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View Full Version : Calling all Track whores! Suspension related.........



bassed
11-08-2007, 12:17 PM
Just got off the phone with TEIN and was told I can have the Super Street 100% custom set to my prefrences and the car setup (spring rates, travel length, etc...). So what would be ideal?

800lb up fron 1000lb in the rear and for travel length I still daily this whip as well?

I was looking at either doing Stasis Track Sports or going for broke with Moton'sm but I just can't swing for the Moton's right now.

onemoremile
11-08-2007, 01:34 PM
that all depends on the type of valving. progressive, digressive, double digressive, etc.. keep in mind that race teams with multiple cars will often have very different setups on identical cars. this is because every driver has their own preferences. some will have less than half the spring rate as others. some like soft springs with stiff low speed damping, soft high speed damping, and big bars. others may skip the bars and go with stiff springs and different damping.

I'm on my cell so searching isn't a viable option but i've posted the link to grassroots motorsports' article titled shocking behavior. don't buy suspension before reading it. the series entitled science of speed is also excellent and covers a variety of topics.

onemoremile
11-08-2007, 01:41 PM
I'm not a fan of high spring rates on street cars even if they see a lot of track duty. tires have to stay on the tarmac to do any good. if the majority of the compliance is the tires themselves you have a problem. you'll also need decent droop or negative travel to keep the inside tires down in corners. a tender spring often helps here. this is why soft springs with big bars needs a lot of low speed damping. soft high speed damping will make for a cushy ride.

high speed is impacts like broken pavement and road bumps. low speed is steady state cornering. with the right mix you can whio around a skidpad with a bumpy section and not worry about a thing.

motons are the shit. also look at the penskes from startup racing.

bassed
11-08-2007, 02:08 PM
Thanks. I'm thinking after a thread and conversations on AW of going KW V3 with 700f/800r or 600/700. I'll read those articles when I get home and dream of Moton's:) If only I had 5k for my suspension right now, but more DE days will suit me better for future EMRA racing and Hill climbs.

AB18
11-08-2007, 02:13 PM
Yeah, 800/1000lb isnt dd friendly AT all. Im running the vogtlands now, and there a good mix of both.

audisnapr
11-08-2007, 02:29 PM
Thanks. I'm thinking after a thread and conversations on AW of going KW V3 with 700f/800r or 600/700. I'll read those articles when I get home and dream of Moton's:) If only I had 5k for my suspension right now, but more DE days will suit me better for future EMRA racing and Hill climbs.


def. read that article if you haven't already. you'll be surprised by a few things you find in there. I know I was.

1000lbs springs for double duty DD/track will be tough on your teeth and your brain, not to mention your OE suspension components. Although I agree with Jim with regards to each driver having their own need for spring rates, most of the time race teams start at least a few hundred pounds higher than what sport springs would offer. but unless you have a ton of seat time on the track, it's really hard to know exactly what you'll want. I haven't been around much and don't know what your experience level is, but if you haven't already spend a year or two doing 3-4 track days per year and you'll have a much better idea of what works best for you and your car. if you are in the market now for suspension, start on the softer side and you can always replace the springs later on for a small amount ie, $25-50/spring

I know for me and my avant, I prefered a lower rated spring with a much beafier rear bar and a lower than "accepted" ride height.

Although I have absolutely no experience with KW's I've heard nothing but good things about them on the track. good luck.

onemoremile
11-08-2007, 07:02 PM
I ran KW V1 with H-Sport bars on the track and it was more than competent. It was a bit rough on the street though. They were stiff enough that I could have removed the bars for street driving and that would have helped comfort quite a bit.

A friend had installed Koni adjustable dampers on his Focus S2 for autocrossing. He had to keep his stock springs to stay in his class. With the Konis on full soft the ride was better than stock. With them on full hard it felt like they had been filled with concrete. We drove home from an autocross like that and the car nearly fell apart. I nearly chipped a tooth.

