Springmount Mod??
I have a 03 Z on a stock suspension it sits a little high in the back would the spring mount mod be an acceptable way to level out the car?? Or is this mod usually done by owners who already have lowering springs installed on their car. Would just like to drop my car a bit in the back not lower it all over..
THANX!!!! |
It is an acceptable way of lowering your rear end, done by anyone who wants their rear end to sit lower.
I have only read one negative review, and think the reasoning behind it was shoddy at best (claimed that the rearward weight transfer had a detrimental effect on his steering feel - something about less weight on the front wheels). I am working on some calculations to debunk (or prove) this logic. Besides, I suppose all Zs with an even drop have this problem then :rolleyes: I didn't notice any ill effects when I cut mine, except for those usually associated with lower ground clearance. |
Originally Posted by guitman32
(Post 7385859)
I have only read one negative review, and think the reasoning behind it was shoddy at best (claimed that the rearward weight transfer had a detrimental effect on his steering feel - something about less weight on the front wheels). I am working on some calculations to debunk (or prove) this logic. Besides, I suppose all Zs with an even drop have this problem then :rolleyes:
I didn't notice any ill effects when I cut mine, except for those usually associated with lower ground clearance. |
Originally Posted by mcarther101
(Post 7385994)
That's just dumb. Lowering the rear by like .2 inches wouldn't change weight distribution.
Originally Posted by mcarther101
(Post 7385994)
It's like saying people on coilovers who are flush in the front/rear suffer from this too.
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Originally Posted by terrasmak
(Post 7386548)
Put a car on corner scales and see what happens. I'll bet your wrong. I'll also bet it changes you caster up from too, also changing the way your car handles.
Yes they do Thanks for defending me Bro......I have been swapping springs and shocks like a MOFO..... I would also like to explain a little more to these guys just so that they can see where I am coming from. OK here goes. lets take a STOCK Z......and put some Hotchkis sways on it. (hang on I want you to understand HOW i discovered this) we are going to go third hole up front and weakest hole in the rear....this puts both bars at 80% stiffer than stock...the car will handle exactly like stock except it will feel stiffer all the way around. NOW....lets cut the recommended HALF an inch from the rear spring mount to even out the car.....WHOA! its not as stiff up front....lets fast farward through the hours of troubleshooting shall we.....in order to get the handling back we need to stiffen up the front swaybar, BUT they are already on the third hole (stiffest...4th hole is for the G35) so in order to get the handling of the swaybars to be as they were BEFORE we cut the springmount we need to stagger the front swaybar...on one side we will leave it in the third hole and on the other side we will move it into the 4th (G35 hole) and go for a test drive....OK we got our handling back.....It fells a little weird because we lost some strut travel but it is doable. Can you guys understand where I am coming from? I did EXACTLY as described except that I had RS-R springs that have a .6inch drop all the way around (this keeps the car in balance same as stock except lower... on a stock car...maybe a half an inch does not really seem like its all that bad....but when you are already lowered .6 inches all the way around.....and THEN do the spring mount mod.....WELL you are now .6 inches lower in the front and 1.1 inches in the rear..... Hope this makes sense. Try to get springs that drop exactly the same in the front as they do in the rear or REALLY close to it. RSR- is even drop front and rear at .6 inches....If you really want to go lower i think the tanabe nf210 is 1.2 inches front and rear but that is a progressive spring... you CAN eliminate wheel gap in the rear by choosing your spring carefully. If you MUST try the springmount mod.....BUY an extra set so you can switch back if you dot like it.....in order to even out the STOCK Z you must cut half an inch off.....not the .2 that you guys were mentioning.... people who do the springmount mod do it for looks....if you look at the comments all you will see it "man that looks low" "looks good" "love it" "like it" but wont see any comments about how it actually feels....I decided to do this cause i wanted to even out my drop....with no comments on anything bad happening i did it myself....immediately feeling sorry that i ever did it in the first place. the 4th hole on the front of the swaybar puts a TON of stress on the endlink and you can feel it binding....I actually tested this...... I am not telling anyone what to do with their car....only warning them what effects it will have in the end.....if you don't mind the negative effects....and want to go for it....do it....but i recommend you buy some extra upper springmounts in case you don't like it....I didn't and now they are on back order and i have been driving around like this for over a month hating it hope this explains everything in detail..... "calculations to debunk (or prove)" wont do anything....you MUST try it out yourself in order to understand whats going on. People who say they didn't fell a difference....please POST your suspension setup. Thanks! |
Originally Posted by mcarther101
(Post 7385994)
That's just dumb. Lowering the rear by like .2 inches wouldn't change weight distribution. It's like saying people on coilovers who are flush in the front/rear suffer from this too.
