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Email Jim
Repairing a Dodge Ram Power Sliding Rear Window
October 24, 2014

I've had this truck since late 2006. The power sliding window broke just after the warranty expired in 2009. It was probably my fault for trying to open it, then close it with a thin layer of ice on it, but Dodge's use of plastic for where the cables attach to the glass was a pretty poor materials choice. In my case, when the cable attaching tab broke, the cables wrapped around the motor shaft and bound the motor up tight. Trying to work the switch back and forth before I knew what had happened made the situation worse and ruined the plastic spool that the cable winds up on. In hind sight, as soon as the window didn't move, I should have stopped. However at four AM on a sleeting icy morning, getting the window closed was the only thing on my mind. The only reason I opened to window was to get a clear view of the driveway behind me so I could back out and get to work.

I ended up prying the window closed. This actually pulled the window out of the lower tray that is used to pull it back and forth. I got it shut and now only open it manually if in dire need. I kept thinking that one of these days I would take a look at it, but it took five years for that to happen. It turned out that I had the truck in my shop the other day because the check engine light had come on. Codes P0541 and P2069. I had gotten lucky and found a broken connection at the air heater relay near the passenger side battery. It had taken me less than a half hour to fix the check engine light and I had planned to be in the shop for most of the day.  Why not take a look at the sliding rear glass?


dodge_window_spool0
dodge_window_spool1
Kind of blurry, but this is the spool that the cables wind up on. It has seen better days.
Drilling the holes that will become the female side of the spline mount. Six holes at 60° spacing.

Removal of the power rear slider is not covered in my Dodge repair manual. However, I had found a PDF of instructions for installing the power slider posted on a forum a few years ago. To gain access to the motor and cables isn't a tough job, but you do have to disassemble a lot of the rear interior of the quad cab to get to it. I have split 60/40 rear seats, so there are eight bolts and four nuts to remove the seats and the storage cover panels. The bottoms of the eight bolts protrude below the truck and are subject to road spray. Once I started unscrewing the first bolt and found it very hard to turn, I crawled under the truck and hit all of the bolts with PB Blaster. This made the remaining bolts a little easier to remove. You also have to remove the seat belts and a couple of plastic panels on the C pillars to gain access to the large piece of trim that covers the inside rear of the cab and the motor/regulator. There are a couple of Torx bolts for the seat belts. If I recall correctly, the size is TX50.

When I finally got everything out and had it stashed in the shop, I could take a look at what had happened to my window. The plastic clip on the tray that pulls the center window closed was broken off. Since I had not been able to find this individual part (center glass tray) when the window tab broke five years ago, I would fabricate something to fix this. The bigger problem was found after disassembling the motor/regulator assembly. The regulator works by using a 2" diameter spool with grooves cut on to the outside of the cylindrical spool. The cables enter from opposite sides and while running, the spool winds out cable from one side as it winds in the cable from the other. Pretty simple and pretty foolproof if the spool can take more force than the motor can produce. Being plastic, this is not the case. When the force of the steel cable got to be too much, it sheared the end of the spool off and wound the cable around the motor shaft. I had two kinked cables as well as a ruined spool.


dodge_window_spool2
dodge_window_spool3
Aside from the plastic flashing, the spline mount looks good and fits even better.
Turning the rectangle into a disk. HDPE cuts like butter. It's fun to work with.

The situation didn't look good. I searched the web for parts to repair the regulator and all I came up with was an Ebay listing for a used motor/regulator/cables. Since you can't tell the condition of the spool and cables without taking the regulator apart, there was a chance that $85 would buy me someone else's ruined regulator. No thanks. Thus began some DIY engineering. Could I fix it? Maybe. I'd need to make a new spool. I'd need to straighten the cables and I would need to figure out a way to attach the cable to the driver's side of the sliding glass. It would take some time to measure and draw up some plans, but I thought that I had a better than 50/50 chance of getting it working. The other options weren't real attractive. Even though I don't use the window much any more, I do open it manually for carrying long pieces like baseboard molding if the need arises. I guess that I just didn't want to put it all back together and admit defeat.

