peterls

So besides pushing the front or rear end of the car down a few times to see how quickly it settles, is there a more measurable way of checking the struts? One method that comes to mind would be to lift front or rear end and measure how far off the ground the bottom needs to be to separate the wheels from the ground - I think that should be a fairly safe method which would produce consistent results.

Any ideas? Anyone with a Lexus service manual who can check?

Shmee

iTrader: (3)

How would that be a measure of wear?
Shocks do not get longer/shorter over their life.

The "jounce test" you described is the only real test. Everything else is obvious visible signs of age like leaks, blown bushings, rusted shock shafts, etc... There are no real specs you can measure that would not be apparent by
other problems manifesting first. Generally age and mileage are the only spec you can go off. Most cars it's about 10years or 50-80k before shocks need to be replaced... But that is a rough guideline and not a definitive spec, as lots of these cars can go well over 100k on a set of shocks...

Do you think you have worn out shocks?

RA40

iTrader: (6)

In addition, odd tire wear. The simple visual test of watching the car drive over rough roads and noticing how the suspension responds. The original shocks in ours were gone by 60K. Depends on road conditions too. I don't know where the previous owner drove to wear them out.

timmy0tool

iTrader: (7)

no actual lexus test since it's a basic part. maybe the air suspension does, but not conventional shock/spring.

you will also feel vibrations or a more "floaty" ride if the shocks go bad, though the car overall is sensitive to vibrations as any broken bushing or motor mount makes the car vibrate. and the car is floaty to begin with lol!

chances are you do have worn out shocks due to the age of our cars.

peterls

Thanks everyone, but since shocks do help hold wheels at a certain position, taking them off the ground could be one measurable, reliable method to know how badly worn they are. I may just try it myself: measure how far I need to jack up the car to have the wheels separate off the ground with old shocks, and then after I install new ones, I will measure it again and see the difference.

I'll post the results, which may be months from now as I really feel lazy these days

Shmee

iTrader: (3)

Shocks do not hold the car in any position. Shocks are strictly an oscillation damper and support zero load. The spring supports the entire car, the shock just holds the spring. In fact on cars that have divorced springs and shocks, you can remove the shocks from the car and there will be no change in how the car sits. How it drive son the other hand is a completely different story.

Also, the travel of a shock as you are suggesting is not a definitive spec as different brands will have a different free length. So anything other than OEM would likely be out of spec, right out of the box.


I can assure you, you are wasting your time with such measurements to test the shocks... That is more a measure of spring tension than the shock wear!

RA40

iTrader: (6)

+1. The spring is held by the shock when at full extension. This is why you'll need a spring compressor to disassemble the unit. Replacements will vary slightly in overall length but generally they would probably measure out pretty close. Once the shock is removed from the spring assembly you can compress-extend them and get a feel for how dead they are. Even the dead ones will have some level of dampening but relative to the springs and weight of the car will determine how well they can perform.

sha4000

iTrader: (1)

Yeah what they said. If the shocks have never been changed just change them out. The bounce test is the only test I would suggest to give you an ideal of their condition.

YoshiMan

A tell tale sign is if you drive over a big bump or train tracks and the car feels like it goes:

BOING-Boing-boing... with the bounces getting smaller each time. That would mean they are REALLY worn out though, like on my GX470

Another thing, like RA40 said, is to have someone else drive your car over rough roads and just look at how the tires react. It's usually fairly obvious if one is completely toast, as that wheel will be getting jounced violently compared to the others.

qha_vn

springs take the job but I think shocks do support car weight a little when the car is sinking. shocks provide some resistance in this case though their main purpose is to soften oscillation. they just do nothing when the car sits.

Shmee

iTrader: (3)

A shock or a strut's job is tow sorb energy by resisting the compression and rebound of the spring. They support no weight of the car beyond the fixture supporting the spring. They simply control the oscillation of the spring, and in the case of a strut maintain the arc path of the suspension through the spring. Absorbing the force of jounce is not the same as supporting weight.

There are numerous cars out there where you can easily remove the shocks so you will be able to see the zero change to the ride height of the car. I've done this myself on a few old Merc's where you can simply pull the shock out from the bottom of the control arm on an alignment rack. Sure the shock acts as an upper and lower limiter by way of its mechanical travel, but as I said before, shocks do not get shorter/longer with age/mileage.

PureDrifter

iTrader: (10)

that being said, well-blown shocks that have lost some or all of their nitrogen charge will "sag".

RA40

iTrader: (6)

The "Gabriel" promotion aside, this is a pretty good list to evaluate the shocks-struts.

qha_vn

just an ad :-)