Dave's Cars, Computers, Great Links

A Small Contribution to the World Wide Wasteoftime

Sport (sic) Suspension (sic)

(so-called) Volvo "Sport Suspension"

For a mere $120 (dealer cost; $150 list), my '95 Volvo 850 Turbo was ordered with the factory "Sport Suspension". Unfortunately -- very unfortunately -- I was unable to locate a car with this option to test drive, so I ordered it 'blind'. This seemed like a good move, as a test drive through the twisties had revealed a tendency for the normal suspension's passive rear steer to come into play at about .5g, making it a nonlinear nuisance to be dealt with every time a corner began to get interesting.

On the day I took delivery of my car, I took the afternoon off to put 'ideal' break-in miles on the car on a nice April day out on the 2-lane highways of the Eastern plains of Colorado. I learned a lot of things on that maiden voyage, as I was being shaken and beaten by the car's cruelly unyielding suspension. For one thing, where the road was medium rough, it was impossible to hold down a radio button continuously for 2 seconds (in order to store a preset)!

The next day I awoke stiff and headachey. Instead of loving my new "pride and joy", I had an instant long-lasting deep natural aversion to it, to which I was reluctant to admit.

The suspension components were so stiff that the suspension had no travel to speak of. In addition to beating the snot out of the occupants, this completely defeats the point of having independent suspension! It also causes one's internal organs to be rearranged on the worst roads. Through the haze of the concussions the car was delivering, I began to understand why there'd been none to test-drive.

Right after I ordered my car, the April '95 Car and Driver arrived, in which they reviewed the 1995 Volvo 850 T5-R, which came with the same "Sport Suspension" as my car. The T5-R came with /45-17 tires to my car's /50-16 tires. But the seating surfaces of the '95 T5-R's seats are leather, against which it is possible to sink/slide down in response to abrupt vertical upheavals. Unlike the T5-R, my car's seats are soft slippery leather around the edges and grippy cloth where my legs/bottom/back are supported, so there is no opportunity to sink/slide down when the whole car is suddenly shot skyward. And they likened that car's ride to "a steel canoe in shallow rapids". (This was my first clue that I might have made a mistake, and yet I was still unprepared for the abject cruelty to which I was being subjected.)

After a Volvo Technical Phone Support person at their 800# (458-1552) told me to squirt WD-40 on the front sway bar bushings in response to another of my complaints (I did not do so), I learned, upon examination/research, that the Volvo sport suspension's rubber front sway bar bushings are vulcanized to the sway bar, opposing its ability to rotate, and thus passively go along for the ride when both front wheels move in unison. It becomes, in addition to a sway bar, a torsion bar. While I admit to not understanding why Volvo felt the need to change the function of this suspension member, I do know that I was assured, prior to ordering the "sport suspension", that the bushings were all the same, and the only differences were spring rates, valving of the dampers, and sway bar sizes. (Imagine, being lied to by a huge multinational corporation...!)

While the car was always ready to change direction immediately, it really beat me up. It never leaned enough for the passive rear steer to come into play. It could not absorb pavement irregularities -- even changes in incline -- in a turn. The suspension wasn't doing its job.

After more miles/years than I care to admit, I swapped out the springs and dampers for standard '95 854 Turbo springs and Bilstein shocks/struts. I'd never before swapped out a car's suspension components. I'd always imaged that if I did, it would be to increase performance, not ride comfort!

The biggest difference is that the car now has body motions. Not much, but enough to matter. Enough to have visible brake dive when the Valentine 1 suddenly sounds. Before, I could talk my way out of almost anything as long as there was at least one other potential speeder around, because I could reign in my speed by an impossible amount with no visible brake dive.

Also, the car is no longer a go-cart, so emergency lane change speeds are no longer impossibly high. Now, after a sudden swerve, it takes a moment before the suspension is settled and fully ready for another swerve.

