Need to figure out diff in ride height w/HAL shocks
08-29-2006, 07:14 PM
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Need to figure out diff in ride height w/HAL shocks Did a search and couldn't find anyone describe this problem. I've had a pair of front 12-way adj HAL QA1 shocks and HAL drag springs and have been happy with them. Recently, the pass side front side has started sagging to the point that I've had to raise the spring perch twice to raise that side of the car and have it ride level.
I'm not talking a diff of just a 1/4" or so. I've got a difference of over 1 1/2" inches in the spring perch positions. Damn! The driver side perch is about 2 inches down from the top of the threads while the pass side is 1/2 inch from the top of the threads. Both shocks are set to the same rebound setting and changing the settings makes no difference....
What the hell is sagging, the spring or the shock is shot?
BTW: The car is a 2002 T/A M6 with 70,000 miles, 30,000 miles on the shoch/spring combo. Never crashed, drives straight.
I'm not talking a diff of just a 1/4" or so. I've got a difference of over 1 1/2" inches in the spring perch positions. Damn! The driver side perch is about 2 inches down from the top of the threads while the pass side is 1/2 inch from the top of the threads. Both shocks are set to the same rebound setting and changing the settings makes no difference....
What the hell is sagging, the spring or the shock is shot?
BTW: The car is a 2002 T/A M6 with 70,000 miles, 30,000 miles on the shoch/spring combo. Never crashed, drives straight.
08-31-2006, 06:14 PM
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I'd swap the springs from one side to the other, but it's such a pain in the ***, to compress/decompress the spring, disassemble/reassemble the strut, remove and re-install everything just to find out and then, worst of all just go and have to do it all over again to replace either the bad spring or shock.
I'm sure someone has seen this before, was hoping to avoid a shitload of non-mod work...
I'm sure someone has seen this before, was hoping to avoid a shitload of non-mod work...
09-01-2006, 11:04 AM
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LOL, I'm blown away by the responses...
Well, I guess I'll share my findings so that someone else can avoid this issue in the future.
I just got an e-mail from HAL in which the Tech has analyzed my particular scenario after requesting the part numbers of what I have installed. He concludes that the springs I have (which are the 275lbs springs) are not designed for a full weight f-body. He recommended the 325lbs for my case. Apparently, the 275lbs are designed for cars that have undergone "significant" weight reduction, while the 300lbs are for cars with "mild" weight reduction.
I hope anyone who is thinking of ordering a HAL shock/springs combo, reads this before ordering the incorrect spring rate for their ride...
Thunder Racing should probably add something to their site in reference to this possible problem, too.
Now, don't go tripping over yourselves to chime in next time...j/k
Well, I guess I'll share my findings so that someone else can avoid this issue in the future.
I just got an e-mail from HAL in which the Tech has analyzed my particular scenario after requesting the part numbers of what I have installed. He concludes that the springs I have (which are the 275lbs springs) are not designed for a full weight f-body. He recommended the 325lbs for my case. Apparently, the 275lbs are designed for cars that have undergone "significant" weight reduction, while the 300lbs are for cars with "mild" weight reduction.
I hope anyone who is thinking of ordering a HAL shock/springs combo, reads this before ordering the incorrect spring rate for their ride...
Thunder Racing should probably add something to their site in reference to this possible problem, too.
Now, don't go tripping over yourselves to chime in next time...j/k
09-01-2006, 11:55 AM
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The answer your vendor provided makes little sense. The stress in the spring when holding up the car and the spring rate are different things. If you had a spring that sagged in a short period of time it was either faulty materials, processing, or design. You do not need a stiffer spring to safely hold up your car. Low rate springs would be used in a lighter car, sure, but being overstressed by a full weight car? Those are very poor quality parts. Hopefully the new ones are designed properly. Never confuse "race" parts for quality. I would suggest you go elsewhere for the springs.
09-01-2006, 10:25 PM
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I think it makes a lot of sense. After an enlightening discussion with the HAL Tech, here's what I think:
1) The spring IS what holds up the car. Not the shock. A shock is just a dampening device that slows down the travel of the piston thru the tube using gas/oil as a friction medium. Hypothetically, if you were able to compress a shock using just your hands on the floor and then release your hand from the rod, the rod will not rebound by itself. It will stay in that same position. Try compressing and pulling the rod out fast, though...
