Re: Suspension Solution? (raycrx)

Quote, originally posted by raycrx »

II leu of simply disconnecting the shocks; why not simply disconnect the accelerometers from the computer that controls the shocks. And then, hypothetically speaking (and someone correct me if they know better) the computer will send a default signal for each given mode ie: shock stiffness; but, would not actively be able to control them since there would not be any input from the sensors. What do ya think?

I think without any signal from the accelerometer the shocks would go into default mode. You'd probably need to use some sort of resistor that sent the correct signal in order to keep the shocks on-line.

 

Re: Suspension Solution? (ChuckV)

That sounds plauseable. Call me overzealous. or Overconfident; but, I think this is a good direction to go. It seems to me that the valve technology and or manufacturing consistancy is just not literally up to speed yet. Does anyone have a good understanding of these types of proceedures. ie sending a dummy signal (neutral) from the accellerometers?

Quote, originally posted by ChuckV »

I think without any signal from the accelerometer the shocks would go into default mode. You'd probably need to use some sort of resistor that sent the correct signal in order to keep the shocks on-line.

 

Re: Suspension Solution? (raycrx)

I have the revision 3 upgrade on my V70R and I like it. Comfort is now comfortable, Sport is slightly firmer and advanced is much firmer, without the terrible jounciness of the original software. There is difinitely more body sway in all 3 modes now, but I prefer that to what I had before.

There are some definite shortcomings to the suspension, but for me it is great to press a button that makes the car fun on the twisties/firm at "very' high speeds, and then tame as a *****cat while cruising down the highway when I am in relax mode.

I plan to add stiffer sway bars, but keep the 4C plugged in.

As an aside, I think it is plain to see that Volvo is trying hard, but is light years behind BMW in chassis/suspension tuning. I drove a friend's M3 (not fair comparison I know) and that baby was pretty decent in regular driving, not especially jarring, and yet I hit 170 MPH on the autobahn and the car was stable, no problem. So BMW is able to tune a susension for daily driving and VERY high speed driving, without needing the electronic gizmo's. By the way, the M3, with clutchless paddle shifter was utterly fantastic beyond words!!!

Nick M. F Green V70R GT

 

Re: Suspension Solution? (raycrx)

Quote, originally posted by raycrx »

I leu of simply disconnecting the shocks; why not simply disconnect the accelerometers from the computer that controls the shocks.

As someone else already mentioned, a failure in any part of the system puts it in fail-safe mode, I believe. I had a loose wire to the accelerometer in the trunk, and when it would cut out (even for a fraction of a second), the "Chassis Setting" message would appear and the three suspension setting buttons would be locked in Sport mode until you turned off and restarted the car.

Quote »

BTW when I went through my favorite S curve this morning with the system off (fuse pulled) The car had more sway; however, it was significantly faster.

My experience as well (I would say "not slower" instead of "faster", just to be conservative. But it may indeed be faster). People have to realize that roll stiffness results in a greater transfer of force to the outside tires. The main advantages of roll stiffness are 1) keeping the geometry in a good position to hold the tires flat on the road, 2) controlability from the driver's perspective.

If you put massive roll bars on the car, for instance, you can indeed have flat cornering, but the car will have lower limits, not higher. That's why cars don't have huge antisway bars that simply prevent all roll.

Quote »

Not to mention the fact that without the system active the tire patch stays planted better. So what if your car doesn't bounce down the street like the ricers do.

Exactly. This same downside is evident with the anti-dive feature of the 4C. Hard braking stiffens the front shocks to prevent dive, but if the road is choppy, the tires skip across the bumps. I experienced this yesterday with a hard stop from about 70mph on a lousy road. More compliance at the expense of more dive would actually have been better in this situation.

In a similar way, using the shocks to limit roll stiffness does the same thing when cornering. You lose bump compliance when the shock goes stiff, thus reducing the controlability of the car over non-perfect pavement.

