katman Posted December 9, 2002 Share Posted December 9, 2002 Originally posted by David Karey: Now the reason i used the 81-83 Turbo rear springs, is that they are 10mm longer in length. Now, when you compress that spring down to the n/a spring spec, you have a stiffer spring. Huh? Quote Link to comment Share on other sites More sharing options...
David K Posted December 9, 2002 Author Share Posted December 9, 2002 its a stiffer spring Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 9, 2002 Share Posted December 9, 2002 Originally posted by katman: quote: Originally posted by David Karey: Now the reason i used the 81-83 Turbo rear springs, is that they are 10mm longer in length. Now, when you compress that spring down to the n/a spring spec, you have a stiffer spring. Huh? I kind of said "huh" too, because a spring rate changes incrementally per inch but a longer spring doesn't neccessarily mean a higher spring rate. Spring rate is determined by thickness of the wire, number of coils, and the median of the spring diameter. Take off a coil and the spring rate goes up, add a coil (longer spring) and no other changes to the spring and you have a weaker rate. Now I think I see what you mean, compress the spring to the starting position of the older spring and you have a higher starting rate, so throughout the rest of the springs travel it would also be a higher rate, although this also means that you could be giving up suspension travel if the spring coils will bottom out on themselves but that again is going to depend on wire diameter and number of coils along with the length that the spring travels. If you felt the car handled neutrally before though, and you increased rate in the rear, then you no longer have a neutral car Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 9, 2002 Share Posted December 9, 2002 Compressing a spring more does not increase the rate of the spring. If you're using the same mounting perches as the previous springs, all you did was increase the ride height a little. Quote Link to comment Share on other sites More sharing options...
David K Posted December 9, 2002 Author Share Posted December 9, 2002 Yes and no. Im using the n/a KYB, so it can only travel up so far. Once it gets there, it stops. Now if you take the turbo spring in its 10m longer length, squish it down to size, and then insert the assembly on the car and then lower it, the car will sit slightly the same height at the previous springs. The spring can only travel what the shock allows it to. So thus, the more compressed the spring is, makes it stiffer and allows the car to recover faster from whatever you throw at it. So yes, and no. The ride height it not higher, yes the spring is stiffer. A little secret a z guy from Japan taught me. Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 9, 2002 Share Posted December 9, 2002 David, I disagree, BUT I'm glad you're happy with how that setup works on your car. Nice burnout pic BTW. John Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 9, 2002 Share Posted December 9, 2002 Huge BS flag! Whoa David. Just a few key phrases that really stand out in my mind before I could even read what you had: This setup takes whatever i throw at it, and i NEVER ever lose control and ran up with the best modded z's at a recent mountain run Here comes my standard spiel. You should know better... First, if you NEVER have lost control, you aren't pushing it to its limit. If it takes everything you are throwing at it, you are throwing enough at it. These two things have nothing whatsoever to do with how well it handles. I can take the fastest and most well setup up Z race car,(lets say a GT-2 300zx), which will blow the doors off everything we could muster Z wise I can still lose it. Control, or a percieived sense of control, has nothing to do with the suspension or handling, but rather with the driver and how far they are taking the car. David, you really ought to go to one of the open track events with a group like NASA or similar. You would love it. Yes, they can get expensive, but think about 2 hours or more at full speed on a race track, reaching speeds of over 130 on some tracks. Stay away from the mountain roads, esp. when I am there. Next, the staying with a heavily modified Z on a mountain road. Again, this tells us the reader, Nothing!. You know better than that. I can tell you that 99% of the drivers on the road have no idea how to maximize their car in a turn. And a good driver can whoop their butt in a stock Honda Accord or Dodge Neon. I won't even go into my thoughts on racing on the "mountain runs" and will assume you were not doing something like the Mullholland Morons,(if you were, I don't want to know). "Mountain runs" are a great way to kill people,(well documented). I can go into this into much more detail if you want to push the issue. I suggest not since I am well armed on this one. I am all for a fun mountain run but I want to be clear about my thoughts on any form of "racing" or "pushing it" really hard on a mountain road vs. any other car. Again, not pointing the finger at you, but I feel very strong about