Suspension Questions
Suspension Questions Current Suspension, Daily Driver
1. Koni SAs (4 sweep from full firm, 1/2 turn from full soft)
2. Ground Control Coilovers w/ Eibach 350# front, stock rear springs??
3. Lower Control Arm Relocation Brackets
4. Spohn Adjustable poly-poly LCAs and Panhard Bar
5. Tailshaft mounted BMR Torque Arm w/ -1* pinion angle
6. UMI bolt-on SFCs
7. 275/40/17 tires
8. Alignment: -.5* camber, ~5* caster, 0 toe
9. stock 30/19 sway bars looking to upgrade
I am currently trying to optimize my suspension, great handling with as much straight line traction as possible.
When I purchase the car last year items 1-3 were already installed. Items 4-5 were basically free because I took them off the 1990 RS that I sold to my brother. Items 6-8 done by me and item 9 done by some Canadian guy.
My first question would be, why would the previous owner use stock rear springs (at least they look stock), not sure about the front spring rate.
My second question: I would like to upgrade the front sway bar to a 35mm solid ST bar (i know its heavy but not too expensive and baby on the way). I have a 24mm 1LE 3rdgen rear bar that i was thinking about using but not sure if i want all of that oversteer. Is there anyway I can tweak the rear suspension to compensate for the added stiffness of the rear bar or should I really look into a 21-22mm bar. If I went with 35/19 for a little while, what would I NOT like about that setup.
Thank you,
David
1. Koni SAs (4 sweep from full firm, 1/2 turn from full soft)
2. Ground Control Coilovers w/ Eibach 350# front, stock rear springs??
3. Lower Control Arm Relocation Brackets
4. Spohn Adjustable poly-poly LCAs and Panhard Bar
5. Tailshaft mounted BMR Torque Arm w/ -1* pinion angle
6. UMI bolt-on SFCs
7. 275/40/17 tires
8. Alignment: -.5* camber, ~5* caster, 0 toe
9. stock 30/19 sway bars looking to upgrade
I am currently trying to optimize my suspension, great handling with as much straight line traction as possible.
When I purchase the car last year items 1-3 were already installed. Items 4-5 were basically free because I took them off the 1990 RS that I sold to my brother. Items 6-8 done by me and item 9 done by some Canadian guy.
My first question would be, why would the previous owner use stock rear springs (at least they look stock), not sure about the front spring rate.
My second question: I would like to upgrade the front sway bar to a 35mm solid ST bar (i know its heavy but not too expensive and baby on the way). I have a 24mm 1LE 3rdgen rear bar that i was thinking about using but not sure if i want all of that oversteer. Is there anyway I can tweak the rear suspension to compensate for the added stiffness of the rear bar or should I really look into a 21-22mm bar. If I went with 35/19 for a little while, what would I NOT like about that setup.
Thank you,
David
Last edited by vjo90rs8; Mar 24, 2007 at 05:47 PM.
Straight line traction and road race handling are almost opposite setups. A road race setup is more street friendly. If you aren't going to be trying to pull off hardcore drag strip runs, just set the car up for autox/road race.
Why would the previous owner put stock springs on the rear coilover? I dont know. That's strange because it would only raise the rear end. Maybe he had a reason for that? I liked my stock springs setup with Koni's though, and won a local spectator drag event with that pair.
A 35mm front and 21mm rear is ideal for balancing things out. I would recommend tossing in a few extra bucks though and getting the hollow Strano 35mm front bar. That suspension techniques bar weighs a ton. Its about 15-20 lbs heavier than the Strano bar! I have one on my car. I could do curls with it for exercise
Why would the previous owner put stock springs on the rear coilover? I dont know. That's strange because it would only raise the rear end. Maybe he had a reason for that? I liked my stock springs setup with Koni's though, and won a local spectator drag event with that pair.
A 35mm front and 21mm rear is ideal for balancing things out. I would recommend tossing in a few extra bucks though and getting the hollow Strano 35mm front bar. That suspension techniques bar weighs a ton. Its about 15-20 lbs heavier than the Strano bar! I have one on my car. I could do curls with it for exercise
autox/road race setup sounds good.
Are there any markings on the stock springs to be able to identify them.
Maybe they are 1LEs or something???
Also, I forgot to check but do the Eibach springs have markings on them to identify the spring rate?
Thanks again
Are there any markings on the stock springs to be able to identify them.
Maybe they are 1LEs or something???
Also, I forgot to check but do the Eibach springs have markings on them to identify the spring rate?
Thanks again
If the back of the car is lowered then it's probably not the stock springs. Even aftermarket springs can look stock, but the rates and ride height will be different.
The 35/19 combo is fine for me. Keep in mind the 35mm front will also stiffen the rear as well to a lesser extent. I would not upgrade the rear bar until you know the spring rates. If it is too soft in the back, then you can get some firmer springs (or mod factory ones like I did). With some 150's lets say it will really help the rear from leaning as well as contacting the bumpstop all the time. Then you can increase the rear shock rebound some to make the rear respond quicker to steering input or respond slower and get a smoother ride. So stick to the 19mm for now.
