Home DIY Tips & Tricks DIY: How to replace an Accu-Slide Gearbox

DIY: How to replace an Accu-Slide Gearbox

by Craig Roberts

Today we are going to tackle another do-it-yourself project by showing you step by step how to remove and replace a failed gearbox on a Norco BAL Accu-Slide cable slide-out system. You may be questioning whether or not this is a project you can manage. But rest assured, if you are comfortable with doing any type of light maintenance using basic, everyday hand tools such as a screw gun or screwdriver and wrenches, you should have no problem performing this fairly simple repair thus saving you hundreds of dollars in the process!

To watch the video version of our own installation you may do so here:

Accu-Slide RV Slide-Out Gearbox Replacement

Some Basic Info & Troubleshooting

So first things first. How to know if the issue your having with your slide is coming from a failed gearbox or some other equipment failure?

The Accu-slide system is in fact a relatively simple design that relies on just a few pieces of equipment in order for the whole thing to function properly. The main ingredients that make up the operational portion of the system are:

  • Drive Motor (1)
  • Gear Box (1)
  • Drive Chains (2)
  • Carriage Brackets (2)
  • Carriage Cables (4)
  • Cable Pulleys (8)
  • Stand-Off Brackets (4)

Diagram of Accu-Slide Drive Assembly
Accu-Slide Drive Assembly

The motor and gearbox are located in the center of the drive assembly.

The gears extending out of the gearbox drive two chains that run in opposite directions to either side of the slide-out. Each chain attaches to a carriage bracket with two cables extending beyond that and to the pullies at the very corners of the slide-out.

One set of cables pulls the slide-out, the other set pulls the slide in. So in total, there are four cables pulling the slide in, and four pulling the slide out. The cables run through the pulleys, down the wall and out to the stand-off brackets.

There are a few clues or symptoms that can help determine if the issue is a failed gearbox, which includes:

  • Slide stops traveling during operation
  • The Slide becomes one-directional, will come in but not out, vice-versa
  • Grinding or popping noise during operation or when slide stops moving

The motor continuing to run when the slide stops moving before it is fully out is important because it rules out the possibility that the issue is with the electrical system or perhaps the slide’s drive motor itself. If you are experiencing different or other symptoms than the ones above you may want to refer to the documentation on Norco’s website for additional troubleshooting tips and suggestions.

Our Story: How we discovered the problem

In our case, it happened when we were setting up for the evening and went to put our bedroom slide out. Nicole had pushed the button as we have done hundreds of times before but then, all of a sudden, the slide began to shutter and move intermittently with a grinding-popping noise coming from somewhere around the slide. Naturally, she immediately let off of the button as we stared at each other with that gut-wrenching OH-No look and wondering what in-the-heck?

Our RV is laid out so that this particular slide needed to be fully extended in order to access the bedroom. We were able to move it by applying pressure and leaning into the slide from the inside while Nicole operated the switch until it was fully extended.

We later discovered that the slide would close without any problem or hesitation, but every time we went to put the slide-out, out, it would repeat the same scenario every time. Although, I also began noticing that it seemed to need more and more help from me each time we had to put the slide-out, out. In other words, it was getting worse! Once we landed at our long-term destination, we started digging and researching to see what could possibly be going on.

What we discovered, is that this issue is a relatively common occurrence with RV’s outfitted with the BAL Accu-Slide Cable Slide-Out Systems particularly with the earlier installations of the system. For what it’s worth incidentally, I did come across some chatter in the forums suggesting that the gearboxes may have been modified or upgraded to last a bit longer, but I have not, as of this writing, verified that information through Norco.

Getting Started: What you will need

Before we get rolling on the steps to fix the gearbox, Let’s take a look at the few things that you will need in order to complete the repair. I have also included a link to the actual gearbox that comes with a mounting bracket.

* Please note that it is a good idea to check the part# on your specific gearbox and use that number to be sure that you are matching product for product before buying anything. The part number should be listed right on the face of the gearbox.

picture of BAL Accu-Slide Gear Box showing location of part number

The gearbox for our slide was Part# R25076 and came with a replacement bracket which, I discovered during the install, was needed. Turns out that the replacement gearbox casing was molded with a small raised collar around the gear shaft that is not present on the old gearbox and makes it necessary, in order to fit properly to install the bracket that comes with the new gearbox. I found the replacement gearbox with bracket here on Amazon, which at the time of this writing was just under $100.

In addition to the gearbox, you will need the following tools:

  • Screw Gun / Screwdriver with square tip bit
  • 3/8″, 7/16″ – Combination wrenches
  • 3/8″. 7/16″ Deep well sockets & Driver
  • Some form of bracing material for supporting underneath the slide (saw horses, lumber, etc)
  • Step ladder

Installation: Step by Step Instructions

Step One: Positioning the Slide

To begin the replacement, it is recommended that you start by positioning the slide approximately halfway in the opening. This allows for equal weight distribution on the slide while we untether it from its cables in a later step. It also provides for better access to the parts that we will be working on.