Don't ever underestimate the role of the dampers. Being able to adjust easily is key. Think of increased damping as a supplemental spring rate. The damper's job is to control how quickly the suspension is compressed or extended. With them on full hard the suspension movement was so slow it barely budged at all. It was hard on a "that bump made my kidneys hurt and now I'll piss blood" kind of way. These are still soft stock springs too.

The other big consideration in a track damper is how they handle heat. Dampers convert motion (energy of the spring rate and the car's weight) into heat. That heat has to go somewhere. Twin tube dampers like the Konis are not as good at shedding heat as monotubes like most Bilsteins. As a damper heats up the viscosity changes and so does the damping. This is why racing dampers have external reservoirs. These add both surface area for cooling and extra fluid for added heat capacity. This does matter on a 3400' car.

onemoremile
11-08-2007, 07:14 PM
Another thing to keep in mind is that the spring rate and low speed damping combine to determine brake dive and squat from acceleration. Acceleration isn't going to be nearly as much of an issue as brake dive since our cars are front heavy and even stock brakes will generate more G's under deceleration than even Mike's car when launching.

Brake dive is countered by stiff front springs and/or (I prefer the or) low speed compression damping up front and low speed rebound damping out back. The flatter the car stays under braking the more work the rears can do. With Toyo RA-1 track tires and Carbotech Panther brake pads I've outbraked Corvette Z06 and Porsche Turbo drivers. I've even been yelled at by them for almost getting rear ended. That will teach them to underestimate a properly set up dual use car. I was running street pads in the rear too. The car was flat enough that rear track pads would have made a real difference. That extra rear effort would have also helped the car stay stable under threshold braking and make trail braking more consistent.

AB18
11-08-2007, 07:42 PM
Well, i just learned alot. Thanks alot for the taking the time to explain that. Id like to see some cut aways of some of this stuff to see exactly how it all works(dampers),visual learner here.

onemoremile
11-08-2007, 08:27 PM
I'd like to see some cut aways of some of this stuff to see exactly how it all works(dampers),visual learner here.

OK. Anything else? [:D]




http://www.eshocks.com/images/Kon_AllB.jpg

MONO-TUBE SHOCK ABSORBERS
The main components are:

* (pressure) cylinder, also called housing
* piston connected to a piston rod
* floating piston, also called separating piston
* piston guide

How Does a Mono-Tube Shock Absorber Work?

Bump stroke.
Unlike the twin-tube damper, the mono-tube shock has no reservoir tube. There is still a need to store the oil that is displaced by the rod when entering the cylinder. This is achieved by making the oil capacity of the cylinder adaptable. Therefore the cylinder is not completely filled with oil; the lower part contains (nitrogen) gas under 20-30 bar. Gas and oil are separated by the floating piston (15)*.

When the piston rod is pushed in, the floating piston is also forced down by the displacement of the piston rod, thus slightly increasing pressure in both gas and oil section. Also, the oil below the piston is forced to flow through the piston. The resistance encountered in this manner generates the bump damping.

Rebound stroke.
When the piston rod is pulled out, the oil between piston and guide is forced to flow through the piston. The resistance encountered in this manner generates the rebound damping. At the same time, part of the piston rod will emerge from the cylinder and the free (floating) piston will move upwards.




TWIN-TUBE SHOCK ABSORBERS

The main components are:

* outer tube, also called reservoir tube
* inner tube, also called cylinder
* piston connected to a piston rod
* bottom valve, also called footvalve
* piston rod guide

How Does a Twin-Tube Shock Absorber Work?

Bump stroke.
When the piston rod is pushed in, oil flows without resistance from below the piston through the outlets A*, B*, C*, and D* and the non-return valve (19)* to the area above the piston. Simultaneously, a quantity of oil is displaced by the volume of the rod entering the cylinder. This volume of oil is forced to flow through the bottom valve into the reservoir tube filled with air (1 bar) or nitrogen gas (4-8 bar). The resistance, encountered by the oil on passing through the footvalve, generates the bump damping.