Have you already replaced the inner sway bar bushings with poly? That helps it to come into play sooner. You could probably add a little more camber up front as well. I run 1* and the front really sticks.
Have you played around with the tire pressures?
The 35/19 combo is fine for me. Keep in mind the 35mm front will also stiffen the rear as well to a lesser extent. I would not upgrade the rear bar until you know the spring rates. If it is too soft in the back, then you can get some firmer springs (or mod factory ones like I did). With some 150's lets say it will really help the rear from leaning as well as contacting the bumpstop all the time. Then you can increase the rear shock rebound some to make the rear respond quicker to steering input or respond slower and get a smoother ride. So stick to the 19mm for now.
Have you already replaced the inner sway bar bushings with poly? That helps it to come into play sooner. You could probably add a little more camber up front as well. I run 1* and the front really sticks.
Have you played around with the tire pressures?
I haven't purchase any rear sway bar bushings yet because I wasn't sure what bar I was going to be using.
I can't determine the if the rear springs are stock based on ride height because it has ground control coilovers which are adjustable.
I guess thats the first thing I need to do when I have a chance is to figure out the spring rates.
Does anyone know if the Eibach springs are marked differently based on spring rate.
Another side question:
Does anyone know the spring rate for the rear springs from a 3rdGen ProKit.
I can always pull them off the car I sold to my brother and replace them with the springs on my 02 Z28. Ill probably do a search right now to see if I can find the result faster.
I can't determine the if the rear springs are stock based on ride height because it has ground control coilovers which are adjustable.
I guess thats the first thing I need to do when I have a chance is to figure out the spring rates.
Does anyone know if the Eibach springs are marked differently based on spring rate.
Another side question:
Does anyone know the spring rate for the rear springs from a 3rdGen ProKit.
I can always pull them off the car I sold to my brother and replace them with the springs on my 02 Z28. Ill probably do a search right now to see if I can find the result faster.
It has the GC rear kit? If so then it's using aftermarket springs for sure. They are available in 25lb increments. It may be printed somewhere on the spring. The front springs are marked for sure.
Here are mine:
The 1000 is the unsprung height (10")
the 250 is the inner diameter (2.5")
and the 0550 is the spring rate (550lb)
Here are mine:
The 1000 is the unsprung height (10")
the 250 is the inner diameter (2.5")
and the 0550 is the spring rate (550lb)
Originally Posted by vjo90rs8
Does anyone know the spring rate for the rear springs from a 3rdGen ProKit.
http://www.angelfire.com/my/fastcar/suspension.html
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Cool man, thanks a lot!
Yes, front springs look exactly like that, just have to check the numbers.
Yes, the rear springs (black springs) are sitting on the GC adjusting sleeves, but I will definitely get the car up this weekend and check everything out and try to find numbers on the rears.
Thanks again!
Yes, front springs look exactly like that, just have to check the numbers.
Yes, the rear springs (black springs) are sitting on the GC adjusting sleeves, but I will definitely get the car up this weekend and check everything out and try to find numbers on the rears.
Thanks again!
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Verdad Gallardo From what I understand, the rear springs come from at least 2 different manufacturers and are always in 25lb increments. You might ask Sam Strano about the rear springs as he sells the GC kits.
The front springs BTW are just generic race springs Eibach makes. They are used in all kinds of coilovers.
The front springs BTW are just generic race springs Eibach makes. They are used in all kinds of coilovers.
just found out my front spring rate is 450#.
can't figure out what the rear springs are but there arent any markings and they look stock.
With the parts listed above and the front spring rate of 450# what is a good setting for the Koni SAs and if the rears are in fact stock, what spring rate should I look into getting if I decide to upgrade them. AutoX/road race setup.
Thanks
can't figure out what the rear springs are but there arent any markings and they look stock.
With the parts listed above and the front spring rate of 450# what is a good setting for the Koni SAs and if the rears are in fact stock, what spring rate should I look into getting if I decide to upgrade them. AutoX/road race setup.
Thanks
Now that I think about it, I believe the previous owner may have had the suspension set up for drag racing?? 450# springs in the front, stock in the rear and it looks like he has the drivers side rear ground control adjuster sleeve higher than the passenger side. passenger side is adjusted all the way down while the driver side is showing about 3-4 threads.
I want the set the car up for better handling so should I upgrade the rear springs to a higher rate to match the 450# front?
What rear spring rate would match better with a 35/19 and 35/21 sway bar setup?
I see Strano rear springs are 150# rears but his are set up for 550# fronts right?
Would something like rear ProKit springs 137lb (high end of progression) work well, or would I be better off with stock rear spring and a bigger (24mm) sway bar.
Thanks
I want the set the car up for better handling so should I upgrade the rear springs to a higher rate to match the 450# front?
What rear spring rate would match better with a 35/19 and 35/21 sway bar setup?
I see Strano rear springs are 150# rears but his are set up for 550# fronts right?
