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LJ Rear springs solution

glockman

I hate Jeeps
Location
Pleasant Grove
I'm using a JKS adjustable rear track bar, the non CV one. It clears everything. But just barely. Speed bumps would be way cool but I'm petty sure they are too long for my 3 inch lift. I think I'd have to give up some uptravel to use them and I don't want to do that.
- DAA
Oddly enough, I picked up a Teraflex dual rate sway bar off KSL today. The guy I bought it from was outboarding rear struts on his TJ with a friend. Turns out the friend works at Teraflex. We got talking and I told him I just bought speed bumps. He said you can use the bracket for the front speed bumps and a hole saw to recess the bump into the frame rail and custom tune the height of the speed bump for lower lifts.

Spent a couple more minutes mentally planning on the jeep today.

I couldn't figure out why my Falcon's were so close to bottoming on compression. I have TF lower shock mount relocators that allowed the 9550s to clear the lower spring perch. Like these
1546742683629.png

This places the shock farther back away from the axle and up higher. The Falcons lower bolt hole mount is off centered so even though the shock body is larger they clear the perch in the stock location.

Damn the engineering in these things is sweet. Now I have about an inch of exposed rod. I am not only clearing the lower spring perch but also the exhaust that was contacting the shock body before.

Full droop without the re-locating bracket.
20190105_143250 (480x640).jpg

Fully compressed at current bump height.
20190105_143119 (480x640).jpg

The dark spot is where the 9550s were contacting the exhaust.
20190105_143024 (480x640).jpg

I'm leaning towards this Metal Cloak rear sway bar to resolve the contact with the cross member. I'm curious if anyone is running that setup and how they like it. I have a CV driveshaft and the bracket on the CV shaft version is tilted forward to move the track bar away from the crossmember.

https://metalcloak.com/tj-lj-wrangler/tj-lj-rear-durotrak-track-bar.html
 

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glockman

I hate Jeeps
Location
Pleasant Grove
I picked up my speed bumps on Tuesday and commenced to install them. The kit is really easy to install and it was mocked up and installed in a couple of hours including removing the stock spring perches.
Here is what you get for the rear of a TJ.
20190108_123045 (640x480).jpg

Here is my setup mocked up and centered over the axle. I used the washer from the original lift bumps as a landing pad/spring retainer for the speed bumps since they don't include one for the TJ kit. The JK kit has a rubber bumper for the axle side. More on that later.
20190108_135734 (640x480).jpg

Her is the kit installed. Looks pretty sweet right?
20190108_175050 (640x480).jpg


Here is the rub. Teraflex claims this kit works with a 4"-6" lift. With no one in the jeep and a 1/2 tank of fuel I have less than 1" of free travel before the bump hits.


Put two adults in the jeep and it is sitting on the speed bumps. Teraflex claims it takes 4200lbs to bottom each speed bump. Put two of those together and remove all free travel and I have resolved my bottoming issue. I think I could get 10' of air and not bottom. However, it rides like a 1 ton truck from the 70's now. Also since there is no rubber landing pad, it sounds like there is an ADHD 8 year old with a ball peen hammer and a piece of 1/4" plate in the back seat. Needless to say, I'm not thrilled with the design on these for a TJ. It looks like Teraflex designed these for a JK and then threw together a bracket to make them fit, not work, on a TJ.

My options now are-

1. Find a way to use a hole saw to cut a hole in the bottom of the frame so the speed bump can be recessed into the frame rail and get me 4" of free uptravel before the bump contacts and starts to do what it was intended. This will be difficult with the bracket in place but may be possible with an extension and a hole saw. I will still have to find some way to get a rubber landing pad to eliminate the noise. It is loud when these things smack bare steel.

2. Cut them off, order some new upper perches and get different springs and the metal cloak track bar and mount.

3. Cut them off, weld on new upper perches and MC track bar and mount. Then see where I am with correctly set bump stops and a track bar that clears. I am leaning this way. Should have gone this way to begin with but I thought I had a perfect excuse for the cool speed bumps.

I contacted Teraflex by phone. They wanted me to send them some pictures and they were going to send them to their "TJ Guy" and see if he had any suggestions. Having already spoke to the Teraflex guy last week who told me you can recess them with said hole saw method, I don't have much hope for an alternate solution.
 

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Hickey

Rusty Girdle
Supporting Member
I definitely think you want some sort of rubber bump pad, no matter what you choose. My fronts are nearly silent on my JK. I really have to pay attention to hear them touch. My rears are very close to touching all of the time though. It doesn't sag and touch unless I put significant weight on the hitch.
 

Gravy

Edd China of Dirtbikes
Supporting Member
Honestly I think you need to raise the speed bump mounts so they only contact the last 4" of travel.

AND you need a higher rate rear spring.