Rebound stroke.
When the piston rod is pulled out, the oil above the piston is pressurized and forced to flow through the piston. The resistance, encountered by the oil on passing through the piston, generates the rebound damping. Simultaneously, some oil flows back, without resistance, from the reservoir tube (6)* through the footvalve to the lower part of the cylinder to compensate for the volume of the piston rod emerging from the cylinder.

onemoremile
11-08-2007, 08:32 PM
It is important to remember than high pressure monotube dampers are position sensitive. Since they compress a high pressure gas they get stiffer as they progress through their travel. That high pressure gas also resists initial movement which is why Bilsteins feel stiffer on the street than Konis. The pressure acts as a supplemental spring rate and is one of the reasons they tend to "crash" into bumps and have a sharper feel to the handling.

Twin tubes are velocity sensitive. It takes much less to get them moving so they tend to have a more forgivable ride. This also dulls response slightly.

These characteristics affect the springs that work best with each. High pressure monotubes are often good with a more linear spring rate while twin tubes often favor progressive springs.


Another place to spend a few hours learning nuances that your significant other will never understand: http://www.eshocks.com/Koni_Cmp.asp

onemoremile
11-08-2007, 08:34 PM
Just to confuse matters further, there are also advances in technology like Edelbrock's IAS inertial sensitive valve.

http://www.eshocks.com/images/valve_open_closed.gif

http://www.eshocks.com/images/valveopens_animated.gif

dingguhlbary
11-08-2007, 09:21 PM
i m so damn impressed right now. one day, when i learn enough, im gonna change my username to twomoremiles. because i will have eclipsed your amount of knowledge.

onemoremile
11-08-2007, 10:44 PM
i m so damn impressed right now. one day, when i learn enough, im gonna change my username to twomoremiles. because i will have eclipsed your amount of knowledge.

I've only begun my learning process. You're not chasing a stationary object. [;)]

loustylez
11-09-2007, 07:56 AM
good lord. when jim speaks, you'd do best to listen up.

Rosati
11-09-2007, 11:15 AM
Ask him about Life Insurance [:p]

loustylez
11-09-2007, 11:52 AM
i took my exam a couple years ago and spent about 4 weeks out in the field (hillbilly towns in western kansas) before i sad f it. so if you don't mind, i'll never ask or talk about life insurance again ;)

VMRWheels
11-09-2007, 12:16 PM
I am sure 1000lbs. in a rear of a Audi is still very daily drivable, but for a Honda or other light weight vehicles, with 1000lbs. you will be dancing everywhere. Custom Teins is a great upgrade. You should be able to bear with it being a bit stiffer. [up]

-Charles@VMRWheels

Tiluleshpingen
11-09-2007, 12:48 PM
WOOW THANX ONEMOREMILE.. i am learning alot be reading this thread.. great posts great thread, (applasues)

onemoremile
11-09-2007, 02:22 PM
Anybody that bothered to read through all the other stuff will want to blow some time at http://www.shock-shop.com/ too. They've got some background info that helps establish a more thorough depth of understanding.

"Shocking Theory

In the mid 80’s shocks were recognized by professional formula car teams to be quite important. By the mid to late 90’s some had gone too far and believed springs were only necessary to keep the car off the ground in the pits, shocks did the rest. Today, based upon greater knowledge from aids like data acquisition and shake rig testing, there is a better understanding of the role of the shocks. The most important function of racecar suspension is to minimize tire force variation (keep the tire quiet on the track) in an effort to maximize grip (also called bite). The shocks are an important part of the suspension system. The role of the shock absorber is to assist in minimizing tire force variation.

Teams should not rely upon shocks to tune balance (under-steer, push, tight, handful, over-steer, loose). That should be done with other tools in the tuning bag. Certainly shocks can affect balance but should only do so as they help to achieve grip. That said, there might seem to be exceptions. Rough track, high aero down-force and tuning tools limited by rules come to mind. At times deviations from the norm are necessary. But in the end, it is important to keep in mind that the shocks can be used to significantly affect tire contact patch behavior.



