I just picked up a 2015 JKU Sport from my local dealer (traded my 2016 Cherokee Trailhawk) and I'm hoping someone can answer some questions for me. The dealer took it in from another local dealer, with the previous owner having done all the mods. I'm trying to figure them out.

It looks like a Smittybilt XRC front and rear bumper, with a Superwinch 9500TS. All lights are LED, with Rugged Ridge LED bar and spots on the bumper. It's running on 33x12.50x18 Sahara rims, with a Teraflex lift (I think). I can see Teraflex 9550vss(?) shocks on the rear, but most everything front and rear has been painted, in an attempt to blackout everything. Are there measurements I can take to see what size lift was installed, and if any other lift components are installed (or need to be)? I was thinking ground to fender or door jam would be consistent, but I don't know what that height would be.



The other thing I'm trying to figure out is a pull to the right and a shimmy/shutter that comes and goes above 65mph. I had the dealer do an alignment as part of the deal, and several things were out of spec, and now green (don't have the printout handy right now). I picked it up on Thursday and left Friday for a work trip (5 hours - all interstate) and it's still pulling right. Also, above 65mph it picks up a pretty bad shutter, but it comes and goes. It doesn's seem like the "death wobble" based on what I read on this site, but I would think that an out of balance wheel would keep a constant shutter, not one that goes away for a few minutes and comes back. The hood latches were replaced with Drake Offroad lockable latches, and the corners of the hood were moving up and down pretty good. I don't know if that was because of the shutter, or if maybe air was getting under the hood and causing the shutter. That seems unlikely to me, and the shutter happened in clean air and in dirty air, in traffic. Thoughts on this? I'm taking it back to the dealer when I get back in town next week and need to give them a starting point. Maybe loose components?

Lastly, tire pressure. The dealer aired the tires to 45 psi, and it drove like an ice skate. I dropped them to 30, and they aired them back up to 40 for the alignment. I dropped them down to 30 again before my trip. Can air pressure cause the shutter? The tires are relatively new. The previous owner had the Jeep for just over a year and he put them on, but they look to have even wear so far.

Thanks in advance!

Jim

 

Start with this pic to measure lift height up front –



Keep in mind that actual lift height is going to vary a bit from what the springs might be. Depending on brand, some springs will net more actual lift, so a 2.5” spring might net 3” of lift. Anyhow, measuring actual lift is a starting point for you. Hard to identify springs. If they have Teraflex shocks on there likely that they are TF springs as well. Pictures are sideways so hard to tell, but looks like you have no front or rear bumpstops. I assume you do not have adjustable control arms on it. The factory arms should be easily identifiable. If they are factory control arms, and you see no cam bolts installed in the axle’s lower CA brackets, and you see no frame-side control arm geo brackets, you are running too low of caster which is not helping your driving situation. Factory caster is 4.2*, and if not corrected, most lifts will drop that down around 3* or lower, depending on height.

There is a chance you could possibly have a bad joint in a steering component, but your starting point is to get your caster set correctly and go from there.

Tire pressure can influence things......but 40-45psi is way too high IMO. For a 33, would think 30-34 would be more appropriate. You'll see many point to doing the chalk test on the drive to check for tread contact. There is no perfect hard and fast XXX psi as every jeep's weight is different due to mods.

 

Oh, I also noticed you have no raised track bar bracket in the rear. You should have one with a lift. The flatter the rear TB angle is, the better the jeep's roll center is gonna be.

If you snap a pic of the front end components, we can easily identify if they are stock or not. BJ's, DL and TR are likely stock still.

 

Post the alignment numbers when you get back to town. A balance and rotate certainly wouldn't hurt. And what tires are they? A few have been reported to cause pulls to the right.

Another thought for the shimmy is that I sometimes get a little with crosswinds while at freeway speeds. Not sure what actually causes it, but feels like lightly out of balance tires, and comes and goes with the strength of the wind.

 

Thanks for the info. I'm out of town in a class and won't be able to check these things out, or post the alignment pic, until probably this weekend. I was planning on doing the chalk test this weekend too. I literally picked it up and left the next day.

Tires are Toyo Open Country M/T 33x12.50x18.

Jim

 

You have a very nice Jeep there.

 

Thanks! It's nice to have one again!

 

I was able to get into the shop yesterday to check the tires and they were all out of balance. They re-balanced and checked all the bushings for wear on the suspension (just to make sure it wasn't something else) and said I was good to go. On my way into work today I got onto the highway/Intestate and up to 75mph with no shutter, but still pulling to the right a little. Kinda disappointed that this was even an issue, as it was Certified Pre-Owned.

I've got some additional photos, but I still haven't been home with enough daylight and time to take measurements. I also snapped a pic of the alignment results. Any comments would be welcome. I think I see bump stops (located at the top of the springs?) but the previous owner tried to blackout everything, so he spray painted most everything in the wheel wells.

resharp001 - You mentioned a raised track bar bracket. I've found them from $50 up to over $150 with a quick search. Some note needing bump stop extensions, and other things that I don't understand. Installation seems pretty straight forward. Is this a front and rear thing, or just rear? Any suggestions on deciding which one? The Jeep won't see hard offroad use. I'm an ag appraiser and mainly use it for looking at groves, pasture, etc. where 4wd and ground clearance is needed. No rocks, etc. Lots of highway use.

Thanks again. Pics below.

 

Positioned above the coils? Those are spacers for a lift kit (thick pucks, used instead of taller coils).
Bumpstops are a bit different. Front, the upper stops will be hanging down 'inside the coils', and the lower stop will be just a metal contact plate above the axle, again inside the coil. Rear, the stops will be outside the coils. Uppers hanging down, lowers just contact plates on the axle

Noticed the front upper bumpstop in one of your pics, it's the white rubber thing.


And in this one you can see the rear coil spacer, it has a long coil guide hanging down.



Just the rear. Find a weld-on, or one with a big ubolt that goes around the axle tube. Synergy and Teraflex are popular options, but as you found there are many to choose from.

When the front trackbar is raised, it is part of a high steer/draglink flip, where the drag link is moved to the top of the steering knuckle. Since the draglink is moved up, more bumpstop is usually required to keep it from contacting the frame. (I assume this is what you were reading about? Bumpstops keep the axle from moving upward to far.) Generally people start wanting to flip the draglink at 3.5 or 4" and higher.

The Caster is a bit low. Low caster causes flighty/wandering steering. Gets worse as you lift higher. Stock caster is around 4.2 degrees. After a lift, most people like to raise it up to 4.5-5* or so. Lots of personal opinion here. If you think the steering is ok, leave it alone. If you want to raise it, snap a few more pics of both ends of the front control arms. (guessing they are still stock, and no cams, but we'll need to know to make suggestions.)

 

Thanks again. I've got a few things to do with it this weekend. The previous owner tinted the windows and front windshield, smoked LED taillights, and moved the license plate to where the spare was. I had the tint redone before I went out of town but I still got a warning from a Georgia sheriff about the smoked taillights, and for not having a light on my license plate. I'm going to replace both of those on Saturday, so I'll take some more pics then.