JK Lift Install & Suspension Lessons Learned
I am doing this write up to help inform JK owners what to look out for and how to set start the process of setting up thier JK's during and after a lift. This write up is not intended to be a "How to" as lifting a JK is the same as lifting a TJ in most regards other than steering, and I have not upgraded any steering components as of yet. I will also begin a build thread of my jeep and update it with more info specific to my Jeep.
The victim: 2010 JK Rubicon Unlimited with 54,000 miles.
The first thing we decided to do was take some before measurements.
Front Uptravel = 3.5 (bumpstop pad to bumpstop cup)
Rear Uptravel =5 (bumpstop pad to bumpstop cup)
Clearance to frame = 13.625
Clearance to gas tank skid = 10.5
Front hub center to fender flare lip = 20.5
Rear hub center to fender flare lip = 21.25
To get an idea just how good Jeep engineers are, we wanted to cycle the axles and get a baseline for a completely stock setup.
We positioned two floor jacks (with wood cribbing on top) under the axle in order to push the axle to full bump. We checked these with a totally stock suspension setup; stock tires and 35s (315/70/17).
The first thing that we noticed was the stock front track bar flag caused interference at the frame. This flag must be positioned horizontally inside the bracket. If yours is sticking out of the top of the bracket like this, then you need to change it so it clears.
You can see the track bar has a severe bend to clear the stock diff cover. You can also see the drag-link, tie-rod, track bar and control arms tuck nicely. The upper control arms actually tuck into the engine compartment in front of the engine. Notice the frame side front track bar mount will tuck well below the tie-rod, and even below the axle tube. Notice the track bar also has a bend to clear the pitman arm.
In the rear, you can see the axle tucks nicely as well, and the track bar has a bend to clear the diff. Notice the frame side rear track bar bracket will pass by the bumpstop pad - beware of this for bolt clearance. Notice the exhaust has a specifically placed dent to clear the track bar on the driver's side.
FULL FLEX & TIRE CLEARANCE:
We installed a tire on each axle, and used the floor jacks to push the axle to full flex on the side where the track bar mounts to the frame, in order to check fender clearances. As expected, no clearance issues are observed with stock tires.
Looking good up front.
As would be expected everything clears nicely with the stock setup.
However, upon installing the new 35 (315/70 R 17) tires, we find major clearance issues do arise.
We find the front needs 2.5 bumpstop extension to prevent major tire vs fender flare damage. Also note the tire rubs the front bumper extension, therefore we did not check lock-to-lock tire clearances in order to check/adjust steering stops.
After taking the Jeep for a shakedown run the rubbing on the front bumper extensions was the largest problem with this lift. For this reason I am recommending anyone with 35's and 2.5-3 inch lift to get a mid width or stubby bumper. Personally I am going to go with the endcaps that go over the stock bumper. Below is a picture of the rubbing that occurred on the trail.
We find the rear needs 3 bumpstop extension to prevent major tire vs fender flare damage.
Bottom line: the stock flares & bumper ends need to go, so bumpstop extension can be reduced to regain uptravel.
BRAKE LINE LENGTH
At full droop the track bar pulls the axle to the driver's side, extending the driver's side brake line tight. We find the front brake lines to be too short, and used a length of string to measure for new lines. We find the new lines need to be about 27.5 from end to end (approx 3 longer than stock).
During full droop check, we find the front brake lines to be too short to allow the axle to rear full droop with the new shock length. It was necessary to loosen the brake lines from the frame, and allow them to hang loosely so we could complete all the necessary testing. Using a length of string to measure for new lines, we find the new lines need to be about 25 from end to end (approx 3 longer than stock).
We also find breather hoses, locker wiring, and e-brake line length will could be adjusted slightly to accommodate the increased travel.
AFTERMARKET TRACK BARS
Before reaching full bump, we find the front track bar has major clearance issues with stock length control arms. We measure 2.5 bumpstop extension requirement to prevent the track bar from hitting the diff. This is a disappointment since this is not mentioned on their website, and this track bar is advertised to fit 1+ of lift. Clearly this is not the case, and you would need 2.5 of lift just to maintain stock uptravel with this track bar. Due to these issues, the stock track bar was reused after the lift install. We may sleeve the track bar to extend its length, but the axle was only off center about ½ after completion.
