Head Banger - Assistance Requseted

oldskool racer · #1 08-30-2018, 02:18 PM

Hey guys,

Long time lurker, rare poster - wanted to ask this wonderful board for some suggestions, as I have seemingly hit the proverbial wall.

02 e53 4.6is with the Dinan Supercharger kit

Experiencing a intense vibration right at 60 mph, all the way through 80. It seems to shake both the front and rear of the vehicle.

After taking it to two indy's and my local firestone; We have been at a standstill trying to identify what is causing the shakes.

I have replaced every ball joint, bushing and thruster arm on her in the last 2 months. Swapped wheels and tires with known good sets, had multiple alignments, and even replaced 2 CV shafts.
The only thing I haven't yet done are the front shocks/shock mounts, brake rotors (which supposedly only have 4k on them) and rear sub-frame bushings. There are no lights on the dash, or codes being thrown indicating errors.

Does anyone have any other ideas that I should try?

Photos for attention/motivation to get her back on the road

Many thanks in advance!

e39_touring · #2 08-30-2018, 02:46 PM

Is there any difference in vibration under load vs. no load (i.e. shift to neutral while going 60-80mph)? Is it a new vibration (i.e. has it always been there since you got the car or has it slowly crept up on you)? I'd look at the the rear driveshaft and its center bearing.

The driveshaft could have been removed and put back in not 'clocked' right causing an imbalance, or the center bearing could be going, which will make a vibration much more pronounced under load than not (causes the driveshaft to sort of whip around where the front and rear shafts come together). Had this problem on my old 750iL, but it was more pronounced at lower speeds.

oldskool racer · #3 08-30-2018, 03:49 PM

thanks for the response e39!

It doesn't seem to matter if there is a load or not, I get the same shake also if I am in 3rd or 5th gear, so seems to be speed related.

The vibration seemed to start about a month ago, at which time I decided it had to be suspension related. Ill double check the rear driveshaft and center bearing and report back.

Overboost · #4 08-30-2018, 03:53 PM

Just checking the obvious. Did you verify the wheels are balanced and didn't lose a weight?

andrewwynn · #5 08-30-2018, 04:07 PM

Do you this test:

At speed, but outside the shaky zone (say 55), brake gently to medium force. If you can force the shake/shimmy it's almost certainly the ball joint. You said you just replaced all bushings and thrust arms but not sure if that's included and you could have gotten a defective one.

If ball joint usually you can get the wobble to chill out on a curve when the wheels are side loaded.

There is another joint ta rarely checked that is at the top of the spring/shock.

Changing wheels front to back can help find a shake if tire related but I'm guessing you have staggered set so that's not happening.

Do you feel the shake in the steering wheel?

+1 on check balance but also: dented rim: did you or other driver hit a bad pothole? The car I'm driving now has a shake due to a pothole dent in the rim.

oldskool racer · #6 08-30-2018, 07:41 PM

the responses are very much appreciated - I might have access to a few sets of wheels and tires, even off another 4.6is, and the issue is still present with one of the good sets.

:sigh: even my 19 inch set with brand new snow tires sees the issue.

The shake is felt through the steering wheel, thinking that is where the bulk of the shudder is stemming. I will try the drive and brake with medium force again, and see where it leaves me.

Ill keep you all posted

Emory39 · #7 08-31-2018, 12:28 PM

Subscribed for results, I have this shake too. I did replaced all suspension components besides the upper strut tower.

X53Jay4.8is · #8 08-31-2018, 03:26 PM

My money is on the drive shaft

oldskool racer · #9 09-04-2018, 12:13 PM

thanks again for the responses - had another indy take a look at it over the weekend, and he is thinking that its the hub itself. We looked at a few of the suggestions here by folks, on the driveshaft, brakes, and wheels and tires, but felt confident eliminating those as the culprit.

his thought was that during the suspension revamp, the hub was damaged. now to find the time to swap it out...

keep everyone up to speed as we get closer

andrewwynn · #10 09-04-2018, 04:18 PM

You mentioned hub damaged: my mechanic when doing the brakes managed to strip out the hex bolt that holds the rotor against the hub: it "blew out" the threads on the rotor. Some of the crumbs of the hub got between the hub and rotor making the rotor not parallel to the hub. Horrible shake in the steering wheel just like you describe. You can take a video of the wheel while driving to see if it wobbles.

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