Front end wobble.

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Kipprc

Kipprc

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FABO Gold Member
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Can anybody lead me in the right direction with this new front end wobble I am experiencing? Underneath the car everything feels solid. I can't find any broken or lose parts. The front wheels wobble in what almost feels like an uncontrollable fashion. Its fairly violent. It can be felt through car and seen in the steering wheel. It can also be felt when applying the brakes. The wheels wobble left to right with no bouncing. After I drive the car for a bit it ends up going back to normal. All of this usually happens around 80 miles per hour only after a WOT pull. If I accelerate at a moderate pace this does not happen. I thought this may have been caused by the exhaust hitting/rubbing on the driveshaft, but that is not likely. The parts on the K frame are fairly new. The alignment isn't off and the wheels and tires have been balanced, but I am going to have it done again. I just don't know what to do other go through the entire front end replacing stuff. Something must be worn out.
 
Shocks and tire balance come to mind. Have someone place foot on brake and rock steering wheel back and forth. Then look at everything,mounts ,welds,radius arms and all the bushings. Something is worn,cracked or loose.
I would knock off the 80 mph stuff until problem is found.
 
I learned this weird "rule of thumb" years ago, if you can feel it in the steering wheel, it's likely something wrong to the back of the car and, if you feel it in the seat or seat back, it's likely a front issue. I'd be checking axle bearings, U-joints, leaf springs, leaf spring mounts, brake drums/rotors and pads..
 
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So it doesn't wobble at 80 mph if you accelerate slowly to 80mph?

If it was a plain old balance issue it wouldn't matter how you get to 80, just that you're doing 80. It would be same wobble at the same speed. Same for the driveline, it would be the same wobble at the same RPM.

The fact that it appears only after hard acceleration is an indication that something is moving under hard acceleration. It could still be driveline or suspension related, but it sounds like you're looking for something that's moving under hard acceleration rather than just a static balance issue.

I agree with tooljunkie, you need to do a thorough inspection looking for cracks, loose or broken stuff. If this has been happening on multiple occasions you can look for shiny parts under the car because if things are moving around you'll see shiny metal where it's been moving.
 
Tooljunkie said:
Shocks and tire balance come to mind. Have someone place foot on brake and rock steering wheel back and forth. Then look at everything,mounts ,welds,radius arms and all the bushings. Something is worn,cracked or loose.
I would knock off the 80 mph stuff until problem is found.
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Thanks. I will enlist the help of my wife this weekend to see if we can figure it out.
 
I would look at toe in / tie rod ends. We had a solid front axle van that if you hit a bump just right at highway speeds would shake the crap out of the front end. Quick stomp on the brake and it would go away.
 
72bluNblu said:
So it doesn't wobble at 80 mph if you accelerate slowly to 80mph?

If it was a plain old balance issue it wouldn't matter how you get to 80, just that you're doing 80. It would be same wobble at the same speed. Same for the driveline, it would be the same wobble at the same RPM.

The fact that it appears only after hard acceleration is an indication that something is moving under hard acceleration. It could still be driveline or suspension related, but it sounds like you're looking for something that's moving under hard acceleration rather than just a static balance issue.

I agree with tooljunkie, you need to do a thorough inspection looking for cracks, loose or broken stuff. If this has been happening, you can even just look for shiny parts under the car because if things are moving around you'll see shiny metal where it's been moving.
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72bluNblu the only shiny part that has popped up so far is the driveshaft. The muffler was dragging on it. I ended up getting that fixed this morning. Before it was fixed the exhaust would shake free and hit the driveshaft. The only other noise I hear when this happens is a resonating hum. I think that is coming from the diff. I was going to take a look at the fluid just to see if the fluid had been changed lately and if I had metal shards breaking free.
 
I have used a gopro camera to help with my rear end setups at the track. Don't see why you can use/borrow one and mount it at different locations to also help with diagnosis. Just a thought.
 
Kipprc said:
72bluNblu the only shiny part that has popped up so far is the driveshaft. The muffler was dragging on it. I ended up getting that fixed this morning. Before it was fixed the exhaust would shake free and hit the driveshaft. The only other noise I hear when this happens is a resonating hum. I think that is coming from the diff. I was going to take a look at the fluid just to see if the fluid had been changed lately and if I had metal shards breaking free.
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If the rear end is making noise you could absolutely have something moving around inside there. If nothing else obvious is going on you will probably need to open up the rear end and inspect the differential. Check the oil first and look for metal, disconnect the driveshaft and see if the play on the yoke is loose first. But a bad bearing, backed off adjuster, etc could absolutely cause that issue.
 
look at trans mount could be broke also do you have a limited slip could be locked up not releasing
 
Demonracer said:
Possible twisted belt in a tire.
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yeah, buddy, in 1978 I had a '74 vette with those Firestone 500 tires that the belt twisted and the tire bulged, in '78-'80 they recalled 19.6 million tires. Bad juju.
 