Front track bar vs diff cover issues are well known in the TJ series, with a multi-year, 100+ page thread still active today.
We find the rear track bar clears nicely from stock height full bump to full droop with the lift. This was a pleasant surprise based on the issues seen in front, and the issues previously seen in the TJ series. The rear track bar was not a limiting factor of uptravel or downtravel, when using the stock mounting points. A raised bracket has high likelyhood of pushing the bar into the exhaust or other components, and would require adding bumpstop extension. Also, if you using adjustable control arm arms, lengthening the arms to push the axle back in the wheelwell may also lead to issues with the bumpstop pad, exhaust clearance, track bar clearances, etc.
We measured the stock shock length to be:
Front = 14 compressed, 22.75 extended (8.75 travel)
Rear = 14.75 compressed, 23 extended (8.25 travel)
At full bump, we measured the distance between the front shock mounts to be 15
The new Bilstein shock lengths are:
Front (PN:24-146708) = 15 compressed, 24.65 extended (9.65 travel)
Rear (PN:24-146715) = 15.4 compressed, 26.4 extended (11 travel)
This indicates the new front shocks could potentially fit with no bumpstop extension and the rear shocks need 0.75 bumpstop extension.
Upon installing stock Rubicon rock rails, we notice clearance issues. The rock rails were cut using an angle grinder + sawzall, and endcaps were reinstalled.
Final Product. You can see the pinch seam is also trimmed. We ended cutting off about 2" from the end of the rock rail.
SWAY BAR LINKS:
Attempted to use JKS links, found them to be too long, even if cut, so we used rear sway bar links and found them to be the perfect length to keep the swaybar nice and level.
Attempted to use JKS links, found major tire clearance issues. Even if axle was centered perfectly, there was very little space between the tire and the sway bar link to allow for flex. We left the rear sway bar disconnected, and zip tied out of the way, until lower profile heim ends can be found to make custom links.
To ensure that the rear links would not be near the tire heim joints were purchased from McMaster Carr. I used 1.5" 14-20 grade 8 bolts as well to finish the simple mod to increase the clearance.
CONTROL ARMS & AXLE POSITION
Eventually all arms will be replaced as funds allow. Due to long wheelbase and long driveshaft length, the rear control arms were left stock, as no immediate pinion angle changes should be necessary. Front uppers remain stock, and Clayton Off-Road front lowers were installed to correct caster.
Eye to Eye measurements were as follows:
Stock front uppers =18-3/4
Stock front lowers =22-5/8
Stock rear uppers = 17-1/2
Stock rear lowers = 19-5/8
Clayton Off-Road front lowers = 22.75
We took a guess on front lower control arm length and ended up being spot on for the caster.
As shown above, we also verified axle position at full bump to ensure proper control arm lengths & bumpstop alignment. As lift height goes up, control arm lengths need to be adjusted to ensure the bumpstops are centered at full bump, proper caster is maintained, and pinion alignment is appropriate while at ride height. This can lead to clearance issues, so make sure you check full bump/full droop/full flex when installing a lift or changing lift components.
This section is more for suspension characteristics and is nothing that can be changed unless you start moving the mounting points of the control arms. The spreadsheet that was used here was created by Dan Barcroft of Pirate4x4. New Version of my 4-link Analyzer & Request for Help - Pirate4x4.Com : 4x4 and Off-Road Forum
This stock 4-door JKU had about 96% anti-squat.
Notice the lift changes control arm angles and yields an increase of the anti-squat to 140% . This is because the mounting points have not changed, and this is expected with any lift using stock mounting points.
FINISHING THE LIFT INSTALL
After all the components were checked and installed, we set the Jeep down on its new feet. We grabbed the Jeep by the roll bar and bounced it violently in order to reset the factory rubber bushings (remember we loosened all the control arm bolts before starting).
During the bounce exercise, we also disconnected the adjustable rear track bar from the frame side, allowing the axle to center itself. We then adjusted the rear track bar to line up to the holes, and replaced the bolts. This works on the front as well, if using an adjustable front track bar.
All bolts were torqued to spec.
Front: LCA = 125 ft-lbs; UCA = 75 ft-lbs
Rear: LCA = 125 ft-lbs; UCA = 125 ft-lbs
Front track bar = 125 ft-lbs, frame and axle ends.
