How-To Install Front Bump Stop Extensions on a 1997-2006 Jeep Wrangler TJ

TrueTexas

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Front Bump Stop Extensions

The front bump stop extensions are to be installed on the lower spring perch. This is the ideal location as installation right above the bump-stop cup will cause interference with the spring when it is at its full extension.

Before starting on the process, my goal was to maximize both up-travel and down-travel for my very mildly lifted TJ (~1.5”). To ensure maximum up-travel, you must determine the ideal height for the bump-stop extension without making it too tall or too short. To accomplish this, it is critical to cycle your suspension. As I was installing new Rancho RS5000X shocks designed for 2.5” lifted Jeep TJs, the first thing I did was to remove the stock springs and then temporarily install the shocks to properly cycle the suspension. I am not going to go thru the process of removing and installing springs as there are excellent write-ups from Fuse on this forum that details the process extremely well. Here is the link to that post:

spring-swap-walk-thru-with-pics by Fuse

bump-stop-check-walk-thru-with-pics by Fuse

(Note that you should cycle your suspension twice - once with the shock installed fully and once with the shock and wheels installed. Also, you may want to loosely connect your trackbar to see if it causes any interference at full flex.)

Upon cycling my suspension, I was able to fully compress the shocks to determine that there was a gap of 1-1/2” between the spring cup and lower spring perch. Adding a little buffer to ensure that I would not bottom out the shocks led me to determine that the ideal bump-stop extension would be 1-5/8” tall with a 3” diameter. This is where I ran into my first problem, there were no 1-5/8” extensions readily available on the market. Also, a standard hockey puck is 1” tall which wasn’t going to work for me either. So I started searching for a better option.

This led me to find a really awesome guy named Mike that specializes in making body lift blocks for Nissans. Mike uses a material called UHMW-PE (Ultra High Molecular Weight Poly Ethylene) that is a super hard plastic for his body mounts. I was pretty impressed by the material for a few reasons including that it can withstand repeated impact and it will not have issues that metal bump-stop extensions have like rusting or corrosion due to dissimilar metals being in contact. Mike also made them in a 3” diameter, which is perfect for the Jeep TJ spring perch. Mike worked with me to determine center-hole size, countersink dimensions, and was able to make them in my specific height. As a bonus, they were very cost effective compared to the options that are currently available. Please feel free to reach out to Mike to purchase or get a quote on custom bump-stop extensions made for your specific needs. He can be reached at:

Click here to visit Mikes website and purchase bumpstop extensions

(256)226-1231

Ok, so let’s get to the install. This process will be the same for any height bump-stop extension installation.

Step 1 – Remove the Springs and Shocks

Remove the springs and Shocks. Ignore the brake caliper and rotor. I was doing both jobs at the same time. As I mentioned above, use the write-up from Fuse for removing the springs and shocks as there is no way I can do a better job than he did.

stock-spring-swap-walk-thru-with-pics by Fuse

IMG_20200112_103647.jpg


Step 2 - Remove the Bump-Stop Cups

This step is to make more room for you to fit your drill above the lower spring perch and give you room to work. If your bump-stop is installed, pry it out of the bump-stop cup and then remove the bump-stop cup with a 15mm socket. Note the bolt is super long and I felt like I twisted the ratchet for days. If you have an impact drill, this is a good opportunity to use it.

IMG_20200112_100330.jpg


IMG_20200112_100316.jpg


Step 3 – Drill Holes for the Bump-Stop Extension Hold-Down Bolt

It cannot be easier to find the center of the lower spring perch, there is already an indentation in the middle of the spring perch. Lower the axle to give yourself as much working room as possible. Make sure you use the correct drill bit size for the tap that you will use in the next step to thread the hole. I used a 3/8-16 tap that came with a drill bit. Also note that you should use some cutting fluid to keep the holes precise and your tools sharp. I used mineral oil, primarily because I had it in the garage already. Do not use WD-40 or motor oil as they don’t make great cutting fluids. In a pinch, bacon grease works well as a cutting fluid. Make sure you drill this hole as perpendicular to the perch as possible. I was able to easily eyeball it but, this is not my first rodeo (see note below). Take your time to clean the chips and re-apply cutting fluid as you go.

Note that as I was discussing this write-up with Fuse, he made an excellent point about using a drill guide to keep the drill perfectly perpendicular to the spring perch while drilling the hole. If you are unsure of your ability to “free-hand” drilling the hole perfectly perpendicular, invest in a drill guide. You only get one chance at getting this right.