What to Avoid

Everyone should work very hard get good car balance. In recent times it was popular to valve shocks with lots of rebound and very little compression to allow a team to make small shock adjustments that the driver could feel and thereby, supposedly, achieve a good balance. Unfortunately, this approach is sure to take away grip. Simply put, compression helps keep the tire on the racing surface, rebound keeps it off the racing surface. If the shocks are so stiff as to significantly affect balance, they are too stiff to accomplish their primary job: assist in minimizing tire force variation.

Further, lots of rebound does not allow the suspension to droop. In cornering, high rebound and low compression forces move the roll center toward the inside tire contact patch causing undesirable if not unpredictable changes in dynamic cross weight (balance). Most often, minimizing dynamic suspension rate changes will make the car easier to balance. Only if a balance problem can be fully described, and then only with a thorough understanding of the suspension can one utilize dynamic suspension rate changes to advantage."

onemoremile
11-09-2007, 02:53 PM
Ask him about Life Insurance [:p]

or home theater... 16ft3, 16hz, 146.2dB (http://s23.photobucket.com/albums/b397/onemoremile/?action=view&current=solidseriesassem1_isoshadedperspect.jpg) [eek]

Rosati
11-09-2007, 07:13 PM
hahaa Autocad ftw

Looks good man, sounds should echo real well

dingguhlbary
11-09-2007, 09:27 PM
damn you onemoremile. damn you.

grip_racer
11-09-2007, 09:54 PM
off topic:
haha what drivers/enclosure design are you using to achieve that SPL that low??

on topic:
would spring rates of 10kg/mm front, 6kg/mm rear be acceptable on a FWD B5 DD?

onemoremile
11-11-2007, 07:52 PM
SolidWorks. No echoes. My wife stopped me from building a real anechoic chamber but I came damn close.

Adire Audio Tempest 15" subs. Alesis 30 band EQ acts as an 8 band for the subs. The LFE signal from an old Onkyo 5.1 receiver runs through an Ebtech Hum Eliminator and then through the Aleses MEQ-230 to a QSC-3500 dual monoblock pro audio amp. The subs are getting 350w each at 8ohms but they might get rewired to 700w each at 2 ohms.

Each of the cabinets has over 8 cubic feet of sealed air volume and weighs over 160 pounds. Each sub's in-cabinet f3 is about 15.5 hz. Q is in the .6 range. This is an audiophile setup that just happens to play very very loud. i can hit mid to upper teens with no problem and no distortion. 20hz is about 112db at the listening position 15 feet back. The system is more or less flat to 13 or 14 hz.

That's just the motor end of the system. The real trick part is the room. It is a floating box within a box. There is a one inch air gap between my stud wall and the outside block wall. All of the 5/8 drywall is mounted on elastic adhesive and floats. The carpet has multiple layer pads of differing densities. The wall panels are 3/4" thick acoustic insulation like used in recording studios. It is covered by a hemp/flax weave fabric. Even the deep texture on the ceiling helps to deaden the room.

The shape and volume of the room, doorway, and hallway all add up one very large bandpass enclosure. That is where the big efficiency kick comes from. The front, center, and rear speakers are Klipsch Reference with incredible efficiency. They only need about 40 watts each to keep up with the subs. The room is also wired for a second set of side speakers if necessary.

grip_racer
11-11-2007, 11:16 PM
seems like youve really got the proper formula worked out there -- sick drivers, clean power, proper enclosures and a well though out room. I remember when Adire Audio was in business, they were building some really incredible HT drivers. I was seeing cheap transmission-line projects with their Shivas all over the internet because of their low cost and great performance.

but also isn't too much room deadening detrimental to the sound? obviously in a recording situation you want things as quiet and anechoic as possible, but I read somewhere that deadening is good to a point for listening and then the sound can become "boring" and lose some brightness and liveliness. correct me if I'm wrong because this stuff interests me.

haha sorry for threadjacking, OP.