2) A spring will hold the weight of the car at the exact point where the force of gravity being exerted on the car (which is resting on the springs) is cancelled out by the internal spring tension that builds while being compressed. That spring tension and resistance to deformation (either by elongation or compression) is a direct function of type of material, diameter of the spring loops, and shape. Like all materials subjected to constant deformation the above indicated variables will determine how long the spring can resist deformation and return to it's original shape (ride height). A 275lbs spring is NOT the same as a 300lbs, nor is it the same as a 325lbs one. The higher the spring rate in lbs, the more resistant it is to deformation and metal fatigue.
4) The e-mail and subsequent phone conversation (see excerpts above) were with a tech from HAL (the manufacturer) not a vendor. I would consider his opinion a qualified one. Matter of fact, I just did a search on "HAL 275" and found several posts discussing precisely this issue. What is interesting is that the overall common theme is that 275s are not suitable for a street driven full-weight f-body. The 300lbs seem to be better suited for that purpose, with some even recommending 325lbs for street-driven applications where hard cornering is frequent.
My mistake was not doing my homework before ordering the springs in the first place.
1) The spring IS what holds up the car. Not the shock. A shock is just a dampening device that slows down the travel of the piston thru the tube using gas/oil as a friction medium. Hypothetically, if you were able to compress a shock using just your hands on the floor and then release your hand from the rod, the rod will not rebound by itself. It will stay in that same position. Try compressing and pulling the rod out fast, though...
2) A spring will hold the weight of the car at the exact point where the force of gravity being exerted on the car (which is resting on the springs) is cancelled out by the internal spring tension that builds while being compressed. That spring tension and resistance to deformation (either by elongation or compression) is a direct function of type of material, diameter of the spring loops, and shape. Like all materials subjected to constant deformation the above indicated variables will determine how long the spring can resist deformation and return to it's original shape (ride height). A 275lbs spring is NOT the same as a 300lbs, nor is it the same as a 325lbs one. The higher the spring rate in lbs, the more resistant it is to deformation and metal fatigue.
4) The e-mail and subsequent phone conversation (see excerpts above) were with a tech from HAL (the manufacturer) not a vendor. I would consider his opinion a qualified one. Matter of fact, I just did a search on "HAL 275" and found several posts discussing precisely this issue. What is interesting is that the overall common theme is that 275s are not suitable for a street driven full-weight f-body. The 300lbs seem to be better suited for that purpose, with some even recommending 325lbs for street-driven applications where hard cornering is frequent.
My mistake was not doing my homework before ordering the springs in the first place.
Last edited by BigBirdTA; 09-01-2006 at 10:32 PM.
09-02-2006, 09:57 PM
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You are correct, the shock holds no weight. It is a damper only.
Your original complaint was that the car required a large adjustment to keep the car level. This means the spring was sagging. Springs can fatigue and/or creep, they are different. A sagging spring that is corrosion free and has no cracks is creeping, its operating stress is higher than the material creep strength. You have garbage springs. It has nothing to do with the spring rate. There are many options for lowering the stress in the spring without altering the rate. A combination of increasing the wire size and adding coils or increasing the wind radius will lower the stress. The other option is to use better wire material. The designer of your springs did none of these things. The fact that the higher rate springs work out better for people has nothing to do with the spring rate at all, just that the operating stress in the metal is lower than the creep stress point.
Fatigue is a phenomenon where a material flaw progessively gets larger and at some point causes a failure to occur, this is not creep or yielding however.
Your original complaint was that the car required a large adjustment to keep the car level. This means the spring was sagging. Springs can fatigue and/or creep, they are different. A sagging spring that is corrosion free and has no cracks is creeping, its operating stress is higher than the material creep strength. You have garbage springs. It has nothing to do with the spring rate. There are many options for lowering the stress in the spring without altering the rate. A combination of increasing the wire size and adding coils or increasing the wind radius will lower the stress. The other option is to use better wire material. The designer of your springs did none of these things. The fact that the higher rate springs work out better for people has nothing to do with the spring rate at all, just that the operating stress in the metal is lower than the creep stress point.
