I have the FX3 on my 95 & I never really noticed a difference until I started drivng on twisty roads. Even then the difference was not dramatic. Did a little experimentation. At highway speeds the suspension seems stiffer when in sport or performance.

The system does a self check on initial start, so if your not getting any "service ride control" on your DIC the system is ok. Yes, the ride on mine is also hard, but thats a Corvette.

 

The Selective Ride Control system is controlled by it's own computer. As delivered, it used special Bilstein shock absorbers. The 4 shocks are only part of the system however. There are dampening adjustment motors and position feedback sensors at each shock that monitor the rotary position of an actuator shaft and if their outputs are not what the computer expects to see, you get a SRS trouble light.

The computer also looks at the vehicle speed sensor plus checks itself. You get the SRS trouble light if there are problems with those systems as well.

The shocks have variable diameter orifices that control how fast the shocks can move up and down. The orifice size is controlled by adjusting a shaft that extends through the top of the shock absorber. The shaft is turned left and right by the actuator mounted on the top of the shock. There is a dampener adjusting motor on each shock that cranks the shaft left or right plus a sensor that reads the position of the shaft and feeds that information back to the SRS system computer.

Based on the input from the driver's select ride switch, the vehicle speed sensor and the position feedback sensor, the computer sends battery voltage to the dampening adjustment motor to move it to the appropriate position.

Power on Checks and System Monitoring

Immediately after receiving power (when you turn the ignition key) the SRC computer does a power on check and if it finds a problem, it lights the Selective Ride System light on the DIC (Driver's Information Center). If all is OK, it does not light the light and presets the shocks to a 60 degree initial position (the full range is 0 to 160 degrees). If things go badly after the initial power on sequence, the light will come on when the problem occurs and go off when the computer is satisfied that things are OK. A trouble code is stored for later retrieval if the problem is intermittent.

Suspension Control

As the speed changes, the computer looks at what kind of ride you have selected and cranks the shaft around to what it thinks is the proper match of shock travel and dampening versus speed based on the selection you made with the three position selective ride switch located within easy reach of the driver's position.

The system is designed such that the dampening rate increases with vehicle speed and decreases as you slow down. In effect, it monitors the degree of stiffness requested by the driver and the speed of the vehicle. It then sends either + or - battery voltage to the dampening motors on the shocks and monitors how the shocks are responding to the commands using the position sensor information.

The result is a constantly changing suspension setup, tuned to the conditions present at the time, instead of a compromise solution tuned to one standard set of conditions. In other words: an active suspension.

Troubleshooting the FX-3 Suspension

If you have a service manual, there is a section that explains how to retrieve any stored trouble codes from the SRS computer which is the first step in repairing the system plus there are troubleshooting charts that walk you through a logical repair procedure based on conditions observed or measured.

On the the early model, all digital dash C4s (which were made through 1989), plus any other mid model year C4s that had a 12 pin ALDL connector, you ground pins A & B on the ALDL connector under the dash just to the right of the steering wheel and count the flashes on the SRS light to see if any trouble codes have been stored. On all C4's with a 16 pin ALDL connector (except the 1996 model), you ground pin G and the trouble codes for the SRS computer will be displayed on the LCD screen that doubles as your trip odometer and speedometer. The appropriate service manual describes exactly how to extract the codes for either system as well as explaining what the codes mean.

Without the computer codes, you are shooting in the dark if you try to troubleshoot a FX-3 problem but a couple possibilities are bad grounds or battery wires going to the dampening adjustment motors or bad ground/signal leads coming from the position sensors to the computer. So, first you should check all connectors associated with each shock and make sure they are not corroded or dirty. Wiggle each of them in turn and see if the problem goes away. If it does, you have a bad connection to deal with.

Another possibility is the driver transistors in the SRS computer itself. If the computer commands the dampening motor to move but the driver transistors are bad or leaky, nothing will happen (or not enough will happen), the expected results will not be fed back by the position sensors, and the SRS trouble light will come on. Changing the actuators or shocks will not correct this sort of failure, you must repair or replace the computer itself.

Lastly, if you install a High Energy Ignition and coincidentally begin to have problems with your Selective Ride System, the wiring from the HEI is cross talking into the SRS wiring. Reroute the wires from the HEI so that it does not run parallel to any OEM wiring and try relocating the HEI control box to a different location to minimize the problem.

