LANCE 1985 – Slide-Out Seal Replacement

I got a text from a buddy last week: a Lance 1985 came through his shop with a quote of $2,100 for slide-out seal replacement, labor included. He asked if I’d ever done it. I have — several times — and it’s nowhere near that number if you’re willing to spend an afternoon on it yourself. The catch: water damage hiding behind a failed wiper and base seal can multiply that bill ten times over before you even notice it’s happening. On the Lance platform, those two seals fail together, and when they do, moisture creeps into wall cavities and floor substrates silently for months. I’ve opened up slideouts where what started as a $60 parts problem had become $2,500 in structural rot. This one’s a straightforward DIY if you go in knowing where the traps are, which seal profiles actually seat in the Lance’s tolerances, and what corroded hardware to swap while you’re already deep in the job.

The Two-Seal Strategy: Why One Wiper Alone Won’t Save Your Walls

A 1985 Lance slide-out assembly depends on two seal components working together — a wiper on top and a base seal along the bottom track. Neither one handles the load by itself. The wiper compresses and splits from thermal cycling, the base hardens and pulls away from the frame, and suddenly you’ve got two independent pathways for water to bypass both. You absolutely need to replace both pieces in the same session, or you’ll be back inside the walls six months later.

Parts and Tools

• 018-341 EK slide-out wiper seal, 35 feet long, matched to Lance 1985 top track profile — check current price
• 018-312-EKD base seal for slide-out bottom track, 35 feet long, exterior grade — check current price
• Stainless steel fasteners (bolts, screws, or rivets) to match existing slide-out frame hardware, sized for Lance 1985 assembly
• Silicone-based sealant rated for RV use, compatible with rubber and aluminum
• Flathead screwdriver or pry tool for seal removal without gouging aluminum frame
• Utility knife with fresh blades for cutting seal material to length
• Degreaser or mineral spirits and clean rags for frame prep before new seal installation

Step-by-Step Instructions

Step 1: Retract the slide-out fully and inspect for water damage

Close the slide-out completely and power it down. Before touching anything, photograph the wiper seal from multiple angles—note any splits, hardening, or separation from the top track. Open cabinet doors and look inside the wall cavity behind the slide-out for soft spots, discoloration, or mold. Probe the floor substrate near the base with a screwdriver; soft wood means rot has already started. Document all damage with photos before proceeding, as this determines whether you’re replacing seals only or need to address structural issues first.

Step 2: Remove the old wiper seal from the top track

The wiper seal on a 1985 Lance sits in a channel along the top of the slide-out frame. Use a flathead screwdriver to gently pry one end free—work slowly to avoid bending the aluminum track. Once started, pull the seal straight out by hand along its full length. If it’s brittle or cracked, it may break into pieces; collect all fragments. Inspect the track channel for debris, corrosion, or deformation. Clean the channel thoroughly with a rag and degreaser to remove old rubber residue and dirt.

Step 3: Remove the old base seal and inspect the bottom track

The base seal runs along the bottom of the slide-out frame where it meets the RV floor. It’s typically glued or mechanically fastened. Pry it up carefully from one end, working along its length to break the bond. Remove any fasteners (screws or rivets) that hold it in place. Once free, scrape away old adhesive and rubber fragments from the track with a plastic scraper or old credit card—do not use metal tools that will scar the aluminum. Wipe the track clean with degreaser and inspect for cracks, corrosion, or bent edges that would prevent a new seal from seating.

Step 4: Prepare the frame and install the new wiper seal

Measure the top track channel length on your Lance 1985 and cut the 018-341 EK wiper seal to size using a sharp utility knife. Test-fit the seal in the channel by hand—it should slide smoothly without forcing. If it binds, check for debris or track deformation. Once satisfied, insert the seal fully into the channel, starting at one end and pushing it straight in along its entire length. The seal should sit flush in the channel with no gaps or twists. Do not use adhesive on the wiper; it relies on the channel walls to hold it in place.

Step 5: Install the new base seal with proper fastening

Cut the 018-312-EKD base seal to match the bottom track length. Dry-fit it first to confirm it seats evenly along the entire run. If your Lance uses mechanical fasteners (screws or rivets), drill or punch holes through the new seal to match the original pattern—typically spaced 12 to 18 inches apart. Apply a bead of RV-grade silicone sealant along the track before laying the seal in place. Install fasteners hand-tight first, then snug them fully. Do not over-tighten; you’ll compress the seal unevenly and create gaps.

Step 6: Seal all joints and edges to prevent water bypass

Run a continuous bead of silicone sealant along the top edge where the new wiper seal meets the frame, and along both sides where the base seal meets the track. Pay special attention to the corners and any gaps where the seals meet the slide-out frame ends. Smooth the sealant with a wet finger or caulk tool to ensure it fills voids completely. Allow the sealant to cure per manufacturer instructions—typically 24 hours—before retracting the slide-out.

Step 7: Test the slide-out operation and verify the seal

Extend the slide-out slowly and watch the wiper seal compress evenly as it moves. Listen for grinding or binding; if you hear it, stop and check for debris or misalignment. Fully extend and retract the slide-out twice more, observing that both seals maintain contact with the frame throughout the travel. Close the slide-out completely and inspect the wiper and base seals from outside—they should sit flush with no visible gaps. Run water along the top track and base with a hose to confirm no leaks appear inside the cabinet or wall cavity.

What works

• Sourcing the 018-341 EK and 018-312-EKD as a matched pair means one order, one shipping cost, and no halfway-through-the-job realization that the first seal alone is inadequate.
• The 35-foot coil length on each seal covers your entire slide perimeter with 8-10 feet remaining for repair patches or other trim work down the road.
• When both seals are properly seated and compressed, the slide operation becomes noticeably smoother, the box feels less sloppy, and condensation no longer pools on the flooring after temperature swings.

What doesn’t

• These seals won’t stick to 40-year-old aluminum unless you strip off every speck of old adhesive residue first — a scraper alone won’t cut it, and poor surface prep guarantees the seal will migrate sideways within weeks of installation.
• The mounting groove on the Lance frame requires hands-on trial fit; the seals come slightly oversized intentionally, so expect multiple trim-and-test cycles before the profile seats flush.

I second-guessed whether 35 feet was actually enough coverage until I ran the numbers and realized I’d overestimated the perimeter by nearly 40 percent — don’t repeat that mistake, and measure your actual slide-out frame before ordering. Grab the 018-341 EK Slide Out Rubber Seal & 018-312-EKD RV Weather Stripping Exterior for RV Camper, 1′ x 15/16′ x 35′ and 1/2′ x 2.75′ x 35′ Combo Slideout Wiper Seal and get both seals done in one job.