WARNING: Shock measurement GM vs Aftermarket measure differently!
10-21-2016, 05:39 PM
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WARNING: Shock measurement GM vs Aftermarket measure differently! I am currently having the entire suspension replaced/fully tricked out due to wear/age of stock 15-year-old components. Currently the car is in the shop. During install, the mechanics were trying to get the ride height dialed in, (installing QA1 double adjustable via Spohn) and we found out that the lowest we could get the tire-wheel well gap was 4-6 fingers. Additionally, we noticed that the suspension had significantly reduced travel from max expansion to max compression (~ 1/2 inch) this was done with correct proper install!
In trouble shooting with Spohn (thanks Dan!) We were asked to get the measurements of the max expansion of my factory SLP Bilstein and compare to the QA1 coil over for Camaro/Firebird. Upon measurement we got roughly the same length for max expansion for both (~19.5") BUT the QA1 still had reduced travel!!! Getting into the details we (The shop, Spohn, & QA1) discovered that what GM considers proper measurement is from bottom bolt of lower arm, to the top rubber bushings and for the QA1 and aftermarket industry considers proper measurement, where bushings are in GM specs but upon install of the shock where the bushings are on stock shocks, there is an triangular hinge (from spohn, QA1 uses something different, but both are unaccounted for in measurements) that connect there, in which is size is NOT accounted for, yet is installed!. Various Aftermarket uses different attachments to the body, but the end hinge is not accounted for in the measurements, leading to a 2 inch reduction of coil over suspension travel of installed shocks
(gist is shaft of shock is ~2 inches to long if you follow existing recommendations)!
The solution was to have QA1 overnight a next size smaller coil over system (17" max travel and 10 spring vs 19.5 max travel & 12 inch spring, as the very nice setup from Spohn had to go back as they didn't have anything that would fit). Just a heads up for FYI, to take into account bracket length from supplier as GM doesn't have said bracket! This solution allows for full wheel-well ride height adjustment from 1-2 fingers to 4-6+ as previously minimum was 4 fingers and not enough shock compression! what turned into a 2 day install turned into a 2 week endeavor. Hope my experience helps future folks!
If interested I can get the spring rates, spring length, and shock length we are going with (I think we are going with 170# rear vs 125# due to smaller length shock, forget front)
In trouble shooting with Spohn (thanks Dan!) We were asked to get the measurements of the max expansion of my factory SLP Bilstein and compare to the QA1 coil over for Camaro/Firebird. Upon measurement we got roughly the same length for max expansion for both (~19.5") BUT the QA1 still had reduced travel!!! Getting into the details we (The shop, Spohn, & QA1) discovered that what GM considers proper measurement is from bottom bolt of lower arm, to the top rubber bushings and for the QA1 and aftermarket industry considers proper measurement, where bushings are in GM specs but upon install of the shock where the bushings are on stock shocks, there is an triangular hinge (from spohn, QA1 uses something different, but both are unaccounted for in measurements) that connect there, in which is size is NOT accounted for, yet is installed!. Various Aftermarket uses different attachments to the body, but the end hinge is not accounted for in the measurements, leading to a 2 inch reduction of coil over suspension travel of installed shocks
(gist is shaft of shock is ~2 inches to long if you follow existing recommendations)!
The solution was to have QA1 overnight a next size smaller coil over system (17" max travel and 10 spring vs 19.5 max travel & 12 inch spring, as the very nice setup from Spohn had to go back as they didn't have anything that would fit). Just a heads up for FYI, to take into account bracket length from supplier as GM doesn't have said bracket! This solution allows for full wheel-well ride height adjustment from 1-2 fingers to 4-6+ as previously minimum was 4 fingers and not enough shock compression! what turned into a 2 day install turned into a 2 week endeavor. Hope my experience helps future folks!
If interested I can get the spring rates, spring length, and shock length we are going with (I think we are going with 170# rear vs 125# due to smaller length shock, forget front)
Last edited by Rhode Island Red; 10-21-2016 at 05:58 PM.
10-22-2016, 10:49 PM
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before you replace shocks/ spring: Measure (or know your) existing max extension length and maximum compression. If stock, verify how top of shock attaches to body (bushings vs bracket or other). Stock GM measure includes up to where the top installs
When you install new shock/ coil over system, verify that the range of motion is not reduced compared to what you had on before! Even lowered (slammed to floor, a proper setup should never reduce range of motion of shock/coil over!)
The definition of what GM considers the measurement of the shock is based upon their connection setup to the car. If an aftermarket supplier, says same exact measure for your car, but has a different connection type vs stock, ensure that the overall length, different bracket be damned, is included in the length.
when car is done, I'll have 1-2 fingers in wheel well, and full range of motion for coil over system, no bottoming out, nicer ride, and full performance whether canyon carving, drag racing autocross, or Silver State Classic (one year, one year... )
A shock install should NEVER result in less range of motion of the shocks/springs!
When you install new shock/ coil over system, verify that the range of motion is not reduced compared to what you had on before! Even lowered (slammed to floor, a proper setup should never reduce range of motion of shock/coil over!)
The definition of what GM considers the measurement of the shock is based upon their connection setup to the car. If an aftermarket supplier, says same exact measure for your car, but has a different connection type vs stock, ensure that the overall length, different bracket be damned, is included in the length.
when car is done, I'll have 1-2 fingers in wheel well, and full range of motion for coil over system, no bottoming out, nicer ride, and full performance whether canyon carving, drag racing autocross, or Silver State Classic (one year, one year... )
A shock install should NEVER result in less range of motion of the shocks/springs!
10-23-2016, 05:26 AM
#4
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You must not have researched about qa1 on here, because i have bad news for you, the only thing that its going to be good at is drag racing as they are non-gas charged drag shocks that some falsely label as "protouring". Ride and handling will be floaty and disconnected, while being either really soft or overly hard with no in between. You were way better off with slp bilsteins.
10-23-2016, 09:35 AM
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I have 12 inch Viking coilovers on the front of my car and i can easily put the wheel inside the wheel well, so I wouldn't go around telling everyone they need a 10" spring for the front of these cars.