A variable stiffness antisway bar -- as with some of the new BMWs -- can prevent roll without losing bump compliance, because the antisway function isn't being handled by the same components that are suspending the car.

The Volvo engineers were most certainly aware that using the shocks to handle both suspension duties and anti-roll/anti-sway duties was a compromise. The only way it would not be is if there were bump input sensors on the suspension that would allow the shocks to detect individual bumps and dips while cornering. Then they could instantly soften to absorb the bump and immediatly stiffen back up after the event was over to continue to prevent body roll. The 4C doesn't do this.

I found that with the 4C disabled, the car has more roll (as you noted as well), but the suspension is more compliant and thus at least as fast over real-world roads. AND, it has better "feel" over these roads as well, because the suspension isn't trying to simultaneously (1) stay completely stiff to prevent body roll while (2) needing to have compliance to absorb bump inputs while cornering.

The right way to reduce roll is to lower the center of gravity so as to not have the roll in the first place. Then you can maintain suspension compliance as well as prevent severe suspension angles that alter the tire patch.

It is quite possible that the understeer "push" is actually aggravated by "Advanced" mode. Yes, the car stays flatter. But the weight transfer is actually greater to the front outside cornering tire, thus overloading it more easily and giving understeer. It is counterintuitive, but the more compliant "4C disabled" might indeed be a faster way around the track, so long as body roll is not so extreme as to screw up the tire contact patch. Though Advanced would probably still be faster through quick transients as opposed to more steady state cornering.

Modified by mgotts at 9:54 PM 4-21-2004

 

Re: Suspension Solution? (mgotts)

Well, me, my service manager AND the regional tech, agree, that for the time being, that the disconnect (4C, off/on) switch that Jim Lill suggested will work just fine.
I am still not sure which suspension I'm going to ultimately wind up with, (I believe that Volvo is working on the situation for me to get back to rev 2 ), but with a simple factory switch mounted on the console, (we think that the child lock switch is a simple toggle switch) will look right should do the trick.
I tested my car today, fuse in, fuse out, fuse in, fuse out and both have their advantages and disadvantages.
This should be an easy install and then I can drive around doing my thing and not be bothered with the 4C BS. Then, if I wish to go into 4C all I will have to do is hit the switch and I'll have all three modes to "play with" if I choose to do so.
This should give me the best of both worlds right now and to choose, instantly, how I want the car to be and feel. http://********************/smile/emthup.gif
I can fool around with stiffer springs and shocks later if I desire to
JRL

Modified by JRL at 6:33 PM 4-21-2004

 

Re: Suspension Solution? (JRL)

Quote, originally posted by JRL »

I tested my car today, fuse in, fuse out, fuse in, fuse out and both have their advantages and disadvantages.

I've been runing around in "4C disabled" mode today too. Great for the city, where it is more compliant than Comfort, yet stiffer in the turns and without any float.

Body roll is more than Sport, but I'm not sure it hurts the handling any. I threw the car around some turns at intersections (i.e. sharp, 90% turns), and it just stuck and darted around them. Quite smooth. No push or tire squeal. I need to try the same ones in Sport and Advanced, but it's possible it is actually more capable this way, so long as you can tolerate a bit more body roll than in Sport (and it is just a "bit", not too much).

Over rough pavement of any kind, "disabled mode" is far superior to any of the 4C settings, at least on my car.

Quote »

This should be an easy install and then I can drive around doing my thing and not be bothered with the 4C BS. Then, if I wish to go into 4C all I will have to do is hit the switch and I'll have all three modes to "play with" if I choose to do so.

Do you know if the 4C system will come back up completely without restarting the car, so that you can indeed turn it off and on again at will? I have not tried replacing the fuse while the car is running (which is basically the same thing a switch would do).

 

Re: Suspension Solution? (mgotts)

Quote, originally posted by mgott »

Do you know if the 4C system will come back up completely without restarting the car, so that you can indeed turn it off and on again at will? I have not tried replacing the fuse while the car is running (which is basically the same thing a switch would do).

