Suspension 101
your talking about ratio'ing out your new stiffer rates to match the ratio in what stock has...a decent start but your still end up with a stiffer rate and the cars weight didnt change, so the handling wont be identical.
Stiffer rate means in simple terms it takes more hit to activate the spring....as in 750#/in spring rate results in it taking 750 pounds to squeeze/compress that spring 1 inch in length...
so you will end up with a stiffer ride yes..
roll has more to do with dampening and the rate of return on the suspension and sway bars used to counter that...
slapping good sway bars set to stiff on a stock 350z does ALOT in my opinion alone in eliminating roll.
now go to bed....
-J
Stiffer rate means in simple terms it takes more hit to activate the spring....as in 750#/in spring rate results in it taking 750 pounds to squeeze/compress that spring 1 inch in length...
so you will end up with a stiffer ride yes..
roll has more to do with dampening and the rate of return on the suspension and sway bars used to counter that...
slapping good sway bars set to stiff on a stock 350z does ALOT in my opinion alone in eliminating roll.
now go to bed....
-J
I think somewhere in my insomnia I forgot about suspension frequency. I think what I meant to ask was that if the difference in frequency between the front and rear are similar to stock will that give me similar handling characteristics similar to a stock z?
I believe a stock z is in the neighborhood of 1.35hz front and 1.45hz rear(1.6 on revised springs) So lets say I get springs and have 1.8hz front and 1.9hz rear, is it safe to assume that the car will have similar handling characteristics as it did on stock unrevised springs?
Last edited by lotteman; Oct 11, 2012 at 02:48 AM.
Thread Starter
Joined: Jan 2006
Posts: 11,204
Likes: 32
From: San Antonio/I miss DFW, TX
I would test drive my car on super smooth hwy and any bump or wave in the road would result in my car bumpsteering to another direction....
u can notice things like holding the wheel straight, then correcting, then correcting again...etc...much like alignment off, well, thats because it IS...due to compression arm bushing...
u can literally have the car aligned...drive around the building, then back on the rack and the alignment will be off again......due to compression rod bushing torn..
just my experience...remember, the compression rod is connected via ball joint to the knuckle..if its not "fixed" like spl bushing makes it, then it pretty much correlates to horrible handling...
-J
Thread Starter
Joined: Jan 2006
Posts: 11,204
Likes: 32
From: San Antonio/I miss DFW, TX
further, my car tracks amazing with spl compression rod bushings and the slew of other mods i have...bumps, waves in the road...all gone.. i mention that somewhere else in this thread...
-J
-J
ya exactly, but thats the least...when compression rod bushings are torn up decently you will notice that your car doesnt track a straight line at all..
I would test drive my car on super smooth hwy and any bump or wave in the road would result in my car bumpsteering to another direction....
u can notice things like holding the wheel straight, then correcting, then correcting again...etc...much like alignment off, well, thats because it IS...due to compression arm bushing...
u can literally have the car aligned...drive around the building, then back on the rack and the alignment will be off again......due to compression rod bushing torn..
just my experience...remember, the compression rod is connected via ball joint to the knuckle..if its not "fixed" like spl bushing makes it, then it pretty much correlates to horrible handling...
-J
I would test drive my car on super smooth hwy and any bump or wave in the road would result in my car bumpsteering to another direction....
u can notice things like holding the wheel straight, then correcting, then correcting again...etc...much like alignment off, well, thats because it IS...due to compression arm bushing...
u can literally have the car aligned...drive around the building, then back on the rack and the alignment will be off again......due to compression rod bushing torn..
just my experience...remember, the compression rod is connected via ball joint to the knuckle..if its not "fixed" like spl bushing makes it, then it pretty much correlates to horrible handling...
-J
That explains why. My camber alignments are (on oem camber arms with brand spanking new Whiteline bushings): front passenger camber : -1.4, Driver side : -1.7.
