I am having a shake at exactly 55 mph on the front end. Below 50 its very slight and above 60 its very slight, but at 55 it is pronounced.
How do I determine if it is struts (valve worn out) or tire (out of round) or wheel (bent)? Or perhaps all three!!
The struts have never been replaced and its 177K miles on them. So planing on replacing them anyway. Does anyone have a recommendation for replacements? I will probably put less than 5,ooo miles a year on the car so will want to go inexpensively because they will age out before they wear out.

 

My experience has been with one rear and one front original shock going bad.
I started to notice a rapid bounce when traveling on highways and over speed bumps. You might think it is a shaking sensation but it was the strut.

If you do not see any type of wear on your tires, I'm going to suggest getting your wheels balanced, at a cost of around $150 total.

Once you start digging deeper it might be your bushings that are worn.

Good luck!

 

Check your Lower Control Arm #2 bushings.

 

SC430 has vibrational resonance around 60 MPH. Anything that is non/optimal in the suspension or even tire pressure imbalances can set it off. LCA bushings, tie rods, alignment, tire balancing are all common culprits. Once ALL are addressed the resonance will go away. Unfortunately you cannot rule any out until you take care of each item. I suggest starting with the cheapest items and work up the list.

 

Good advice. I will start with wheels and tires as I really want to do those ANYWAY because I dont like low profile tires and the OEM wheels are prone to leak when they get old and the chrome flakes off. Then the list with struts last because of their cost.

 

It’s common problem. It’s a central ring or bushing, I can’t remember. Do a search on wheel vibration at 60 mph.

 

My guess is that you have a tire balance issue that will go away when you get your new tires and wheels. Don't go cheap on these to avoid future issues. Too, I always pay extra for lifetime road hazard insurance which includes lifetime rotations and re-balancing as wheel/tires go out of balance often throughout their lifetime. The smoother and quieter a car is, the more noticeable these issues are. Thus, while it isn't a big issue in an economy car, SUV or pickup, it is huge for luxury cars like the SC.

 

Did you ever figure this out?

I have same issue, thought it was wheel alignment - went to get alignment, guy said it was good. Thought it was the balance -- had all 4 wheels rebalanced.. -- it helped.. a little? but still having issue.

Thinking I'll grab new LCA's but not sure what part #

 

Still waiting on my wheels, backordered.

 

Ahh, yeah wheels seem to be lacking as well -- I'm going to get new tires for the fronts, and see if it helps (can't rotate -- back wheels/tires are different size).

I'm really hoping its not the LCA's or any of the suspension .. I lack the experience doing those.. only done once on my other car.

 

LCA #2 - Driver Side 48670-24020
LCA #2 - Passenger Side 48660-24020
or you can get the one from figs with the poly bushing installed. https://shopfigs.com/v3/by-vehicle/c...sc430/FE-L6009

 

Thank you so much! I'm 99% sure it has to do with the suspension so I might as well just bite the bullet.

 

If your LCA#2 bushing is cracked, replacing it will help fix the vibration, provided that you already checked the front disc rotors, tires balancing and have hub centric rings (after market wheels)

 

It's center ring. Common problem.

 

would that be the case if you had stock wheels?