1999 Jeep Grand Cherokee Laredo: Coil Springs!
Just because you have the tools, doesn't mean you need to use them. This is the lesson I learned from this project. That, and when it comes to safety, don't buy tools from China. Coil Springs pack a lot of punch. They support the weight of a vehicle, and when they compress, the power that they store in themselves is quite high. I am not even going to pretend like I would know how to calculate that stored energy, but it does become practically lethal. Like a bomb that you are going to have to manhandle and manipulate in order to get the job done.
Video of coil spring compression tool failure with professional mechanics
This is a video from Car and Driver Magazine where the compression tool they were using failed on them. Something very similar happened to me yesterday, and this post is going to highlight some of the things I did to avoid having to use those compression tools in order to complete the job in a safer manner. In the manner I probably should have in the first place, once I realized how much safer it was.
The compression tools I was using in the first place, were threaded shafts, which you turn with a ratchet or impact wrench. You place one on either side of the spring and then tighten a little on each side to compress the spring evenly. This does work quite well for the most part, and in some cases, you will need to use these tools. Some vehicles will not allow you to do what I did to get around the use of them. My friend Jason says that usually chains are placed around the coil spring once it is compressed by the tool in order to ensure they stay compressed. I can't say I have ever seen this practice myself, but it could be a good idea I suppose. With the amount of force packed in these springs, I could see it snapping the welds on some thinner chain however, if it did release in an explosive decompression instance. The video above, if you continue watching after the incident, they ended up using vice grips to hold the tool to the coil spring. I think that is likely a more suitable option. I was even thinking of welding the tool temporarily to the spring, but that would damage the spring in a major way, making it useless. Maybe, however, for the old springs your removing, that might be an option. In any case, when dealing with coil springs, you need to be careful. I was lucky I was wearing safety glasses, and I was also lucky that my injury was only really minor, and not painful at all (I continued working after it happened).
This is the video I was following for what I needed to do. It shows the compression tool, similar to one I was using. However I did not follow all the suggestions of the video, initially. I didn't remove the sway bar connection. The 'incident' happened while I was removing the coil spring from the vehicle. It was a bit stuck in place, slightly embedded into the rubbery gasket at the bottom, and I was tugging on it a bit to try to loosen it up. This is when the compression tool gave way, and the spring spring out of place, luckily freeing itself from the mounting, and also luckily missing me in the process. The failed compression tool went flinging off and is what hit me in the face. It all happened so fast, and I was stunned for a second, and then said "wow.. well... I guess its off now." My wife who was there and witnessed this happen, told me that it hit my face. I was like "Oh? really? I don't feel anything...." She told me to look at her, so I did, and then shes like, yup, you are bleeding...
Anyhow, the safer way, was to remove the sway bar. On my vehicle it was a bit easier than on the XJ in the bleepin' jeep guys video. They had redesigned that linkage, and dropping the sway bar seemed to drop the whole axle far enough to insert the whole spring without compression needed. So I got that spring installed, and it went a lot smoother using this method. The other side, I decided to go with this method right from the start, and I took pics!
Of course, it goes without saying that the body of the jeep has to be on jack stands. Because you need to let the whole axle fall down. I place my jack on the metal part just below the wheel hub assembly in a grove so as to hook it in place. I ensured that there was some pressure on the jack to hold the axle in place while I unbolted the shock, and the sway bar linkage.
First I unbolted the lower bolts holding the shock in place. This is fairly easy, and I typically use a metric 10 wrench, and then my air ratchet with a metric 10 (I think?) long socket to get the nut on the bottom. Sometimes you have to feel for those nuts as they can be kinda hard to find. ;-)
Next, I unbolted the sway bar linkage. A little bit of Thrust or PB Blaster will help loosen rusty bolts. I believe this was a Metric 15 on one side, and a Metric 18 on the other. The impact wrench worked well. Once it was out, of course, now the jack is all that is holding the axle up.
Lowering the jack steadily and slowly, you release the spring of its energy, and ...
It is able to be pulled right out. I still had to pry a little at the bottom, as it was really stuck on that old rubber. But it came off easily enough. And the new one went on in exactly the same way, except the reverse order. Using the jack to compress it up into place, and then attaching the sway bar linkage, and shock.
All in all, a much safer method.
I think that if it comes to replacing coil springs on a vehicle where they do require a lot of compression to install, I may end up taking it to my mechanic in the future. This kind of stuff is quite risky, and I very easily could of been knocked out, or even received fatal injuries.