Trampoline Spring Replacement is a Regular Practice
The problem of spring overstretching is relatively new to the trampoline industry. Until about 1999, nearly all trampoline manufacturers equipped full sized round trampolines, which are usually 14 feet in diameter with between 96 and 104 springs, with springs that were at least 8 inches in length. Since the late 1990s mass merchants, like WalMart, have pushed vendors to produce cheaper trampolines. As a result of this push, manufacturers began producing trampolines with less spring quantity and quality. Typical mass merchant trampolines now have only 72 to 88 springs that are only 5.5 inches to 7 inches in length. This spring configuration is especially prone to overstretching.
Industry experts have reported that customers with older trampolines (who have 96 to 104 springs that are at least 8 inches in length) buy only 5 or fewer springs when replacing their jumping mat. However, it is common for owners of newer trampolines to buy many more (or replace all) springs. The customers state that the springs have overstretched.
For customers who discover this problem at the same time their jumping mat needs replacing, there is an easy and free opportunity for correction. Manufacturers, such as Trampoline Pro Shop who produce the trampoline mats, can adjust your mat size to fit your trampoline with longer, durable springs. This produces a much better trampoline that will be cheaper to maintain over its life.
When extending the spring length it is safe to add an extra inch to the overall measurement of the spring, including the hooks on each end. For example, if your current trampoline is equipped with 7 inch springs it would be safe to increase to 8 inch springs. Experts do not recommend adding more than 1 inch due to the increased risk of touching the ground while jumping because the trampoline height was designed with the shorter spring length in mind.
If you elect to extend the length of your springs, you will need to order a new trampoline mat to keep the entire trampoline components tensioned correctly. Keep in mind that you will need to order the new mat based on your frame dimensions and not your mat dimensions. You will not need the same size as the original mat if you are changing the length of your springs.
If you are unsure if your trampoline springs need to be replaced you can perform these two tests to make your determination. You will need to remove springs from the trampoline so they are in a relaxed state for both of these tests. Any spring that does not recoil when in the relaxed state is considered overstretched and will need to be replaced. Sometimes the spring can appear to be recoiled when it is not installed on the trampoline, yet the spring still needs replacing. To determine this you should clench a spring in your fist, grabbing the spring at one end. Shake the spring back and forth to see how tight the spring is. Trampoline designers recommend that you should do this to at least 10 springs that pass the first test, to see the variance in the amount of tension in the body of the springs. The springs that are loose should be replaced. The only limitation to this test is that it will be difficult to recognize particularly loose springs if every spring is loose. If you are still unsure we recommend that you contact a trampoline manufacturer.
New springs typically bounce better than old springs; however, if a spring passes both of the tests mentioned above the benefit of investing in new springs will be small and is not usually practical. Rust on springs may become a problem eventually but rusty springs that pass the above tests can usually continue to be used.