IMG_20200112_103744.jpg

IMG_20200112_104208.jpg


Note - You certainly have your choice of the size of the bolt you want to use but 3/8-16 was perfect for me. For my specific bump stop height, I used a 2” bolt. General rule of thumb should be to use a bolt that is ~1/2” longer than the bump-stop height. I believe Mike will be including bolts and washers in his kits that are 3/8-16 so you can avoid a trip to the Hardware store.

Step 4 – Use a Tap to Thread the Holes
One of my biggest concerns with tapping threads into the spring perch was having enough threads to securely hold the bolt. Using a 3/8-16 tap was perfect as it hollowed the sides of the indentation, which allowed me to get a little bit more than 3 full threads into the spring perch. Make sure that you tap the hole that you drilled as perpendicular to the spring perch as possible. You have plenty of room to use a taper tap (which is the easiest to use as it allows you to get multiple turns before actually cutting the threads. Just make sure you turn the tap back ½ turn for every full turn you make into the material. This will clear the metal shavings and make for a cleanly threaded hole. Remember to use cutting fluid to assist in tapping the threads.

IMG_20200112_111625.jpg


IMG_20200112_120251.jpg


Step 5 – Test Fit the Bump-Stop Extension (Optional)
Now is a good time to test fit the bump-stop extension. I simply bolted down the bump stop to make sure fitment was good. Once I was satisfied, I removed it as it is virtually impossible to install the spring with the bump-stop extension in place.

IMG_20200112_150614.jpg


Step 6 – Install Bump Stop Cups
Go ahead and re-install the Bump-Stop Cups, using a 15mm ratchet. As Fuse points out in his write-up, there is no published torque spec so use your best judgement. They were not super tight to begin with.

Step 7 – Install Spring, Jounce Bumper, and Bump-Stop Extension
Put the Jounce bumper and bump-stop extension in the spring and re-install the spring. Now bolt the bump-stop extension down inside the spring. Be sure to use a little blue Loctite (242) on the threads of the bolt to ensure it stays put over the long haul. After that is done, reinstall the jounce bumper into the spring cup.

IMG_20200112_153604.jpg


Note - One of the things I found extremely helpful was to use a small bottle jack and 2x2 piece of wood placed in-between the lower and upper shock mount to push the axle down fully. This allowed me to easily install the new springs with the jounce bumper and bump-stop extension rattling around inside the spring.
Note – As I was using new jounce bumpers, they were very tough to push into the bump-stop cups. This is where hockey pucks can actually come in handy. Slide them (or any suitable spacer) in the spring above the bump stop extension then jack up the axle like you are cycling the suspension to seat the jounce bumper. This worked so well for me to seat the jounce bumpers that I thought it would be a shame not to share.

Step 8 – Reinstall the Shocks
Reinstall the shocks. Continue with Fuse’s instructions to finish reconnecting all the components you disconnected to get the springs out.

For those of you wondering, those are Rancho RS5000X shocks painted black in the pic.

IMG_20200112_193318.jpg


Step 9 - Sit Back and Admire your work.
Congratulations!!! You are done.

IMG_20200120_205959.jpg
 
Bravo, fantastic write-up, and one that should be very helpful to new members. Thanks for doing this!
 
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Nice write up, and great pictures! This is just what I did for my bump stop extensions, except I didn't do as nice a job as this. These instructions will definitely help anyone else who is doing it for the first time.

Just one note. You definitely MUST have the track bar connected when you cycle the suspension. The track bar changes the horizontal position of the axle as it cycles in various positions, and this makes a measurable difference in where the shocks reach full compression or where the tires might contact the fenders.

Edit: Just looked at Mike's page for the UHMW-PE bump stop extensions. Those look nicely made, and that's a great price for custom sizing!
 
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could use some input. Put 2.5” rancho shocks on the rear of my LJ and reattached everything. Jacked it up and the first component to bottom out first was the track bar mount, it hit the bottom of the tub. I measured the distance between the metal “cups” on the upper and lower coil mounts and got about 4” between the two. This did not include the height of the Jaunce cup.

If you subtract that height of it, it should be around 2.5”-3”of extension needed, which I’ll need to double check.

To be safe I’d add on 1/4”. Does my reasoning sound correct?