What's the Clunk in my front suspension after swaybar bushing refresh?

[Thrasher]

I just completed replacing my crossmember that had a minor issue but was making me feel unsafe. While I was "in there" I decided to replace my swaybar bushings and clean up the torsion bars and all the swaybar hardware, wire-brush wheeling to remove minor surface rust and repainting them all with rust-inhibiting paint. Part of removing the swaybar required me to undo the front mount of the right a-arm so I could swing it out of the way, but I got that all replaced just as before.

I did notice my left side torsion bar bushings were sagging (the right a-arm is only 3 years old and looks fine), and the left torsion bar had a very minor notch from rubbing - but I've never heard any clunking before. Since I didn't want to address the torsion bar bushings right now, I thought it might be a good idea to rotate the left t-bar 180 to minimize the depth of that notch (although possibly creating a second notch on the other side). Here's the pic of my left t-bar bushing:


After I got it all reassembled, I took the car out for a short drive to shake down the suspension so I could re-dial in my front ride height. Whenever I would do a "slalom" move, I heard a "clunk" coming from the front suspension. The left side was sitting pretty low after the ride, and I gave the adjuster screw 3 full revolutions (should be 3/4" rise).

Anyone want to speculate what might be causing the clunk? I reassembled it all per Bentley's including proper torque. I greased the inner portions of the new swaybar bushings also using White Lithium grease and completely coated the t-bars using standard moly grease.

Could it be the left t-bar where I know it was rubbing before I rotated it? Could it be the sway bar slipping in the new bushings?

[juanbenae]

mine did something of that sort after a suspension rebuild, except mine had a little "click" right off the center position of the wheel. mine did not do it when i got the car moving, only when sittting still and turning the wheel.

does not sound exact as mine was, but if you follow the steering colum out of the drivers compartment there will be two U-joints on the shaft that takes the steering inputs to the center of the car to go into the steering rack. you might try loosening those two u-joints and moving the wheel while sitting to get it to "resettle in". some have recommended driving a bit to get them settled, but driving with the steering not tight is a personal sort of choice (dangerous)... i was also told that if you hit the joints with a hammer (not a bfh, or real hard) that will help them settlee in too.

i have been told that as you raise and lower the car it changes the geometry/angle of the steering shaft and this may cause the issue you have. this is one idea, i would also go over everything you touched and make sure it's tight.

let us know what you uncover.

[Wavey]

Originally posted by Thrasher
Could it be the left t-bar where I know it was rubbing before I rotated it? Could it be the sway bar slipping in the new bushings?

You just can't leave things alone, can you Craig?

That's the two things I first thought of too, although I'd expect a squeak from both of them, not a clunk. Can you pinpoint the location better? It almost has to be something loose if it's a clunk.

Are you sure you got the crossmember bolts tight enough?

[Thrasher]

Toby, that's a good point about the steering u-joints, although I would have to assume that the new crossmember is the same height as the old one, but it is worth a loosening/tightening, much as I did when the bump steer spacers were installed.

Wavey, No, I guess without using the impact to really pound them in, I can't say they are as tight as before. Just 66 ft-lbs as Bentley recommends.

I'm going to remove that left t-bar and put it back to its original position since I'm not happy with the way my adjusters are skewed, with the screws almost fully threaded in it puts them at a greater angle than I'd like.

Which brings up another question - can t-bars stretch? I followed the advice of starting the adjuster caps at 4 and 8 clock positions (with no load). by the time I drop the car and raise it to normal ride height, they end up needing nearly the full range of preload adjustment.

It's almost like I'd need to extend the shock downward and then set the caps at 4 and 8 if I want my adjusters to be even close to centered.

[Chuck Moreland]

The groove worn in the tbar provide some extra clearance for the sagging control arm. Now that you turned it over that clearance is gone, your control arm and tbar are cozy.

You need a new tbar and new bushing(s).

Also, you need to do a corner balance when this is done. Just turning the adjuster till the ride height is correct can leave the corner balance way off. The result is odd handling and a car that pulls even with correct alignment.

[Thrasher]

Chuck, thanks for the input. That groove is very, very shallow, but I'll take your word for it. Like I said in my other thread, the right side a-arm is only a couple of years old, but the left is original. My plan is to ride on the existing setup until next Winter, when I'll put your Polybronze bushings on both sides (and replace that left torsion bar).

Actually, I did CB the car last year, to within 19 lbs on the diagonals. Before disassembling everything last week, I took reference measurements on the chassis, counted threads, etc so I could reassemble it as it was. The only really changed items of consequence are the swaybar bushings, and they're not binding anything up.

I'll re-check it all once I get this resolved.

edit: If this in fact the tbar meeting the a-arm, shouldn't I hear some creaking when the suspension is compressed? I'm only hearing a distinct thud/clunk when I whip the car from side to side - which would lead me in the direction of the swaybar.

Unless it's a stiction kind of thing and all of a sudden that releases and it thuds. It does it when swerving either direction, but not when turning normally.

[Chuck Moreland]

The groove may be shallow, but that is the space the control arm wants to occupy. That is why the groove is worn in. Fill in the groove and you have contact.

Even turning the tbar bar back to its original position will likely only reduce the noise. The bushing will only sag further with time and rubbing will continue.

That said, you may have other issues making noise too.

[Thrasher]

Right, I plan to revert it to the original orientation and do the replacement at the end of the driving season.

Hopefully that is the cause of my clunk, but it's odd that it would only happen on severe swerving.

[Thrasher]

This is resolved now.

Turns out I had cross-threaded the rearmost bolt that holds the swaybar mounting strap and when I torqued it, it was only partially seated, so the strap was able to move about 1/2 inch up and down as the swaybar was loaded/unloaded.

I got it all removed and chased the threads on both parts, all is well. It's pretty easy to get that thing cross threaded since I was working from outside the wheel well, on sort of an angle and you have to put the bolt thru 5 things (belly pan, bushing retainer, mounting strap, lock and flat washers), all with the swaybar resisting it all lining up. This time, I put a jack under the swaybar to help hold it in place while I concentrated on starting the threads.

[antares]

As per the photo it appears your rubber bushings have set and compressed. ie smaller at top due to weight compression. the bar itself is hitting the cross member. you can weld a small wad on tbe end of the cap where it rests/stops against the alum cross member to build it up so the bar wont hit the cross member. In addition it has been my experience that although white lithium grease is a good water resistant product it should only be used on metal parts not rubber. it will start to eat the rubber if you for example put it on the rubber bushings for the sway bar. USE synthetic that is made for rubber application. one such product is the synthetic high temp lube for calipers and their associated parts and rubber seals.

antares
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