Look Ma, No Hands

It’s about time our bus made its official debut. As we’ve mentioned before, we own a vehicle that once enjoyed life as a coach bus. One of the outstanding items that’s been driving me bonkers since we bought it, is the lack of any functioning air springs on all of the various storage compartments. Nothing’s more obnoxious when you’re digging for a tool, or trying to work inside a storage compartment and having the door swing down on your head or back. Or having to find a scrap of something to prop the door up. That got old, fast.

So now you know the why. Before I jump into the how, I’d like to show you something never seen on our bus for as long as we’ve owned it, and likely for years prior.

Look Ma, no hands!
Look Ma, no hands!

If our bus has anything, it’s plenty of storage space. There’s a massive luggage compartment in the center of the bus, and many smaller compartments on either side. Each of these doors, and each of the doors covering various mechanical access points, have 2 gas springs to assist in opening the door and to hold the door in the open position. They look like this:

gas-spring

In total, I had about 20 failed springs. I started at the one place I knew I’d be able to get them: MCI. Our bus is a Setra S215. Setra is a luxury coach bus brand owned by Daimler AG. Their distributor in the United States is Motor Coach Industries (which is odd, because MCI is a competitor to Setra, but I digress). If I need a Setra specific part, MCI can get it for me and it’ll probably be expensive. The springs were no exception to either part of that rule. They could get each of the springs, and they’d run me a minimum of $62 each. Yikes.

A while back, on a separate order I was a few dollars short of the free shipping amount so I grabbed a pair of springs for the battery compartment door because at the time I was frequently connecting/disconnecting the battery maintainer in the shop. That brought me down to 18 springs. One night I pulled 16 of them (the last two are on the engine door and with the position of the bus in the shop, I couldn’t open that door without moving the bus – something I wasn’t doing that night). To get those 16 springs from MCI was going to be just over $1,000. I can think of about a million other things I’d rather spend that kind of money on than 16 stupid gas springs.

I asked around town who could get me replacements, and NAPA seemed to be my best bet but even they couldn’t get exact matches. They found ones that were close but ultimately too long. NAPA’s also known for being rather pricey, and the whole point is to save money over MCI. Replacements are pretty easy to find if you have a standard part number, like a Chrysler #123456789 for all Grand Caravan rear door springs, since 1995. Life’s not so easy when your vehicle is one of about two thousand ever produced.

I decided to give AliExpress a shot, as I’d used them in the past for a few obscure items. It turns out a vendor was offering a spring that was nearly identical to one of the 3 sizes I needed, and the listing mentioned custom sizes were available. The cost per spring? About $10. Now that’s more like it! I placed an order for one pair, figuring it’d be a test run. If they seemed decent, then I’d go back and buy the remaining sets. A week or so later, they arrived from China. The build quality looked acceptable. Longevity could be a concern, but as long as they last 1/6th as long as the German alternatives, that’s fine by me – and I have no reason to believe they won’t.

Two failed OEM springs on the left, two new Chinese springs on the right.
Two failed OEM springs on the left, two new Chinese springs on the right.

One thing you’ll notice immediately if you ever need to replace a spring is that old springs are a piece of cake to remove. New springs, on the other hand, can be a real bear to get in. Often you’ll need to compress the spring no more than an inch or so before it’ll line up with the post/ball on the other end. Even though it’s not far to go, compressing the spring requires significant force to overcome the pressure of the gas pushing the piston out. The old leaky spring no longer exerts the same force it once did, so compressing/expanding it is easy. The new spring, however, comes with the piston being extended at full force. Depending on the application you might be able to attach one mounting post and lean into it to compress it enough to line up the hole, or you might have no feasible way to get the leverage necessary to overcome the force of the air inside the spring. I’ll let you guess which situation I found myself in.

That's how much I needed to compress it, when the door was completely open.
That’s how much I needed to compress it, when the door was completely open.

