Do Bilsteins wear out -How can you tell
01-02-2008, 08:16 PM
#41
Melting Slicks
Revalve costs $65 per shock. I 've had mine done several times, most recently the rears in Aug '07.
Call the Poway performance office, ask for the technician. I can't remember his name but it starts with an "M". (Mario? Manual?) For years it was a guy named Jack French and you'll probably see that name here and there on the RR forums, but the last few times I've called it was the new guy. He's still extrememly helpful.
Tell him exactly what you want and he'll suggest a few options. Pick one that sounds right and you're set. Trust me, they do a LOT of these, they will understand your needs and you'll be happy.
Call the Poway performance office, ask for the technician. I can't remember his name but it starts with an "M". (Mario? Manual?) For years it was a guy named Jack French and you'll probably see that name here and there on the RR forums, but the last few times I've called it was the new guy. He's still extrememly helpful.
Tell him exactly what you want and he'll suggest a few options. Pick one that sounds right and you're set. Trust me, they do a LOT of these, they will understand your needs and you'll be happy.
01-02-2008, 08:25 PM
#42
01-02-2008, 10:54 PM
#44
Le Mans Master
Member Since: Jun 2006
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Why wouldn't you thank a guy who took the time to write paragraph upon paragraph of helpful information instead of calling him wrong?
Maybe your shocks are fine, maybe they're not. But one case of shocks lasting longer than 100K miles does not mean they all do. Look at the 5 other posters who said theirs went bad in less than 60K. They must also be wrong. Apparently I probably shouldn't have rebuilt mine, either. They had less than 2000 miles on them so they were clearly "ok".
And what is Z51's agenda that you're referring to? The original question was about Bilstiens, I never once saw him tell anyone to buy only Bilsteins, and frankly, he probably coundn't care less if the OP buys them or not as he's not going to see it in his personal paycheck.
Your attitude seems strange to me.
Maybe your shocks are fine, maybe they're not. But one case of shocks lasting longer than 100K miles does not mean they all do. Look at the 5 other posters who said theirs went bad in less than 60K. They must also be wrong. Apparently I probably shouldn't have rebuilt mine, either. They had less than 2000 miles on them so they were clearly "ok".
And what is Z51's agenda that you're referring to? The original question was about Bilstiens, I never once saw him tell anyone to buy only Bilsteins, and frankly, he probably coundn't care less if the OP buys them or not as he's not going to see it in his personal paycheck.
Your attitude seems strange to me.
01-02-2008, 11:56 PM
#45
Racer
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Do yourself a favor, ride on a patchy uneven road with a few s turns and pay attention to your speed and the ride and handling characteristics. Then go out and buy and install a new set of shocks. I guarantee you will notice a huge difference. Like I said earlier my car handled like night and day with a shock change on rough pavement. Besides unless you are the original owner I would bet your shocks have been changed at least once by now. Any self respecting corvette owner would properly maintain the performance of their car. Hell they may have been changed 2x by now.
Change the Shocks and stop worrying about a couple of 100 dollars. Your saftey is worth more than the cost of the shocks. Then report back to us with your findings.
Thank You.
Change the Shocks and stop worrying about a couple of 100 dollars. Your saftey is worth more than the cost of the shocks. Then report back to us with your findings.
Thank You.
01-03-2008, 09:05 AM
#46
Safety Car
05-02-2017, 10:21 PM
#47
Actually, that is not a true statement at all. You would be surprised by the number of shocks I've seen that have gone 150K+ street miles and still test within the tolerance for a new shock. Again, as I stated above, the way the parts are used and the age of the parts greatly impacts the life expectancy.
Also, what many people do not realize is that replacement shocks are usually valved more stiffly than OEM shocks. This is done to compensate for wear of other chassis components like control arm bushings, etc. In fact, most of the change you feel in a car over time is typically due to changes in other components and not the shocks. Think about what would happen to a piece of rubber if you heated it up and cooled it down a few thousand times and twisted it about 10 million times and you can start to get an idea of the hard life that chassis components lead. By valving replacement shocks stiffer than the originals, you can restore that "like new" feeling to the chassis. That is not to say that shocks don't wear out -- they certainly do -- but in many cases shocks are replaced when in fact they are still perfectly good. That is why I outlined the procedure for checking the shocks by removing them from the car. If they pass that test and they are not leaking, they are still good.
All the stories you hear from mechanics, commercials, etc. about needing to replace your shocks every 20-30K miles are mostly old wives tales. That was somewhat true 50 years ago because the sealing technology was primitive, but it is not at all true today. TBH, the replacement philosophy was established by Monroe in their commercials so that they could sell more replacement shocks. Currently, all the OEMs demand that even the most basic shock absorber be designed to last at least 100K miles under normal road usage.
This is true in most cases. However, a light film of oil on the rod and seal pack (the aluminum piece in the top end of the tube that positions the rod) is quite normal, especially after many miles of use. Believe it or not, a shock will lose some oil over time even if there is no external sign of leakage because of evaporative losses.
Also, I have seen cases where a set of shocks will get very,very hot after severe usage (i.e. really hammering the gators in every turn for 20-30 laps in a row at a track day) and they may "burp" a bit of oil due to excessive pressure build-up in the shock. Once they burp, they may never leak again. Bilstein shocks are all designed with an oil reserve so that we can guarantee that they will still function properly even if they do lose some oil.
(.... stepping down from soapbox ....) 