I am not advocating this point, and am in fact trying to prove that the weight transfer benefits outweighs the purported drawbacks in steering feel. My hypothesis is that the weight transfer to the rear, and corresponding weight removed from the front tires, is negligible and acceptable compared to the benefits of lowered CG and improved weight distribution (aesthetic benefits non withstanding). Furthermore, once I get a ballpark figure on exactly how much weight is transferred to the rear (and off the front wheels/tires), I will be able to hypothesize whether this weight transfer can even have a noticeable effect on steering feel. This can all be resolved with math, and given a certain set of assumptions (e.g. car weight distribution - f/r and left/right, ride height, etc), the exact weight transfer off of the front wheels can be calculated. As I said, I'm working on it. |
To danimaldaisy-
Read my previous post. I disagree with you touting running an even ride height as being detrimental to steering feel. And even if it is, I posit that the benefits outweigh the drawbacks. It is an interesting case, as I am running the same springs as you (RSR). I'm running Koni SAs. Hotckis sways front and rear (edit: these are 2nd gen sways, with 4 levels of adjustability up front). As I stated, you are correct that the weight does transfer to the rear (and off the front wheels, to your point) when cutting the springmount. But until you come to me with some math, I will disagree with your assumptions (which is what they are, at best). I cut my springmount 1/2" and didn't notice the same detrimental effects as you. |
Originally Posted by guitman32
(Post 7386713)
My hypothesis is that the weight transfer to the rear, and corresponding weight removed from the front tires, is negligible and acceptable compared to the benefits of lowered CG and improved weight distribution (aesthetic benefits non withstanding). Furthermore, once I get a ballpark figure on exactly how much weight is transferred to the rear (and off the front wheels/tires), I will be able to hypothesize whether this weight transfer can even have a noticeable effect on steering feel.
. Most people say it feels fine , but then again most people will also drive around for weeks with a tire 15 psi low. I don't believe most people. Suspension tuning is not rocket science, but dam close. |
Originally Posted by terrasmak
(Post 7386776)
You forgot one big thing, when bike is lowered or lifted the rake changes, that is an important aspect of handling, also the angle fo the swingarm to the ground. When you raise or lower a car you also deal with these same aspects (caster )
Suspension tuning is not rocket science, but dam close. If we want to get real fancy, we can take acceleration into consideration given all the other variables (longitudinal acceleration pitch and weight transfer, etc). I am not doing this (yet), as the first step is to get the weight transfer figures given a ride height change in the rear. Rocket science, exactly. Talk is cheap, but automotive engineering, well it's science. |
Originally Posted by guitman32
(Post 7386723)
To danimaldaisy-
Read my previous post. I disagree with you touting running an even ride height as being detrimental to steering feel. And even if it is, I posit that the benefits outweigh the drawbacks. It is an interesting case, as I am running the same springs as you (RSR). I'm running Koni SAs. Hotckis sways front and rear (edit: these are 2nd gen sways, with 4 levels of adjustability up front). As I stated, you are correct that the weight does transfer to the rear (and off the front wheels, to your point) when cutting the springmount. But until you come to me with some math, I will disagree with your assumptions (which is what they are, at best). I cut my springmount 1/2" and didn't notice the same detrimental effects as you. if i wanted to reproduce the effects without doing the springmount mod....i could leave the front swaybar setting in the 3rd hole and stagger the rear....one side softest and the other side middle...or maybe even both middle. I am glad we can agree on the weight transfer to the rear which was my point... what part did you not agree on? the differences on our cars is that you are running Koni's and i am running D-specs (not as good as the koni) can you post your swaybar settings....and also front and rear strut settings? you may have just tuned the suspension to work properly..... remember my post was speaking for the newb on a completely stock suspension with no way to tune struts or sways.....i had to throw the sways in there in order to better explain where i was coming from...fortunately everyone understood me.....I know what we agree on...just not sure what we don't agree on. by the way...at least the OP now knows that he will have some weight transferred to the rear. |
one last point....I may have a problem with the stock endlinks......reading on a thread about adjustable endlinks....it is possible that i am getting no preload on the rear endlinks making the car handle sloppy.......but I plan on looking into this....and quickly
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Originally Posted by danimaldaisy
(Post 7386821)
I am glad we can agree on the weight transfer to the rear which was my point...
