Front Suspension Basics 101
 

First, I want to identify the major parts.
Then, I want to understand what they do, and how they fail.
My 1998 XJ is not quite the same as the photo, so I will post a few.

https://www.cherokeeforum.com/attach...suspension.jpg


Can you verify I have the names correct?
Yellow = Sway Bar (Most forward bar)
Red = Drag Link
Purple = Tie Rod
Green = Track Bar (Has a big bend in it)
http://i45.tinypic.com/30ucscw.jpg



Below is my driver's front wheel.
1) End of Drag Link (ball joint)
2) Sway Bar Link? (Isn't the sway bar at the very front, under the grille??)
3) End of Track Bar (ball joint)
4) Tie Rod
http://i49.tinypic.com/mb06ds.jpg



Red = Drag Link
Green = Tie Rod
Yellow = Track Bar
http://i48.tinypic.com/359l3de.jpg


Sway bar? At the very front, under the grille...
http://i48.tinypic.com/2jebjt1.jpg



There is a 4th bar that has a "strut".
What is this called? Does the bolt ever get loose? (Like the trackbar?)
http://i48.tinypic.com/2w1t9au.jpg http://i48.tinypic.com/2qbdpps.jpg



The dealer told me that I needed a new track bar.
I grabbed this "crooked" bar and it did not move, for what it's worth.
Is this why he said it was bad? Ball joint seal is shot?
Or, is it because the bolt on the other side might be loose?
http://i45.tinypic.com/k3pr5.jpg http://i49.tinypic.com/2w7lkbr.jpg

1. Sway Bar
2. Track Bar
3. Tie Rod
4. Drag Link
5. Sway Bar Link

For each of these, is anyone here able to explain
a) What is does. What is it for?
b) Does it ever wear out? When does it need replacing? How do you know?

Thanks.

Alright man, i just recently went through the same experience man. Ok basically what ya gotta do is get a friend to turn your steering wheel back and forth while you look under the truck and check to see what components look to have slop or play. On my jeep i just replaced the following in order to eliminate death wobble:
new track bar
Drag link
Tie rod and ends
Steering stabilizer
Sway bar end links
Steering box itself.
Over time man those parts all get old, the rubbers in em dry out and crack. Do a check then take necessary action. Based on your pics, looks like you could use some work man. Hope that helps yo

Thanks, but I'm not looking to diagnose a problem, I am just trying to learn what the front suspension even is in the first place.

The pitman arm turns when you turn your steering wheel. It then pushes or pulls the drag link which connects down to the passenger side wheel, turning that wheel. That is connected to the driver's side wheel by the tie rod, this way they turn the same direction and the same amount. The track bar is to help keep the axle centered under the vehicle (AFAIK). The anti-sway bar, or "sway bar" for short is kind of a stabilizer that assists your suspension in reducing body roll. It keeps your axle from moving up or down too much witout the body to keep it in check. The reason the links are back by the coil is that is where the bar connects down to the axle. If you follow the top of the links, it will lead back to that bar in the front where it mounts to the unibody.

As far as your question about wearing out and replacing the parts, yes and no.

The bushings are what will wear out. The parts you circled and called ball joints are tie rod ends or TREs and bushings. The rubber or polyurethane can dry rot and either crumble and allow too much play or seize up and not allow enough.

If it looks old and rotted or is behaving in the aforementioned ways, replace those parts. The metal parts themselves, unless rusting through or bent, typically will not need replaced but of course can always be upgraded.

Yes, all correct. The anti-sway bar is bent backwards and connects to the links. The bar itself needs these 'arms' so that the bar twists properly. Yes the metal is deliberately under torsion.

Here's a diagram to help:

http://www.jeepey.com/media/workspac...spension_1.png

1. The sway bar twists to limit body roll. When cornering one link pushes UP on the respective sway bar link and the other one pulls down. Without it the body will roll pretty freely as coil springs are relatively soft. I've never heard of them every being replaced.

2. The track bar is to keep the axle centered under the vehicle. Some people replace them but I'm not entirely sure why, I was under the impression the Tie Rod End/Ball Joint at the track bar mount was replaceable, the axle-end too. However I might be wrong. Any movement in either one after being greased means they're worn out.

3. The tie rod is responsible for turning the driver's side wheel. In other vehicles (and aftermarket steering kits for the XJ) it is run directly to the passenger's side steering knuckle instead of the drag link. The tie rod on the XJs is sheet metal and bends easily. Lots of people upgrade to one from a V8 ZJ, which is solid. The tie rod ends and adjusting sleeves are a regular wear item. Any movement at the joints or grease blow-out is cause for replacement.

4. The drag link is moved by the steering box via the pitman arm and turns the passenger-side wheel and in this case the tie rod. Same note about TREs here.

5. See #1

Thanks. Very informative. So, of these parts, which are the most common to wear out?

Not sure if that'd be the tie rod ends on the steering linkage or the sway bar bushings. They all see shock when hitting bumps

There are a lot of variables in determining which front end parts will wear out first, and no real sure-fire way to make a definitive call. However, there are some very loose general operating conditions that might cause certain parts to wear out before others. The following are only examples, and only might be indicative of what could fail next, not certain:

If this was mostly street driven on smooth roads, but with lots of curves, the tie rod ends will probably wear out faster than other parts.

If it's mostly smooth roads but it was driven hard around corners a lot (I'm guilty of this) your sway bar links can go. On my 2002 TJ I replaced three sway bar links before replacing any other components.

If it was used a lot off road with a lot of rock crawling or lots of frame twisting-type maneuvers, your control arm bushings and track bar bushings can wear faster, but that will also be dependent on things like heat, how dirty and what kind of dirt, whether they used lots of salt/chemicals on the roads where it was driven, etc.

If it was driven on roads with lots of pot holes, or used extensively off road in general, all bets are off, and anything could be the next thing to go.

In short, the best thing to do is regular visual inspections. Generally speaking, most of your bushings will be easily visible, and will be pretty obvious if they are wearing out. You'll see cracking, shrinkage, or chunks missing. For inspecting beyond just the visual, put the front up on jack stands and move things around checking for play. You want the key in the ignition and turned to allow the steering wheel to move freely.

X2

Any more questions?