Step Two: Bracing the Slide

Next step is to secure the slide in place by placing some sort of bracing underneath the exterior side of the slide. We used a set of 4×4 fencing posts cut to length and placed on top of a short 2×6 that I drove a piece of 3/4″ trim under to wedge the fencing post in tight.

The main point behind this step is to try and secure the slide to keep it from moving while you perform the work on it. It will make things much easier when it comes time to reconnect the drive chains and cables if the slide is in the same position it was when we started. Here is a picture of the bracing we used during our repair:

picture of bracing used to support slide-out
4×4 fencing post used for bracing the slide-out

Step Three: Removing the Trim

Now that we have the slide-out braced and supported it is time to remove whatever trim that is currently in place to hide the mechanical parts that operate the slide. Unfortunately, there are just too many RV manufacturers that have gone with the BAL Accu-Slide system to be able to go into much detail about removing this trim piece.

We were pretty fortunate with our Keystone Montana as the center of the slide was decorated with an accent or crown molding in the center directly in front of the gearbox and motor. This accent piece was secured with just four standard wood screws on either side that allowed it to be removed and creating an access window that I could then use to work through if needed. Here is a shot of the trim piece in our trailer:

picture of Craig removing crown molding  on slide-out
removing crown molding to reveal access to gearbox

Step Four: Marking the Chains

Step four is a simple but very important step! Once we have gained access by removing whatever trim that was in our way, you should then be able to see most, if not all of the drive assembly to include the motor and gearbox which should be directly in the center of the slide-out.

The gearbox will be the portion that has a shaft with two gears protruding out the top of it and a chain wrapped around each gear running off toward either side of the slide. Here we will want to focus on the chains and more specifically, where those chains wrap around the gearbox sprockets.

You will want to use a marking device, preferably white or lighter color to mark a chain link that is on either side of the front-most tooth of each gear (See pic below) This will give us a guide for making sure that we reattach these chains back in the same position as they were when we took them off.

picture of drive chains with white painted links
Chain links marked white

Step Five: Releasing the Chains

At this point we are ready to release the tension on the drive chains and then to remove them from the sprockets on the gearbox. Before we do however, you may notice that, from the sprocket, each chain end is connected to what I refer to as a carriage bracket, which then is connected to a set of cables that run further toward the ends of the slide where they meet up with a set of pulleys before disappearing behind some trim.

Each carriage bracket should be labeled, one with “IN” on it and the other with “OUT” on it. And then additionally, they will also each have a “Top” label and a “Bottom” label on them as well. All of that labeling refers to the specific function of that set of cables.

Making adjustments to the slide is outside of the scope of this article so I won’t go into the procedure for making those adjustments here but, I will point out that there is usually a sticker mounted on the wall somewhere near one set of carriage brackets that give basic information that can assist you in making those adjustments if needed. This is what to look for:

picture of Accu-Slide adjustment instruction sticker
Accu-Slide Adjustment Instruction Sticker

Another thing that I want to point out, as you are looking at the carriage/adjuster brackets, is that you should notice that one set of cables/chains on each side of the slide will have quite a bit more tension on it than the other that is located either directly in front of or behind the other. This is because, depending on the direction you moved the slide during Step One, in order to position it halfway in the opening, will determine which set has more tension on it.

For instance, if you had been running the slide out to center it, then the cables with the carriage brackets that are labled as “OUT” on either side of the slide should be the ones with the greater amount of tension because it was those chains/cables that were doing the work at the time that we stopped moving the slide. On the other hand the chains/cables with the carriage brackets labeled “IN” will have slightly less tension on them, to the point that they should have enough play (slack) to be able to move them easily up and down about one-half inch.

Its important that the cables have this difference in tension between them, otherwise there will be too much tension on the system as a whole to function correctly causing excessive pressure and wear on the motor, gears, and cables. It’s a good idea to make a mental note of the tension on each set of cables before removing them so that you will have a reference to what the cables should feel like when you begin putting those cables back together.

Picture of Accu-Slide Carriage Brackets with Labels
Carriage Brackets with Designation Labels
picture of Accu-Slide Cables with proper tension
Cables with half inch of play in tension of inactive set

Now that we have covered the importance of the cable tensions and their functions, it is time for us to disconnect those cables so that we can easily and safely remove our gearbox.

The best way to do this is to pick one of the carriage brackets. I chose to start with the ones that had the greater tension on them and began loosening the bolt located in the center of the bracket using my deep well socket wrench.

picture of Accu-Slide Adjuster Bracket
Accu-Slide Carriage / Adjuster Bracket

If you will notice, the center bolt has a back-up nut on it that will help guide us when it is time to reattach these cables so be sure to avoid letting these backup nuts move from there set positions.

Loosen the chain bolts a little at a time and then move to another bracket similar to the method used for removing a wheel from a car. My thought on that was to avoid creating an awkward torque on the slide during this process. Simply repeat this step until all the cables are detached from the carriage brackets and then remove the chains from around the gearbox sprockets.