Also, what many people do not realize is that replacement shocks are usually valved more stiffly than OEM shocks. This is done to compensate for wear of other chassis components like control arm bushings, etc. In fact, most of the change you feel in a car over time is typically due to changes in other components and not the shocks. Think about what would happen to a piece of rubber if you heated it up and cooled it down a few thousand times and twisted it about 10 million times and you can start to get an idea of the hard life that chassis components lead. By valving replacement shocks stiffer than the originals, you can restore that "like new" feeling to the chassis. That is not to say that shocks don't wear out -- they certainly do -- but in many cases shocks are replaced when in fact they are still perfectly good. That is why I outlined the procedure for checking the shocks by removing them from the car. If they pass that test and they are not leaking, they are still good.
All the stories you hear from mechanics, commercials, etc. about needing to replace your shocks every 20-30K miles are mostly old wives tales. That was somewhat true 50 years ago because the sealing technology was primitive, but it is not at all true today. TBH, the replacement philosophy was established by Monroe in their commercials so that they could sell more replacement shocks. Currently, all the OEMs demand that even the most basic shock absorber be designed to last at least 100K miles under normal road usage.
This is true in most cases. However, a light film of oil on the rod and seal pack (the aluminum piece in the top end of the tube that positions the rod) is quite normal, especially after many miles of use. Believe it or not, a shock will lose some oil over time even if there is no external sign of leakage because of evaporative losses.
Also, I have seen cases where a set of shocks will get very,very hot after severe usage (i.e. really hammering the gators in every turn for 20-30 laps in a row at a track day) and they may "burp" a bit of oil due to excessive pressure build-up in the shock. Once they burp, they may never leak again. Bilstein shocks are all designed with an oil reserve so that we can guarantee that they will still function properly even if they do lose some oil.
(.... stepping down from soapbox ....) PS- I see you live in Centerville. I live in Bellbrook, just next door. I've had the Vel. Yellow C4 at Americana Festival several times. She is showroom in every way, inside and out. Perhaps you have seen her.
05-03-2017, 09:57 AM
#49
Le Mans Master
I realize this is an old thread, but I had never seen it before.
The information that Z51L9889 (a shock absorber design engineer) posted matches to my experience. I was in charge of the mechanical commodities group for an auto manufacturer (including shocks, steering, suspension, brakes, etc.).
His comment about oil leakage matches my understanding also in that a light film that is on the rod can leave a small amount on the top edge of the seal and so the top of the shock can show something. This is normal. However if there is more oil than that it is a sign of a failed shock. I also agree with him on a test by compressing them and releasing them. If the gas fill has leaked they will not extend on their own (or slowly) and/or very easily compress. If you have experience with them you can also feel the resistance in both directions. Although the test is very subjective and not scientific for any value of performance they can give an idea if they are still functioning or have failed. Depending on shock design they can degrade in performance over age and cycles. Some designs are more robust and can take much more use without significant changes. Bilsteins for our Corvettes are some of the better ones.
That being said, I have seen Bilstein shocks last for a very long time. In the Impala SS/9C1 forums, there are a number of them at about 200k miles and say they are still good. I have had some go for about 100k and still be good.
I have also seen some fail at 50k on mine.
So I don't think there is any magic number where they are still good and then they are bad after a few more miles or time.
In practice, I generally lean towards replacing them (probably before they are needed) on mine just so I know what they are and to upgrade to a better or firmer shock (I like the Z51 Bilsteins even on a base suspension car). In the scheme of things, shocks aren't that big of an expense and I like working on the car, so I do it.
Sorry for the response to an old thread, but it interested me.
The information that Z51L9889 (a shock absorber design engineer) posted matches to my experience. I was in charge of the mechanical commodities group for an auto manufacturer (including shocks, steering, suspension, brakes, etc.).
His comment about oil leakage matches my understanding also in that a light film that is on the rod can leave a small amount on the top edge of the seal and so the top of the shock can show something. This is normal. However if there is more oil than that it is a sign of a failed shock. I also agree with him on a test by compressing them and releasing them. If the gas fill has leaked they will not extend on their own (or slowly) and/or very easily compress. If you have experience with them you can also feel the resistance in both directions. Although the test is very subjective and not scientific for any value of performance they can give an idea if they are still functioning or have failed. Depending on shock design they can degrade in performance over age and cycles. Some designs are more robust and can take much more use without significant changes. Bilsteins for our Corvettes are some of the better ones.
That being said, I have seen Bilstein shocks last for a very long time. In the Impala SS/9C1 forums, there are a number of them at about 200k miles and say they are still good. I have had some go for about 100k and still be good.
I have also seen some fail at 50k on mine.
So I don't think there is any magic number where they are still good and then they are bad after a few more miles or time.
In practice, I generally lean towards replacing them (probably before they are needed) on mine just so I know what they are and to upgrade to a better or firmer shock (I like the Z51 Bilsteins even on a base suspension car). In the scheme of things, shocks aren't that big of an expense and I like working on the car, so I do it.
Sorry for the response to an old thread, but it interested me.
05-03-2017, 10:05 AM
#50
Melting Slicks
Anecdotal evidence but the the original 100,000 mile Bilsteins I removed from my 94' were just fine. I did replace them since "I was in there" but they still had plenty of life left.
05-03-2017, 10:42 AM
#51
Drifting
Bilstein
Here is a recent thread that I commented on with my experience, look at pages 2 &3.
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Best handling upgrades for 92??
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Best handling upgrades for 92??
05-03-2017, 10:54 AM
#52
Team Owner
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General rule I follow is at 75K, replace them.
