Corvette Z06 Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
437 Posts
Discussion Starter #1
Does anyone have a clue what is causing all of these broken valve springs? Are these defective springs or what? Any ideas? Any comments from technicians who have fixed collateral damage? C4C5 Specialist where are you!!!!!!!!
 

·
Moderator
Joined
·
21,354 Posts
High tensile steel is very brittle and will eventually fatigue after "X" amount of time. My tuner recommends changing springs every two years instead of "X" amount of miles.
 

·
Registered
Joined
·
136 Posts
The gm mechanic thats replacing my motor said it might have been over reving/missing a shift, that did my motor in...
 

·
Registered
Joined
·
118 Posts
if you have duals, you need to warm the motor up first to normal temps before hammering it. when cold they are very brittle.

also, patriot golds and comp 921s are the best
 

·
Registered
Joined
·
3,817 Posts
eamador11 said:
if you have duals, you need to warm the motor up first to normal temps before hammering it. when cold they are very brittle.

also, patriot golds and comp 921s are the best
That would be a negative on the Patriot Golds.... :roll: folks have been having problems with them. Go Comp. 921's. :thumb:

Bob
 

·
Registered
Joined
·
722 Posts
I've only read one post where someone with a stock cam broke a spring. Did I miss something?
 

·
Registered
Joined
·
2,110 Posts
I ran over 20,000 miles on the 921's with the g5x2 and never had a problem, but I do that silly always let my oil temp get up around 180 before taking the car above 3000 rpm thing
 

·
Registered
Joined
·
9,957 Posts
I have about 15K miles on dual crane springs ....I try to follow the BMW valvetrain protection protocol (where I believe it changes the rev limiter to 4000 rpm at startup until the oil temps hit 150 degrees or thereabouts.....).
 

·
Registered
Joined
·
1,600 Posts
Yeah... very troubling indeed especially with the stock setups. Are the LS1 motors having similar probs or is it just the LS6? Changing out valve springs every two years sounds to be a real PITA.

Out of curiousity what does a shop charge to change them out? Fingers crossed.
 

·
Registered
Joined
·
9,957 Posts
bigbadbevo said:
Yeah... very troubling indeed especially with the stock setups. Are the LS1 motors having similar probs or is it just the LS6? Changing out valve springs every two years sounds to be a real PITA.

Out of curiousity what does a shop charge to change them out? Fingers crossed.
I've been quoted 300 dollars to change out dual valve springs(including the cost of the parts) ..and for the improved performance I don't see this as a problem.
 

·
Registered
Joined
·
2,388 Posts
JBsZ06 said:
I've been quoted 300 dollars to change out dual valve springs(including the cost of the parts) ..and for the improved performance I don't see this as a problem.
Is that something that could be done by a competent owner? I'm assuming you need to pressurize the cylinder with air when on TDC so the valve springs can be removed and replaced without the valves falling down in the cylinder. Would also need a special tool to remove/install the springs.

Anyone do this at home? If so, please give a few details.
 

·
Registered
Joined
·
891 Posts
Fatigue fractures in springs is governed by metallurgy, stress and number of cycles.

Bad metallurgy in a batch of springs would be the most probable cause of stock valve springs failing.

The stress is caused by compressing the spring which is limited by the cam lift to a fixed amount. So unless you change the valve lift there isn't any real way to over stress the spring.

The number of cycles is just what it sounds like. I suppose that if you drove 100,000 miles at redline your springs would have more cycles and be more prone to failure than if you never revved over 1500 RPM for the same mileage.

Probability says that some springs will fail for no apparent reason at low numbers of cycles and other springs will have infinite life at the same stress levels.

If you had to change valve springs every two years with a stock GM engine it would be in your owners manual.
 

·
Registered
Joined
·
437 Posts
Discussion Starter #15
Thanks for all of the replies. I'm sure quite a few of us have worried about this problem, since it appears to cause catastrophic results.
John
 

·
Registered
Joined
·
4,384 Posts
I have almost 50,000 miles on my bolt-ons only '01 z06 w/ about 10 HPDE's on her and lots of hard driving. I don't take it over 3000 rpms until the oil temp hits 150 on the DIC every time.
 

·
Registered
Joined
·
9,957 Posts
ZeeOhSix said:
Is that something that could be done by a competent owner? I'm assuming you need to pressurize the cylinder with air when on TDC so the valve springs can be removed and replaced without the valves falling down in the cylinder. Would also need a special tool to remove/install the springs.

Anyone do this at home? If so, please give a few details.
If your car has a stock cam then don't worry about the stock valve springs. IMHO...Just warm the car up to 150 degrees oil temp before you go over 4000 rpms and your car will last for a hundred thousand miles...

If you put in an aftermarket cam and valve springs then its been suggested to change out the springs about every 20K miles....but many go over that...

The valve spring swap is best left to tuners who do this for a living. 300 dollars for parts and labor is money well spent in my opinion. Its so inexpensive...why bother? JMO

Ferrari's maintaince costs are huge comparatively...three hundred bucks is chump change for 400 or more rear wheel hp

When its time I will have TTP who installed my cam and the present valve spring kit replace the springs....
 

·
Registered
Joined
·
214 Posts
ZeeOhSix said:
Is that something that could be done by a competent owner? I'm assuming you need to pressurize the cylinder with air when on TDC so the valve springs can be removed and replaced without the valves falling down in the cylinder. Would also need a special tool to remove/install the springs.

Anyone do this at home? If so, please give a few details.

I wouldn't hesitate to do it myself. Then again i do almost everyhting myself. I found this spring compressor on a quick search. http://www.lmperformance.com/1801/4.html It looks pretty nice and I'm suprised how cheap it is, and it comes with the air fittings. I've swapped valvesprings on other V-8s with the far less elegant pry bar type compressor you screw onto the rocker arm stud, and it's still easy.
 
1 - 19 of 19 Posts
Top