From what my regional rep said, YES, it will just turn back on
I wouldn't try putting in the fuse while it's running though.
It's different flipping a properly wired switch than trying to install a fuse while running, that isn't the best way of doing things. If you miss a little and it arcs, you could blow said fuse.The worst situation would be that if it needs a reboot, and I don't think it does, would be that you pull over, turn off the car, hit the switch and restart the car, but from what I understand you/we/I won't have to do that
JRL

 

Re: Suspension Solution? (mgotts)

Quote, originally posted by mgotts »

The Volvo engineers were most certainly aware that using the shocks to handle both suspension duties and anti-roll/anti-sway duties was a compromise. The only way it would not be is if there were bump input sensors on the suspension that would allow the shocks to detect individual bumps and dips while cornering. Then they could instantly soften to absorb the bump and immediatly stiffen back up after the event was over to continue to prevent body roll. The 4C doesn't do this.

Shock absorbers can only affect body roll in transient conditions, not steady state. Ultimate body roll is controlled by the spring and anti-roll bar. Stiffening up the damping only increases transient body roll stiffness. For absolute cornering you don't want an extremely stiff damper but one that is perfectly matched to the spring and anti-roll bar stiffness such that bumps while cornering are properly absorbed and dissipated with as little chassis perturbation as possible.

 

Re: Suspension Solution? (ChuckB)

I think I said that in another post that for the R to be more capable it need a CORRECT set of matched shocks and springs
JRL

 

Re: Suspension Solution? (ChuckB)

Quote, originally posted by ChuckB »

For absolute cornering you don't want an extremely stiff damper but one that is perfectly matched to the spring and anti-roll bar stiffness such that bumps while cornering are properly absorbed and dissipated with as little chassis perturbation as possible.

Just what I said. My reference to a shock with an accelerometer attached is ahypotehtical reference to a pseudo active suspension -- which is not the 4C. Also, with regards to not affecting steady-state cornering, you're assuming that the shocks can't be set to near-infinite damping, as can the magnetic-fluid shocks in the new Caddy SLR.

I've got a sample of the magnetic fluid at home. It can be changed from a fluid to a solid material (for all practical purposes) in the presence of a decent magnet. That would indeed affect steady-state cornering.

 

Re: Suspension Solution? (mgotts)

Thank you for your eloquent analysis of suspension concept! http://********************/smile/emthup.gif I was concerned that everyone would rather cry on each others shoulders.

That is really embarassing.

I want to pool our intelligence towards a solution not just a psycho-therapy group session.

Quote, originally posted by mgotts »

As someone else already mentioned, a failure in any part of the system puts it in fail-safe mode, I believe. I had a loose wire to the accelerometer in the trunk, and when it would cut out (even for a fraction of a second), the "Chassis Setting" message would appear and the three suspension setting buttons would be locked in Sport mode until you turned off and restarted the car.

Don't you think that if the computer gets a constant neutral signal (not a failure , ie disconnect) it will simply maintain the median setting weather it be comfort /sport/or advanced mode?? And if you agree is there any way to generate a false constant signal for the computer to think the car is just standing there (no movement)?
Kirk

 

Re: Suspension Solution? (mgotts)

In regard to 4C restoring while the car is running, yes it does. I have done this with no problem. This was with a temp switch I was using for testing that has the blades from a defunct fuse.

I am not interested in a more permanant solution since my issue is noise, and there are no conditions that would make me want to return to the 4C, but noise mode.

You might want to consider using a relay or at least a toggle switch that can handle the current. It is a 15 AMP fuse. Interestingly I have measured the current through the fuse and it is only about 250 mA. That is in all modes, car is static. I was surprised it did not change to a higher current in the SPORT and ADVANCED modes since they increase the current in the solenoids for greater damping. May not be able to see this in a static mode however.

