Room geometry: level, height, square and plumb
A room that binds, leaks or racks is usually a room that's no longer where it was built to sit. Measure it the same way every time (coach level, reveal at the flange, diagonals, plumb and the system's own measurements) so you know whether to adjust the mechanism, the coach or the structure.
The short version
- Level and stabilize the coach in the order the OEM gives before you measure anything. Lippert towables level first; HWH runs rooms at ride height.
- Reveal: the flange overlap on the sidewall should be even all the way around with the room in, and the fascia even on the inner wall with it out.
- Unequal diagonals on the room box mean it's racked, and no mechanism adjustment fixes a racked box.
- Each family adjusts differently: tube brackets and stop nuts on through-frame, rack measurements and timing on in-wall, programmed stops on SlimRack, cable tension on cable rooms.
- A room that drops at the sill tears the floor covering and keeps doing it until the support is fixed.
Start with the coach
Lippert's motorhome slideout service manual says four parts have to work together: the chassis, the room, the coach and the slide system, and if any one doesn't, the room misaligns. Measure on a coach that's level and stable, or you'll be adjusting the room to fit a twisted frame.
Lippert's towable manuals say to park on the most level surface available and actuate the leveling or stabilizing system before running the room. HWH's motorhome room manual says to run the room at ride height with the jacks retracted. Use the OEM's order, and measure in the same state the customer runs the room.
Reveal at the flange
With the room in, look at how the flange lands on the sidewall. The overlap should be even across the top, both sides and the bottom. Then go inside with the room out and check the fascia against the inner wall the same way. Heavy overlap on one corner and a gap on the opposite one is a room that's out of square or twisted in the opening, not a seal problem.
Lippert gives a number for in-wall rooms: about 1/4 in nominal seal overlap with no binding. Jayco's BAL slide repair on Highland Ridge rooms worked to a 5/8 in gap from the slide outside wall to the wall mechanism, measured at all four corners with the room nearly in and fully out. Those numbers belong to those systems and models; get the right one for the coach in front of you.
Height, square and plumb
Height: on a Lippert through-frame room, height is set at the vertical adjustment bolt on each tube bracket. On an in-wall room the floor rollers tell you a lot: they should touch the room floor without digging in or spinning free.
Square: with the room out, measure the outside wall of the room corner to corner both ways, and measure the opening the same way. If the room's diagonals don't match, the box is racked and the mechanism can't fix it. If the box is square but sits crooked in the opening, the mechanism or its mounting is your problem.
Plumb: hold a level on the room's outside wall and on the coach wall beside it. A plumb room next to a coach wall that isn't plumb points at the coach being unlevel or the frame twisting, not the room.
System measurements to check
Each family has its own measurements and adjustments, and the system courses cover the procedures. What matters here is knowing which numbers apply before you pick up a wrench.
| Family | What the maker has you measure or set |
|---|---|
| In-wall (Schwintek) | Column edge to gear rack face at all four racks: 2-1/2 in plus or minus 1/8 in, fully out and again 3 in from fully in; racks parallel within 1/8 in; motors shut off together at both ends |
| Electric and hydraulic through-frame (Lippert) | Side to side and height at the tube brackets; in and out stops at the actuator or cylinder nuts; sync by measuring both sides from the T-molding to the coach wall at about half travel and moving the passive tube |
| SlimRack | Stops programmed at install, or set each cycle on auto-programmable controllers; a single-motor button brings one side in further for seal |
| Cable | Cable tension per that maker's procedure |
What moves a room out of adjustment
When a room was right and now isn't, something moved it. Find the cause before you adjust, or it'll be back.
- Running the room with the coach unlevel or unstable.
- Running an in-wall room in electronic override, where the motors aren't synchronized, or moving one side by hand. Lippert says keep both sides even and resync after override.
- A loose actuator or loose jam nuts at the drive bracket on a through-frame room.
- Worn guide parts or debris in the racks on in-wall rooms. Lippert TSB 146-001-2022 covered damaged guide shoes on inverted-rack systems built around October 2021 to January 2022.
- Flex in the structure under the room, like Forest River's riser fix on the Leprechaun and Freelander.
- Added weight, toppers, seals or rollers, which Lippert says all change how the system performs.
Floor damage from a room dropping
When a room's outer edge drops off the sill or a roller, the room floor comes down on the sill edge as it moves. Jayco's 23-105 describes it: the room caught the metal sill pan, dropped, and the floor covering caught. The repair set the pan within 1/8 in of flush, recessed the rollers and made sure the roller cleared every screw head.
Look under the room floor edge for gouges, check the floor covering at the sill for tears or rolled edges, and push on the floor edge for soft wood. Fix the support first; a new floor on a room that still drops won't last a season.
On the job
- Level and stabilize the coach in the OEM's order, and note how you did it.
- With the room in, check the flange overlap all the way around. With it out, check the fascia on the inner wall.
- Measure the diagonals of the room and the opening, and check both for plumb.
- Take the system's own measurements (in-wall rack measurements, through-frame sync, stop positions) and write them down.
- Find what moved the room (loose hardware, flex, wear, debris, override use, added weight) before adjusting.
- Adjust per the system manual, then recheck every measurement with the room in and out.
- Inspect the floor and sill for damage from a dropping room and fix the support.
Numbers
- Lippert in-wall column edge to gear rack face: 2-1/2 in plus or minus 1/8 in, fully out and 3 in from fully in
- Lippert in-wall rack parallel: Less than 1/8 in difference
- Keystone KSB-220630 inverted-rack check: 6 in out and fully out at all four corners; 2-3/8 to 2-5/8 in, 2-1/2 in ideal
- Lippert in-wall seal engagement: About 1/4 in nominal overlap
- Jayco TSB 22-070 (Highland Ridge, BAL): 5/8 in gap from slide outside wall to wall mechanism, all four corners
- Jayco TSB 23-105 sill pan: Within 1/8 in of flush
Shop tip
Write the measurements on the RO before and after, with the room in and out. When the customer comes back in six months saying it leaks again, you'll know in five minutes whether the room moved.
Where this comes from
- Lippert, Electric Slideout System Motorhome Operation and Service Manual, revB, pp. 9 to 11, 14, 16
- Lippert, Hydraulic Through Frame Slide-Out Owner's Manual, CCD-0001616, rev 11.14.19, pp. 3, 7 to 9
- Lippert, In-Wall Slide-out Service Manual, rev 06.14.2016, pp. 4, 9, 10, 12, 21
- Lippert, In-Wall Troubleshooting Guide, CCD-0001771, rev 08.07.18, p. 9
- Lippert, In-Wall Slide-Out Assembly Manual, rev 05.12.21, p. 4
- Lippert, SlimRack Slide-Out Owner's Manual, CCD-0001459, pp. 3, 5, 12
- Keystone KSB-220630 with Lippert TSB 146-001-2022 and 146-001-2022C (via NHTSA)
- Jayco TSB 22-070 (May 2022); Jayco TSB 23-105 (May 2023); Forest River bulletin dated 12/07/2018 (via NHTSA)
- HWH room extension operator's manual ML17127, room extend procedure (Tiffin owner hub)