Rear track bar = 125 ft-lbs, frame and axle ends.
After the completed install:
Caster (factory spec = 3.2-5.2°):
After lift install = Left: 3.9°, Right: 4.6°
The steering wheel was off center slightly, and corrected. In trying to correct the slight change in toe, the tie-rod adjusting sleeve was found to be seized. The tie-rod needed to be replaced. If your Jeep is still under the warranty for steering go and check to see if the sleeve is seized. If it is take it in to the dealership to get it replaced. From the dealer the whole assembly runs just under $300 dollars. After speaking with my local dealership they informed us that this is a common problem on even the 12 and 13s. The design of the sleeve allows water to get deep inside the sleeve and rusts. If the sleeve is not seized take the tie rod off and apply anti seize to all the threaded surfaces.
Below is what the sleeve of the trackbar looks like, you can see how the sleeve has "mushroomed" out. only way to fix this that I know of is to replace the tierod.
LIFT HEIGHT GAIN:
The lift is still settling, but post-install measurements are....
Front uptravel = 7.5"
Rear uptravel = 8.625"
Clearance to frame = 18.625
Clearance to gas tank skid = 15.5
Front hub center to fender flare lip = 24
Rear hub center to fender flare lip = 24.5"
The after uptravel numbers do not include the bumbstops that will be required. These will be added at a later date as we needed to set the system up to find out what bumpstop lengths were needed. Overall I am very happy with the amount of clearance that was gained and how the lift and tires look in general.
I also want to thank Unlimited 04 for his help in creating this writeup and his help with the lift itself. Zetto was also a valuable resource during the lifting process and I thank you as well.
I think I missed it somewhere, what lift mfr. and height did you do?
Outstanding write-up! WF is not worthy :whistling:
Springs: 2" OME HD (Netted almost 3.5" right after the lift, has settle a little to 3.25" now)
Shocks: Bilstein 5100s
Rear Trackbar: JKS Adjustable. (Working with JKS on the front to see if I can solve the clearance issues)
Tires: 315/70R17 Goodyear Duratracs
Wheels: 17" Rugged Ridge
as well as the modified rear swaybar links from JKS
Excellent write up! Thanks.
One of the best write ups I've seen here. Great job!
Cool thanks for the info. Now I'm trying to remember why I wanted it lol. I know I was trying to compare something in relation to lift height gained/etc to mine and I had 17/59 springs stock.
Great Write-up! Thanks for your attention to details.
I didn't see it mentioned, but was curious if you did a rear end gear change with the 315's?
fooking nice write up!
Great information, thanks.
bumping this, becuase it rocks
i'm trying to figure out if I can run 315s on my current setup.
i'm settled but still light
i figure I'll go from 25 (center to fender) in front to 24.75 or 24.5 if I do a full width aftermarket bumper and winch
i'm not too worried about the back except for hating how my hardline is routed/bracketed (otherwise the lift height I settled at should be ok out back even with more weight)
it's the flexing I don't want to lose down the line, so I'll probably trim and go with metal fenders at some point (probably have to save up fun-money for a year to do that, lol)
Have not revisited this thread in awhile. I will answer some questions and will soon update the post with some bumpstop install pics and knowledge.
Alright here is an update to setting up a suspension to any Jeep JK. I want to say that what I post here can be done with any setup whatsoever. This stuff here is what I have done to help everyone out there when they ask "will this work"
I have discovered through this that a high majority of offroad parts out there are trusting/assuming that you have atleast 2.5" of bumpstop. We saw that in how the JKS adjustable front trackbar hit the diff without the 2.5" being added. I also encountered problems with a component that I will talk about more below.
First I will start with a few comments about my particular setup and how it has treated me through the summer.
This setup has been great so far. I have taken it on 12+ hour wheeling trips and never been uncomfortable or ready to get out of the driver seat.
Tires: The Duratracs keep surprising me even after owning them for the last 4 years. They take abuse like any mud tire out there and never slip up. The most damage that they got was getting the outer treads chewed up a bit when trying to rescue a hydro locked JK out of the bottom of a canyon by spinning all my wheels up a gravel inline of about 30 degrees.