I wasted a good 2 hours trying to scrounge up a way to make this work. First, I tried just grabbing the piston and pushing. But unless the spring was disconnected and I was pushing it straight down into the ground, I didn’t have the strength required to overcome the gas. I certainly couldn’t do it at the awkward angle required for the door. Next I tried putting the spring in an Irwin bar clamp, compressing it, and then mounting the spring while still in the clamp. But the clamp was too long/bulky. I tried attaching the top of the spring to the door, and using a pry bar to force the piston into the spring. But the piston would slide off the pry bar once I applied force. I tried a ratchet strap around the piston. The goal here was the same as the clamp: compress it, and then install it compressed. But the spring kept rotating 90 degrees, so that the mounting holes were covered by the strap. Eventually I gave up and went home to brainstorm.

One the way home, I settled on the following design. If I was able to get a piece of metal sufficiently strong, yet sufficiently small, I could put a plate at the top/bottom of the spring, and compress it by tightening nuts attached to some threaded rods connecting the two plates. If, however, there wasn’t enough room near the mounting holes, I’d need to buy a larger piece of metal and make a strap that went over the mounts and then returned to somewhere closer to the middle of the spring. I sketched out my ideas for Mama B’s feedback.

Plan A
Plan A
Plan B
Plan B

Today I started making the rounds across town looking for parts and evaluating the best way to accomplish the goal. Of course, I spent far too long in the aisles trying to determine the “best” and the cheapest way instead of just throwing some money down on a solution that would just work. Eventually I settled on two U clamps, a piece of threaded rod (or as some crazy tow truck driver in Grand Prairie, Alberta calls it – “ready rod”) and a few extra nuts. I bought the U clamps because they came with a plate that was just the right length/width. It was cheaper and less work than buying a piece of flat steel which would need to be cut to length, and then drilled. Total cost of everything was $7.18.

cable-clamp

I started by cutting a slot that the mount/fitting would recess into just a bit so that it wouldn’t slide, twist, or otherwise move on me while I was tightening the nuts. After those were ready I cut my threaded rod to length, and dry fit everything. It sure looked like it’d work, but the real test was moments away.

Slots cut into the plates
Slots cut into the plates.
Dry run. Ready to install.
Dry run. Ready to install.

As luck would have it, I cut one of the slots just a hair too wide, and as I compressed the spring the mount/fitting slid just far enough into it to block the hole that the mounting post slides into. You can see this a bit in the bottom of the photo above. Thankfully I only did this to one of the plates. I used that “faulty” plate on the top side as that was already resting on the post, and secured by a snap ring. A few spins around each of the threaded rods and the spring was compressed enough to slide it into place. At that point, all I had to do was close the door a bit to compress the spring more, relieving pressure on the nuts which then easily backed off and my whole apparatus came off. The second spring took about 45 seconds to install. Piece of cake.

At the top, ready to be compressed
At the top, ready to be compressed.
At the bottom, ready to be compressed
At the bottom, ready to be compressed
Tada!
Tada!

After knowing that the sample springs would work, and I had an easily reproducible means of installing all of them, I went back to AliExpress to try to figure out how I could go about placing an order for custom sizes. As it turns out, that was considerably easier than I was expecting. A 5 minute online chat with the seller was it. I stated what I needed, she gave me prices, and I paid the bill. Done. Grand total for 16 springs (I decided to buy an extra pair as a backup): $207.80.

I also found out during this project that no one in town sells metric snap rings. Almost every one of the nearly 40 rings I took off was rusted, and many of them broke when removed. I ordered a bunch of 8mm rings for this project, and an assortment of internal/external rings for the future. As soon as everything makes its way across the Pacific, I’ll make quick work of the install with my new tool.

I love projects that end in success. Fix something broken, create a solution to a challenging problem along the way, save a bunch of money over an alternative option, and best of all, enjoy the sense of accomplishment having done it myself. It doesn’t get any better than that!

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