Thread: What's the thunk?

I'm finally making a post about this because it has gotten to the point of driving me a little crazy, and also got me a little worried about something failing.

For as long as I can remember since I got the car I noticed that I could wiggle the steering wheel back and forth in a slight sawing motion and feel a little "thunk" as I did so. I assumed at the time it was either strut mounts, or possibly sway bar bushings and just figured I would let it go until I really needed to change them.

Fast forward and now it seems to have gotten worse. The issue is a little hard to describe, so I might get a little long winded, but please bear with me.

Basically, I can be holding the steering wheel at 12:00, perfectly straight, and when I move the wheel ever so slightly to the left or to the right, there is a thunk that can be felt in the steering wheel. So, lets say 12:00, move right to 12:02, thunk felt at 12:01, back to 12:00, move left to 11:58 thunk felt at 11:59. The thunk only happens right after leaving or returning to 12:00. Sometimes it feels like the steering wheel is harder to move to get out of 12:00, but once moving, moves with ease.

It only makes the thunk when the car is running (obviously with power steering assisting.) Also you can physically feel the thunk in the body of the car. I took it to my uncle's to use his garage to look at it when I did. I had my cousin get in the car and saw the wheel back and forth so he could feel what I was feeling. I was standing next to him with my hand on the open door and could literally feel the door "popping" when the steering was thunking.

I checked the tie rods and front end components and the front end seems "tight."

The possibilities I have run through my head are

-Steering joint on the rack is binding
-Entire rack is going bad

There is another possibility running through my head too. I also have an issue that makes the car feel like the motor mounts are worn, such as sometimes it feels like the engine is moving a lot when I have to get on the throttle sometimes, however I inspected the mounts and they all appear in good shape. Also brake torquing the engine shows no massive movements. This makes me think that possibly I have bolts that have worked themselves just loose enough on the subframe causing both my thunking steering and thunking "engine movement."

With the weather and temps I have not had a chance to get back under it, but I am just looking for some guidance on the issue for when I can finally get another look at it so I can cure it for good.

I had found a thread in my searches about GM's fix being to grease something, but it wasn't a detailed post, and didn't really say if it was similar to the symptoms I am experiencing, so it very well could be, and is I guess what I was getting at when I said "the joint on the rack."

I guess I never really thought of the intermediate shaft as a whole being replaced and a quick search on it after reading your post sounds like it very well could be the culprit and is more common than I thought.

I will await additional advice and opinions before I lock in on that, but you have definitely helped already.

my last rack, if i stood by the drivers door car off or on, and rocked the wheel and put my other hand on the tire, i could feel a knock.

car was having a bit of a drifting issue too. but not bad. then i added the 3.4 and all and the car started to just pull what ever way it wanted to when on the gas, let off back on the gas and it was pulling the other way now.

after this that same knock was worse and the wheel had more play.

so with one wheel jacked up, i had a friend push and pull one tire, while i held the other side, it had no play tie rod wise, but it did have a lot of back and fourth play with the steering wheel locked you could see, and feel how much play.

installed a new rack, that knock when the wheel is rocked is gone and the car no longer pulls like a tard when hard on the gas.

Stealthee,

I have an 08 and have experienced both issues you are describing and I've likely tried many of the same things you've done to try to find the noise. In regards to #1, try turning the wheel to 3 o'clock and wiggling the wheel in the same manner there, does it exhibit the same noises? I will try it on my car next time I am in it. I was really worried about this issue on mine for a while but eventually I decided that this is not a normal thing to do in a car and stopped worrying about it. It drives fine, and doesn't make noise under normal turning conditions - so I just stopped wiggling the wheel at a stop, problem solved. If anything, I decided it is wear or normal play in the rack.

In regards to #2, I think I have had a similar feeling. I would describe it as drivetrain slop - similar to a motorcycle when you are engine breaking and the tire is forcing the engine to turn faster - when you jump on the gas and now the engine is forcing the wheel to move faster, any slop or flex in the drivetrain is made up in a split second and can result in a bump or bang. This probably happens in a manual transmission car as well. In my auto GP, when I'm coasting and jump back on the throttle I get this feeling sometimes especially if I don't ease into the throttle. I don't know much about auto transmissions but there has to be a similar amount of slop in the drivetrain and I have chalked it up to this phenomenon. Just as a test, start off in 1st gear and just drive around a bit getting on and off the throttle without much finesse. You'll probably feeling a lot of bumping as you get on and off the throttle.

I wouldn't worry about either issue if your can feels tight and drives well.

All advice appreciated fellas.

