I assume they lose dampening rate, as mileage stack up, before failing completely. What is the rate of dampening loss vs. mileage? Is it linear?
How do shocks wear out?
- Thread starter Jonny Z
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They wear out kinda like an engine, some last a long time some fail right away and some fail inbetween.
Oil breakdown + seal leakage + rubber bushing deterioration + water and dirt intrusion + overloading causing actual structural damage....yada yada yada...
Shocks/struts wear out kind of like the knees on an athalete.
Originally Posted By: Jonny Z
I assume they lose dampening rate, as mileage stack up, before failing completely. What is the rate of dampening loss vs. mileage? Is it linear?
No idea on the rate of degradation. Replacing shocks when you do tyres is a reasonable rule of thumb
I assume they lose dampening rate, as mileage stack up, before failing completely. What is the rate of dampening loss vs. mileage? Is it linear?
No idea on the rate of degradation. Replacing shocks when you do tyres is a reasonable rule of thumb
Shannow, I'd have to say that's probably a little too frequet, especially if on good hard surface roads. Seems they (like all the rest of modern cars), last much longer than in past years. I'd never expect to replace before 100,000 miles.
Quote:
Oil breakdown + seal leakage + rubber bushing deterioration + water and dirt intrusion + overloading causing actual structural damage....yada yada yada...
Another factor personal experience (from actually cutting a few open over the years)is oil breakdown, loss of viscosity, seems plausible as that stuff is BLACK and thinner than water.
Having a bit of a dilemma personally over wether to replace shocks on recently purchased 04 Silverado SS,,,,,has 125,000 miles, but still rides great, and corners like a gokart.
All that said, shocks (and struts) deteriorate so gradually, you'll usually not notice till you've installed replacements and go for a ride,,,,,DAAAYUM this thing rides like a new vehicle!
Bob
Quote:
Oil breakdown + seal leakage + rubber bushing deterioration + water and dirt intrusion + overloading causing actual structural damage....yada yada yada...
Another factor personal experience (from actually cutting a few open over the years)is oil breakdown, loss of viscosity, seems plausible as that stuff is BLACK and thinner than water.
Having a bit of a dilemma personally over wether to replace shocks on recently purchased 04 Silverado SS,,,,,has 125,000 miles, but still rides great, and corners like a gokart.
All that said, shocks (and struts) deteriorate so gradually, you'll usually not notice till you've installed replacements and go for a ride,,,,,DAAAYUM this thing rides like a new vehicle!
Bob
Highway miles vs. Chicago streets with pot holes make a LOT of difference for this component.
They DO seem to last longer than before, however.
Normal use should be approx. linear - a leak will speed up problems greatly.
They DO seem to last longer than before, however.
Normal use should be approx. linear - a leak will speed up problems greatly.
Originally Posted By: Char Baby
Shocks/struts wear out kind of like the knees on an athalete.
Yeah you are not kidding....
I ruined my knees in High School football & track. Now 40 years later I can still fell all those hits.
Shocks/struts wear out kind of like the knees on an athalete.
Yeah you are not kidding....
Originally Posted By: alreadygone
Shannow, I'd have to say that's probably a little too frequet, especially if on good hard surface roads. Seems they (like all the rest of modern cars), last much longer than in past years. I'd never expect to replace before 100,000 miles.
And on the three different cars that I replaced shocks on, I was disappointed at how little difference it made. Seems all new suspension bushings were what was really needed.
Shannow, I'd have to say that's probably a little too frequet, especially if on good hard surface roads. Seems they (like all the rest of modern cars), last much longer than in past years. I'd never expect to replace before 100,000 miles.
And on the three different cars that I replaced shocks on, I was disappointed at how little difference it made. Seems all new suspension bushings were what was really needed.
Originally Posted By: alreadygone
Shannow, I'd have to say that's probably a little too frequet, especially if on good hard surface roads. Seems they (like all the rest of modern cars), last much longer than in past years. I'd never expect to replace before 100,000 miles.
Quote:
Oil breakdown + seal leakage + rubber bushing deterioration + water and dirt intrusion + overloading causing actual structural damage....yada yada yada...
Another factor personal experience (from actually cutting a few open over the years)is oil breakdown, loss of viscosity, seems plausible as that stuff is BLACK and thinner than water.
Having a bit of a dilemma personally over wether to replace shocks on recently purchased 04 Silverado SS,,,,,has 125,000 miles, but still rides great, and corners like a gokart.
All that said, shocks (and struts) deteriorate so gradually, you'll usually not notice till you've installed replacements and go for a ride,,,,,DAAAYUM this thing rides like a new vehicle!
Bob
Silverado SS = go-kart like? Come on...
