magnetic ride control question....
Thread Starter
Instructor
Joined: May 2009
Posts: 174
Likes: 0
magnetic ride control question....
i was thinking about lowering my rear about an inch. since i have the magnetic ride control feature, would lowering the car (via bolts) have any adversive effects in it? 
Race Director
Joined: Oct 2007
Posts: 11,367
Likes: 211
From: Edgewood Washington
St. Jude Donor '11-'12-'13-'14-'15
Maybe........search is your friend. 
No one (that I've seen) has posted anything quantifying the SOTP result of lowering the F55 suspension.
There was a detailed thread with the technical explanation about how the system would be compromised, which was enough for me not to do it.
YMMV.
No one (that I've seen) has posted anything quantifying the SOTP result of lowering the F55 suspension.
There was a detailed thread with the technical explanation about how the system would be compromised, which was enough for me not to do it.
YMMV.
Last edited by Knob Jockey; Jun 11, 2009 at 09:28 PM.
Race Director
Joined: Oct 2007
Posts: 11,367
Likes: 211
From: Edgewood Washington
St. Jude Donor '11-'12-'13-'14-'15
Some members have done it without any major problem like Active Handling intervention.
The reduced travel of the shock changes the effectiveness of the MR manipulation.
You could try it and always set it back if you felt a "problem".
CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
In my quest to modify the F55 suspension I became acquainted with one of the lead Delphi engineer's responsible for the F55 suspension in the Corvette (Darin Dellinger). The topic was more related to the question of repositioning the F55 sensors in a lowered car but it has some relevance to your question.
"...The position sensors do sense position, but internal to the MR ECU a calculation (differentiation) is made to turn that information into velocity - the rate of change of position with respect to time.
Very simplistically, I’ll say that velocity is really the main signal of interest, as many handling, stability, body and wheel control strategies use this basic information in various ways. Also, don't forget that dampers are velocity devices - even though we usually say the MR device is not really damper, but an actuator. Position is used, too but that information is only critical to a few control strategies. Of course, we have a strategy to do simple position-sensitive damping control, but it's not used in the Corvette.
In the end, regardless of where we're at in the suspension travel, it's the rate of change of the position signal over time that matters - that's why we don't have to change the position sensor mounting when lowering or raising the car.(emphasis added)
Almost everything for MR (sensing, processing, output control, etc.) is done at 1kHz or 1000 times per second.
The main reason I suggest cutting bumpstops is that "free suspension travel" is everything, in my opinion. (I'll define "free suspension travel" as the amount of travel of the shock absorber between full rebound and jounce bumper engagement.) When the car is lowered, compression travel is taken out. The jounce bumper is a secondary spring. It will engage even on relatively smooth roads (emphasis added)(I still remember "discovering" this fact on one of the access roads at the Desert Proving Grounds many years ago, during the course of developing the profile, length and hardness of the C5 jounce bumper). Also, and maybe most importantly, during turning events the jounce bumper may engage, leading to oversteer or possibly understeer - and sometimes we can be snookered into thinking the oversteer/understeer is coming from another source like the main suspension spring rate or the stab bar or tire pressures or ?? (another story: the CERV IV had terrible max lat numbers for some time. Everybody was really upset, because these numbers were really low. Turns out, the jounce bumper was simply too long in the rear. Spring rate goes up, traction goes down.)..."
"...The position sensors do sense position, but internal to the MR ECU a calculation (differentiation) is made to turn that information into velocity - the rate of change of position with respect to time.
Very simplistically, I’ll say that velocity is really the main signal of interest, as many handling, stability, body and wheel control strategies use this basic information in various ways. Also, don't forget that dampers are velocity devices - even though we usually say the MR device is not really damper, but an actuator. Position is used, too but that information is only critical to a few control strategies. Of course, we have a strategy to do simple position-sensitive damping control, but it's not used in the Corvette.
In the end, regardless of where we're at in the suspension travel, it's the rate of change of the position signal over time that matters - that's why we don't have to change the position sensor mounting when lowering or raising the car.(emphasis added)
Almost everything for MR (sensing, processing, output control, etc.) is done at 1kHz or 1000 times per second.
The main reason I suggest cutting bumpstops is that "free suspension travel" is everything, in my opinion. (I'll define "free suspension travel" as the amount of travel of the shock absorber between full rebound and jounce bumper engagement.) When the car is lowered, compression travel is taken out. The jounce bumper is a secondary spring. It will engage even on relatively smooth roads (emphasis added)(I still remember "discovering" this fact on one of the access roads at the Desert Proving Grounds many years ago, during the course of developing the profile, length and hardness of the C5 jounce bumper). Also, and maybe most importantly, during turning events the jounce bumper may engage, leading to oversteer or possibly understeer - and sometimes we can be snookered into thinking the oversteer/understeer is coming from another source like the main suspension spring rate or the stab bar or tire pressures or ?? (another story: the CERV IV had terrible max lat numbers for some time. Everybody was really upset, because these numbers were really low. Turns out, the jounce bumper was simply too long in the rear. Spring rate goes up, traction goes down.)..."
_Sloth Whisperer_
Joined: Jul 2008
Posts: 3,369
Likes: 9
From: Malaysia Air Flight 370
Have it, did it, enjoying it.
My F55 C6 showed no discernable adverse characteristics after cranking my stock bolts all the way up into the leaf springs, far as they'd go. No error messages, no unexpected results.
I have a set of Pfadts on the way though, and will be using the Casper's F55 manipulators to keep the Active Handling nanny occupied. Allows me to return the car to fully stock should I decide to sell it F55-equipped.
My F55 C6 showed no discernable adverse characteristics after cranking my stock bolts all the way up into the leaf springs, far as they'd go. No error messages, no unexpected results.
I have a set of Pfadts on the way though, and will be using the Casper's F55 manipulators to keep the Active Handling nanny occupied. Allows me to return the car to fully stock should I decide to sell it F55-equipped.