I drew up some plans, a quick sketch in LibreCAD that took a little longer than I planned. The regulator and motor are metric, but I converted to inches because my machining tools support it. The motor shaft appears to be 8mm, but we'll call it 0.316" since I'm using inchesl and I have a letter drill bit, size O, in this diameter. I drilled a hole in some plastic and test fit it on to the shaft. Nice and snug. I chose to make the new spool out of HDPE plastic as I had some in about the correct thickness. This is the type of plastic used for kitchen cutting boards and I've purchased a bunch of these boards in different colors. I considered using aluminum, but I figured that the HDPE would deform a bit under pressure and handle the kinked cables better than aluminum. The spool is about 5/8" wide and my plastic was 3/4" thick so I would need to shave it down a bit, but that's not much of a chore. I started work. After drilling a 0.316" hole, the next step was to set the plastic up on a rotary table on my milling machine and get it centered. With this done, I drilled six holes 60° apart that would become the outside of the splined shape that fits the motor shaft. I then bored a hole for the smaller diameter of the splined shaft. A little work with a thin wood chisel to turn the six round holes to rectangles and I had a hunk of plastic that fit the splined shaft snugly. At this point in the fabrication, I have no clue if it will work, but I'm in the mood to try it anyway. This project is a nice break from working on our home. I have been working on it for a couple years without many breaks and any excuse to get some shop time is welcome.


dodge_window_spool4
dodge_window_spool5
Adding the threads. 10 threads per inch with a little extra meat left on each end.
I had faced off what I could reach on the lathe and now needed to cut the remaining button down to 5/8" thickness.

Day 2 - lathe work. I made a mandrel to hold the plastic square using an 8 mm bolt, some washers and some nuts. I chucked this up on the lathe and turned the diameter to 2.07" - about 52.5 mm. Working with HDPE plastic is kind of fun. The stuff turns like butter. The only thing I dislike is that even with very sharp tools, you get a little flashing that needs to be removed with a razor knife. I get a lot more flashing on the mill than the lathe, but that may be indicative of using milling cutters that aren't quite as sharp as I can make my lathe tools. I am using high speed steel lathe bits that have been sharpened on Arkansas whet stones and they're darn near sharp enough to shave with.

Adding the threads to the outside of the spool required me to form a new cutting tool with the correct shape. Rather than cutting threads with a 60° V shape, the cable required a U shaped channel. I ground a tool from a broken 1/8" milling tool bit and reduced the profile to about 0.090". I gave it about 5° of rake and sharpened the tip. Rather than doing the threading under power, I turned the big pulley on the counter shaft by hand. I left the lathe in direct drive so it would take fewer turns of the counter shaft to make the 5 revolutions to cut the threads/channels. The original spool had these channels formed about a tenth of an inch deep and I did my best to copy the design.


dodge_window_spool6
dodge_window_spool7
Button removed.
New spool - old spool. Test fit.

The last job on the lathe was to narrow the spool from 3/4" to 5/8". Since I had a bolt head sticking out of the center of the spool, I faced the spool up to that area. The remaining button would be removed on the milling machine. After I got the button removed, I compared the two spools. The new one looked like a pretty good copy. The next step was to drill the hole that would hold the cable ends. On the original spool, there was a molded rectangle that passed through the spool at an angle. The angle captures the cable end and holds it tight under tension. I set my drill press table to 35° and drilled the hole by eye. From the newly drilled hole to the threads, a channel for the cable needs to be cut on either side of the spool. The threads don't quite make 5 revolutions on the spool and and end about an eighth inch from the edge of the spool. These two new channels need to intersect both the angled hole and the end of each side of the thread. The channels also need to have a slight curve so that the cables aren't kinked making the transition from the side of the spool to the threads on the circumference.

With the hole drilled, it was back to the milling machine to cut the first channel with a 3/32" bit. The second channel needed to be cut to 1/8" width and depth due to the cable being frayed near the end. I had re-twisted the cable the best I could, but it still looks pretty ratty. The deeper and wider slot would allow the frayed end of the cable to not drag along the spool housing. New cables would have been a better option, but apparently they're not available separately. For the transition from the side channels to the threads on the circumference, I used a small bit on a hand held rotary tool and made the radius free-hand.


dodge_window_spool8
dodge_window_spool9
Drilling the hole to hold the cables. The table is set at 35° so that the cables don't slip out.
Cutting the slots that connect the hole I just drilled with the threads on the circumference.

With the spool done, it was time to see what I could do about the broken holder on the driver's side of the rear glass.  I had been thinking about this since the window had broken and had decided that a thin strip of metal could be wedged between the glass and the tray that holds the bottom edge of the glass. Something like a feeler gauge would work. It so happened that I have an assortment of long feeler gauges that I use for shim stock. I tried a short three inch one and found that it was pretty strong when I pulled on it from the side. A longer one would have even more contact area - more friction to overcome - and would probably be even stronger. I would use the 12" feeler gauge. Too bad it wasn't just a couple inches longer so it would cover the entire bottom of the center glass and not leave a bit of a gap near the passenger side of the window frame.  However, when I tapped the feeler gauge into place, only an eighth of an inch of the top of the feeler was visible. When the seats are installed, you won't be able to see the feeler gauge at all.


dodge_window1
dodge_window2
A long 0.010" feeler gauge.
The feeler gauge slips between the glass and the tray that holds the glass in the channel. Tap it down as deep as you can get it.