Would something like rear ProKit springs 137lb (high end of progression) work well, or would I be better off with stock rear spring and a bigger (24mm) sway bar.
Thanks
As I said earlier, if you have the GC adjustors in the rear then those springs are not the stock ones. They can't be. The GC springs have to be shorter to compensate for the adjustor. Below are some pics of a GC spring and a spring close to stock size.
I do find it odd that the adjustors are so low. Usually they are fairly high. One possible explanation is if the previous owner decided to cut the factory springs to increase their rate and lower their height to work better with the GC adjustors. Can you pull one out and take a picture?
Since the rear rate is unknown, here's what you can do. Buy some rear LS1 springs from a salvage yard for cheap. At least then you know what you are getting. 115lb/in. Each coil is worth about 20lbs. So if you cut off one complete coil the new rate will be 135lb/in. See how this feels. If you cut off 1/2 a coil more the rate will be 145/in.
This is much better than the prokit. Their rear springs are not so great anyway.
On adjusting the front Koni's, just set it to the middle (4 sweeps) and see how it is. If the ride is too rough, adjust it a sweep or two softer. If it feels good and you want more, adjust it a sweep or 2 firmer. I personally liked it as firm as I could stand. Once you get too firm the freeway ride gets kind of like a rollercoaster, your stomach just drops as the car drops on the low spots and it can make you quesy. So I softened it back up just a little.
Oh, and 450 is a good rate up front. No need to change out the springs for stiffer ones unless you just have to. Keep in mind the stock ones are 300 so it's a good bit stiffer.
Just get the 35mm front bar for now and then tweak your shock settings and tire pressures and see how the car handles. Only then will you know if you need a bigger rear sway bar.
I do find it odd that the adjustors are so low. Usually they are fairly high. One possible explanation is if the previous owner decided to cut the factory springs to increase their rate and lower their height to work better with the GC adjustors. Can you pull one out and take a picture?
Since the rear rate is unknown, here's what you can do. Buy some rear LS1 springs from a salvage yard for cheap. At least then you know what you are getting. 115lb/in. Each coil is worth about 20lbs. So if you cut off one complete coil the new rate will be 135lb/in. See how this feels. If you cut off 1/2 a coil more the rate will be 145/in.
This is much better than the prokit. Their rear springs are not so great anyway.
On adjusting the front Koni's, just set it to the middle (4 sweeps) and see how it is. If the ride is too rough, adjust it a sweep or two softer. If it feels good and you want more, adjust it a sweep or 2 firmer. I personally liked it as firm as I could stand. Once you get too firm the freeway ride gets kind of like a rollercoaster, your stomach just drops as the car drops on the low spots and it can make you quesy. So I softened it back up just a little.
Oh, and 450 is a good rate up front. No need to change out the springs for stiffer ones unless you just have to. Keep in mind the stock ones are 300 so it's a good bit stiffer.
Just get the 35mm front bar for now and then tweak your shock settings and tire pressures and see how the car handles. Only then will you know if you need a bigger rear sway bar.
thanks for the help. After doing a little thinking I realized exactly what you stated, that they can't be stock springs or at least if they are they have to be cut because they are definitely shorter than the ones you pictured. Ill try to get some pictures soon. I'll also try to see if one of them has been cut because one adjuster is definitely lower than the other.
Thanks again.
Thanks again.
Don't worry about the one adjustor being different. It doesn't mean anything. The drivers side of these cars is typically 1/4" higher than the passengers side from the factory. Since these springs are not stock the adjustors probably had to be tweaked to get the car sitting level. No big deal and it doesn't have anything to do with drag racing.
okay, kinda jacking this old post but since you guys have actually installed GCs in the rear....How did you get the driver side perch in the rear end housing. My 10 bolt and now my new Strange 12-bolt both have a reinforcing plate on the driver side (for the panhard mount) that won't allow the GC perch to go all the way down and seat properly. I've attached a pic with the part of the plate that interferes highlighted in red.
Originally Posted by vjo90rs8
Attached a pic for fun
Sorry, the GC coilovers were already installed when I purchased the car. If I have a chance Ill get under the car and check them out.
I love the sound of the exhaust and I really like the tips, similar to the stock rectangular tips but much bigger.
Originally Posted by Badguy7
this has nothing to do with suspension, but just out of curiosity. how does that exhaust system sound with those tips???? im lookin to change the style of my tips, cuz it seem's like everyone around here has that look on there car's or trucks.
Originally Posted by HossinatorSS
okay, kinda jacking this old post but since you guys have actually installed GCs in the rear....How did you get the driver side perch in the rear end housing. My 10 bolt and now my new Strange 12-bolt both have a reinforcing plate on the driver side (for the panhard mount) that won't allow the GC perch to go all the way down and seat properly.
Since it won't sit flat in the rear anyway, some folks cut a new piece of tubing in a wedge shape and weld it in. It raises the mount and tilts it at the same time. I think others just let it ride kind of high.
thanks man that's the kinda stuff i was looking for. I was thinking about cutting an angled wedge out of the GC perch so that it would fit flush in there. Has anyone seen something like this?