears similar to these.

Power Gear^® originally recommended 3-IN-ONE^® oil applied to the outside bearing and nothing on the gear or track itself. Lippert now owns Power Gear and they also recommend a lightweight oil. You can find the documentation at LCI1.com and the Power Gear For Fleetwood Owner’s Manual here.

I have also found some technicians that spray the gear and track teeth with CRC Silicone spray and wipe it off, as it helps get rid of the rust.

Inspect the gears

Since the thumping sound is every 3-4 seconds, I would closely inspect the gears to see if one of them is broken or bent. This would be the revolution time of a gear, so have someone extend or retract the room and watch the gears turning to see if there is an issue with that. Also pay attention to the track gear and see if something is broken or misaligned.

If the gears are fine and the thumping is coming from somewhere else like the floor, as you mentioned, check out the underside of the slide room for any foreign objects both inside and out. Here is a diagram of how your slide mechanism is mounted.

Notice how the outer rail is welded to the frame. You might have a cracked weld and the rotation of the motor and drive shaft creates resistance, or the inner rail assembly is bent and binding. There are several points that could have resistance, and you should be able to isolate where the thumping is coming from.

Check the gear motor

Another potential spot would be the motor, as it has a brake, rotating shaft held on with a pin, and the motor gearbox. Here is an example of one style motor used. It could even be a faulty brake engaging too soon or a warped motor shaft, which again would thump at each rotation. Also, make sure the brake lever is not engaged.

Then, the final inspection would be the integrity of the box and how it slides in and out. I have seen rooms that twisted due to the corner trim becoming loose due to broken screws or pop rivets. Check all corners such as the floor to vertical walls, vertical wall corners, and roof to vertical walls. Then make sure it is sliding on either the rollers or pads, depending on how Fleetwood decided to install it. Rollers are preferred and should be rolling freely. Again, every 3-5 seconds could be a flat spot on a roller.

 You might also enjoy this from Dave 

Should I lubricate the cables on my RV’s slide room?

Dear Dave,
Our trailer has a cable-driven slideout. Is there any maintenance I should be doing on the system? I can’t see where lubricating the cables would work. —William, Heartland Mallard M301

Read Dave’s answer.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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