I think shocks degrade more or less linearly and then one day you realize they're shot. On the TL I hit a normal speed bump that I go over at least once a week and twice in a row I hit the bumpstops at the same speed as usual. It bounced up and down twice. A week later I had Koni Yellows at the doorstep. I didn't notice much degradation until the speedbumps. Once I put the Konis in, even on the softest setting to break them in, it reminded me of what the car used to be like.
Shannow, I'd have to say that's probably a little too frequet, especially if on good hard surface roads. Seems they (like all the rest of modern cars), last much longer than in past years. I'd never expect to replace before 100,000 miles.
Quote:
Oil breakdown + seal leakage + rubber bushing deterioration + water and dirt intrusion + overloading causing actual structural damage....yada yada yada...
Another factor personal experience (from actually cutting a few open over the years)is oil breakdown, loss of viscosity, seems plausible as that stuff is BLACK and thinner than water.
Having a bit of a dilemma personally over wether to replace shocks on recently purchased 04 Silverado SS,,,,,has 125,000 miles, but still rides great, and corners like a gokart.
All that said, shocks (and struts) deteriorate so gradually, you'll usually not notice till you've installed replacements and go for a ride,,,,,DAAAYUM this thing rides like a new vehicle!
Bob
Silverado SS = go-kart like? Come on...
I think shocks degrade more or less linearly and then one day you realize they're shot. On the TL I hit a normal speed bump that I go over at least once a week and twice in a row I hit the bumpstops at the same speed as usual. It bounced up and down twice. A week later I had Koni Yellows at the doorstep. I didn't notice much degradation until the speedbumps. Once I put the Konis in, even on the softest setting to break them in, it reminded me of what the car used to be like.
I saw a newer Honda Odyssey minivan today (I think it was an '04 or newer) with the right rear hopping like mad. Even my wife noticed it.
PT1,
I too played HS football and was also a catcher in baseball and my knees feel the pain of the last 35 years. I even caught a little(very little) after HS in a 2 local semi-pro leagues,(hard ball and slow pitch) but, job demands limited my play and the fellas weren't going to put up with me partialy showing up for games/practice. Who knows, "I COULD HAVE BEEN SOMEBODY"!!! LOL!
I too played HS football and was also a catcher in baseball and my knees feel the pain of the last 35 years. I even caught a little(very little) after HS in a 2 local semi-pro leagues,(hard ball and slow pitch) but, job demands limited my play and the fellas weren't going to put up with me partialy showing up for games/practice. Who knows, "I COULD HAVE BEEN SOMEBODY"!!! LOL!
Originally Posted By: BuickGN
On the TL I hit a normal speed bump that I go over at least once a week and twice in a row I hit the bumpstops at the same speed as usual. It bounced up and down twice. A week later I had Koni Yellows at the doorstep. I didn't notice much degradation until the speedbumps. Once I put the Konis in, even on the softest setting to break them in, it reminded me of what the car used to be like.
Really? You think you wore out shocks in two years?
On the TL I hit a normal speed bump that I go over at least once a week and twice in a row I hit the bumpstops at the same speed as usual. It bounced up and down twice. A week later I had Koni Yellows at the doorstep. I didn't notice much degradation until the speedbumps. Once I put the Konis in, even on the softest setting to break them in, it reminded me of what the car used to be like.
Really? You think you wore out shocks in two years?
Shocks last about 40,000kms at best. They go off so gradually nobody notices till they replace them
Hi,
actually the modern Euro "gas" shocks do have a long life - 120kkms or more
They tend to "wear out" due to pressure loss (gas) and valving deterioration
Damage to shocks is often caused by sudden impacts that tend to damage valves and casing structures
I have seen shocks last very well to beyond 250kkms
Testing modern Euro shocks requires very reliable and advanced equipment. The old take off and "pump up & down" is long gone!
It is hard to generalise as there are many variations on the theme of shock structures of any type
Australian roads are VERY hard of shocks of any type and brand!!!!!
actually the modern Euro "gas" shocks do have a long life - 120kkms or more
They tend to "wear out" due to pressure loss (gas) and valving deterioration
Damage to shocks is often caused by sudden impacts that tend to damage valves and casing structures
I have seen shocks last very well to beyond 250kkms
Testing modern Euro shocks requires very reliable and advanced equipment. The old take off and "pump up & down" is long gone!
It is hard to generalise as there are many variations on the theme of shock structures of any type
Australian roads are VERY hard of shocks of any type and brand!!!!!