this, and want to make my position clear. That being said, you do offer a good setup. However, there is also 225/50/15 tires which would offer a slightly larger contact patch,(assuming at least 7in wide rims). And the Tokico's are a well known, stiffer shock which perform well when used in a performance application. However, when you pointed out the cost of the KYB's, the Tokico's would be more expensive. Just an alternative. These are just to give more choices. Your setup offers a cheaper setup that works as well or better than more expensive options. And the rear strut brace doesn't do much for the car, or rather not nearly as much as a front brace. The front is the weak spot in both the Z's and ZX's. The rear is surrounded by that thing called the body, offering good support for the shock/strut towers. Last, time to go to school with this spring issue. Your little guy in japan is incorrect. John,(jt1), and Mudge are dead on. You even proved their point for them. Let me see if I can explain. First, lets assume a 2800lb car,(maybe conservative). That means each tire in a static situation is supporting 700 lbs. So regardless of the spring, each tire still supports 700lbs. I think we can agree that the car will compress the spring some portion, regardless of which spring you start with,(remember, we are talking about two identical rate springs, one is just longer). Let me put out two figures, made up, but for this illustration. Lets say both springs have a rate of 175lbs/inch. And the NA spring must be compressed 1 inch to fit in the struts fully extended and the Turbo spring must be compressed 2 inches,(because it is 1 inches longer). That means before we even compress the strut, the NA spring is exerting 175lbs on the strut and the Turbo spring is exerting 350lbs on the strut. So the NA spring must travel 3 inches before the car will settle. The Turbo will travel 2 inches before the car is stationary. Net result? Higher ride height. 1 inch is not much and in your case, it would be about 10mm or less than one inch. Next, it is still not a stiffer spring. How stiff a spring is is solely detemined by the spring rate, which is the same in this example. And the effective wheel rate will remain the same as well. The difference is you are starting with a higher point. The neutral point is still, and will always be 700 lbs per tire until you start moving. For a longer spring with the same rate, it just means it starts at a higher point, which also gives you a higher center of gravity...... You still have a 175lb/in rate spring, but its neutral point is 1 inch,(in your case, 10mm), higher. It reacts the same and everything. The difference is you have 1 inch less compression travel, and you are now taking the chance of compressing the spring to the point where the coils touch each other. That is not good at all for handling. Before I dismiss class, let me say that you still suggested a good setup. However, if the turbo spring is indeed the same rate, I would not run it. -Bob Quote Link to comment Share on other sites More sharing options...
David K Posted December 10, 2002 Author Share Posted December 10, 2002 Originally posted by Bob H:David, you really ought to go to one of the open track events with a group like NASA or similar. You would love it. Yes, they can get expensive, but think about 2 hours or more at full speed on a race track, reaching speeds of over 130 on some tracks. Stay away from the mountain roads, esp. when I am there. -Bob Thanks for making the suggestion, but it would make no sense to offer such advice when i already DO IT. Buttonwillow, WSIR,...thanks. Yeah and what you said about the spring is what i was trying to say all along. What i do mean, is once the spring is compressed, it makes for a stiffer assembly . I know nothing of these "spring rates" you fellows keep mentioning. Thanks for that too. Quote Link to comment Share on other sites More sharing options...
David K Posted December 10, 2002 Author Share Posted December 10, 2002 Ok this goes for 79-83 Z guys. If you are looking for excellent handling, i will share with you. This setup takes whatever i throw at it, and i NEVER ever lose control. I ran up with the best modded z's at a recent mountain run. Shocks and Struts: KYB Gas-A-Just Springs: Stock n/a fronts, Stock 81-83 Turbo rear Bushings: stock rubber Wheel: 15" Tires: 205-60-15 Misc: Custom solid angled rear tower brace. Now the reason i used the 81-83 Turbo rear springs, is that they are 10mm longer in length. Now, when you compress that spring down to the n/a spring spec, you have a stiffer spring. I hope this helps some of you who have a ZX and are looking for a fairly inexpensive setup that you can run balls to the walls in. Good Luck Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 10, 2002 Share Posted December 10, 2002 Awesome, then I'll see you when I get stationed out there. And just to be clear, a stiffer assembly still has no bearing on how the car rides. It must means it starts physically higher. The reaction to bumps and turns are the same. -Bob Quote Link to comment Share on other sites More sharing options...
