355: suspension differences

+1

 

Lots of confusion and I was obviously not alone in not really feel a clear mode difference. But I'll drop it as a faulty system. The light #19 is not on either which seems to be faulty system indicator.

 

Guys, here are the differences in the programs:

http://www.ferrarichat.com/forum/attachments/348-355-sponsored-bradan/1090264d1266568726-f355-sport-suspension-setting-susp.jpg

It shows that the comfort vs. sport setting is very different starting at 40 km/h and then gradually gets closer as speeds ramp up. Looks like beyond 200km/h they no longer adapt and stay at their respective angles. The other lines (sense S and sense C) may indicate that the actuators go to those settings if you hit a preset G force in for-aft or lateral directions (not sure which or at what point) and looks like if there's an error they all default to 56 degrees.

 

Why would you think that? It matches my owners manual (1997) illustrations (and description of function of the switch) (as also shown in post #16 in this thread, which is a copy from a 1998 USA F355 owners manual), as well as matches my two friends 1997 F355 spider dashes as well.

 

I think it's because past threads have resulted in 1995-light-on=comfort. 1996-1999-light-on=sport. Not saying it's right or wrong. That's just what I took away from the 14 or so threads on the topic, and can see why he would think that.

 

Because every 95 that I've seen shows a little shock on the dash for the light, and all others that I've seen 96 and up have the word sport on the dash for the light.But who knows with Ferrari anything can happen maybe they were using left over dash's for some newer cars.
My 99 owners manual shows the word sport

 

You cant have both the sport light and the the little shock light. it's one of the two.. on the left side of the dash.The light that your seeing with the car on top with too little shocks on your right side of the dash is your suspension light telling you that you have a problem.

 

I have a 1996. Light on is comfort. Light off is sport. Its an early '96 so clearly some 96's are like the 95's.

 

When your light is on. the left side of the dash is it a picture of a shock,or does it say the word sport?

 

I thought that the switch controlled the actuator on the shocks and dialed in a stiffer setting. I doubt you're going to notice it unless she's being pushed.

 

It has been a long time since I reviewed the subject, but I recall the symbols on the dash, as well as the default setting varied based on year, model (spider versus B or GTS), F1 or manual and country/market. While Ferrari has done some various incongruous things, I don't think your assumption would apply in this case.

 

It does, see post 28. You should actually notice the largest difference at speeds between 40km/h and 70km/h.

 

I think this is correct, maybe along the lines of spider default position (no light) is comfort and gtb default is sport? Not sure on the GTS's.

 

Default on my 1997 F355 spider is "Sport". Flipping the switch and activating the light (symbol of shock) is comfort setting.

 

Interesting, maybe an f1 vs. 6 speed difference? That or there really is no rhyme or reason to it, which wouldn't surprise me much.

 

Mine is a 97 Spider and as everyone with a 97 spider has said it have a picture of a shock for the light not the word sport. My 97 owners manual shows this is the way it should be and in section F page 10 it clearly shows which way is sport and which way is comfort with pictures of the switch position. My light comes on when I flip it down to comfort mode. I can't scan but will attach a picture.

Seems like they made every other car different so it would probably be best to check the respective owners manual for the year/ model of car if you have it.
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Another great reason to buy an F1 lol.

 

It shows a picture of a shock.

 

Yes, sport is default. I have figured that out too now. Anyhow, the difference is minor between sport and comfort. It's not at all as in my old Volvo V70R. Good or bad...?!

 

Any more wording? This doesn't explicitly state that illuminated = on or off, just that it's an amber light for the comfort setting.

My 1997 355 Spider has been in the shop for a while so I don't have access to its manual right now.

 

The F355 active damping system is misunderstood for sure; I field questions about its operation all the time...

The system works well, it's the first active damping system put into road car volume production by Ferrari (with technical partner Bilstein), subsequently every road car since has some version of active damping as the technology has evolved.

Q: I can't feel a difference between the two modes

A: Under certain driving conditions this is not surprising. If one were to switch modes whilst driving on fairly smooth pavement, especially something like Interstate/ Motorway driving where cornering is almost a non-event it would be very difficult to discern differences.

Why? Because the shocks are not moving all that much under these conditions, perhaps less than 1 inch/ sec, and without lateral acceleration the computer is told to adjust very little.

The previously posted graph from the WSM only tells part of the programing: adjustment related to road speed only. The active damping system also monitors lateral and vertical acceleration plus throttle position. So under high cornering forces and bumpy conditions the program is also adjusting accordingly. The WSM graph should look more like the ECU topographical map of fuel injector open time, with the above variables on different axes.

The true test is to find choppy pavement, then the chassis experiences short but high velocity inputs so you'll feel the difference. Another method is driving on track.

Also, keep in mind that the system never quite goes to the extreme settings of 0° or 90°.

The adjuster moves a wedge shaped valve that controls oil flow past the main piston valving and meters oil past specific discs just to control the bypass (aka "bleed") oil flow.

Attached image is actually from a Mondial T, I don't have a good quality image on this computer for F355. The Mondial T adjuster is Generation One of this system, the adjuster wedge is shaped differently and the shock rod doesn't have additional flow control discs for bleed, just an open port as seen in the photo. Mondial T also adjusts over about 270° vs about 90° for F355. The change was made to improve response time.

This system is misunderstood so much that virtually every F355 Challenge we've worked with has the system removed from the car....

Best,
Rob
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The system can fault and not cause a suspension error light to illuminate. The computer only monitors electronic sensors and actuators: accelerometer, solenoid motors, and any continuity issues...

It cannot sense leaks or hydraulically locked dampers. That's where a road test, bench compression and visual inspection come in. Ideally testing on a shock dynamometer tells the whole story but that's typically not feasible.

Bumper pushing only tests the gas force in the shock and low speed damping. A better field test is to remove the shock and compress it by hand, with the adjuster full soft and full hard. Most telling is if the damper doesn't compress to the point where only about 3/4 inch of chrome shock rod is seen. If more than about 3/4 inch shows and it won't compress by hand any more, the shock has leaked a lot of oil and is definitely malfunctioning.

The good news is we've received shocks completely empty of oil after neglect and successfully rebuilt them without difficulty.

Also common is that the dampers produce more force as they age due to oil degradation, after rebuild their more compliant, and offer improved grip as the tires follow the road more effectively.

Best,
Rob

 

+1 .... thanks for posting ......

 

From what I can tell there is a difference between 6 speed and F1 cars. For 6 speeds the icon is a shock, the default is sport and the light illuminates when switched to comfort. For the F1 the switch and light are labeled SPORT, the default is comfort and the light illuminates when sport is selected. I'm not 100% sure on the default for F1 cars, but it seems logical that comfort would be the default since when placed in sport mode the F1 trans is supposed to shift faster and harder.