to sum it up, im curious if the weight of the front (or rear) of the car has an impact on shock selection.

i have been using zeal s6 for a few months on a 92 hatch. rates from zeal were 12/8 .... i removed the lower cups and switched the shocks front/rear so i could run the higher rates in the rear without affecting the valving/springrate combination. it seems to be working well. end of story.

i recently received 14/10 superfunctions, but i will be running 10/12.. im planning on switching the shocks front to rear again but im having second thoughts.

how can i know what would be the best setup as far as shock valving? if i was doing a custom gc/koni setup and i decided on 10/12 rates for my 2100lb front heavy car, would i want stiffer valved shocks for the higher springrates in the rear? or would the extra weight on the front of car demand stiffer valved shocks for the front even though the spring rates are lower?

can someone please explain this alittle better for me, thanks

btw: this is for mainly street racing with occassional light auto-x/roadrace

 

I will hope that Lee fields this, because he will obviously be able to explain it better, but i do know that the weight does play a factor.

I have seen shock workup sheets that include such data as Corner weights and unsprung weight. (along with the old standards "L-max," "L-min" and motion ratio.)

I would love to see an explanation on what each of these affects.

Jon K
http://www.seat-time.com

 

The weight of the car, the spring rates, the layout (FF, FR, MR, etc.), motion ratios, etc. are all taken into consideration when developing the valving for the car but generally it isn't all plugged into a numerical calculation from which pops a magic valving number. I would say that spring rate is going to be higher on the list of importance than vehicle or corner weight in determining valving because one of the shock's primary jobs is to control the motion of the spring but don't fall into the common misconception that spring rate is the only consideration. Generally the spring rate will follow along with the weight of the car to a point but as we FWD drivers know there is commonly a departure from that after a point at relatively higher than stock rates where we may change the springs to net a preferred handling situation. Then the spring rates may not reflect the actual weight any longer.

Maybe you will have some success by swapping the front dampers to the rear if it is a style that that uses a semi-generic threaded shock body and stroke length with a thread on lower mount that can be swapped from unit to unit, but it is basically a shot in the dark. If you don't have any actual information like dyno numbers to see what the damper really does, where in the range of function it builds force, and how much force is actually built, then you are just doing trial and error.

As a generality, the front end of a generic car will tend to prefer a bit more low speed damping on both rebound and compression than will the rear end as these are some factors that effect some roll control and turn-in in a goal of basic chassis stabilization. However as soon as you say that, you can immediately come up with examples that don't work in that general model. A MR car like a Fiat X1/9 especially with stiff springs will push like a pig with too much front low speed force for it although that same number may be great for an FF car like a Civic. If ride quality, tire grip, surface irregularities are potential issues, then you must be very cautious with how much low speed to use.

Often the rear may not want as much initial low speed as the fronts but dynamics of the suspension of the car will have a lot of say in that. A BMW seems to like less low speed rear damping than some other cars, especially if the spring rate is not the highest.

Also as a generality, the higher the spring rate often you tend to see the more your high piston speed rebound damping will increase. This follows along with the calculations that you get when you calculate the critical damping of the spring. But remember that you are driving a car made of many parts and you are not just driving a spring so critical damping or even being close to it in some parts of the piston speed range can make the car very bad. High damping forces at high speeds that critical damping would suggest can quickly become counter to tire grip effectiveness and your car now wants to skate across the ground and have no grip which is a very bad thing. So that is when a more degressive curve can be better (if the specific car can take it) because initially the low speed rebound may start strongly at very low speeds to be near, at or over critical damping but then as piston speeds grow it will fall farther down below critical damping in an effort to maintain grip and potential ride quality. On a race car with rear race tires, at some speeds the car may run 80% of critical and a street car may run 60% of critical at realistic piston speeds that the car will see. Then at extreme piston speeds that the car may see rarely (berm whacking, sharp bumps, etc.) then the force may drop way below critical just in an effort to keep the tire on the ground and maintain some grip.

So you can see that there are a huge number of variables that all are to be considered and have different weights in consideration of valving. The important thing is that you can't really just calculate it on paper like so many people want to be able to do. You must keep the car itself in the equation and put a driver's butt in the seat as there are so many new variables that you have introduced that you can't calculate. That is why I tend to go nuts when people ask "How high a spring rate can this valving hold?" as you are totally ignoring most of the pertinent requirements. Parts, car, use, and driver all factor in at various levels so if a valving is well designed for the general use to get most people into the ballpark, then you want as big an adjustment range as you can get to then refine it to the wants of the driver and his immediate situation. The bigger the adjustment range, the more variables that can be accounted for without needing to change the overall valving.