On the other hand, on uneven surfaces, the car's constant-radius cornering speeds are way up, now that the car has a functioning independent suspension, which allows one wheel to move in response to a change in pavement height, instead of forcing the entire vehicle to feel the brunt of the change.

And, like a real road car, it now rewards smoother driving with higher speeds. Near the limits of cornering adhesion, the car leans just enough to cause the passive rear steer to help bring the rear around just enough to lessen the demands on the straining front tires. ("Good car!")

So by softening the suspension, I actually increased ride comfort and performance! I know that sounds backwards, but if you think about it, if too-stiff was really better, there'd be no need for independent suspensions, or suspensions at all for that matter -- race cars would just replace those heavy damper units with lightweight solid aluminum bars! But, as any racer can tell you, the basic suspension tuning guideline is to make the suspension firm enough to keep it from bottoming out. By that 'rule', my car is still way too firm: I mildly jumped the car on some whoop-de-doos and the suspension did not bottom out (it did not feel like it even came close!) upon landing.

Volvo: what the hell were you smoking when you packaged and labeled that ultra-heavy-duty-cop-car-suspension (probably intended for transporting 2 - 4 burly cops plus a hundred kilograms of equipment as they hunted down speeding Porsches on smooth level pavement) as a "Sports Suspension"? Maybe you should have called it the "Autocross Competition With The Whole Family And Dog Aboard Suspension"?!

When I think of "Sports", I think of athleticism, responsiveness, predictability, performance, agility, and fun. I do not think of needless cruelty and suffering. Apparently Volvo, in 1995, did. With a nearly-empty fuel tank and just the driver aboard, the vehicle simply had insufficient mass against which that overly-stiff suspension could ever do any appreciably useful work.

If you are considering Bilsteins, I recommend you use the softest springs you can find for your car (too-soft springs do not exist for the 850). The Bilsteins' 2-stage damping firmly controls body motions but allows the sharpest blows (as determined by suspension velocity) to pass at a lower damping level, so the suspension travel -- rather than the entire vehicle -- can absorb the blow. But if the entire travel is only one inch due to too-firm springs, the high velocity will only last for 1/2 an inch, and the car will not enjoy much of the comfort potential of the Bilsteins' "2nd gear", which will allow your car's wheel to move upward in response to the quick (too fast to be a body motion so why try to damp it too much?) jolt without upsetting the rest of the car, much the way an old phonograph needle could follow the information in the grooves of a record without causing the entire tonearm to move up and down. You can imagine what the frequency response of the stylus would be if it could not move without taking the entire tonearm with it.

My car is still over-sprung. The car can never utilize most of its suspension travel. My barely-opened can of Coke still sloshes a bit, and the trunk-mounted CD player still skips occasionally in response to a sharp pavement breaks. I suspect Bilstein arrived at their valving values for this chassis before the Turbo, with its stiffer(?) springs, arrived on the scene. If I drive to lower altitudes and fail to compensate by adding 1 or 2 psi of air to the tires, the tires become softer, diminishing the sharpness of the blows as seen by the Bilsteins, which keeps them from achieving their "2nd gear" (lower damping mode), resulting in unacceptably rude ride quality!!! That's how critical the suspension fine-tuning is with standard '95 Turbo springs and Bilsteins. Being over-sprung and over-damped is no way to cruise through life.

The bottom line is that the handling is now satisfactory and the ride is now tolerable. And this is a huge improvement over the unsorted, unfinished $30K "kit car" Volvo sold me.

My prescription for 850 ride/handling compromise (such as it can be) is relatively soft springs and Bilsteins. And uprated sway bars if you enjoy speedily carving curvy roads and/or don't want the passive rear steer function to behave intrusively prematurely.