 

Re: Suspension Solution? (rogersampson)

I believe that when the system is deactivated, no power at all is going to the shocks. They just revert to thir original spec which of course would be the softest.
When the system is working it can pump up but can't go below the original shock spec, hence that's why they are in "comfort". That would be the softest.
It doesn't go into a fail safe mode it just becomes a stock shock. No lights are lit on the dash.
JRL

 

Re: Suspension Solution? (JRL)

I do not disagree. When the fuse is pulled, there is no power to the shock solenoids, and the valve orifice is at maximum. I also believe there is a mechcanical fail safe that in effect makes the shock a conventional, passive shock, with valve orifice approximately equal to the static sport setting.

I believe I read somewhere that the 4C is deactivated in reverse. I am not sure just what is deactivated, because in my car the clunk is there whether in a forward gear or reverse. The clunk is gone in either with the fuse pulled.

I will take some more current measurements this weekend, while in motion, because I also recall that the car must be at 1 Km/h or greater for 4C to activate.

I find it very difficult to find reliable information on this system, or it's components. Volvo is not very forthcoming, so I just need to dig around in SAE pubs, vendor info, etc.

 

Guy's I find this interesting.

I've only owned my R for about 5 weeks and due to work commitments only drivren it for about 400 miles.

I've purchased the R to be a comfortable machine to use on a long journey with a bit more performance than average. I can use the Evo for ultimate kicks.

I've a fair amount of experience in a number of different cars, from 4x4's to mid engined supercars (a V8 Esprit mainly). I'm not completely convinced by the R's suspension yet. I don't have the clunks but I do have the step out at the rear over small undulations in comfort mode others have reported.

The main problem is that I can't get a feel for what its doing, partly this is lack of experience with it but not completely.

Now I'm not suggesting that I or any of us are close in abilities to F1 drivers but there is a story from 1970 that I'm reminded of by the R.

Lotus designed the 72 initially with anti-dive and anti-squat and although the drivers thought the car fast they did not like it because it did not give the usual feelings they expected. As such it made it harder for them to drive it to the limit and hard to setup.

They changed the car to a more convential setup and the drivers liked it much more.

Is that what we feel, because it does not give us the usual clues it feels alien to what we expect.

Just a thought and as I say I have not done enough miles yet to fully form an opinion.

Regards
Gary

 

Re: (FredBasset)

I was also told by the factory rep that if we get rid of the PZero and go with another tire that will help the "hopping" around in the rear.
???
JRL

 

Sure, that seems plausible. I've got PZero's on the Evo, wonder why that does not hop then

 

Re: (JRL)

JRL, I use ContiExtreme Contacts as my winter tires and I haven't noticed any improvement to the hopping problem.

Fred, my sense is that it's somewhere in the middle between just getting used to new/different handling behavior and something that's just not right. The hopping/squirreliness behavior is something you can adjust to and live with but it's an indication that the system isn't quite there yet. Similarly with the floating/harshness aspects of "Comfort".

I plan to try the fuse-pulling experiment this weekend to see if that confirms my suspicions that my sense of what's slightly off is related to the 4C. I don't have any clunk-in-trunk problems and am generally happy, but being a greedy SOB, I want perfection!

 

Re: (JRL)

Quote, originally posted by JRL »

I was also told by the factory rep that if we get rid of the PZero and go with another tire that will help the "hopping" around in the rear. ??? JRL

Jim,

That's a joke; surely he doesn't actually believe himself? We've had Continental ContiExtremeContact tires on our V70R now for about 3000 miles (I've got the original Pegs with the Pzeros still mounted also, so I can switch back at any time), and it had no effect on the rear end squirrel/hopping issue. That is purely a suspension issue as you've seen by pulling the 4C fuse.

 

Re: (ChuckB)

That was my suspision too, but since he's helping me get rev 2 back, I'm not gong to start any arguments with him.
He IS trying to help me regardless that he's wrong this time
JRL

 

Re: (Knickerhawk)

Quote, originally posted by Knickerhawk »

The hopping/squirreliness behavior is something you can adjust to and live with but it's an indication that the system isn't quite there yet. Similarly with the floating/harshness aspects of "Comfort". I plan to try the fuse-pulling experiment this weekend to see if that confirms my suspicions

That's been my experience with pulling the fuse. The car is softer, but more composed and predictable, especially over choppy stuff. It also doesn't "float" the way that Comfort can at times (again, depends on your car and 4C software revision, apparently).

