Shorter hatch lifters to keep hatch from opening as wide? Mazda3(but my PT Cruiser had same problem)

I have a 2010 Mazda 3S hatch which I totally love. Just about it’s only shortcoming is that it’s hatchback opens too wide for our very low garage door. I currently have a variety of padding materials glued to the garage door,but this feels like a real stopgap measure.
Would it be possible to simply install shorter hatch lifters to limit the opening of the hatch? An inch or two shorter overall lifter/strut length would do the trick. Would this prevent my closing the hatch fully?

For gas lifters, there are two important numbers. The length (closed and extended) and the force provided. There is at least one company that sells gas lifters in a variety of lengths and force numbers and will even customize them. I’ve used them for work although sorry, I don’t have the name handy.

You would need to know the length and force (lbs or newtons) of the current lifters, and you would need to determine the desired new length, then order replacements. Note that the lifters only work properly if they are allowed to fully extend when open and fully close when closed, so make sure you measure properly.

Then, you need a way to mount them. The new gas lifters will probably come with mounting holes for bolts or screws but may not come with swivel bearings or the clips or hardware for your car. You may need to build some kind of adapter.

I only give you this information because it is possible to do what you want. I might think about this for an old car when the originals wore out and needed replacement. I personally would not modify a brand new car in this way, and would try to find some other way to live with the issue. I had the same problem with my 2006 Saturn Vue, and I stuck a thick piece of foam to the garage door and lived with it for 5 years. Because the door was curved slightly, I only needed to cushion the door at one spot where the center/most curved part of the gate touched the garage door.

As long as the installation ends are the same, the angles are proper, and the loading capacity of the struts is sufficient to hold the trunk lid up this will work. The struts hold the trunk UP, so they’ll never be under tension. They’ll only hold it up as high as they are long.

Be careful, however. You need to be sure the installation ends are the same and the OD is not greater. The housing OD has to fit the channel into which the originals go when you close the hatch. In short, you need to be sure they’re properly load rated and physically fit. You can, however, order gas support struts to physical dimensions rather than by installation, so what you say is in fact feisable.

You need to match the force because, while the struts don’t do much work when the door is fully open, they are needed to help lift the door. Too much force and you won’t be able to close it, too little force and you won’t be able to open it. And, you are trying to stop the door part-way through it’s designed travel limits, so the force needed to hold it in the desired position might be more or less than designed for full travel. It can be done, but could be tricky.

Personally I think you could accomplish the same thing by using a couple of pieces of rope to keep the hatch from opening too far.

Rope might be hard to attach and stretch but light chain attached as a limiter might be easier and less frustrating to find.

How can I find the force on the current struts? Are there spec sheets for parts like this?
Chain as a limiter is an interesting idea if I can figure out how to attach it. I can envision it getting caught in the hatch though.

Feed the chain inside clear plastic tubing and it won’t tangle or rub the paint off. Any sturdy place where you can attach a screw to the hatch and the body should do. Also might want to use a clip so you can detach it quickly when you want it to open fully.

Yes, there are such spec sheets. Visit the websites of gas lifting strut manufacturers. You can find the load ratings, end configurations, and the physical dimensions for yout OEM replacements, and use those (with a shorter length) to order your replacements.