And all the symptoms you just mentioned are there on the car. Bumpsteer, especially when the steering wheel is almost at full turn and I slightly hit the brake, it turns by itself by about 1cm or so. Time for a set of SPL!
I guess my new Whiteline LCA bushings overpowered the OEM rod bushings.. Man these things give out easily! I replaced them just about 15k miles ago.
Last edited by 350Zdj; Oct 18, 2012 at 09:44 PM.
thanks for the valuable info.
That explains why. My camber alignments are (on oem camber arms with brand spanking new Whiteline bushings): front passenger camber : -1.4, Driver side : -1.7.
And all the symptoms you just mentioned are there on the car. Bumpsteer, especially when the steering wheel is almost at full turn and I slightly hit the brake, it turns by itself by about 1cm or so. Time for a set of SPL!
I guess my new Whiteline LCA bushings overpowered the OEM rod bushings.. Man these things give out easily! I replaced them just about 15k miles ago.
That explains why. My camber alignments are (on oem camber arms with brand spanking new Whiteline bushings): front passenger camber : -1.4, Driver side : -1.7.
And all the symptoms you just mentioned are there on the car. Bumpsteer, especially when the steering wheel is almost at full turn and I slightly hit the brake, it turns by itself by about 1cm or so. Time for a set of SPL!
I guess my new Whiteline LCA bushings overpowered the OEM rod bushings.. Man these things give out easily! I replaced them just about 15k miles ago.
^ Only 1/2 joking... Bought my car at 40k with a blown comp bushing. Lowering springs (-1.2") had been installed just 20k miles prior. I replaced them with the whiteline w83389 and it has lasted 25k so far.
Would installing roll-center adjusters ( i.e. moonface, megan) ease the tension on the comp bushing on a lowered car? My line of thinking is the comp arm is brought closer to parallel which would be more of an oem-like position. The reason for doing this would be to avoid having to use the noisy SPLs on a DD non-track vehicle. From what I understand the change would be very minor, though.
Would installing roll-center adjusters ( i.e. moonface, megan) ease the tension on the comp bushing on a lowered car? My line of thinking is the comp arm is brought closer to parallel which would be more of an oem-like position. The reason for doing this would be to avoid having to use the noisy SPLs on a DD non-track vehicle. From what I understand the change would be very minor, though.
^ Only 1/2 joking... Bought my car at 40k with a blown comp bushing. Lowering springs (-1.2") had been installed just 20k miles prior. I replaced them with the whiteline w83389 and it has lasted 25k so far.
Would installing roll-center adjusters ( i.e. moonface, megan) ease the tension on the comp bushing on a lowered car? My line of thinking is the comp arm is brought closer to parallel which would be more of an oem-like position. The reason for doing this would be to avoid having to use the noisy SPLs on a DD non-track vehicle. From what I understand the change would be very minor, though.
Would installing roll-center adjusters ( i.e. moonface, megan) ease the tension on the comp bushing on a lowered car? My line of thinking is the comp arm is brought closer to parallel which would be more of an oem-like position. The reason for doing this would be to avoid having to use the noisy SPLs on a DD non-track vehicle. From what I understand the change would be very minor, though.

Of course, don't quote me on that. Everything I said is just pure speculation.
Last edited by lotteman; Oct 19, 2012 at 12:43 AM.
Figured I would give an update. I've had my SPL compression arm bushings in for about 6 months now and can say I have no noticable noise coming thru the cabin except on cobble stone roads.
I am on stock springs right now so I'll update when I install the springs and shocks.
I am on stock springs right now so I'll update when I install the springs and shocks.
I can tell you my car feels 100x more connected to the road.
I acutally pm'ed JasonZ-Ya this question a couple of days ago and here it is again (wondering if someone could chime in and help me out with what type of bushing to select, thanks!):
Hey JasonZ-Ya,
Firstly, I would like to thank you so much for your Suspenion101 post. It was beyond helpful and one of the best technical stuff one can find on the internet. Even with all the information, I cannot make a good hypothesis on what type of bushing to select for these certain parts on the G37/370z (that differ from the G35/350Z).