I've had a half dozen or so different brands and different spring rate coils in my shop at one time or another and tried them all. The right way to do it would be to get corner weights and match the spring rate to that.
 

RockChucker

English is important. Engineering is importanter.
Location
Highland
I've installed speed bumps in the rear of a few different TJs. The last one I did was an LJ where I stretched the rear roughly 7" if I remember correctly. I hate those toilet seat mounts (they look like a toilet alright?) that they come with. The mount the bump so low that you lose all your uptravel. And like Stratton said, you don't want to contact until the end. You have fancy shocks. Let them do the work. Also, in my experience, they bottom out at much less than 4000 lbs of force....but that is a totally different conversation.

Exhibit 1. Cut a hole in your frame.


Exhibit 2. Cut the frame mount apart and reconfigure.


Exhibit 3. Another view.


Exhibit 4. Insert in frame.


Exhibit 5. Another view.


Exhibit 6. Fish plate.


Obviously this eliminates the collar that holds the speed bump in. I drilled a hole and tapped it and used a grub screw (set screw?) to hold it in place. I also used a judicious amount of silicone when I installed them. This setup worked quite well, and when it had 5" springs, it had something like 5" of up travel before it hit the bump. 8ish to bottom out. The owner of the Jeep ended up with a 2" spring I think to make the Jeep sit level with 5" front springs. The springs were obviously mounted about 1" lower on the frame, giving some lift, but the majority was because it was moved backward. Ask @Greg about that. He had super small springs that actually came of my Jeep to make his TJ level back in the day....

I've used the front mount kit to mount the bumps and frenched them in the frame. it works ok, but I think this setup worked much better and was much less cutting in the frame.

Food for thought.
 

Hickey

Rusty Girdle
Supporting Member
I have a JK, but I would also do something different for my rear Speedbumps rather than the JK spec rears. I would buy the front bumps with the mounting cans and sink them in the frame.
 

glockman

I hate Jeeps
Location
Pleasant Grove
I've used the front mount kit to mount the bumps and frenched them in the frame. it works ok, but I think this setup worked much better and was much less cutting in the frame.

Food for thought.
Thanks for the great pics Dave. I actually looked at sinking them into the frame. Did they line up with factory axle spring perches in this configuration? I swear mine would have protruded out the inside of the frame rail in order to be lined up with the lower perch. I'll have to take a look at it again.
 

RockChucker

English is important. Engineering is importanter.
Location
Highland
Thanks for the great pics Dave. I actually looked at sinking them into the frame. Did they line up with factory axle spring perches in this configuration? I swear mine would have protruded out the inside of the frame rail in order to be lined up with the lower perch. I'll have to take a look at it again.
Yep, they end up protruding slightly to the outside of the frame. The fish plate was bowed to go around the mount. I was putting a 14 bolt in the rear of this jeep at the same time, so I was able to make it line up, but I don't think it was so far off that you wouldn't be able to just leave your factory perches in place.
 

astjp2

Active Member
Location
Riverdale/Alaska
You should also look at putting on a set of Fox's and get them outboarded, that way you can get good up and down travel with the proper clearances...I just bought an LJ and I thought about the LCG but then with all of the interference you encounter on up travel, I am going with a 1.125 body lift, and 4 inch springs.
 

glockman

I hate Jeeps
Location
Pleasant Grove
Well today I decided to go ahead and copy rockchucker and sink the bumps into the frame. Driver side is done, started the passenger but ran out of time. I raised the bumps approx 5" so I should have that much free up travel with the hard stop at 8".
I also installed a metal cloak track bar and relocation bracket. It clears the upper cross member perfectly. Hope to get everything buttoned up next week and test it out.
118583
 

glockman

I hate Jeeps
Location
Pleasant Grove
Finally got the other side done. I have just over 3" of up travel before contacting the bumps. I can hit the drainage gutter on my street at 25 and just barely touch them, which is perfect. Now I need to source some rubber coated lower bump pads.

These might work.
 
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LJTim

Active Member
Location
Herriman, UT
I'm digging this project. Wishing I did something similar instead of my artec coil re-locators. Check out what a friend did.... uploading, hold on.
 

glockman

I hate Jeeps
Location
Pleasant Grove
Like everything I do, I am already thinking about ways I could have improved this install. Then I see things like that setup Tim and I am just happy I didn't burn the jeep down with how unskilled I am. :D
 

LJTim

Active Member
Location
Herriman, UT
I think you did great stuff. I think I may give that a shot at some point. Like I said, I'm wishing I would have spent the effort of that Artec kit, and spent it on speedbumps. I was intimidated to chop my frame at the time. I have since outboarded, and literally cut my frame to stretch it sense then, so...118766
 

astjp2

Active Member
Location
Riverdale/Alaska
Nice welding, but what is your true up travel? I am ordering a set of fox 2.0 reservoir's and I hope to get 6-6.5" of up travel before I contact the bump stops.
 
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