by Martin Verburgt
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Bumpstops are a very important, and often over looked, part of a properly tuned suspension setup. Bumpstops allow you to maintain control of where the upward travel of your suspension stops and prevents over compression and premature wear to your springs. As you add more lift to your jeep, you need to add more length to your bumpstops. I have found that in most cases, the added length of your bumpstops should equal that of your lift height. For example, if you add 5" of lift, you should add 5" of bumpstop. Now this isn't always the case, but it gets you in the right ball park. The length of your bumpstops is actually a part of an equation consisting of lift height, compressed shock length, tire size, wheel size and backspacing, and amount of trimming on the jeep. The best way to figure bumpstop length, is to just get everything together and flex your jeep. Do not figure your bumpstops when your flex has maxed out and tires are rubbing fenders, wheel wells, suspension components, etc. The point of adding bumpstops is to control flex. You want your suspension to stop when you want it to.
To determine the length of added bumpstop, flex your jeep to the point where the compressed sides are where you want them to stop. With your jeep flexed, use a tape measure or ruler, and measure the distance between the stock (or existing aftermarket) bumpstops and the areas on the axles that the bumpstops would hit under stock circumstances. The areas the bumpstops should hit would be the axle tube to the inside of the leaf spring perch in the rear and inside the coil spring on the spring perch in the front. Once you have the measurements, add 1" to those measurements to factor in compression of the bumpstops.
There are several aftermarket bumpstop extensions on the market for the front. There are extended polyurethane bumpstops that replace the stock rubber bumpstops that are seated in the retaining cup of the bumpstop post. There are also extended bumpstops that mount to the coil spring perch on the axle. These aftermarket items are nice, but they are a bit pricey and they usually only come in 2-3" lengths. I go about adding bumpstops to the front a little more on the cheap end. I use rubber Hockey Pucks. Hockey Pucks are nice, because they are the perfect dimensions to fit inside the coil spring, and are 1" thick, making it easy to figure out how many you need to purchase to get the desired bumpstop settings. The best thing about rubber hockey pucks is the price. I get them at a local sports store for $.99 each. For about $10, I can have 5" of added bumpstop in the front, whereas aftermarket bumpstops would run nearly $50 for the same amount of bumpstop.
For this write up, I needed to add 5" of bumpstop to the front. The lift kit came with Rubicon Express 2" front bumpstops, so I needed to add three hockey pucks. Start off by drilling a 5/16" hole in the center of the coil spring perch, then use a 3/8" self tapping bolt like provided in the RE bumpstop kits, or a 3/8" tap, to thread the hole.
To install your bumpstops, you will need a 3/8" bolt long enough to go through the bumpstops and leave 3/4 - 1" of threads exposed. You will need to drill holes in the center of the hockey pucks for the bolt to go through. Since the pucks are rubber, you will need to drill a 1/2" hole in the pucks for the 3/8" bolt to go through easily.
Now comes the fun part, installing the bumpstops. The reason I say it is fun, is because you have to install the coil springs at the same time as the coil, so things could get a little tricky, especially if you are doing this alone. Set your coil spring into a position where it is not seated yet, and you can fit the bumpstops inside the bottom of the coil like so.
Now, holding the bumpstops in this position, maneuver the coil spring into position on the spring perch. Be careful not to smash your fingers during this step.
With the coils spring and bumpstops in position, you can bolt the bumpstops to the spring perch. Using a 9/16" deep socket and a socket wrench, fit the socket and wrench in between the coils and tighten the bolt down.
Once you have the bumpstop tightened down, repeat for the other side, and you are finished. Pretty simple procedure for setting your bumpstops at the correct amount for the front.
Of the front and rear bumpstops, the rear are usually the most overlooked. Leaf springs are substantially more expensive than coils springs, so it is important to make them last as long as possible. Over flexing the rear springs will quickly lead to premature wear and sag. For the rear bumpstops, there are several options available for lengthening. There are some companies that make extended polyurethane bumpstops that replace the stock rubber stops. There are block kits available that fit between the unibody/frame rail and the bumpstop, or you could make your own spacer blocks to do the same thing for much less. Another option are the Adjustable Bumpstop plates from companies like JKS, DPG Offroad, TNT Customs, and Full Traction to name a few. These plates replace the stock leaf spring UBolt plate, and extends out over the axle tube, which, with just the UBolt plate, adds about 3" of bumpstop over stock, depending on the thickness of the leaf packs. Adding the adjustment plates to the UBolt plate adds more bumpstop to each.
(The following pictures were borrowed from Jason West's website, www.jeepin.com)
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