Here is the front suspension system for clarification.
http://i1112.photobucket.com/albums/...jubii_/FSU.png part 7 the z34's version of the translink, now called the transverse link. notice that box2 didn't exist in the past and box3 (how the strut mounts to the link) is somewhat different from how it used to be (the bushing is actually in the strut HERE whereas it's in the translink in the z33s).
- box1: since, it's very much similar to the z33, i can take your suggestion (can get away with a poly bushing, however, ideal to have spherical-solid)
- box2: this seems to have, oddly, similar function to the compression rod bushing but rotated upright? i'm not too sure what should be used here since i'm not the subject matter expert in suspenion and cannot predict it's axis of rotation. this is the bushing of biggest concern to me and i'll explain why in a bit.
- box3: since, it's connected to the strut, not sure if it's sensible to replace it. utilizing aftermarket coilovers' rubber (or poly? not sure).
my driving style: i do NOT (not plan to) track and this is my DD. i drive spirited a bit more than occasionally (and i would love to take her out to canyons and nice long twisty roads).
aftermarket options:
-SPL has been saying for the past year they're going to release their sphericals. word on the street is that they are finally going to unveil them at sema!
-Whiteline same with SPL and supposedly going to release a poly set
-Doran Racing w/ Nissan Moto (and other private fabricators) have already tested (tracked) and used a complete set of delrin bushings. there are some 370 guys with a full delrin swap.
*delrin i hear has less maintenance (supposedly 'self lubricating' to an extent) and is harder than poly. when 'dented', it does not 'pop back' and can cause issues. need extra effort to investigate the usage of delrin/poly because you do not want to restrict extra axis's of rotation*
2 more things...
not too worried about the bushings on the upper A arms because SPL is supposedly releasing them soon.
i'm having feathering issues on my front tires (which is why i'm researching bushing upgrades); driver outter and a bit on the passenger inner. currently, i have asymterical tires so i can remedy it by swaping the front 2 wheels with each other. a reputable shop (west end alignment) has pointed me in the bushing upgrade modifications to cure this (their alignment is spot on and remained so). they tested and showed me that the OEM bushing 'gave' too much allowing major fluctuations in toe causing the feathering.
here's a pic of a set of tires that i ran for 3k miles (got new rims and tires. so theyre just sitting there).
http://i1112.photobucket.com/albums/...i_/photo-1.jpg if you notice, the top 2 have wear that's sort of like someone dragging the meat of the tire across a dirt pavement where as the bottom 2 have rolling, babybuttsmooth wear.
my current front tires are similar to the top 2 and have feathering (not slight, not major) in a way that if you move your had along the rotation of the driver's tire, each tread block would go low to high (high hitting the ground before the low).
FINALLYmy #1 concern is safety and the longevity of the tires. i figured if i yelled at the dealership enough theyd replace the oem rubber bushing (or yell at me for having coils and some gt spec braces) but then i'd have to get it realigned. i figured i might as well get some UNDERRATED performance out of a bushing upgrade.
THANKS FOR READING THROUGH ALL OF THIS. I tried to be as complete as possible because I don't want to annoy you by having you to explain the stuff that has already been said. Any help would be greatly appreciated. I really appreciate the help you've already giving me and will be eternally grateful for more to come
Thanks!
Ellick
Hey JasonZ-Ya,
Firstly, I would like to thank you so much for your Suspenion101 post. It was beyond helpful and one of the best technical stuff one can find on the internet. Even with all the information, I cannot make a good hypothesis on what type of bushing to select for these certain parts on the G37/370z (that differ from the G35/350Z).
Here is the front suspension system for clarification.
http://i1112.photobucket.com/albums/...jubii_/FSU.png part 7 the z34's version of the translink, now called the transverse link. notice that box2 didn't exist in the past and box3 (how the strut mounts to the link) is somewhat different from how it used to be (the bushing is actually in the strut HERE whereas it's in the translink in the z33s).
