Piston Slap: Suspension Wear and Tear to Infiniti?

Sajeev Mehta
by Sajeev Mehta
piston slap suspension wear and tear to infiniti

TTAC Commentator CoreyDL writes:

Hey Sajeev,

I have had several questions floating around in my head for quite a while about proper suspension maintenance. My story begins a couple of cars ago when I couldn’t find answers, and ends here with this multi-part, OCD-approved question. My 09 M35x has just gone over 56,000 miles and I’m thinking I am past due for shocks (they’re originals, I believe). After riding in a G37xS the other day and noticing how much more compliant it felt over speed bumps and the like, my awareness of the issue increased.

When I go and look at various message board/etc. sources online, seems like whenever someone has tried to ask a serious question about their suspension, some dudebro usually replies with, “Aw man just put Bilstiens on there and lower it brah.”

So my questions are of the general variety. What sort of mileage intervals can someone reasonably anticipate a need for replacing suspension components? I’m talking passenger cars here, and what parts need replaced: shocks, struts, various bushings, sway bars, control arms, linkages… how far does this list go mayne?! I know putting new shocks on won’t be nearly as effective if the bushings and struts are worn out as well.

I want to take proper care of my suspension and keep it riding correct!

Second portion:

Since all these people here at the B&B love talking used (Cadillac), usually higher mileage (Town Car) rides (including myself) (LS400), what would you recommend as far as a “suspension refresh” if someone buys a decade-old car with 100k miles or more? I know you can help us all out.

Thanks for your help.

Sajeev answers:

Let’s quickly answer Question One about suspension wear and tear, partly with your comment:

“OCD-approved question. My 09 M35x has just gone over 56,000 miles and I’m thinking I am past due for shocks (they’re originals, I believe)”

There could be a good reason for needing new shocks at this age/mileage, but it’s just not that likely. I’m pretty frickin’ OCD about car stuff myself (see photo below) but if an Infiniti M rides worse than a (newer?) G37 with a (maybe?) more compliant wheel/tire package, I wouldn’t blame the car. Blame the manufacturer, and do a -1 or -2 wheel/tire package like we’ve discussed recently.

More to the point: odds are the shocks are fine, but you go right ahead and test them. Now for Question Two, using a quote from Question One:

“What sort of mileage intervals can someone reasonably anticipate a need for replacing suspension components? I’m talking passenger cars here, and what parts need replaced: shocks, struts, various bushings, sway bars, control arms, linkages… how far does this list go mayne?!”

Well, okay mayne…I’ll show you how OCD you can be:

How ’bout ‘dem Chocolate and Caramel coated Apples?

At some point a “keeper” could get stripped/reconditioned. Because at some point all the rubber goes bad. Or too many potholes busts up the ball joints. And maybe the wheel bearings might be shot. And if you’re gonna spend the time/effort/money to do all that, fully addressing suspension wear and tear via 100% replacement isn’t totally stupid.

I know what I just wrote about the above photo is an illogical extreme. But your question merits discussing all aspects. So if you live in Boston, you probably need new control arms/shocks/ball joints before you’ll need new shocks in Wyoming. And if you drive something fragile (which these days is more of cars than we’d like to admit) with tiny tires on pristine roads, don’t be surprised if they need more replacement “stuff” than a Panther on somewhat horrible roads. (i.e. not Boston)

This is the part where we list common wear items, and let the B&B take it from there:

  • Shocks, too loose or too tight (they can gum up inside).
  • Springs, they get softer, saggier and even (sometimes) break.
  • Spring pads: the rubber underneath the springs can go bad too!
  • Control arms: changing bushings (or ball joints) here isn’t that common anymore, now it’s easier/cheaper to get a new control arm instead.
  • Tires: even if there’s plenty of tread, rubber degrades over time and ride/handling suffers.
  • Swaybar links/bushings: these tend to work very hard, but they’ll get noisy before they totally die.
  • Swaybars: check if yours are hollow. Don’t be surprised if they are toast, especially if you live in the Rust Belt.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Join the conversation
8 of 76 comments
  • SOneThreeCoupe SOneThreeCoupe on Nov 18, 2014

    I bought an M3 with 165k miles on it and proceeded to replace literally everything in the suspension (to include wheel bearings and repacking axle joints) that is considered replaceable. The difference is night and day. I had to buy some tools and borrow a press but it took me no longer than two days to replace everything, including subframe and differential bushings. I suppose the ability to completely align a car in my garage is a significant help as well. I cannot understand why anyone would allow their cars to go 50k+ miles without refreshing bushings, dampers and revisiting spring and sway bar choices. A tighter car is a safer car for you and everyone else around you, especially if it's an econobox to begin with. Not everyone's an enthusiast, and not everyone has the luxuries I have, but if I'm piloting a 3400lb (with driver) machine capable of causing death or destruction, I'll do everything I can to ensure that it is safe. Maybe there's bias involved- my track car has spherical bearings or solid bushings everywhere and the purity is impossible to beat. A small increase in NVH is acceptable for a large increase in predictability.

    • PonchoIndian PonchoIndian on Nov 19, 2014

      " cannot understand why anyone would allow their cars to go 50k+ miles without refreshing bushings, dampers and revisiting spring and sway bar choices." Seriously? I'd be doing it less than every 2 years. I applaud your enthusiasm, but replacing all of these things is not only not economical, but in most cases, pretty wasteful. Of the 2 dozen cars+ I've owned through the years I can only think of two that have had any kind of bushing replaced, and those two were only sway bar links, and that was at over 100K miles. Most drivers, even in faced with an emergency situation, don't use their car's full handling/braking capabilities anyway.

  • Dr_outback Dr_outback on Nov 18, 2014

    I am amazed at how many people balk at the idea of replacing their vehicles struts/shocks. A mechanically inclined co-worker mentioned that his 200k mile '03 Taurus was on its third set of end links. I mentioned that the problem is likely that the struts have lost their dampening ability. He didn't realize that the condition of the struts could be at fault.

    • See 4 previous
    • Corey Lewis Corey Lewis on Nov 19, 2014

      @Eiriksmal Thanks

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