rear suspension noise, 95 YJ

[djcrigh]

Hi:

I have a clunking sound coming from the hind quarters of my 1995 YJ when I go over an uneven bump. If I go over, say a speed bump, with both rear wheels hitting the bump at the same time, no clunking sound. I suspect the rear traction bar. I had to replace the bar recently because the bolts had seized inside the bar's bushings. This broke the mount on the left side of the rear axle housing. I re-welded this mount using heavier sections of flat bar on either side. I noticed that the holes in the old mount were elongated, so I dutifully filed out the new holes to match. I guess my questions are: did I elongate these holes enough, why are they elongated in the first place? Does anyone have any other clues as to where this clunking sound may be coming from? I have crawled around under the back end and looked for anything else amiss, but can find nothing. The car runs and sounds good in every other respect.

Thanks Don

 

[Bounty__Hunter]

Take the rear track bar off, it's not needed on a YJ. It helps an axle track straight, and the YJ's rear axle tracks behind the solid frame spring hangers just fine.

Second, look for worn shock bushings.

 

[Gregorypaul]

Yep, got rid of mine on my 93 long ago.

 

[superj]

The 93 yj I got my wife previously was our first wrangler. I was hesitant to toss the trac bar but I kept thinking about what it does, versus leaf springs. I pulled it off and went for a ride and ever since then, they have been off. Then the day I got my 87 yj home, I immediately pulled those off.

 

[jdmuncy]

So I understand takin off the rear track bar. What about the front track bar? I have heard some people take that one off too..... Pros and cons please.

 

[superj]

same deal, toss that sucker. don;t toss the sway bars though, you need those

 

[djcrigh]

Thanks for the advice. I will take it off first thing tomorrow. I tend to be a worrier though. What happens if take it off and the noise is still there. I guess I might not sleep tonight.

Cheers DON

 

[GaJeepy]

Do you really think that the Jeep engineers put the track bars in there for no good reason at all? The track bar is there for a reason, I would not remove it until I understood just what its function is.

 

[steady.foot]

They put them on there to try to turn a wrangler into a sports car. It didn't help. For those that want to drive a wrangler like a sports car and don't know the difference. They are needed.

 

[superj]

the trac bar is for a coil spring type of suspension and is used to keep the axle in place under the jeep, to keep it from moving side to side because coil springs don;t have the strength to hold the axle in place since they are so flexy. a leaf spring holds the axle in place by how they are bolted to the frame. they hold the axle from moving forward / aft/ side to side but they allow the axle to move up and down in its plane of movement. a trac bar moves a little bit sideways when its coil spring axle moves upwards, just because of its length versus the angle on it. if you put a trac bar on a leaf spring axle, he trac bar will be fighting the leaves to let the axle move upward in the leaf springs natural plane because the trac bars natural arc and this fighting is what gives yj wranglers such a horrible rough ride.

look under the back of cherokees, which use leaf springs also. no trac bar there but there is one in front to hold the axle from moving side to side and upper and lower control arms to keep it from moving back and forward while driving

 

[Gregorypaul]

Well put Steady.foot!

 

[superj]

They put them on there to try to turn a wrangler into a sports car. It didn't help. For those that want to drive a wrangler like a sports car and don't know the difference. They are needed.

they actually have nothing to do with whether you want to drive like a sports car because they don;t have anything to do with body roll or lift and diving from accelerating and stopping.

the sway bars (proper name: anti-sway bars) are what let you drive like a sports car as they are what keep your jeep from rocking and rolling like boat on the high seas. there are a number of different thickness sway bars that came on our jeeps too. mine have almost the thickest being almost an inch and a quarter thick so i have very very little roll through the turns, which is what i like. i like turning fast and not feeling like i have to put my hand out to keep the jeep from tipping over.

your shocks are what keep you from nose diving and lifting during hard stops and accelerations. if you are nosing down and lifting up, replace your shocks or upgrade to a heavier duty set

 

[steady.foot]

they don;t have anything to do with body roll or lift and diving from accelerating and stopping.

This is my point. It was jeeps attempt to keep people from sueing them because they were driveing CJs like a sports car and rolling them over. This and other sports car like changes. Lower center of gravity. Smaller tire hight. Wider track.

the sway bars (proper name: anti-sway bars) are what let you drive like a sports car as they are what keep your jeep from rocking and rolling like boat on the high seas. there are a number of different thickness sway bars that came on our jeeps too. mine have almost the thickest being almost an inch and a quarter thick so i have very very little roll through the turns, which is what i like. i like turning fast and not feeling like i have to put my hand out to keep the jeep from tipping over.

your shocks are what keep you from nose diving and lifting during hard stops and accelerations. if you are nosing down and lifting up, replace your shocks or upgrade to a heavier duty set

I'm not advocating taking the anti roll bar or the shocks off.

 

[GaJeepy]

They put them on there to try to turn a wrangler into a sports car. It didn't help. For those that want to drive a wrangler like a sports car and don't know the difference. They are needed.