- box1: since, it's very much similar to the z33, i can take your suggestion (can get away with a poly bushing, however, ideal to have spherical-solid)
- box2: this seems to have, oddly, similar function to the compression rod bushing but rotated upright? i'm not too sure what should be used here since i'm not the subject matter expert in suspenion and cannot predict it's axis of rotation. this is the bushing of biggest concern to me and i'll explain why in a bit.
- box3: since, it's connected to the strut, not sure if it's sensible to replace it. utilizing aftermarket coilovers' rubber (or poly? not sure).
my driving style: i do NOT (not plan to) track and this is my DD. i drive spirited a bit more than occasionally (and i would love to take her out to canyons and nice long twisty roads).
aftermarket options:
-SPL has been saying for the past year they're going to release their sphericals. word on the street is that they are finally going to unveil them at sema!
-Whiteline same with SPL and supposedly going to release a poly set
-Doran Racing w/ Nissan Moto (and other private fabricators) have already tested (tracked) and used a complete set of delrin bushings. there are some 370 guys with a full delrin swap.
*delrin i hear has less maintenance (supposedly 'self lubricating' to an extent) and is harder than poly. when 'dented', it does not 'pop back' and can cause issues. need extra effort to investigate the usage of delrin/poly because you do not want to restrict extra axis's of rotation*
2 more things...
not too worried about the bushings on the upper A arms because SPL is supposedly releasing them soon.
i'm having feathering issues on my front tires (which is why i'm researching bushing upgrades); driver outter and a bit on the passenger inner. currently, i have asymterical tires so i can remedy it by swaping the front 2 wheels with each other. a reputable shop (west end alignment) has pointed me in the bushing upgrade modifications to cure this (their alignment is spot on and remained so). they tested and showed me that the OEM bushing 'gave' too much allowing major fluctuations in toe causing the feathering.
here's a pic of a set of tires that i ran for 3k miles (got new rims and tires. so theyre just sitting there).
http://i1112.photobucket.com/albums/...i_/photo-1.jpg if you notice, the top 2 have wear that's sort of like someone dragging the meat of the tire across a dirt pavement where as the bottom 2 have rolling, babybuttsmooth wear.
my current front tires are similar to the top 2 and have feathering (not slight, not major) in a way that if you move your had along the rotation of the driver's tire, each tread block would go low to high (high hitting the ground before the low).
FINALLYmy #1 concern is safety and the longevity of the tires. i figured if i yelled at the dealership enough theyd replace the oem rubber bushing (or yell at me for having coils and some gt spec braces) but then i'd have to get it realigned. i figured i might as well get some UNDERRATED performance out of a bushing upgrade.
THANKS FOR READING THROUGH ALL OF THIS. I tried to be as complete as possible because I don't want to annoy you by having you to explain the stuff that has already been said. Any help would be greatly appreciated. I really appreciate the help you've already giving me and will be eternally grateful for more to come
Thanks!
Ellick
Last edited by jujubii; Oct 22, 2012 at 04:18 PM.
Hi there guys,
where can i get the SPL O-rings other than from SPL? im planing to get a used compression rod with the SPL bushings pressed on it. and i thinks its the older version as it doesnt include the o rings. what other things should i inspect before buying it other that its "physical" condition.
where can i get the SPL O-rings other than from SPL? im planing to get a used compression rod with the SPL bushings pressed on it. and i thinks its the older version as it doesnt include the o rings. what other things should i inspect before buying it other that its "physical" condition.
Hi there guys,
where can i get the SPL O-rings other than from SPL? im planing to get a used compression rod with the SPL bushings pressed on it. and i thinks its the older version as it doesnt include the o rings. what other things should i inspect before buying it other that its "physical" condition.
where can i get the SPL O-rings other than from SPL? im planing to get a used compression rod with the SPL bushings pressed on it. and i thinks its the older version as it doesnt include the o rings. what other things should i inspect before buying it other that its "physical" condition.