Step Six: Remove the Gearbox

Once the drive chains have been removed from the gearbox sprockets, we can now remove the gearbox and separate it from the electric drive motor. This step simply involves removing the two carriage bolts that drop down through the bracket that hold the gearbox in place. Once those have been removed the gearbox should just slide straight off of the drive shaft coming out of the motor itself.

You will then want to check and see if you will need to remove and replace the existing bracket with the one that came with the new gearbox. At first, I did not think this was going to be necessary, but after a few minutes unsuccessfully trying to mount the new gearbox onto the existing bracket, I noticed that the new gearbox had a slightly altered profile in the casing where a small raised collar had been added just around the spindle with the gears, which caused it to not fit onto the existing bracket. So, check and see if you find the same to be true for you as well and perhaps I just saved you some extra head scratchin!

Step Seven: Putting it all back together

All that is left at this point is to reverse the steps to start putting it all back together again, just the way it came apart, with a few handy tips to keep in mind along the way, which I will mention here.

  • Remember to wrap your chains around the gearbox sprockets so that your white marks on the links align with the front facing gear tooth as before.
  • When attaching the chains to the cables with the carriage brackets, be sure to tighten the bolts in small increments looking for the correct tension at each set.
  • When you are finished tightening the brackets, it is important to make sure that the brackets are straight up and down meaning that one cable on the bracket is not pulling more than the other so that it leans forward or back. Also be sure that both the bracket in front and the one behind are positioned so that they are parallel with each other so that they won’t hit or come in contact with one another as they travel past during operation.

Step Eight: The Big Test!

And with that, we have finally arrived at that big moment where we get to test all that we have done and to find out if all of our blood, sweat and tears…. OK, well hopefully there wasn’t too much of that!, But you know what I’m sayin!

Before we step up and hit that magic button though, we’ll want to be sure to remove that bracing that we put under the slide to hold it in place. After that, its magic button time. And I would recommend if at all possible having someone assist during this part so that you or the other can be free to watch and listen closely to the slide while it is in motion.

The way that Nicole and I did it was to run the slide in several inches at a time and pausing for just a moment to get a full inspection of the distancing of each jamb as it came closer to sealing inside and then again on the outside. As well as to watch each of the sets of cables to be sure that none of them develop too much slack during the operation. If this happens, then you will want to consult the sticker we mentioned earlier regarding making adjustments to the slide. You can also take a look at the documentation materials Norco has posted here at their website to see if the information you’re needing is there.


Hopefully, this how-to article served it’s purpose and was able to help get you back to operational again. If so, I”d like to be the first to offer a great big congratulations on a job well done! Nicole & I know first hand what a relief it is to overcome some of these exciting obstacles that spring up from time to time.

And if you did find this article helpful or perhaps would like to share a few details about your experience, we would definitely enjoy hearing from you in the comments below. We would also love it if you would consider subscribing to our newsletter so that we can stay in touch and to let you know when we are able to put new content up that you might find useful.

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Jim Zullo October 18, 2020 - 6:32 pm

Thank you for the video on the gearbox replacement. You saved me a chunk on cash. I was nervous about doing it, but knew it was expensive to have a dealer do it. From start to finish was about hour and a half.

Again thank you!
Safe travels

rvroadramblers October 20, 2020 - 3:29 am

Glad you were able to get it fixed and to save the $’s! It feels good to know that this information is helpful to our fellow RV’ers out there! Thanks for stopping by and letting us know!

RONNIE MCCREIGHT May 11, 2021 - 1:50 pm

I can’t get my slide to open at all. Is it possible to do the gear with it closed?

rvroadramblers July 27, 2021 - 11:07 pm

I can’t really say for sure without knowing more about your specific Rig, but I can say that when we finally got the opportunity to replace our Gearbox our slide-out would not slide out either without applying pressure to it from the inside while activating the extend switch. If that’s not possible then I think that you could replace it while closed its just gonna be a bit more difficult. First, for obvious reasons related to access, but also due to the fact that the closing cables will be at their greatest tension being at the fully closed position. You will want to be very careful when loosening the tensioners making sure that they relieve enough tension before letting it come apart. I hope that helps.

Roger Circle August 25, 2021 - 2:08 pm

Your article and video are excellent. I will be able to replace the gearbox on my 2016 Thor Challenger 37KT with confidence because of your excellent instruction. I appreciate the little tips given in the video… how to tell the difference between old and new gearbox/bracket, proper cable tension, orientation of carriages, etc. Parts ordered. Gonna find me some 4×4’s.

rvroadramblers October 24, 2021 - 12:20 am

Hey Roger!
Thanks for the comments! I’m glad you found value in the article. I hope all goes well with your replacement. I just discovered that I have another one to do myself! lol Anyway, Let me know if you run into any trouble or have any questions that come up.


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