Guest eric-z Posted December 10, 2002 Share Posted December 10, 2002 how much did that end up costing for you? eric Quote Link to comment Share on other sites More sharing options...
David K Posted December 10, 2002 Author Share Posted December 10, 2002 Eric, I bought the rears for $40/both and fronts $80/both at a small vietnamese shop in my area. The wheels are 81 Snowflake Turbo 280zx wheels. The tires are Firestone Firehawk SH30's, but i know there are better 15" tires out there. Look around, the Gas-A-Just is not expensive. Info on GR-2's http://www.kyb.com/shocks/gr2.html Gas-A-Just http://www.kyb.com/shocks/gasajust.html AGX http://www.kyb.com/shocks/agx.html Notice the pictures of the cars on each page. Thats kind of how they should be used. For you early Z guys, it really sucks they dont make Gas-A-Just for 70-78, from what i have seen. Quote Link to comment Share on other sites More sharing options...
David K Posted December 10, 2002 Author Share Posted December 10, 2002 it would be great to run! Quote Link to comment Share on other sites More sharing options...
katman Posted December 10, 2002 Share Posted December 10, 2002 Originally posted by David Karey:Yes and no. Im using the n/a KYB, so it can only travel up so far. Once it gets there, it stops. Now if you take the turbo spring in its 10m longer length, squish it down to size, and then insert the assembly on the car and then lower it, the car will sit slightly the same height at the previous springs. The spring can only travel what the shock allows it to. So thus, the more compressed the spring is, makes it stiffer and allows the car to recover faster from whatever you throw at it. So yes, and no. The ride height it not higher, yes the spring is stiffer. A little secret a z guy from Japan taught me. He teach you wrong, Grasshopper. Makes no difference how long the spring starts as long as the weight of the car makes it compress beyond what the constraint of the shock is. If the ride height didn't change, then the spring rate was the same, and the rate at the loaded height is the same. As stated previously, stiffness is a function of wire diameter, material, coil diameter, and number of coils. stretching one out 10mm and then compressing it back doesn't change the stiffness. Recovering faster has more to do with shocks than springs. Transistions are shocks, steady states and ride heights are springs. I'm with Bob. All cars handle great at 9/10ths. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted December 10, 2002 Share Posted December 10, 2002 Not trying to make an example of young David here, but This is a good example of a young, enthusiastic guy who has been told some basic BAD info... To all you youngsters out there (And age has NOTHING to do with this, experience does...) YOu guys have people Like Ross Courigan, John Coffee, Doug Carroway, Bob H, JT1 and others who.... RACE CARS or attend MULTIPLE TRACK EVENTS yearly... If you guys are smart, and I hope you are, because you are here in the first place, I would PICK THEIR BRAINS and L-E-A-R-N from their VAST EXPERIENCES... Seriously guys, this is an opportunity you are missing if you want to truly understand the physics behind MASS in motion... David, Good try, atleast you are experimenting... However, I bet dollars to donuts that that car wouldn't hang with a Honda Civic with the right driver behind the wheel of the civic... What Bob H said is largely true... What you are throwing at your car may seem like a lot to you, but to those who spend time on race tracks alot, it probably isn't a tick above spirited driving... Now let the class room sessions begin... Mike Quote Link to comment Share on other sites More sharing options...