Scotty, the car doesn't pull one way or the other that I have noticed, its just the thunk, and the steering wheel slightly "sticking" as I move right or left.

I guess I could replace the shaft first as it is cheaper and easier than the rack, and if the issue is still there then I could move on to the rack.

I found a TSB on it, http://ww2.justanswer.com/uploads/PE...602_impala.pdf so that says it is a pretty common issue.

Hopefully the weather warms up in the next few weeks, like it is supposed to, and I can get it swapped and it fixes it.

If it doesn't fix it, I will end up replacing the whole front end, rack, struts, tie rod ends, LCA's and everything since it will be apart and need an alignment anyway.

try touching the wheel while rocking the steering wheel. do it car off. if you feel the clunk i bet its the rack. mine didnt always pull. as it got older it did tho. and thats when i felt the whole rack having the slop and the knock sound when the wheel was rocked.

I can't get it to thunk with the car off. I was hoping to be able to do that so I could better hear, but it wouldn't do it, at least with the tires on the ground.

I can definitely feel the thunk in the floorboard right at my feet when it is really acting up which is making me lean more toward that steering shaft.

Either way, it is probably one, the other, or both at this point. LOL The car has 175k miles and both are probably original to the car.

the shaft dont touch the floor tho. i changed that pos too thinking it was the my knock, no dice.

jack the whole front up, lock the wheel, and push and pull one side, how much does the wheel move now?

my wheels would move a good 1/2 inch before the steering wheel moved. you know how it will move a little bit when locked.

unless its a bad ball joint, about the only other thing i can thing that will move and knock and then transfer to the cars body.

Ball joints looked good upon inspection too.

I just took the car for a quick ride to pick up rock salt and there is absolutely zero pull one way or the other when on or off throttle.

As for the feeling it in the floor, the shaft runs and attaches right there. If it is binding it should be felt right there.

As for locking the steering wheel, I don't think my wheel locks. I even just went out to verify and I turned it lock to lock with no key in the ignition and it never locked.

What you described about your issue sounds like a slop issue, which would definitely point to the rack. I have no slop, just a thunk. When we had it jacked up we wiggled the wheels to look for play and there was none.

Just lurking along and thought I'd drop a couple pennies worth... although I know nothing of 04+.

Yeah if theres a GM intermediate shaft bulletin, I'd go to that first. Play in whatever bearing the column might have down low?

If the set screw on the lower end of the intermediate shaft is loose and / or worn, maybe

Steering shaft boot could be out of place and hitting.

Slightly loose steering wheel? Loose rack? Loose dash bracing (there are several pieces), loose column mounting?

Production quality varies in all makes. Hunt for resistance welds that have popped loose and have rust dust coming out between two sheetmetal layers in areas where the steering and dash are mounted. Check strut towers for the same plus cracks, and look at the rack mounting tabs for cracks. These things do happen.

Or as previously suggested ... stop playing with the steering at red lights!

Or as previously suggested ... stop playing with the steering at red lights!

LOL, if it was only at issue at red lights I would leave it alone. That's all it was at first, then it starting "sticking" at times while curves in the road, which is what led me into wanting to correct it.

its only bolted to the column, and the rack, that fat boot covers the shaft, you'd feel that big time in the steering wheel if the shaft was binding.

Originally Posted by stealthee

As for locking the steering wheel, I don't think my wheel locks. I even just went out to verify and I turned it lock to lock with no key in the ignition and it never locked.

This is definitely a problem! Maybe not the problem but its a safety issue. Not supposed to work like that. I wonder if theres a problem at the top end of the column now.

I am feeling the thunk in the steering wheel, but I can also feel it at my feet.

Wonder if there was ever a theft recovery and column repair afterward, in the car's history.

my 03 gmc the steering wheel didnt lock either, they stopped making em lock on some cars and trucks, why idk. seems odd, but thats gm for ya.

Originally Posted by stealthee

I am feeling the thunk in the steering wheel, but I can also feel it at my feet.

then its traveling through the bolts for the column to the body. cause it touches nothing but the rack and column shaft.

Originally Posted by stealthee

I am feeling the thunk in the steering wheel, but I can also feel it at my feet.

Seriously, it coulld be a sway bar mount too. I mean the good bushings involve some preload when initially tightened, so I wonder (if you have been into all that already) if maybe a bushing has shrunk enough that now it could be tightened more. I know sway bar clunk is awful but the symptom doesn't really fit, just the sound.

Originally Posted by Scottydoggs

my 03 gmc the steering wheel didnt lock either, they stopped making em lock on some cars and trucks, why idk. seems odd, but thats gm for ya.

No doubt? News to me! That IS wierd.