what part did you not agree on? I have a problem with you decrying this mod as being detrimental to steering feel and handling. You (in this thread and others) have commented on this mod as being a negative to steering feel and handling. I didn't notice these same effects. But, you obviously have a point in regards to the rearward weight transfer, so I am trying to get to the bottom of things. I simply want to know how (using math, not just hearsay) weight distribution is altered given a 1/2" change in rear ride height, and discuss the direct and indirect effects of this change. That's all really. |
Originally Posted by guitman32
(Post 7386796)
I didn't forget it. That exactly what I'm trying to get at, as the rake - or height difference front to rear, is elemental to the calculations involving right height, weight distribution and center of gravity.
. So basically for a few , forget the weight transfer stuff and think of what changing the angles on the steering components does. |
Originally Posted by guitman32
(Post 7386847)
I simply want to know how (using math, not just hearsay) weight distribution is altered given a 1/2" change in rear ride height, and discuss the direct and indirect effects of this change. That's all really.
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Originally Posted by terrasmak
(Post 7386865)
rake on a bike is the angle of the head tube to the ground. Yes weight transfer is changed but the whole dynamics of the suspension are also changed. These dynamics have a lot of effect, thats what i'm trying to get across, even in cars.
For the sake of this conversation, we first have to deal with the aforementioned effects on weight transfer off the front wheels from the 1/2" decrease in rear ride height. After that, we can talk about the associated suspension geometry alterations and their effect on handling. For what we are trying to prove, suspension geometry changes are secondary to the effects of weight transfer and CG. Besides, the point seems relatively moot since you can adjust the suspension geometry on the Z (caster, using aftermarket upper a-arms). Now, if you're telling me that the Z needs a rake to handle properly because of it's inherent suspension design, then we are opening a whole other can of worms, and I would obviously ask you to prove it to me.
Originally Posted by terramask
Call a shop that does corner balancing, they may be able to give you a better idea of how muck movements like that effect balance and how much weight transfer actually happens.
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wait a second, neither of you have called each other an idiot ricer yet.
I'm not used to all this rational discussion |
well
Thats because I don't respond right away with insulting comments which lead to a flame fest. You know....I can type something and 10 people will all read it differently...some will understand, others will not, and others will think you are insulting them. I work at a school and deal with all kinds of people....maybe i have learned the art of "getting along". We are all after answers here....but so far we at least agree on the weight transfer part. Maybe if i was still in my 20's i would be an idiot, but it gets tiring after a while. I joined this forum to get valuable info and contribute.... |
Did some research and came across these threads in some forums:
http://bimmer.roadfly.com/bmw/forums...8862391-1.html http://forums.bimmerforums.com/forum...t-1209398.html Cliffnotes from the above threads: Lowering the rear of the car or altering rake does not significantly affect static weight distribution. I am still not happy though, and am working to prove it mathematically. To terramask's earlier point, I think the next step after calculating the change in static weight distribution is to quantify the change in caster and it's effects. |
I cut mines w/ stock suspension.. it brought the rears down 0.5" looks a lot better now..
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Im not as learned on the engineering aspects of car suspension systems, nor do i even know the workings of each part, but one thing here does not make sense to me while i sit here thinking about what you both have said and am trying to grasp this concept:
Why in the hell would increasing or decreasing rake on a car even effect static weight distribution? If all weight on the car is fixed to begin with and not shifting according to an increase or decrease in rake (like raking a jar half full of water one way or the other and the more water shifting to one side therefore weight distribution), how could rake effect this? There must be some physics i am missing here? Basically, despite how raked the car sits, the weight on both ends remains the same. I could see how changing rake could effect the involved suspension parts, as they are specifically engineered according to the cars initial ride height (ie raising the front could weaken handling due to the suspension components working below normal tolerances, but not a shift in weight having any effect, only angle of compenents like stated by terr.) What am i missing? :confused: |
Originally Posted by GeauxLadyZ
(Post 7408420)
Im not as learned on the engineering aspects of car suspension systems, nor do i even know the workings of each part, but one thing here does not make sense to me while i sit here thinking about what you both have said and am trying to grasp this concept:
Why in the hell would increasing or decreasing rake on a car even effect static weight distribution? If all weight on the car is fixed to begin with and not shifting according to an increase or decrease in rake (like raking a jar half full of water one way or the other and the more water shifting to one side therefore weight distribution), how could rake effect this? There must be some physics i am missing here? Basically, despite how raked the car sits, the weight on both ends remains the same. I could see how changing rake could effect the involved suspension parts, as they are specifically engineered according to the cars initial ride height (ie raising the front could weaken handling due to the suspension components working below normal tolerances, but not a shift in weight having any effect, only angle of compenents like stated by terr.) What am i missing? :confused: Not a thing, I completely agree with you. If any weight does shift one way or another, I believe it will be completely insignificant. Thats what Im trying to prove. |
Originally Posted by guitman32
(Post 7411183)
Not a thing, I completely agree with you. If any weight does shift one way or another, I believe it will be completely insignificant. Thats what Im trying to prove.