I've got the fuse back in today (left it out all of yesterday), and I do like the additional tautness of Sport over "disabled" mode. But it still intervenes in unanticipated ways at times. Not "bad ways", just unanticipated.

Your Lotus analogy might be spot on. It's probably faster, but humans like predictability -- and expect it. That might be what makes the suspension behavior seem unusual at times.

I think the suspension is marvelously safe, even at the very limit. You don't see posts on this forum about Rs flying off into the weeds

You can indeed drive the absolute hell out of the R without getting over your head. It's fantastic in the rain; very confidence inspiring. The R doesn't bite; that's a huge virtue.

The 4C and DSTC are certainly to thank for this. The car isn't raw and elemental. It's a fun, fast, luxurious, sporty, family sedan that is a Volvo, and thus safe. It's got electronic gee-gaws helping us drive very fast and stay on the road. Current Mercedes models are much like this.

Quote »

I don't have any clunk-in-trunk problems and am generally happy, but being a greedy SOB, I want perfection!

I don't have a clunk either (thankfully). But even my suspension is quieter in "disabled" mode -- though I would not have noticed had I not pulled the fuse. The "quieter" part is strictly in comparison, and once over 30mph normal road noise masks the subtle difference between the two anyway.

Despite what many see as "complaining" in these posts, I really love my R. I think it can be even better. That's why I'm here.

 

Re: (mgotts)

Quote, originally posted by mgotts »

Your Lotus analogy might be spot on. It's probably faster, but humans like predictability -- and expect it. That might be what makes the suspension behavior seem unusual at times. I think the suspension is marvelously safe, even at the very limit. You don't see posts on this forum about Rs flying off into the weeds You can indeed drive the absolute hell out of the R without getting over your head. It's fantastic in the rain; very confidence inspiring. The R doesn't bite; that's a huge virtue. The 4C and DSTC are certainly to thank for this. The car isn't raw and elemental. It's a fun, fast, luxurious, sporty, family sedan that is a Volvo, and thus safe. It's got electronic gee-gaws helping us drive very fast and stay on the road. Current Mercedes models are much like this.

I agree with you above mentioned points. Very well stated.

Quote, originally posted by mgotts »

Despite what many see as "complaining" in these posts, I really love my R. I think it can be even better. That's why I'm here.

Ditto.

 

Re: (pino)

I think it's the DSTC, is what keeps you confident and safe NOT the 4C, per se.
Volvo's DSTC does work very well (at least something does).
JRL

 

Re: (JRL)

Quote, originally posted by JRL »

I think it's the DSTC, is what keeps you confident and safe NOT the 4C, per se. Volvo's DSTC does work very well (at least something does). JRL

They BOTH work to keep you on the road, Jim. If the 4C does not keep the car composed on a curve, then DSTC would have to work more frequently and harder. But out of the two, I would agree that DSTC is the system that keeps you from visiting the cows (or whatever else) residing on the side of the road.

Yannis

 

As far as Thumping noises related to the 4-C system, my thinking is that Volvo's sampling rate (500 measurements per sec) should be changed, so that it is Speed Dependent.

Driving at 10mph works out to ~ 15 feet/sec.
At this speed, sampling at 500 measurements/sec means that for each foot traveled, ~ 33 measurements are collected, processed etc.

This is a bit of overkill, and it may lead to the 4-C system trying to overcompensate & overcorrect.
Of course we know that the 4-C shocks cannot react instantaneously, but trying to control them too quickly may still cause a response time problem i.e. too stiff?, too soft? etc.

Who knows, maybe Volvo is already working on yet another software upgrade.

--------------------------------------------------------------------------------

John T
S60R, 6-spd, 18's, Silver Metallic