If you are considering ordering a new Volvo _70 and reading this, you should know that Volvo belatedly heeded my advice (and the laws of physics): the newer models' "sport suspension" has been softened somewhat. You should (as always) drive before you buy or even order. And if you do order, test drive the car critically, alone, preferably with a light fuel load, trundling along uneven road surfaces at slow to medium speeds, before you accept delivery, but after you check the tire pressures. Do not spend $35K on a new car that will beat you up. OTOH, even if you decide you will eventually, as I did, change both the springs and dampers anyway, then you might only have to decide whether you want to wind up with the prescribed beefier sway bars from Volvo as part of their package, or from the aftermarket (some of which have been prone to breakage).

P.S. (Dec 2000) - After more than 40K miles on these springs/dampers, they've become more civilized, and so rarely rude that I no longer wish I'd gone with softer springs. The speeds at which the suspension works well have come down to the point where it's almost as likely to be too soft at high speeds as it is to be too hard at low speeds. But it's still a pain to have to keep the tire pressures so consistent (in order for the suspension to work sufficiently well) through temperature changes.

P.S. (May 2001) - After having bought 1 set of expensive replacement MXMs, this time around I decided to try Toyo Proxes T1-S (still 205/50-16). The 2 tires have identical load ratings, but the T1-Ss reach theirs at a significantly lower maximum pressure (44 vs 51), which basically means that they don't feel as deflated at the correct (32-33/29-30 psi F/R) pressures, which means they're springier/bouncier, which works out much better (at least in terms of comfort) with the Bilsteins than the MXMs ever did. The Toyos have a fluffier, more mashmallowey feel and behavior, which is fine for grand touring but not autocrossing (they take a while to take a 'set' in a turn). They have a "rim-protection" design, which means the beads are recessed into the sidewall, which then extends outward beyond the edge of the wheel, to protect the wheel from curb scrapes.

P.S. (Spring 2003) - Toyo sucks. I hit a bump (lane-wide pavement break in a 1-lane-each-way-on-the-interstate destruction zone) at 60 mph and the 2 left side Toyos were destroyed in an instant -- each outer sidewall suddenly had a bubble. Toyo consumer relations declined to help me out at all (I wanted to buy a new set of 4), so I decided to try the new (released late 2002) Goodyear Eagle F1 GS-D3, which has already shown well in several high-performance tire tests (unlike other recent Goodyear tires). Though they share the Michelins' 51 psi max inflation pressure and higher weight (the Toyos are the lightest at a claimed [and acceleration-enhancing] 19 lbs; GS-D3 = 22 lbs @ 205/50-16), their sidewalls have nearly as much flex as the Toyos, as evidenced by how much how they flex in my bare hands when I try to squeeze the sidewalls and how much they bounce once they've been mounted and inflated. These GS-D3s seem to be an attempt by Goodyear to out-Toyo the Toyos, and it appears to have been successful. With the Michelins, every bump was too hard. With the Toyos, no bump was painful (except to the tires!), and sometimes big/sharp bumps were felt less than were small/smooth bumps. With the Goodyears, the ride is in between, and bigger bumps are felt more than smaller bumps. I believe I may have finally found Goldilocks' tires -- not too stiff, not too soft; they are smooth-rolling (the tread pattern of the GS-D3s is so radical that there is no sense of tumbling off of one tread block and onto the next as the tires roll -- they feel like slicks in that regard) with quick steering response. I'm hopeful (I just got them today) they will give me most of the durability of the hard-riding Michelins and most of the ride quality of the flimsy Toyos. Their rim-protection outward offset is twice that of the Toyos -- these are beefy-looking tires.