So back to the original post, go ahead and play with it but I highly recommend that you get at least a dyno graph on your parts to quantify what they are really doing and what effect the adjustment really has if they are adjustable so you aren't working with no data and risk having your basic assumptions be throwing you off reality. If you had an opportunity to get some actual hard data to then know what piston speeds your car is really operating at, then you now have some real data to work from but this is rare without pretty good data acquisition. Without dyno or data logging info, you are shooting in the dark. From what I have seen in many mass market kit dampers, I am guessing that the valvings front and rear really aren't that that very different from each other in low speed and may be mostly but not greatly different in high speed so this would make it easier to make the car less unhappy of you switch them around. If they were highly refined for actual purpose and the front had a lot more low speed and the rear had a lot less, swapping them around could make the car quite unhappy.

Hope this isn't too long, confusing or boring so maybe it helps a little.

 

Interesting.

So how much spring rate can on OTS Koni handle?

Scott, who hears that MS likes linear valving..."I'll have what He's having"...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">So how much spring rate can on OTS Koni handle?</TD></TR></TABLE>
GRRRR!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">Scott, who hears that MS likes linear valving..."I'll have what He's having"... </TD></TR></TABLE>
And how often do you drive his car on his tracks? I'm betting he doesn't like linear on all cars and all driving circumstances. I know he has a family and children so I'm sure that he doesn't want to thrash them around too much on the street.

Parent voice- "If Billy down the street was to jump off a building, would you do it too?" I hear some people in the world eat bugs and like them. Feel free to follow them blindly too.

 

Lee,

Hahaha.

There's so little info that gets out anymore, but one of the race engineering mags had a story that went into drivability and mentioned MS's personal tastes.

We read that the initial response of the chassis, thru the dampers, is what we feel we're driving, and so "more" low speed force generation is important to a drivers confidence and hence speed.

MS on the other hand, isn't dependent on that kind of feedback, and is able to "trust" the setup to be there when he's done turning the wheel.

Which makes his "slow hands" that much more impressive.

Scott, who says "Lee, come on Doood, you know we're all a bunch Michael Schumachers around here".... ... ....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RR98ITR &raquo;</TD></TR><TR><TD CLASS="quote">We read that the initial response of the chassis, thru the dampers, is what we feel we're driving, and so "more" low speed force generation is important to a drivers confidence and hence speed.

MS on the other hand, isn't dependent on that kind of feedback, and is able to "trust" the setup to be there when he's done turning the wheel.

Which makes his "slow hands" that much more impressive.
</TD></TR></TABLE>

Entirely valid. I think also most people realize that F1 tires are often a limiting factor in grip compared to the other mazing capabilities of the car so less initial low speed nose angle might help that. Also mix that with the info that I have heard from the Koni engineers who worked with BAR and said that the suspension really doesn't move hardly at all and modern F1 dampers are extremely responsive but don't really make that much force anymore would would lend the shape to being more linear than digressive as well.

Whether we want to be Michael Schumachers (not me but I would like his paycheck, talent and physique), our cars aren't the same as his so the set-up info crossover is nil other than generalities. Generally add as much low speed as the car and grip opportuntiy can deal with but we are talking about graph shapes when talking linear and digresasive and not talking about real numbers. A line drawn vertically, a line drawn at a 45 degree angle, one at a 20 degree angle and a horizontal line are all "linear" but obviously very different. A degressive curve can have many different knee angles and hit any number of actual force values at a given higher speed and still be degressive.

 

thanks for the response, it was confusing but ill read over it afew times for better understanding

these are graphs of the s6 shocks (not mine, but same shocks that are on my car now). dynoed and posted by el pollo diablo, he said they were raced on for a season so they are not fresh, but hopefully it will help this discussion.

the superfunctions use aluminum piston rather than a teflon used in the s6, also superfunction have free floating piston to seperate oil from nitrogen, but according to endless usa the valving it set very similar between the two with slightly more rebound going to superfunctions.

loosly based on what you said about he low speed valving, looking at these graphs i think the front shocks should stay in the front. but i really dont know how to interpret these graphs properly.

thanks for any additoinal info you can provide.

edit: i originally swapped these front to rear based on the much higher numbers for the front shocks, i figured the higher numbers meant it could handle a stiffer springrate, i didnt want to put he 12k springs on the rear shock that is "designed" or whatever for an 8k. shocks are are foggy area for most peopel i think, there is alot of misunderstanding and just plain misinformation



Modified by euclid at 3:50 PM 9/3/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by euclid &raquo;</TD></TR><TR><TD CLASS="quote">
also superfunction have free floating piston to seperate oil from nitrogen

</TD></TR></TABLE>

FYI, All new Zeal shocks use the free floating piston.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RineRacing &raquo;</TD></TR><TR><TD CLASS="quote">

FYI, All new Zeal shocks use the free floating piston.</TD></TR></TABLE>

only afer may of 2002, before that it was only the superfunction, so im not sure these s6 that were dynoed have it or not. el pollo diablo posted a few months ago and said they were raced on for a year

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by euclid &raquo;</TD></TR><TR><TD CLASS="quote">only afer may of 2002, before that it was only the superfunction, so im not sure these s6 that were dynoed have it or not. </TD></TR></TABLE>

I would be interested in how they define "full floating divider piston". I think you may find that it really is no different between any other divider piston which is a disc shapped piston made of steel, aluminum or plastic and an O-ring seal around it to keep the nitrogen gas charge on one side and the oil on the other. I can't think of what a divider piston in a mono-tube would be if it wasn't "full floating". In every mono-tube I have seen inside of, they are essentially to exactly the same.