There is a hole in one end of the feeler. I threaded the cable end though that hole and used a small split washer, crimped around the cable, to prevent the cable from pulling back through. I installed it in the window and tapped the feeler gauge as deep as I could get it using a block of oak and a mallet. I pulled the cables from each end and opened and closed the window a few times. This just might work. I spent some more time straightening the cables. They were kinked in a number of places. I have been in the situation where I had to make on-the-road repairs to cables on a couple of old motorcycles years back and had always been able to fix them well enough to get home. That said, I also ended up replacing those cables once I got home. In this case, I was going to ask these cables to work without replacement. The one thing I have learned is that you need to re-twist the strands of the cables after you straighten out a kink. Two pair of pliers will help to accomplish this.

With the cables as straight as I could get them, I put the cable ends in the spool and wound them up. There didn't seem to be quite enough cable to make the required number of wraps and still have enough free cable to get the spool into the housing. I tried one less wrap and I had too much cable left over. What to do? The only thing I could come up with was to lengthen the cable by shortening the sheath. I wrapped the cables up again and measured how much more free cable I needed. 1.5 inches. I got out the rotary tool (Dremel) and a cut-off disk and cut through the metal sheath. The sheath is a coiled piece of flat steel so once it was cut through and separated from the main sheath, I needed to then cut each wrap of the steel to remove each coil. Tedious work, but it came out OK. There is a plastic insert inside the coiled steel sheath that separates the steel cable from the steel sheath. It can be pulled out. Before cutting the coils, I pulled the plastic from the sheath and cut an inch and a half from the inner end before I cut the coils. Once the coils were removed, I reinstalled the plastic tube in the sheath. This should keep the metal to metal contact to a minimum.

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dodge_window4
This cable is in pretty bad shape. Fortunately it resides in the side of the spool and doesn't need to be wound on the spool.
For some reason the cables weren't long enough. To lengthen, I cut about 1.5" out of the sheath with a rotary tool and abrasive disk.

As for the difference in cable length between the stock spool and my copy, all I can do is speculate. A radius difference of 0.05" in the depth of my cable grooves could account for a as much as a third of and inch in circumference for each wrap of the cable. Multiply this by five wraps and and it comes close to solving the 1.5" difference. My placement of the hole that holds the cable ends and the shape of the channel that connects the hole to the outside grooves could also add or subtract to the cable length. Since both sides of the original spool were destroyed, I just took a guess at how they were routed.

With the cable now the right length, I was able to insert the spool into the housing and reassemble the regulator. I reattached the motor/regulator to the rear of the truck and plugged it in. I gave it a try. The window opened. I hit the switch the other direction and the window closed. No drama, it just worked. I took the motor back out and took out the three screws that hold it together and slathered on some silicone grease on to the spool and cables, then reinstalled the three screws (TX25, if you're curious). I worked the window a few more times and added some silicone grease to both the window channels and the cable that was exposed on either side of the window. Success. All I need to do now is reinstall the truck's interior. The fun never ends.

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dodge_window7
The regulator is installed.
Window open.

So the window lives again. I'm happy that I was successful, but I'm pretty wary of using the window much. The cables were in pretty bad shape and my HDPE replacement spool is a little less perfect than the original part. This is mostly due to having to guess what the side channels looked like. The ones on the old spool were destroyed and I just guessed at how they were originally designed. The one good thing is that the rear glass is now not able to be slid open from the bed. Not that many thieves would be able to enter through that window, but it is now locked in place.

If you are reading this article because your window has jammed or the tab has been broken off, I hope this article gives you a little more information so you can decide what to do. Even if you have a mill and lathe at your disposal, if your cables are as damaged as mine, the repair is going to be questionable. If I really cared about the rear slider, I would pay the cost for a new motor and cable assembly from Dodge. However, I do think that the feeler gauge mod is a cheap way to get your window working again if the tab has broken and the cables didn't destroy the spool. I wonder what the chances of that are?

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dodge_window9
Window closed.  Time to put the interior back together.
Make sure you put some anti-seize on those seat bolts if you ever hope to remove them again.

As a parting shot, I'll share a couple mistakes I made on reinstalling the seats. If you have the 60/40 split seats, install the larger seat first. The rear seat frame bolt at the center of the cab will be a lot harder to get in if you install the smaller seat first. Yes, I ended up installing, then removing the smaller sear. Also, when installing the larger seat, the center seat belt, the one with the retractor, needs the loose end of the seat belt installed over the top of the seat back before you attach it to the floor. The last tip is to use some anti-seize on the 8 bolts that hold the seat frames down. Since the bottoms of the bolts exit through the floor and will get hit with water, mud, and whatever, the anti-seize will make them easier to remove in the future.

© Fager October 24, 2014