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Old 08-16-2012, 10:24 PM   #1
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Join Date: Feb 2009
Location: St. Paul, MN
Posts: 1,818
Default Liftco slide repair

My slide is a Liftco, vintage about 2002. It's a pretty small one, just the sofa slides out. It's got an electric motor that drives a threaded rod. There is a lateral connecting rod that goes to a gear type box that then turns another threaded rod. These two rods drive the slide in and out. It's worked very well for the 3 years I've owned it. Until July 4th. I was running the slide out and heard a "clunk" kinda sound and then it shifted a bit and then another "clunk." Then it quit moving. The motor kept turning. The rods were turning (I had a kid push the button while I looked up from underneath to see them turning). The slide moved in and out pretty easily by pushing. I found some access panels under the sofa. Lift them out and can see the rods. When the slide was in the right spot I could see there are these aluminum blocks with brass inserts that the threaded rods go through. These blocks are supposed to be bolted down to a large metal plate. The bolts had broken. Two bolts in each block. I'm guessing maybe one of the bolts in each one might have been broken for some time? Just because I find it hard to believe all four bolts broke at the same time. So, just have to remove the broken bolt from the plate, right? There are captive type nuts attached to the underside of these plates. No access from underneath. The bolts all broke off flush with the nuts. Nothing to grab with a vise-grip. Tried drilling a bolt and using an easy-out. Bolt is stuck solid. Broke the easy-out. Then I called Liftco for advice. They told me these bolts are designed to be the weakest link so if the slide hits something or jams the bolts will break preventing more costly damage to the unit. I told them the bolts are stuck in there. They make a repair plate that has new captive nuts. Just use a hole saw to saw out the old nuts/bolts. That creates an open area for the new captive nuts to rest in when you affix the new plates over the original plates. Worked on it yesterday and got it fixed. The new plates I screwed down with some pretty good sized thread cutting screws (not sheet metal self tapping ones). The original bolts were just regular looking allen head bolts. I think they used locktite on them. You want the bolts to not be tight on the blocks. The blocks need to be able to float up and down on the bolts when it's moving in and out. Otherwise it'll bind up if not perfectly aligned. And the amount of travel makes that impossible. The new plates came with shoulder bolts. 3/8" by 1". The shoulder is the main length of the bolt which is smooth and 3/8" diameter. I bolted them in but they weren't long enough and bound up. I went to Fastenal (lucky I've got one about 1/4 mile from my shop) and bought 3/8 x 1.5". Perfect. Allows the blocks to float as the room travels in and out. I used anti seize on the threads, as well as around the shoulder so the blocks won't stick. I plan to take them out every couple years and lube with anti seize so they don't get stuck in the threads like the originals did. I think the shoulder bolts should be stronger too, since they have that larger diameter of the shoulder and when tightened down to the plate that should stabilize the bolt and add strength, shouldn't it? I didn't find anything about this when I searched after I broke it so figured I'd post this just in case anybody else has a similar problem. I took a couple pictures, let's see if I can get them to show up.
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'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio
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