When Do I Need Struts

um.....when the mechanic tells you that you need them?

Most common form of tire wear indicating worn struts is "cupping" - you may not see it, but can feel irregularities in the tread by running your hand over it. (try this with a glove first, to insure you don't get cut by bits of metal or glass that may be stuck in the tread) Would be created by struts losing damping effectiveness and thereby allowing excessive tire movement in response to road irregularities. Edge wear or center tread wear would be indicative of alignment problems or incorrect inflation pressure. My own idea, is that I do not replace struts solely based on mileage. As long as they perform well and are not leaking, I leave them in.

--------------------------------------------------------- copied from someone else: Best test for a shock (short of dyno-testing) is to drive it fairly aggressively - but carefully - over rough road. If the car remains under control, then the shocks are, likely, okay.

If one end or the other tends to "wash out", then new shocks (or struts) are indicated. ================================== The "test rig" that Jason refers to is known as a shock absorber dynamometer.....and I own one.

Basically, it gives you a graph of the pressures produced as compared to the shaft velocities at which they are produced when the shock is moved at different speeds - ranging from a shaft velocity of one-inch-per-second to

20 i.p.s.

Basically, a shock that creates 200 pounds of resistance pressure while

moving at a shaft velocity of five i.p.s will better control a car than a shock that only produces 100 pounds of resistance pressure at the same shaft velocity.

We use these graphs a bit differently in racing applications to "fine-tune" the suspension with shocks, but the above information is pretty much all you need to know for standard passenger automobiles....more shock pressure at a given shaft velocity controls better than less pressure at the same velocity.

When internal valves and springs weaken and wear out (imagine how many cycles a shock valve control spring experiences in 50,000 miles of compressing to open and close the valving each time the shaft moves in or out) , they allow fluid to pass more easily at lower pressures - usually with no external leakage to suggest that any sort of problem exists.

The so-called "bounce test" only tells you if a shock will control a car while negotiating "Mickey D" parking lot speed bumps at less than five mph with a carload of rug rats and Happy Meals.

"Hand-testing" a shock off the car moves the shaft at a velocity of approximately one-half i.p.s.

A shock can "feel" good at slow "bounce-test" or "hand-test" speeds of one i.p.s. or less because it is only passing fluid through its designed, low-speed, bleed orifices and/or bypassing the seals, but be a complete

failure at higher shaft velocities once it gets up onto the valving....sometimes, actually providing less resistance at five i.p.s.

then at "bounce-test" velocities once the valves open up.

On a smooth road, the shocks will likely be working in the 2-6 i.p.s. shaft velocity range....which simply cannot be duplicated by bouncing on the bumper of the car.

Best test for a shock (short of dyno-testing) is to drive it fairly aggressively - but carefully - over rough road. If the car remains under control, then the shocks are, likely, okay.

If one end or the other tends to "wash out", then new shocks (or struts) are indicated.

Wear out of struts is gradual and takes place most in the 3/4" or so they normall travel. Under normal conditions they are most likely not nearly as effective as new after 60-75k miles. Surely shot after 100k. If you leave longer the springs deteriorate as result of bad struts. Struts don't have to leak to be worn out. You'll notice a significant improvement in ride quality (to include braking safety) with new ones. Your mechanic is definately right! Just parts are $400 and you'll need 4 wheel alignment after the installation so - it is costly.

By 113K miles your struts are gone. For struts that take structural loads of the vehicle, most of the damping is gone by 50K miles, but since it went away so gradually, most owners never realized it until new struts are put on.

There are many types of wear patterns, which ones is he referring to?

Michelin's site will explain (text only) wear pattern and cause:

When you change the struts, you should also change the mounts while at it. Companies such as Monroe and Gabriel have so call Quick-Strut or ReadyStrut for fast turn around.

Keep an eye out for buy-3-get-1-free deals from companies such as Monroe and Gabriel (~$250 for four corners). Bilsteins touring class struts will run you about $500 for all four corners. They may be a bit stiff for you but are engineered with excellence.

Installers usually want you to buy from them at list price and then add $50 each strut to install. Afterwards an alignment. So the cost does add up unless you do your own work. But this is not something for novice.

For strut condition advice, also check:

I perosnally don't care for KYB struts (Keep Your Bilsteins).

KYB struts are good (more sporty than Monroe's) -- Gabriel are really hard. Stock are Tokico and they made one not sold by dealer that is ok. I prefer the mount/dust boot sold by Yota -- $35 each.

Thank you for all the comments. Looks as if I will be getting new struts. pestocat

I changed my fronts at about 140,000 with toyo units. I thought I was driving a new car, felt great. Going with aftermarket may change the ride drasticly, usually stiffer.

The last 2 sets Ive had actualy got harder not softer, offering no rebound cold at 50000m, replace them, it will drive like new,