P.S. (Fall 2004) - Goodyear sucks! Despite their many admirable qualities, the GS-D3s have 2 problems, possibly related: 1)They are nail/screw magnets; they've picked up more nails and screws and needed more repairs in 10K miles than in the previous 140K miles combined, with no change in driving habits except fewer miles. 2)They do not work in unison with one another; they each constantly seek to go their own way. Despite 2 wheel alignments in 10K miles, I always found myself steering left, to varying degrees, in order to go straight, especially once the tires were up to temperature. Even when they were brand new, they acted as if they always needed/deserved a better-than-perfect alignment. And as the tread depth decreased, and they were better-hooked-up to the road, this GS-D3 need for a better-than-perfect wheel alignment increased. And this wasn't "tramlining", either, except in the sense that no road was ever good enough for them, either. After 2 summer seasons (plus last year's winter season), the car suddenly felt perfect again as soon as I removed the Goodyear GS-D3s on factory mag wheels and installed the old Pirelli 210A winter performance tires on steel wheels (which was done in stages, with a swap, to verify that the Goodyears on both axles were bad). I won't forget what your tires did for (to!) my capacity to enjoy driving, Goodyear!

P.S. (Spring 2005) - I believe I have finally found Goldilocks' tires. 205/50-16 Michelin Pilot Sports. When I got the Goodyears, I wished they'd been closer to the weight of the light/fragile Toyos. The Pilot Sports are that compromise, at 20 lbs. They feel better new (full mass) than the GS-D3s (or MXMs) felt after some wear, in terms of how well they mate up with my car's suspension, which requires low unsprung mass for high enough frequency response for the Bilsteins to do their thing, which they are now doing better than ever. I still have very few miles on the tires, so these are very initial driving impressions: Slight sense of vagueness to the steering (nothing serious or even significant; the Toyos were about 10X more vague), great strength with good flexibility (I haven't hammered it yet, but no sense of any "torque steer" which is often really just tire deformation). If the pavement is not smooth, they are noisy. The Pilot Sports have rim protection (bead offset from sidewall) that the MXMs lacked, but less than the Toyos or especially the Goodyears. The MXMs' sidewalls were more vertical and less bulgey than these, which I think is why the MXMs' ride was thuddier than these Pilot Sports with their bouncier, more vertically flexible (via the more bulging contour's pre-existing greater curvature) sidewalls. So, except for the fact that they're noisy on rough pavement, the Pilot Sports are going to be better touring tires for my car's non-linear suspension than the MXMs were, which is backwards from Michelins' designations. I feel like I'm sensing some sidewall flex (which my car's suspension demands), but no tread squirm (unlike most other tires when new), which is all to the good for this application. The one other notable physical/geometrical characteristic is that these Pilot Sports are much closer in size to the OEM MXMs than those seriously-oversized GS-D3s, which put nearly 1/2" wider tread pattern on the road (which probably sounds good, and also looked good, except that undoubtedly contributed to my car's inability to go where steered with those accursed Goodyears of same size designation mounted on the original factory wheels). So my car now feels better than it has in years, and, right now, I'm thinking, "Thank you, Michelin." (And also "Thank you, Discount Tire." They gave me a considerable allowance on those terrible Goodyear tires they'd sold me.)

P.S. (Late 2006) - Dreading the switch from the lightweight Pilot Sports on alloy wheels to heavy Winter 210 SnowSports on steel wheels (because the suspension wouldn't do any work because the suspension travel wasn't rapid enough), I replaced the Bilstein (heavy duty) dampers with newer Bilstein "touring class" dampers (and also replaced upper strut mount and replaced torn CV joint boot). The car is no longer supercar-like in its lack of body motions, and the ride is no longer abusively harsh. The first alignment was no good; it's like the suspension settled for real in a different position once the car had been driven a while with the new struts installed. The steering feel has also changed, though; the steering effort is much lower, and while it builds at near full steering lock, it then disappears and the car can "chase its own tail" with hands removed from the steering wheel. If you can explain what could cause that, please tell me. BTW, I also recently got to try the Pirelli Winter 210 SnowSport tires in loosely packed snow and they are not nearly as good in loosely packed snow and ice as were the 210Ps and 210As. In fact, they were not much better in those difficult conditions (unplowed side street after deep snow and some traffic) than what I'd expect from all-season tires. For most winter driving, I prefer the W210SSs to the 210Ps and 210As, but now I've finally encountered the conditions under which the trade-off goes the other way.