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Originally Posted by terrasmak
(Post 7411672)
If thats the case, why does corner balancing make such an improvement ??
Static weight and crossweight are two seperate measurments. To corner balance, you first get the static weight distribution where you want it, then you proceed with cornerbalancing. Per the articles below: "The only way to change the static weight distribution percentages is to physically move weight around in the car. Jacking weight will not alter the left side or the rear percentages. " http://grassrootsmotorsports.com/art...orner-weights/ http://books.google.com/books?id=BJU...num=5#PPA62,M1 |
Originally Posted by guitman32
(Post 7411881)
We aren't talking about corner balancing, we are talking about modifying static weight distribution.
Static weight and crossweight are two seperate measurments. To corner balance, you first get the static weight distribution where you want it, then you proceed with cornerbalancing. Per the articles below: "The only way to change the static weight distribution percentages is to physically move weight around in the car. Jacking weight will not alter the left side or the rear percentages. " http://grassrootsmotorsports.com/art...orner-weights/ http://books.google.com/books?id=BJU...num=5#PPA62,M1 EXACTLY!! This is basic physics, if even that. The only thing one would have to worry about when changing rake is applying increased pressure to the rear suspension components, but its no different than lowering the car with springs....just in the rear, though. If you have, per say, a camber kit, rear camber arms, toe bolts, etc. or a variation of these according to your drop, then everything is FINE. There is no way doing this spring mod could change handling or weight distribution any more than getting springs or coilovers. If there are any changes, they would be insignificant. |
Originally Posted by GeauxLadyZ
(Post 7412282)
There is no way doing this spring mod could change handling or weight distribution any more than getting springs or coilovers. If there are any changes, they would be insignificant.
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Quick question guys, does this springmount mod work for guys with true coilovers?
Thanks |
Originally Posted by guitman32
(Post 7411881)
We aren't talking about corner balancing, we are talking about modifying static weight distribution.
to the person asking about the spring mount mod when using true coilovers, just think about it. Would this work if your springs are no longer in this location. His comment is a great example of how many people actually know what is going on , let alone what these mods actually do to the handling there cars. |
I asked this question originally and to be honest after reading everything I am afraid to do it!!!
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Originally Posted by striker27
(Post 7414619)
I asked this question originally and to be honest after reading everything I am afraid to do it!!!
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But there is also no reason (proven anyway) not to do it. I would do it for a 1/4" BUT thats all i would cut. I try to stay away from doing "half-azzed" mods such as this. but to tell you truth i may do as the seat is easily replaceable, and very cheap.