Reminds me of when my stepdad mentioned something that was made of "aircraft aluminum". His point was, "what kind of aluminum hasn't been used in an aircraft?". They are trying to make it sound like a distinction when there really isn't one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by euclid &raquo;</TD></TR><TR><TD CLASS="quote">loosly based on what you said about he low speed valving, looking at these graphs i think the front shocks should stay in the front. but i really dont know how to interpret these graphs properly.</TD></TR></TABLE>

As I said above, even having not seen the graphs I didn't think there would be that much difference. Now that I see the graphs (which we made at Koni) I still say the difference is essentially moot on rebound other than the max max value. The fronts have a max rebound of about 3000 Newtons at .33 Meters/sec and the rears are only at 1700. I wish I had put the OTS Koni on that graph as I am sure it would have more low speed than both and liklely more high speed at least on the back. The revalved ones have a lot more of both. Generally in this less than ideal situation, I would say that the higher rebound value should follow the stiffer springs but then I look at the compression damping numbers and see that the low speed numbers down in the knee area are double on the front what they are on the rear. By doing the front to rear swap, you would be losing the low speed bump response so I am afraid the car would lose some of the initial turn-in response and levelling effect on the chassis, especially since the higher spring rate is also not there to hold it up.

So I would say the potential gain of the swap of more rebound force at high speed is going to be offset by loss in turn-in response from bump damping. My vote would probably be to leave them where they are. Actually my vote would be, if you are really serious about it, to sell them to someone else who wants to to make his car really low on a cool kit and get some better dampers but that probably isn't what you are wanting to hear.

 

its not about what i want to hear. thanks for the honest info

for comparison sake do you have any graphs of ots koni or revalved, double adjustables or anything? thanks again


Modified by euclid at 10:06 PM 9/3/2004

 

does the piston speed depend on the cars corner weights? i am imagining the same shock with the same springrate on the front and rear of an FF car hitting the same bump... if there is more weight over the front it seems the piston speeds would be faster and the shock and spring would compress more. even at low speed the added weight trying to lean the chassis would subject the front shocks to more force

this makes me think that by moving the rears to the front like i did is overworking them; and the much stiffer front shock now on the lightweight rear are underworked and not nearing full potential; as the high and low speed capabilty of the stiffer shocks is not being approached

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by euclid &raquo;</TD></TR><TR><TD CLASS="quote">does the piston speed depend on the cars corner weights? i am imagining the same shock with the same springrate on the front and rear of an FF car hitting the same bump...
</TD></TR></TABLE>

Yes it has to be some minor factor but pretty marginally I would think as part of the overall mix that is the car and the circumstances. I would think the input of the energies from the road surface, inertia of the moving car, and other things on the car are going to be of larger value. Remember that the damper or car are only going to spend a tiny, tiny amount of time with each input and move onto the next so they are all linked steadily together rather than having time to deal with them much as isolated circulstances. Don't make too much out of single events because again there are so many things going on, working together, and moving pretty fast. Overworked and underworked to me sound more like heat building issues and I really hope they aren't so poor that heat is having that much effect.

It is more the differences in the bump valving in your situation that concerns me about the swap. The lack of low speed forces and general max number on the rear on the rebound on both make neither of them really much to write home about or be concerned about having one be a negative effect over the other.

We recently looked at the files saved on that particular dyno that it was run on and I think the guys did not find any of our Honda racing stuff on it. We have multiple dynoes with varying software so you can't just load a file from one to another and get a layover print plus we don't test all shocks that we built on the force vs. velocity dyno or save all files. All shop work orders are tested on a force vs. displacement dyno which looks totally different and is saves with every work order.

 

im going to leave the fronts on the front and see if the turn-in improves over my current setup. ill post back sometime this week. thanks for all your time Lee. you and koni in general get a from me.

 

Hey I'm willing to trade..I have apex-i N1 Type-V with 8/9K spring rates, the only problem is I'm waiting on some spanner wrenches and bottom mounts since they are the same design as your rear buddy clubs..and they got bent a little when I hit a pot hole... so I'm awaiting new bottom mounts from HT member "blueR".. lemme know if you're interested...