Bilstein 5100s: During the first 500 miles or so I thought that the Bilsteins were really stiff, that changed however after they broke in and now these puppies absorb everything. Taking them on forests roads is a breeze and they make the ride seem like your cruising down the street in front of your house. Can't say enough about these. One drawback that I do have for them though is the amount of down travel that they have. I know this is not anything that they can help but if I had to be picky thats what I would say. I am looking at either shock extension now, or maybe even swapping the shocks out for a p/n 2" longer if it exists.
OME HD 2" lift springs: These things are great. Even after about 7k miles on the Jeep they have only settled about 1/4".
Clayton control arms: I love these control arms. There is nothing that is going to bend them. They are massive. I highly recommend them. I was concerned that they only had one JJ at the axle end, but these things flex like no other. I can only say good things about these arms.
Now, let's get to the informative stuff. While doing the lift the bumpstop measurements were taken, you can read about that in the first couple posts.
The front bumpstops were the most involved. The install started with tearing down the front end again. The shocks where removed the trackbar disconnected from the axle end, and for good measure the front lower control arms were disconnected from the axle end as well. Finally, with all this disconnected I was able to just pull the springs out, no need for spring compressors!
First step was to prepare the bumpstops themselves. For the front Zone Offroad body lift pucks 3" tall by 3" in diameter were purchased. The spring perches on the JK axle are 3.5" wide so a 3" diameter puck works perfectly.
Since only 2.5" of bumpstop were needed the pucks were trimmed down by 1/2".
To attach the pucks to the perches grade 8 1/2-13 bolts 3" long were used.
The spring perches were then drilled and tapped.
And lastly the pucks were installed.
We did not end up cycling the suspension in the rear, thus we did not remove the springs, shocks, trackbar, or control arms. The setup in the rear actually allows for bumpstops to be installed with the Jeep sitting on the ground at ride height.
The rear were far easier than the fronts. On the rear axle of JK's there is a spot that is flat with two holes already on the flat. Perfect for bumpstop extensions (maybe Jeep knew people were going to install aftermarket parts on their product?)
For the actually bumpstop 3" tall x 4" wide x 1/4" wall sqaure tubing was used. the two holes were traced onto the tubing and then holes were drilled on the tubing and the bumpstops were installed.
While crawling around the front of the Jeep it was discovered that the lower control arms were rubbing on the top of the control arm brackets. Time to bring out the angle grinder to fix this problem.
So after reinstalling the control arms and reattaching the trackbar the front suspension was cycled to check to make sure everything was clearing. TIme for lots of pictures.
On the last picture you can see how close the tire gets to the tub mounts and the front swaybar. Because of this I recommend anyone with 35's to atleast run 2.5" of bumpstops to avoid hitting anything under the front end under full flex.
Now, in the first post I showed the interference between the front tires and the stock bumper. To fix this I ordered the VDP stubby endcaps. Eventually I want to upgrade to an aftermarket bumper, but as I want to get the suspension and drivability of the Jeep up to where I want it, a bumper is just not in the budget quite yet so these will work for now. The install on this was very easy. More pictures to show the process.
The color on the endcaps is different when you install them, but it get a lot less noticeable after you get them a little dirty.
Finally I have some flexing pictures while out on the trail.
As you can see these pictures were at almost full bump, still had maybe 1/2" of uptravel but did not feel safe getting out of the jeep when I had the back tire off the ground.
Everything works well and I get no rubbing, except for one little spot that was not tested.
Looks like it will be a stubby bumper that I upgrade to when the time comes.
Finally a fun wheeling shot at a trail in the area that I did this weekend.
So, that is all for now. I hope this write up helps someone out there when they are researching their lifts. There will be more to come, but I might move that stuff over to a build thread since most of it will not be relevant to a proper suspension setup.
Reviving this awesome thread!
When I put my OME 2 inch lift on my JKUR I didn't record all my baseline measurements.
I am trying to verify ideal bumpstop and shock lengths to unleash my flex potential. After off-roading mine post lift, it really feels like I have too much bumpstop and not enough shock length. This thread gives me a lot to work with in figuring out my ideal lengths. Thanks.
After measuring everything on my jeep and comparing to the measurements here, I see the results are almost identical.
The only differences are I used the Teraflex track bar bracket in the rear, and have 33s for now.
I was considering the Bilstein 5100s before I saw this thread. Now my mind is made up.
|All times are GMT -5. The time now is 11:57 AM.|
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.