My s-techs are great but could use a 1/4" butt drop. |
I still think the spring mount mod affects the balance of the car somewhat but realized that my SLOPPY HANDLING was contributed by something other than the spring mount mod....I would like to apologize for this
just today i realised my problem on my car....I have had chitty handling for the past 40k miles and have thrown 3 sets of struts at my car as well as 4 sets of springs hotchkis sways and upper tubular A-arms with adjustable camber..... EVERY time i thought i fixed my problem the sloppy handling came back..... when i finally got hotchkis sways i thought my problems were gone, but all this did was put more pressure on the already blown bushings and work for a minute and then further damage the bushings until i was right back where i left off with sloppy handling once again....first i bought KYB struts which was a mistake cause they were weaker than factory....then i got tokico blues but they weren't up to the UNKNOWN task that they were compensating for bad bushings and a sway bar that was almost barely working cause of the bushings....enter the d-spec and it is drivable now.....but the bushings are so bad now that the one that connects to the chassis SEEMS to the eye to be fine but once you tear apart the suspension it has seperated...... To sum things up. My lower control arm has 2 bad bushings.....the bushing that the strut attaches to is cracked on the bottom and sagging (WHY couldn't the nissan tech see that?????) also the main bushing on the inner part of the lower control arm that connects to the chassis is separated and basically is in the same condition as a blown motor mount......but it is still in place.....i can literally twist the lower control arm left and right with little effort as if i was grabbing the end of a pipe and twisting it. The same exact problem on both sides of the car. So HOW you may ask would this affect handling????? well the swaybar is connected directly to the lower control arm by an endlink, and the swaybar is NOT working because of this....and even if it is it is TOO LATE.....I need to replace these bushings in order to fix my problem..... by the way...I pulled the d-specs and tested them and the are strong as hell on the stiffest setting.....i had them set to full stiff to overcompensate the front swaybar not operating correctly..... this problem showed up at 50kmiles and now i have 100k miles.... if you have weird swaybar problems or are confusing it with struts being blown just remember that in order for the sways to work....the bushings on the lower control arms need to be in good condition or replaced with something better in order for the swaybars to work correctly... I believe my rear control arm bushings are just fine...and i replaced my endlinks 9 months ago.....GLAD i don't have to purchase a full blown coil over kit now only to be disappointed..... I just swapped back in my tanabe gf210 springs and had it aligned today and told the tech what happened just so that he knows.... i plan on getting whiteline linear springs and swapping them in since they lowered the Z EXACTLY the same as the tanabe's i have now. WHEW! |
Originally Posted by danimaldaisy
(Post 7491688)
I still think the spring mount mod affects the balance of the car somewhat but realized that my SLOPPY HANDLING was contributed by something other than the spring mount mod....I would like to apologize for this
in my experiences with these cars, rear toe plays a huge roll in response--moreso than i have noticed in other cars. |
I had it aligned the next day after the spring mount mod.
guess your going to have to read my entire response before your post...sorry. |
Originally Posted by danimaldaisy
(Post 7493823)
I had it aligned the next day after the spring mount mod.
guess your going to have to read my entire response before your post...sorry. how was it related to cutting your springmount? what is your rear toe set at? please answer in an understandable/to the point response. |
Originally Posted by guitman32
(Post 7386713)
Look, I had the same gut feel when I read it. But it is true. It is a fact that lowering the rear of a car, while keeping the front at the same height, transfers weight to the rear (and off the front wheels). This is a known and used principal in motorcycle tuning.
I am not advocating this point, and am in fact trying to prove that the weight transfer benefits outweighs the purported drawbacks in steering feel. My hypothesis is that the weight transfer to the rear, and corresponding weight removed from the front tires, is negligible and acceptable compared to the benefits of lowered CG and improved weight distribution (aesthetic benefits non withstanding). Furthermore, once I get a ballpark figure on exactly how much weight is transferred to the rear (and off the front wheels/tires), I will be able to hypothesize whether this weight transfer can even have a noticeable effect on steering feel. This can all be resolved with math, and given a certain set of assumptions (e.g. car weight distribution - f/r and left/right, ride height, etc), the exact weight transfer off of the front wheels can be calculated. As I said, I'm working on it. |
danimaldaisy,
Good find on the lower control arm bushings. I also think you need to get some adjustable endlinks though. Unless you are running the settings that keep the stock endlinks perpendicular to the ground you will experience binding and odd behavior IMO. |
Originally Posted by beezee
(Post 7508202)
So how soon can we expect the results of your "Math". Even though the Z(like any other car) has its own design problems, a Nissan engineer would not take this long to do your math. Point is, they knew what they were doing when they worked on the design. And if you prove with your "math" that this is one of the design problems, that would be great.
We were not discussing a "design problem" with the Z here, we were discussing the effects, if any, of doing the spring mount mod which is basically just cutting or shaving down the upper spring seat by 1/4 to 1/2 an inch. This discussion has nothing to do with any "design flaw" from Nissan. This mod is purely cosmetic and we are studying the possible effects it may have on the overall handling/ride/weight distribution, etc. |
Anyone had a shot of their car with this mod on stock suspensions?
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The other thing I'd like to point out is that there are a number of members who switch to same size wheel/tire combos for track days instead of the factory staggered setup. Wouldn't this have the same theorized effect of transferring weight as cutting the rear spring mount?
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Originally Posted by 350Zenophile
(Post 7509121)
The other thing I'd like to point out is that there are a number of members who switch to same size wheel/tire combos for track days instead of the factory staggered setup. Wouldn't this have the same theorized effect of transferring weight as cutting the rear spring mount?
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