I know that shocks are supposed to be matched to spring rates and that stiff shocks probably ruin ride quality more than stiff springs (to a point). If I take a car with soft suspension and put stiff shocks on it will it ride better or worse than if I used the same stiff shocks with some stiffer springs that were better matched?
I'm sure the stiff spring and shock combo will handle better but I'm curious about the trade off in ride comfort.
You have to control oscillation. If the shocks are "too soft", you bounce around too much. The shocks are designed to limit the "springiness" of the springs. Ideally, you would want the spring to compress, and then Decompress. And not compress, decompress, compress, decompress, etc.
all in the name of controlling body movement.
Stiff springs= "stiff" shocks. "Stiff" in quotations because that's relative to regular shocks. It's entirely possible to blow an entire life's savings on gold encrusted shocks that give it all.
Fairly open ended question; with soft springs and stiff shocks it's possible to end up with a car that crashes over sharp edged bumps and jacks down over sets bumps.
This is how nearly Yamaha mono shock motocross bikes earned the nickname Yama-swapper. The spring was to soft and the shock had to.much rebound so over a set of whoops the spring could push the wheel back down fast enough. After 3-4 bumps you'd run out of travel and because the energy had to go somewhere the back of the bike would start bouncing from side to side.
There's more to it than "stiff" and "soft". It's the overall shock valving and spring rates that are in sync with what the shocks were designed for.
That said, here's an over simplified observation from when I used a similar terms before learning more about this stuff:
on my e36, Bilstein Sport shocks aka the stiffer Bilstein compared to the HD, rode a lot worse than the HD. That was regardless of whether stock or aftermarket springs were used.
Also, aftermarket springs on the e36 shocks had bad ride quality because the valving of the stock shocks was not sufficient to control the higher rate springs and deceased suspension travel (associated with the shorter lowering springs
Stiff shocks on soft springs will generally ride worse than stiff shocks on stiff springs, but "stiffness" of shocks contains 2 main components, being compression damping and rebound damping, and they affect ride quality differently.
When a shock/spring combo is compressed, they both present resistance to compression and work together.
When a shock/spring combo is rebounding, the shock is resisting the spring when it's trying to return to full length, so they're working against each other.
Using stiffer shocks on stock springs will cause the ride to be harsh over bumps because of increased compression damping, and may suffer "jacking" as mentioned if the increased rebound damping overwhelms the stock springs.
When going from stock springs to stiffer springs, the compression damping should be decreased to maintain ride quality, and the rebound damping should be increased to control the rebound of the stiffer springs.
The question is maybe too broad and simple, but generally the job of the springs is to control the car's chassis position with stiffness, and the job of the shocks is to control the speed that the springs compress and decompress with damping. So in a semantic sense shocks really don't have "stiffness" because their stiffness is constantly changing depending on how fast they're moving. Shocks also have different damping under compression than they do under rebound by design.
When springs are under-damped they tend to oscillate up and down. When they're overdamped the dampers work against the springs trying to do their job in a somewhat unpredictable manner. There is a mathematically correct amount of damping that corresponds to a spring's stiffness for it to be critically damped, which requires the least amount of time for the system to "settle" after being perturbed by a bump. Usage conditions and driver preferences vary so adjustable shocks are a thing, but as a general rule the further you get from the ideal mathematical match between spring and shock the less predictable the car will be.
The springs should be matched to the car's chassis geometry and the amount of grip in the tires. The shocks should be matched to the springs. IMO too often people try to address spring rate problems by adjusting dampers, but it's the wrong approach. good for minor tweaking but it can only get you so far.
I also think your assumption that stiff springs and shocks always handle better is off. If you define handling as the act of controlling the motion of the chassis over uneven ground surfaces, the suspension that best complies to the ground conditions will be best at maintaining tire contact and controlling the car. In theory you want the most compliant suspension possible without the car riding on the bump stops in hard corners.
ShinnyGroove (Forum Supporter) said:The question is maybe too broad and simple, but generally the job of the springs is to control the car's chassis position with stiffness, and the job of the shocks is to control the speed that the springs compress and decompress with damping. So in a semantic sense shocks really don't have "stiffness" because their stiffness is constantly changing depending on how fast they're moving. Shocks also have different damping under compression than they do under rebound by design.
When springs are under-damped they tend to oscillate up and down. When they're overdamped the dampers work against the springs trying to do their job in a somewhat unpredictable manner. There is a mathematically correct amount of damping that corresponds to a spring's stiffness for it to be critically damped, which requires the least amount of time for the system to "settle" after being perturbed by a bump. Usage conditions and driver preferences vary so adjustable shocks are a thing, but as a general rule the further you get from the ideal mathematical match between spring and shock the less predictable the car will be.
The springs should be matched to the car's chassis geometry and the amount of grip in the tires. The shocks should be matched to the springs. IMO too often people try to address spring rate problems by adjusting dampers, but it's the wrong approach. good for minor tweaking but it can only get you so far.
I also think your assumption that stiff springs and shocks always handle better is off. If you define handling as the act of controlling the motion of the chassis over uneven ground surfaces, the suspension that best complies to the ground conditions will be best at maintaining tire contact and controlling the car. In theory you want the most compliant suspension possible without the car riding on the bump stops in hard corners.
I'd add one more criteria to that. Not just keeping the car off the bump stops, but also keeping the car from rolling far enough to expose any suspension geometry flaws that may harm grip. That's why BMWs with struts up front typically gain front end grip from a bigger front sway bar or stiffer front springs. The camber curve sucks, so reducing roll up front ends up adding more grip from reduced camber loss than what it loses from anything else.
Thanks for the replies. To add a bit more context, what got me thinking about this was looking at shocks for a full size 60s Mopar. There are Bilsteins available but opinions seem pretty split on how well they ride. I noticed that the comments from people who had also fitted stiffer torsion bars were generally more favorable than those who were still running stock ones. Of course this may be because they are expecting a harsher ride anyway but it could be because they are better matched to the stiffer torsion bars.
I think I'll probably go with the Bilsteins and bigger bars - not looking for a slalom monster just a bit more level in the corners without destroying the ride quality.
i have always like Sir Colin Chapman , idea.. supple( soft springs) big roll bar..so when i set up my alfa spider..( i run qa1 double adjustable shocks on both ends..) i had a feind drive down diff roads, and highways and film my wheels.. and i would voice tape what i am feeling in the car..
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