David K Posted December 10, 2002 Author Share Posted December 10, 2002 no, no, no, no, NO! you guys do not seem to understand what i am saying. Lets start with this. Examples: BOTH SPRINGS ARE THE SAME RATE! Spring #1, If you take this spring that is 1 1/2' in length, compress it to a certain length, than it would be only so stiff. Spring #2, if you take THIS spring that is in example 2' in length, compress it to the same height as spring #1, than you have a STIFFER assembly than spring #1. Do you guys not see where i am going with this? I know i am right because i have in front of me 2 different length springs from RC cars that i compress to the same length and the longer spring pushes back harder and wants to pop out from between my fingers more than the shorter spring. I never said "spring rate". Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted December 10, 2002 Share Posted December 10, 2002 David I am going to toss in something that no one else has mentioned yet that I feel may have a more direct impact on you. Since you are using a spring that is longer and you are creating a stiffer assembly in doing so you still have only two things that keep that spring contained, the first is the weight of the vehicle and the second is strut. Because of this one of two things are going to happen either your car is going to sit higher because of the longer spring or your strut is going to have its valving jammed into the top of the tube. If your ride height is increased you increase the height of your center of gravity and get less stability, if your valving is hitting the top of your strut tube you are going to be replacing struts on a very regular basis. Dragonfly Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 10, 2002 Share Posted December 10, 2002 According to the MSA catalog there is no difference in rear strut or shock application for 1981-83 turbo and non turbo ZX's which means the turbo springs in David's ZX are compatiable with the shocks.David should be given credit for experimenting and without this adversion to convention ,we all would be packing things around with are hands and relying on our feet for transport.About the only thing I know about mechanical science: a lot of exceptions variations, and deviations to the rules. I do not fully agree but apparently this combination is working for David's needs and is an economical approach to stiffer springs in his personal application. Quote Link to comment Share on other sites More sharing options...
katman Posted December 10, 2002 Share Posted December 10, 2002 Originally posted by David Karey:no, no, no, no, NO! you guys do not seem to understand what i am saying. Lets start with this. Examples: BOTH SPRINGS ARE THE SAME RATE! Spring #1, If you take this spring that is 1 1/2' in length, compress it to a certain length, than it would be only so stiff. Spring #2, if you take THIS spring that is in example 2' in length, compress it to the same height as spring #1, than you have a STIFFER assembly than spring #1. Do you guys not see where i am going with this? I know i am right because i have in front of me 2 different length springs from RC cars that i compress to the same length and the longer spring pushes back harder and wants to pop out from between my fingers more than the shorter spring. I never said "spring rate". Yeah, that's right. However, if the weight of the car is the same as it was with the stock springs, then they would both be compressed to what you are calling the "stiffness" at the compressed height. Your ride height HAS changed and you have the exact same stiffness. Regardless of where it's compressed it has the same rate, which means as far as handling is concerned the characteristics are the same as stock as far as weight transfer. All you have done is raise the ride height. Maybe not enough to notice. Sorry. Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 10, 2002 Share Posted December 10, 2002 David, first of all let's define terms. "Spring Rate" is how much a given spring deflects under a given load. It is commonly expressed in the units of pounds per inch (#/in). For instance, a 200 #/in spring will compress 1" under a 200# load, 2" under a 400# load, 3" for 600#, etc. Mudge and Katman have stated the factors that affect spring rate, wire dia., number of coils, etc. LENGHT of the spring does not affect the rate. You can have a 200 #/in spring that is 8" overall or 12" overall. It will still take 200# to compress the spring 1", and an additional 200# for every additional in. of compression. Universally in the world of high performance cars, if someone says a "stiffer" spring, they mean a spring of a higher rate, for instance, a 300#/in spring is stiffer than a 200#/in. Remember that lenght of the spring is not a factor. I think MiKelly is right that you have been given some bad information that you believed, so lets talk about what happened. You put some springs off another car onto yours and the car felt better in turns. Cool, you like it. Someone told you compressing these longer springs more would make them stiffer, i.e., increase the spring rate. Wrong. Compressing the spring more just increases the load on the spring. Since the force (the weight on the rear of your car) compressing the spring is the same, if the springs are the same rate, a spring with a longer free lenght will still be longer than a shorter spring. This will increase the ride height of the car, since the longer spring is still longer under compression. The force required to assemble the strut has nothing to do with this, only the spring lenght, rate, and load. The fatal assumption is that the new springs were stiffer. Since they were longer, it probably took more force to assemble the strut, but that doesn't make them stiffer. The only way to be sure of spring rate is to test them on a spring checker. Then you know. Probably what happened is that your old springs were fatigued. As springs are used, they wear out. They get shorter and the rate decreases. Since the new springs were longer, they were probably in better condition that your old ones. The newer springs made your car feel better. That's good. I am not being critical, just trying to help you understand some of the terms and physics involved. Many books have been written about suspensions, and many more will be. There are a lot of people more knowledgable than me. You made a change to your car and liked it. Keep working on it and learning about it. John Quote Link to comment Share on other sites More sharing options...
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