Well I have had people turn the wheel while I was underneath the car and nothing. I have pushed and pulled everything under that car and nothing in the front suspension has play. I tried the crowbar under the wheel as suggested in other posts. There is no free play that I can see or hear. There are some torn bushings and covers do need replacing. I just have no solid idea of what is causing the wobble.

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did you pull the front hubs apart and repack and adjust the wheel bearings too?
 
My bet is if you lifted the car letting the front wheels hang and unloaded the adjuster screw on both torsion bars, lifted the wheels to normal ride height you would find all kinds of slop.

Normal ride position that gets 99% of the wear, so when the wheels are hanging they are not in their normal position, and as such might be tighter AND with other forces acting in other directions then at normal ride height.
 
Dana67Dart said:
My bet is if you lifted the car letting the front wheels hang and unloaded the adjuster screw on both torsion bars, lifted the wheels to normal ride height you would find all kinds of slop.

Normal ride position that gets 99% of the wear, so when the wheels are hanging they are not in their normal position, and as such might be tighter AND with other forces acting in other directions then at normal ride height.
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Just to make sure I am tracking, I should reinspect the vehicle on the ground.
 
well, weight on the wheels, same thing. you can use ramps or make a set of THESE to make it easier to get under it

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Well I got under there and nothing. The car was on the garage floor and I squeezed under there with plenty of light. Everything I touched was solid with no play. I then jacked up the car under the lower control arms on both sides. There is a baby clunk when the wheel is wiggled from the top and bottom. Almost to the point of not being able to hear the clunk at all. I did the pry bar under wheel to see if there was any independent movement in the suspension and got nothing. Now with the steering wheel locked and wiggling the wheel side to side (9 o'clock and 3 o'clock position), there was some play. I don't know if that type of play is supposed to be there? Best I can tell is that the upper control arms need new bushings and new ball joints. The upper boots are ripped and contaminants are getting in there. The bushings on the upper control arms look dried out as well. The lower control arm bushing looks fine and moves as one with the rest of the suspension. Can I replace the upper control arms independently or must it be done in conjunction with the lower control arm? If I have lower control arms from 73 should I get oem UCAs from 73 or can I go with tubular UCAs? I think I have gotten to the point where I just need to replace stuff to chase the problem away.
 
Kipprc said:
I think I have gotten to the point where I just need to replace stuff to chase the problem away.
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i hate doing that, but i'd be lying if i said i never have :rolleyes: you can do just the uppers. stock bushings, offset bushings or new after market arms (a lot of choices and opinions). is the car large or small upper ball joint?
a lot of it depends on what you want to do with the car.
WHY DO WE UPGRADE OUR SUSPENSION
 
Kipprc said:
Well I have had people turn the wheel while I was underneath the car and nothing. I have pushed and pulled everything under that car and nothing in the front suspension has play. I tried the crowbar under the wheel as suggested in other posts. There is no free play that I can see or hear. There are some torn bushings and covers do need replacing. I just have no solid idea of what is causing the wobble.
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look how far off center that bushing has gotten.
Also lower control arm bushings can absolutely cause what you described.
My Dart did the shake randomly when i ran over one of the reflectors in the road.
Think about the fact that a control arm moves and affects the direction the wheels point.
Once I replaced the LCA bushings the problem went away.

This is the upper bushing way off center.

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I am going to start with those uppers. They do look rough. If I keep having issues, I will try and flush it out piece by piece. Basically working from the outside of car (passenger and drivers side) in towards the k member. Eventually the problem should go away. A little disheartening though. I was eyeing those viking adjustable shocks everybody speaks highly of on here. Oh well, one day.
 
Instead of throwing parts at it, take it to a competent alignment shop & let them get it on the rack to see what & where your problems are. Throwing parts at a problem only costs you more money & you never get a true reading as to what the problem was to begin with.
 
Demonracer said:
Instead of throwing parts at it, take it to a competent alignment shop & let them get it on the rack to see what & where your problems are. Throwing parts at a problem only costs you more money & you never get a true reading as to what the problem was to begin with.
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I agree, but as time has rolled on I believe competent alignment shops no longer exist. I had an in issue with my magnum. I went to 5 shops. They all just stuck it on the machine and did what the machine told them to do. In the end I went to a guy who had done work for me in the past. He worked out of his fathers garage at his house. He broke out tape measures rulers and string. It was the best damn alignment I had ever had. Lost contact with him and haven't been able to find him. The pictures are pretty clear in this instance. The bushings are shot and the boots on the ball joints are shot. I just need to replace/repair and drive. If the problem pops up again, time to dig a little deeper.
 
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