Lets consider two scenarios
SCENARIO ONE
The Jeep engineers had a meeting one day and decided that the Jeep was really a sports car and figured the best and easiest way was to put a track bar on the axles. They forgot to tell the rest of the design and marketing teams of the change. Fortunately we have the internet now and can learn the truth of the track bar, it serves absolutely no function, Jeep added this component for no good reason, it only added to the cost and complexity of the vehicle but otherwise has no function and should therefore be discarded immediately.

SCENARIO 2
On the other hand you may want to consider that the engineers at Jeep actually did some real calculations and testing and found that, in fact, the track bar did have a function on this vehicle, (perhaps it helped locate the axle properly under the car even with leaf springs). That they took into consideration how the vehicle would be used and under what kind of conditions it will be subjected to and after considering other alternatives (including not having one) decided that a track bar and the front and rear axles was warranted.

I leave it to you to decide which scenario was most likely.

 

[superj]

even leaf spring vehicles newer then our wranglers don;t have trac bars.

the name trac bar comes from the what the bar does, keep the axles in line with each other (called tracking). ever notice how some vehicles on the highway in front of you look like the rear axle is riding kind of off center from the other axle and it makes the vehicle ride a little crooked? its not tracking properly. i bet it is a lifted vehicle that is riding crooked too. when you lift vehicles, you have to adjust the trac bar on coil spring vehicle to make them longer to keep the axles centered. that is why they have adjustable trac bars and different bars or mounts that come with lift kits. other wise your stock length trac bar will pull your axle off center and cause it to not track properly.

on leaf spring vehicles, if the track is not right, they have either been in an accident, broken their center pins at the spring perch, or not properly welded new spring perches on.

 

[GaJeepy]

even leaf spring vehicles newer then our wranglers don;t have trac bars.

And how is that relevant? Are those vehicles identical in every respect to the YJ?

You think that Jeep made a mistake in their engineering by including them on this vehicle? Just because another vehicle does not have a track bar does not mean that every vehicle does not need a track bar, no matter how similar they may be.

Look I am new to this forum, and don't want to start out on the wrong foot. I don't have access to JEEP's engineering data or design information, I don't know why they put a track bar on but in my opinion they put them on for a sound reason. Now maybe it is over engineered, and maybe you are fine without it, but I think it was manufactured that way for a good reason. Are they necessary for all conditions? maybe, maybe not.

I came here to find some tech on a driveline noise I am having and found this thread as is seemed relevant. I thought it might help the original poster to point out that you should understand what you are doing before blindly removing parts. I will keep looking for the tech.

 

[superj]

it is relevant because leaf spring suspension has been around for many many moons and we are the only ones with a trac bar on ours. if you wish to run yours, or if you wish to remove it, that is fine. i am just pointing out how our suspension works and how every other manufacturer since leaf springs all work the same on every type of vehicle.

lots of peole get a noise from the back or front of their jeeps and sometimes it happens to be from the trac bar mounts being broken off because the trac bar is fighting against the natural movement of the leaf spring. if factory parts are breaking because they are fighting against each other, obviously one of them is not right.

you can try driving with no trac bars and have no ill effects. try driving without your leaf springs. that will tell you which one you need.

i am not trying to argue with you or make you mad. the trac bar was installed for some reason. what it is, we may never ever know. all i know is you can take it off and have a jeep that rides a lot smoother and without a clunking noise, or you can leave it installed and have a jeep that rides like a covered wagon. its your choice.


have you ever taken your trac bar off? i have driven with it on and off so i feel i have a fair bit of experience in saying you don;t need one.

 

[GaJeepy]

the trac bar was installed for some reason. what it is, we may never ever know.

That is all I am saying. They did not add a track bar for no reason.

all i know is you can take it off and have a jeep that rides a lot smoother and without a clunking noise, or you can leave it installed and have a jeep that rides like a covered wagon. its your choice.

The ride is not very good no matter what, it is a JEEP not a Caddy. That we should agree on.

have you ever taken your trac bar off?

Yes, the front broke on a off-road trip and I replaced it, the bolt holding the bar to the axle backed out and has been disconnected for a while, but I fixed it. I frankly did not notice any change in ride quality but I then I drive like a grandma on the street. I reconnected them. Your experience may vary.

 

[superj]

sound good to me.

 

[djcrigh]

Thanks everyone for the input into the track bar situation. I was going to take it off and I may still do so just to see how the jeep rides. However, I do believe it was put there for a reason and who am I to second guess the engineers that built and designed my baby. On the other hand I hate rattles and clunks that emanate from the inner workings of the machine. So for now I am going to see if I can't find away to make the clunks go away and still keep the track bar. When I rebuilt the old axle mount I elongated the mounting holes like the existing ones, but I didn't measure or check to make sure the elongations exactly matched the original holes. From looking at the original holes and wear patterns from the nut and bolt it appeared as if the bolt had been sliding back and forth in these holes. I am still not clear why these mounting holes are elongated, for ease of fitting the track bar, to allow movement of the bolt, or ? So I am going to check into the these elongated mounting holes and see what I can see. The holes where the other end of the bar mounts to the frame are just that holes.

Again thanks for all the great advise. If I am successful in my efforts I will let everyone know.

Don