# Mystery shaking at 60+



## Scl77 (Apr 5, 2016)

Hello,

I'm hoping someone will have some insight as to what's going on. 2003 Sentra GXE 1.8L automatic. A little background first. A month ago I hit a center divider in town at about 30 mph. I bent the rim and the alignment went off slightly. I replaced the rim and had all 4 tires balanced. I took it to get an alignment but was told the tierods needed to be replaced first. I replaced them and had the alignment done. It wasn't out too bad, just a small adjustment. Got up to speed, still shaking. I went all in and changed the struts (all 4), half shafts, lower a arms, wheel hub, wheel bearing and sway bar ends. After a second alignment it is still shaking at 60+ mph. The brake rotors and pads are still good with no rubbing or shuttering while braking. I looked over the motor/tranny mounts and they didn't seem to be bad. The engine doesn't have a miss and the transmission shifts normally. Just to be sure, I replaced all four tires yesterday in case there was a steel belt issue. My next step is going to be the three mounts, but I'm just not sure it's going to correct the problem.... I'm at the point where I've spent about as much money as the car is worth. Any ideas?


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## OhmsLaw (Mar 29, 2016)

Broken weld in the frame, only shows up with the stress of freeway driving?

A rational decision maker does not let past costs influence future decisions (to junk the vehicle?).
https://en.wikipedia.org/wiki/Sunk_costs
and
"Behavioral economics recognizes that sunk costs often affect economic decisions due to loss aversion"


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## SPEEDO (Jun 9, 2003)

when the struts where replaced did the mounts and or the bearings get changed too??


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## Scl77 (Apr 5, 2016)

I replaced everything except the knuckle...


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## Scl77 (Apr 5, 2016)

OhmsLaw said:


> Broken weld in the frame, only shows up with the stress of freeway driving?
> 
> A rational decision maker does not let past costs influence future decisions (to junk the vehicle?).
> https://en.wikipedia.org/wiki/Sunk_costs
> ...


Have you seen this before? Or is it just a guess?


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## OhmsLaw (Mar 29, 2016)

Scl77 said:


> Have you seen this before? Or is it just a guess?


You've replaced so much else, I didn't know what was left.
If a weld check device can be rented for some bucks, I'd do it.
But feel free to come up with more candidates that can cause this symptom, if you can. 
If anybody can.

I did learn one thing from this book 
Mastermind: How to Think Like Sherlock Holmes: Maria Konnikova: 9780143124344: Amazon.com: Books

written by a quirky Russian lady:
use your imagination to figure almost every possibility and then use evidence and logic to narrow the choices. 

You've already done considerable narrowing by trial and error and educated guesses but given your vehicle's recent history I don't think a cracked frame is totally off the wall.

From my own experience troubleshooting many electronic circuits, plumbing circuits, appliances, vehicles, house problems, HVAC stuff & 
the behavior of people, 
if you come up against something that doesn't seem possible, it means you are assuming something that is not true. 
But what? 

We are not conscious of the many assumptions we make each minute and making them conscious can be difficult.

Have a drink: it disables the conscience 
http://www.google.com/search?client=safari&rls=en&q="decommissions+the+parent"&ie=UTF-8&oe=UTF-8
and lets a person be creative without fear of being judged.
Then when you're sober take another whack at this. 

At the most general level it seems to be a problem with vehicle rigidity. 
It could also be a resonance issue if it only happens at a band of speeds but in your case it may be dangerous to test for an upper speed limit for this problem. Vehicles have many resonances at many frequencies but they are usually damped out (harmonic balancers and shock absorbers, for example).

A dyno test may be useful, not to check hp but to see the symptom in a lab environment.

Good luck.


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## SPEEDO (Jun 9, 2003)

might check the bushings etc of the suspension cross member..


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