Fatigue is a phenomenon where a material flaw progessively gets larger and at some point causes a failure to occur, this is not creep or yielding however.
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09-03-2006, 06:43 PM
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>>>You have garbage springs. It has nothing to do with the spring rate.<<<
Of course it does. It's basic materials engineering.
Material creep is occurs in three stages, with stage I being pronounced and short-lived, happening as soon as load is applied at operating temperature. That's why new springs usually require a few weeks to finally "settle" at their expected ride height and then stay there over a long period of time.
Once the material has undergone it's Stage I creep, with load being relatively constant and temperature, it slows to what's called stage II creep, also called steady-state creep. Perceived (and measurable) as being generally "stable" with creep slowed down to an acceptable rate (but never stopped entirely) over the expected operating life of the object/structure.
After Stage II or "steady-state" material creep has effected a critical amount of deformation, you have what's called tertiary or accelerating (Stage III) creep which usually quickly progresses to fracture.
The key to understanding this particular case is that at a given load and temperature the stage II creep can be longer or shorter. It all depends on how close the load excerting strain on the material initially is to that point at which "steady-state" creep progresses into "tertiary" or accelerated creep.
My understanding now is of this issue is that putting a 275lb spring on a full-weight f-body will result in an unacceptably short Stage II or "steady-state" creep, which probably could be measured in terms of low thousanths (1/1000's mm) of creep per day. A short Stage II makes the failure/fracture point arrive sooner.
With load and temperatures being relatively constant, a 300lbs or 325lbs spring will result in a slower Stage II creep rate, which will be perceived as a much longer "steady-state" or longer operating life in plain english.
Of course it does. It's basic materials engineering.
Material creep is occurs in three stages, with stage I being pronounced and short-lived, happening as soon as load is applied at operating temperature. That's why new springs usually require a few weeks to finally "settle" at their expected ride height and then stay there over a long period of time.
Once the material has undergone it's Stage I creep, with load being relatively constant and temperature, it slows to what's called stage II creep, also called steady-state creep. Perceived (and measurable) as being generally "stable" with creep slowed down to an acceptable rate (but never stopped entirely) over the expected operating life of the object/structure.
After Stage II or "steady-state" material creep has effected a critical amount of deformation, you have what's called tertiary or accelerating (Stage III) creep which usually quickly progresses to fracture.
The key to understanding this particular case is that at a given load and temperature the stage II creep can be longer or shorter. It all depends on how close the load excerting strain on the material initially is to that point at which "steady-state" creep progresses into "tertiary" or accelerated creep.
My understanding now is of this issue is that putting a 275lb spring on a full-weight f-body will result in an unacceptably short Stage II or "steady-state" creep, which probably could be measured in terms of low thousanths (1/1000's mm) of creep per day. A short Stage II makes the failure/fracture point arrive sooner.
With load and temperatures being relatively constant, a 300lbs or 325lbs spring will result in a slower Stage II creep rate, which will be perceived as a much longer "steady-state" or longer operating life in plain english.
Last edited by BigBirdTA; 09-03-2006 at 06:49 PM.
09-03-2006, 09:05 PM
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Damn, now you're making me laugh 
. Your technical expertise seems to be growing geometrically since the beginning of the thread.
However, spring rate and stress can be adjusted differently by design. If you don't believe me, read up on spring design as you seem to have done for creep. Saying that a 275 lb/in spring cannot be used is just inaccurate. If your spring is poorly designed, maybe. In fact read more carefully what you quoted.
By design, you should make the strain much lower than what your springs apparently are, problem fixed.
Anyway, I am done here.
. Your technical expertise seems to be growing geometrically since the beginning of the thread. However, spring rate and stress can be adjusted differently by design. If you don't believe me, read up on spring design as you seem to have done for creep. Saying that a 275 lb/in spring cannot be used is just inaccurate. If your spring is poorly designed, maybe. In fact read more carefully what you quoted.
Originally Posted by BigBirdTA
It all depends on how close the load excerting strain on the material initially is to that point at which "steady-state" creep progresses into "tertiary" or accelerated creep.
Anyway, I am done here.
