Standard Suspension Bump Travel

[Mikem53]

Originally Posted by Racecomp Engineering

We sell our lowering springs with a very mild drop (less than an inch) and we include replacement bumpstops front and rear. We wouldn't do it any other way.

Yes to get a lot of travel you need coilovers.

- Andy

Does your lowering springs cause any issues with the half shaft CV angles to where they are compromised in durability?
Also when you go with coilovers, does this situation with the half shaft angles get worse? Or is there a way to correct or adjust the angles so that isn't an issue... Spindles?, etc.. Newbie question on this.. Thanx..

[ZDan]

May seem nit-picky, but...

Originally Posted by 7thgear

- A spring has a rate, this rate determines the speed at which weight transfer occurs, the stiffer the spring, the faster the weight transfer.

This is a better description of damping. Springs (and also sways in cornering) determine how much total roll or pitch you'll get under fully developed cornering or braking, dampers play a bigger role in how fast you'll get there.

- Many things can act as a spring… or an energy absorbing device, if you will

Springs *store* energy and give it back with very little lost or absorbed. Dampers *absorb* kinetic energy, turning it into heat.

[bfrank1972]

Just to continue the pursuit of knowledge, found this series of suspension articles pretty interesting:

http://www.initialdave.com/cars/tech.htm

Touches on the mini suspension (incidentally says it's non-hydrolastic), as well as hydrolastic, hydragas, etc. Neat stuff, makes me think why more manufacturers don't use rubber springs vs metal coil springs?

[7thgear]

Originally Posted by ZDan

May seem nit-picky, but...
Springs (and also sways in cornering) determine how much total roll or pitch you'll get under fully developed cornering or braking,

well, we can nitpick further and say that roll is a function of geometry..

we could theoretically build a car that does not roll, or rolls with the turn and the springs wouldn't have a thing to do with it.

[Racecomp Engineering]

Originally Posted by Mikem53

Does your lowering springs cause any issues with the half shaft CV angles to where they are compromised in durability?
Also when you go with coilovers, does this situation with the half shaft angles get worse? Or is there a way to correct or adjust the angles so that isn't an issue... Spindles?, etc.. Newbie question on this.. Thanx..

No issues with CV angles. Our springs are one of the more mild drops out there.

Coilovers generally go much lower but I wouldn't expect problems unless you really slam the car.

- andy

[solidONE]

Originally Posted by DarkSunrise

Interesting. Will you be switching to coilovers?

Yes, I plan on upgrading the dampers to adjustable coilovers. These springs and cut bumpstops were to tide me over until then.

Never thought of having the suspension 'ride' on bumpstops during compression to effect handling characteristics. Always thought of them as a safety. Something for the shock to bounce off of to prevent damage to the assembly.

[DarkSunrise]

Originally Posted by solidONE

Yes, I plan on upgrading the dampers to adjustable coilovers. These springs and cut bumpstops were to tide me over until then.

Never thought of having the suspension 'ride' on bumpstops during compression to effect handling characteristics. Always thought of them as a safety. Something for the shock to bounce off of to prevent damage to the assembly.

Yeah I think that's the traditional thinking, but more and more, I'm reading about cars that integrate the bumpstops into the suspension design.

If/when you upgrade to coilovers, post up your impressions

[ZDan]

Originally Posted by 7thgear

well, we can nitpick further and say that roll is a function of geometry..
we could theoretically build a car that does not roll, or rolls with the turn and the springs wouldn't have a thing to do with it.

Yes, roll center height does play a role, and most cars will have some anti-roll geometry (roll center above ground). Designing a production car for zero roll or "anti-roll" (leaning into corners) would be an extraordinarily bad idea, suspension would basically lock up in cornering. Throwing away mechanical grip = bad idea unless you're trading it for even more aero grip (high downforce race cars).
Any case, my point remains valid: Dampers determine roll and pitch rates much more than spring rates do, while spring rates (along with geometry of course) determine how much total roll you get. So yer welcome for that

[Suberman]

Originally Posted by 7thgear

well, we can nitpick further and say that roll is a function of geometry..

we could theoretically build a car that does not roll, or rolls with the turn and the springs wouldn't have a thing to do with it.

Roll transfers "weight" (momentum forces actually) by the reaction of the springs on the suspension geometry. Reverse roll or zero roll suspension can and has been designed. It fails to work because of sensory limits in the driver. The car would be quicker with reverse roll but undrivable except by a non human computer. Mind you both McLaren and Mercedes Benz are working on computer controlled zero roll or at least minimal roll suspensions but they are not geometry based. They rely on gas and oil springing systems controlled by computers. Williams F1 did the same in the early 90's. That way the geometry still signals to the driver so he can actually avoid cornering so fast the car leaves the road abruptly.

Since suspension geometry on your BRZ is fixed for practical purposes the reduction in roll is effected by increasing total spring rate: tires, bushings, roll bar rates, spring rates, bump stop rates and position and any gas springing effect in the shock absorbers.

[ZDan]

Originally Posted by solidONE

Yes, I plan on upgrading the dampers to adjustable coilovers.

Not all adjustable coilover dampers are going to be an upgrade over stock dampers. Choose wisely!

[solidONE]

Originally Posted by DarkSunrise

Yeah I think that's the traditional thinking, but more and more, I'm reading about cars that integrate the bumpstops into the suspension design.

If/when you upgrade to coilovers, post up your impressions

Originally Posted by ZDan

Not all adjustable coilover dampers are going to be an upgrade over stock dampers. Choose wisely!

Will do!

[mike156]

A decent way to approach bumpstop selection might be an energy balance. Load up a stock strut/spring/bumpstop and chart out force vs displacement. Integrate for total energy storage.

Design your replacement system to accommodate the same total energy by balancing shock gas pressure, spring rate, and bumpstop design to give the force vs. displacement curve you desire.

Although, this doesn't account for the dynamic forces associated with the damper. After all, the damper is the major source for force reaction to bumps so the energy balance method above would allow accommodate a steady state energy balance.

[solidONE]

Originally Posted by mike156

A decent way to approach bumpstop selection might be an energy balance. Load up a stock strut/spring/bumpstop and chart out force vs displacement. Integrate for total energy storage.

Design your replacement system to accommodate the same total energy by balancing shock gas pressure, spring rate, and bumpstop design to give the force vs. displacement curve you desire.

Although, this doesn't account for the dynamic forces associated with the damper. After all, the damper is the major source for force reaction to bumps so the energy balance method above would allow accommodate a steady state energy balance.

You are saying this as if there are actual different choices to "select" from. Aside from the higher end dampers, I don't these there is much on the market to "select" from. Even then I dont think there is much of a selection to choose from. Most cases we are stuck with the factory bumpstops or modifying them (cutting factory bumpstops or torching them ).

[Turdinator]

Originally Posted by solidONE

You are saying this as if there are actual different choices to "select" from. Aside from the higher end dampers, I don't these there is much on the market to "select" from. Even then I dont think there is much of a selection to choose from. Most cases we are stuck with the factory bumpstops or modifying them (cutting factory bumpstops or torching them ).

http://www.koniracing.com/bumpstops.cfm