They are stupid crude devices, as called in kinematics, the harmonic motion dampeners. I think their importance is a bit exaggerated, at times to compansate for the poor overall suspension design. If harmonic modes and possible resonances aren't checked in design stage then best "shocks" would help a little. Opposite applies, you'd notice very little degradation with shocks in desperate shape. A good design shouldn't primarily rely on continuously degrading components, but I don't think every car get the expensive proven harmonic/resonance analisys-design-test cycle.
lifespan varies by model, brand, application, use.
'97 Subaru legacy desperately needed new rear shocks at 70,000 miles. fronts were fine, but did all 4 with kyb gr2, very happy. KYB was also oem supplier on the car, btw.
oem were also kybs on our grand caravan; were great at 60,000 with no perceptible signs of wear.
Honda accord & CRV at ~90,000, ride stiff and firm, no shocks needed.
M
'97 Subaru legacy desperately needed new rear shocks at 70,000 miles. fronts were fine, but did all 4 with kyb gr2, very happy. KYB was also oem supplier on the car, btw.
oem were also kybs on our grand caravan; were great at 60,000 with no perceptible signs of wear.
Honda accord & CRV at ~90,000, ride stiff and firm, no shocks needed.
M
Shocks can exhibit visually observable symptoms of wearing out, such as breeched seals allowing the fluid to exit the shock. Internally, it's hard to say whether mechanical wear or sheared damping fluid is more prevalent as a cause.
I believe that one of the things you get when you buy higher quality shocks is better fluid, which better resists shearing.
Another thing you get is better design and construction, which should lead to less bore wear, and longer lasting valving.
I'm not sure if one of the above elements is more important than the others, or if they are all needed together, but one thing that we at BITOG should be interested in is the damping fluid that is used by the various shock manufacturers in their model line-ups.
I wonder if this kind of information is available?
I believe that one of the things you get when you buy higher quality shocks is better fluid, which better resists shearing.
Another thing you get is better design and construction, which should lead to less bore wear, and longer lasting valving.
I'm not sure if one of the above elements is more important than the others, or if they are all needed together, but one thing that we at BITOG should be interested in is the damping fluid that is used by the various shock manufacturers in their model line-ups.
I wonder if this kind of information is available?
Originally Posted By: Big O Dave
I believe that one of the things you get when you buy higher quality shocks is better fluid, which better resists shearing.
Another thing you get is better design and construction, which should lead to less bore wear, and longer lasting valving.
I'm not sure if one of the above elements is more important than the others, or if they are all needed together, but one thing that we at BITOG should be interested in is the damping fluid that is used by the various shock manufacturers in their model line-ups.
I wonder if this kind of information is available?
as to fluid specs, I've done some crude viscosity tests on (new) Koni fluid and it's pretty poor IMO, at least in terms of VI.
Silkolene Pro RSF in the appropriate viscosity was markedly superior, and the best fluid I have specs on is blended by none other than our Bruce381.
When I get back to playing/re-valving dampers one day, I'll use Bruces' oil.
Damping has a marked behaviour on vehicle dynamics, not just 'mere' harmonic modes. Speed of transients in roll, squat, pitch and warp can be influenced as heavily by dampers (using the low speed circuit, generally considered under 4"/sec and critically important in circuit race cars) as basic suspension design.
There is a lot of good stuff here http://www.peterverdonedesigns.com/damping.htm
and while it primarily deals with mc suspension, the basics apply to all damping.
And I've used his chart for years
FWIW, Koni fluid is approximately equal to Silkolene Pro RSF 5wt @ 20*C and Fox use Torco fluid.
I believe that one of the things you get when you buy higher quality shocks is better fluid, which better resists shearing.
Another thing you get is better design and construction, which should lead to less bore wear, and longer lasting valving.
I'm not sure if one of the above elements is more important than the others, or if they are all needed together, but one thing that we at BITOG should be interested in is the damping fluid that is used by the various shock manufacturers in their model line-ups.
I wonder if this kind of information is available?
as to fluid specs, I've done some crude viscosity tests on (new) Koni fluid and it's pretty poor IMO, at least in terms of VI.
Silkolene Pro RSF in the appropriate viscosity was markedly superior, and the best fluid I have specs on is blended by none other than our Bruce381.
When I get back to playing/re-valving dampers one day, I'll use Bruces' oil.
Damping has a marked behaviour on vehicle dynamics, not just 'mere' harmonic modes. Speed of transients in roll, squat, pitch and warp can be influenced as heavily by dampers (using the low speed circuit, generally considered under 4"/sec and critically important in circuit race cars) as basic suspension design.
There is a lot of good stuff here http://www.peterverdonedesigns.com/damping.htm
and while it primarily deals with mc suspension, the basics apply to all damping.
And I've used his chart for years
FWIW, Koni fluid is approximately equal to Silkolene Pro RSF 5wt @ 20*C and Fox use Torco fluid.
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