One final thought: like most electrical problems with a C4, check the connectors first and make sure they are free of corrosion and making good contact before you go on to more exotic solutions. In the absence problems caused by a HEI system, poor connections and/or grounds are where most of the SRS problems originate.

 

Just wanted to follow up to this post. I had my 90,000 mile service last week and the Corvette mechanic told me the shocks are shot. This explains why I feel NO change in suspension when adjusting the ride control.

However here's the question: He states that adjustable ride is somewhat of a farce and going from tour to performance won't shave a second off your track time. I'm not exactly looking to race so that's no matter to me. But he says he typically removes the adjustable ride system and puts on performance shocks, and it will out-slalom any C4 with the FX3 option. Do you agree? What have most of you done?

I would prefer to keep the car original but costs are a concern since spending a lot of money on shocks won't do much to the value of my C4. At the same time it seemed like removing all the actuators and FX3 gear would be labor intensive.

What shocks should I put on? Do I just have him put in Bilstein replacements for the FX3 (which I hear is pretty expensive), or do I have him remove the system and eat it in labor?

I have to admit, this is an area I don't know much about. Any help is appreciated!!!

 

When I switch between modes, I really don't notice any difference in the ride.

Normal

Is there a way to test this? Should the ride feel drastically different between touring and performance?

Find some railroad tracks, and drive over them in the different modes. If the shocks are still working properly, you will feel a difference (no matter what the tech tells you).

During the startup self test, I see the indicator on the dash illuminate then turn off as expected.

Good :thumbsup:

I had my 90,000 mile service last week and the Corvette mechanic told me the shocks are shot. This explains why I feel NO change in suspension when adjusting the ride control.

So the tech looked at the 90k on the clock and just told you the shocks are shot?... Without actually driving your Vette?

But he says he typically removes the adjustable ride system and puts on performance shocks,

But did he say the reason why? No. It is not because the other type of shocks are any better. It is because they are usually cheaper than new FX3 shocks. It is all about money.

 

no not based on the odometer, based on the condition. he did a thorough inspection and it looks like i have the factory shocks still on (after 90k... whoa). since i just got the car a few months ago, i have no idea how is it "suppose" to feel.. and i am curious what the FX3 system feels like when it actually works.

so, another question is: i have been reading all the posts and i see that the standard shocks were the bilstein HD, and the z51 suspension upgrade shocks were bilstein sports. the sports are less expensive compared to the FX3 system. but if you put the FX3 in performance mode, is it better or worse than the z51/bilstein sports? does the FX3 provide flexibility but sacrifice performance on the firm setting?

thanks!

 

The three settings overlap and are speed sensitive. In other words, at 60 mph, the "touring" setting is stiffer than "sport" at 30 mph, but sport will be stiffer than touring at 60 mph.

 

New the shocks are about $735 a set and they perform well when new, keep it original. FX3 is desired option in my opinion. But I'm biased.:cheers:

 

Have a 150 dollar set of KYB installed and send your FX3 shocks to bilstein for rebuilding at 150 per shock.:thumbsup:

 

After reading this thread the other day I drove my Vette in today. It's a 93 Coupe, Auto(It's a RUBY). My tires are getting old and they flat spot after sitting in the garage for a couple of weeks. Coming in today i could feel the tires more in Perf. then in Soft. Not much of a difference, but don't push the car too hard. My tires are getting old, still have lot's of tread, but they are hard and they will spin easy.

 

I once had a c4 with fx3, and I could only tell the difference when I was either on the freeway or on a twisty mountain road. On the freeway, there was definitely more of a floating sensation in touring mode, which got firmer if you switched it to perf and then sport. On winding mountain roads, the sport selection was really obvious to me, there was definitely a difference, the car felt very firm around the curves. If you're just driving through town you won't notice a difference in the three settings.

 

92 c4 actuator maintenance

My 92 had a system malfunction for a while. When the actuators were rebuilt, I was astounded how the ride improved. The system defaults to the firmest (Performance)setting and deactivates when a fault registers. With FX3 when operational, Tour is compliant and bobs a bit, absorbing pot holes and roadway gaps, more like a typical sedan. Sport removes the floating, firms the damping, a good compromise. Performance is tight and hard, communication between vehicle and road is greatest, but ride is harsh. The differences are easy to discern. Too bad one faulty component fouls the whole system.