Why would a spring go at only 5K?
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Staging Lane
Joined: Oct 2003
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Why would a spring go at only 5K? I'm trying to understand why a spring would let go and drop a valve at only 5K turns. Car is an M6 with FLP's and MTI C2 (224/224 .581 112) which were installed with Manley springs and Manley tit retainers.
Car wasn't cold (happened just downshifting coming off highway after driving a while) and oil level is good. It's fixable but I want to understand all the variables so I avoid repeating the experience.
Just a fluke? or are other reasons possible?
Car wasn't cold (happened just downshifting coming off highway after driving a while) and oil level is good. It's fixable but I want to understand all the variables so I avoid repeating the experience.
Just a fluke? or are other reasons possible?
Could have been a weak spot in the spring, or a slew of other things. Any possibility it over revved and you only caught the tac at 5k and maybe it revved higher than it should have? Granted if it had done that it might have done more damage but I figure its always a possibility 
TECH Resident
Joined: Nov 2002
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From: Orlando
Not if there was a faulty area in the springs preperation from the factory. If I were you, I would call the vendor and give them the lot number of the spring and see if there were any other failures with someone else. I think the C2 is an XE-R grind, too. That combined with fast ramp rates can cause springs some strain. Ask around.
I broke 3 REV springs a while back in only a few thousand miles. I was told it was a bad batch of springs. We all have see a very high spring failure rate on these engines with high lift cams, so my opinion is that the aggressive ramp rate and high lift is just a little too much to ask out of a 1.25" OD spring. I think the real answer is to machine for a larger spring and then ther should be no worry. Another observation I made was with an older set of Morgan heads I had on my car. They really gained little between .500 and .550 and fell off drastically above .550 causing pulsation. With this data, I belive that my next cam will be in the .530 to .550 range and hopefully there will be little horse power lost and no spring failures. Just something to ponder.
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Staging Lane
Joined: Oct 2003
Posts: 71
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From: Florida
Someone mentioned bad harmonics with the spring in a previous post. A lot of companies today are pushing these single beehive springs for LS1's. Single springs for hi-reving motors suck! At high RPM the spring hovers around it's adverse harmonic and can fatigue very quickly.
The way to go for these engines is with a good dual spring. The two springs work together to protect each other from harmonics through the RPM range, much the way a dmaper does in traditional single and dual springs. The added benefit of the dual is that if in the worst case scenario you break a spring, teh second spring will keep the valve up nd won contact the piston causing major engine damage.
Dual springs are also stronger and better able to handle more aggressive lobe ramps.
It's possible that your spring could have come from a bad batch, but it might be more likely that the spring fatigued from being around it's fatal harmonic too much. If the spring is surging or close to surge, it will make a ton of heat and this will fatigue the spring material very quickly.
Another point about these beehive single springs. The top of the spring where the smaller coil is over a larger one, this makes a severe stress point in the spring. This is because you have these two different size coils smashing into each other at various RPM's, and everyone knows that whe you have coils rubbing together you have instant stress points ripe for failure.
Save cylinder head machining, go with one of the good dual springs that are out on the market.
The way to go for these engines is with a good dual spring. The two springs work together to protect each other from harmonics through the RPM range, much the way a dmaper does in traditional single and dual springs. The added benefit of the dual is that if in the worst case scenario you break a spring, teh second spring will keep the valve up nd won contact the piston causing major engine damage.
Dual springs are also stronger and better able to handle more aggressive lobe ramps.
It's possible that your spring could have come from a bad batch, but it might be more likely that the spring fatigued from being around it's fatal harmonic too much. If the spring is surging or close to surge, it will make a ton of heat and this will fatigue the spring material very quickly.
Another point about these beehive single springs. The top of the spring where the smaller coil is over a larger one, this makes a severe stress point in the spring. This is because you have these two different size coils smashing into each other at various RPM's, and everyone knows that whe you have coils rubbing together you have instant stress points ripe for failure.
Save cylinder head machining, go with one of the good dual springs that are out on the market.
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Thread Starter
Staging Lane
Joined: Oct 2003
Posts: 50
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I can't believe this stuff is so fragile!
Springs went thru at least 2 weeks of daily heat/cooldown cycles before I even stepped on it. And then, I don't take it to the track or abuse the car in any other way (I hardly think 5K RPM for a *brief* period during downshifting is "abusing" the car). The whole setup had a total of only 4-5 weeks on them total!!!!
Jeez, I went with both the Manley springs and retainers in the first place "because they are good springs for high lift cams, and bla, bla, bla". In fact I ordered the complete set (cam + springs + retainers + pushrods) from MTI directly as a matching set, precisely to AVOID this kind of cr*p!!!
Quote from their site: "MTI Valvetrain Package (For use with performance camshafts on stock cylinder heads. Includes Manley springs, titanium retainers & MTI hardened push rods.)"
I wonder now if MTI will stand behind this stuff. Not to mention any damage to my motor.
Springs went thru at least 2 weeks of daily heat/cooldown cycles before I even stepped on it. And then, I don't take it to the track or abuse the car in any other way (I hardly think 5K RPM for a *brief* period during downshifting is "abusing" the car). The whole setup had a total of only 4-5 weeks on them total!!!!
Jeez, I went with both the Manley springs and retainers in the first place "because they are good springs for high lift cams, and bla, bla, bla". In fact I ordered the complete set (cam + springs + retainers + pushrods) from MTI directly as a matching set, precisely to AVOID this kind of cr*p!!!
Quote from their site: "MTI Valvetrain Package (For use with performance camshafts on stock cylinder heads. Includes Manley springs, titanium retainers & MTI hardened push rods.)"
I wonder now if MTI will stand behind this stuff. Not to mention any damage to my motor.
Last edited by newbie_tace02; Dec 6, 2003 at 01:46 AM.
Remember the tach in these cars is pretty lazy. Even though it said 5K rpm it may have peaked a lot higher. As I understand it, you were down shifting to de-accelerate, not speed up. So in this case the engine is mechanically forced by the weight of the car to spin a certain rpm so the rev limiter can't help you.