I recently bought a 87 GT with a 88 cradle and coil overs. Man does it ride hard. The rear springs are 350# springs. They are so stiff they make the stock front suspension feel like a pogo stick when encountering bumps. Feels like a low rider in the front.
My 84 with the 88 cradle still has the Duke so I used #250 springs. they are firm but not too harsh. My son has a V6 GT and he went with #275 springs. The are firm too. I think 350 pound springs are way too much for a Fiero.
Not sure how the roads are in Texas but in Michigan, as in NY, springs that are too stiff can really be a PITA, literally. If I didn't have to deal with potholes and construction, I would probably not feel any issues with stiffer springs but for my DD I needed something a bit softer.
Not sure how the roads are in Texas but in Michigan, as in NY, springs that are too stiff can really be a PITA, literally. If I didn't have to deal with potholes and construction, I would probably not feel any issues with stiffer springs but for my DD I needed something a bit softer.
Roads in Michigan are bad. I live Grand Rapids and our worthless city fathers are trying to patch the patches. They are bad.
Why would making the rear springs stiffer cause the front to "pogo stick" when hitting bumps? If your front is "pogo sticking" when you hit a bump, you need new front shocks.
And totally unrelated my friend's racing miata has 700# springs which I think is nuts... it weighs 2300#
[This message has been edited by zkhennings (edited 05-14-2013).]
Why would making the rear springs stiffer cause the front to "pogo stick" when hitting bumps? If your front is "pogo sticking" when you hit a bump, you need new front shocks.
And totally unrelated my friend's racing miata has 700# springs
Front springs are weak? According to the PO the shocks should be fairly new. Monroe he says. I would rather have KYB or Koni.
My fronts are 325 right now, my rears are 350 on my 85. I like it. Tucson roads are the reason my front cross member was replaced. It cracked the factory welds and my front upper control arm was held in by the 5 bolts that comprise my front shock upper mount bracket (the upper bolt in portion on each side of the cross member). 3800, auto for a drive train. Ryan/Held suspension.
Why would making the rear springs stiffer cause the front to "pogo stick" when hitting bumps? If your front is "pogo sticking" when you hit a bump, you need new front shocks.
And totally unrelated my friend's racing miata has 700# springs which I think is nuts... it weighs 2300#
I was thinking that but was told the current ones were fairly new. Guess my hunch is correct.
I recently bought a 87 GT with a 88 cradle and coil overs. Man does it ride hard. The rear springs are 350# springs. They are so stiff they make the stock front suspension feel like a pogo stick when encountering bumps. Feels like a low rider in the front.
What # springs do you use?
Something to consider is how you would like your car to ride and handle. Typically, a good ride and crisp handling don't happen with the same set up. Stiff springs and performance struts/shocks (KYB) will provide superior handling, but perhaps not ride as well as rear springs that are less than 300 lb and Monroe Sensatrac shocks. My car had coil overs when I bought it, but I didn't like the ride. No idea how old the struts were (very rusty), but I replaced them with Monroes and the car rides much better than it did previously. I think that my rear springs are 275 lb. The set up works for me, but others may prefer stiffer springs.
The stiffer the spring, the stiffer the shock you need to go with it. I real stiff spring in the back of the early cars will cut down on bump steer. on my sbc/4t60 car 400# 10 inch was to stiff/tall. 250# 7 inch was to soft. Now I have 350# 7 inch in the rear, stock in the front with lowering ball joints. When I get to drive it off the property I think this will be right.
Mine are 325# with Koni struts, but then I have a heavy motor back there (3.4 DOHC). I was skeptical at this advice, but the ride is firm but not at all annoying.
My 86 V8 car has 375# -10" coil overs with KYB struts in the rear . The front has 1 coil cut off the base model spring with KYB shocks. The front is slightly soft , the rear just right.
Bear in mind your wheel/tire choice will have a significant impact on the handling/ride - you can get away with some stiff suspension if you have floppy tires. I've got 300lb/in springs on the back on my V6, and with 225/60s in back it's about the most comfortable car I own.
had 350#/KYB with a WCF kit (7" spring). ditched them and went with Koni's and 400# (10" spring). I have a LS3/F40 in the trunk so its a little heaver.
I also had 400# front springs (WCF) and hated it. Now I have QA1 with 350# spings, 1.5" dropped spindles and i'm hoping for a firm yet lowered stance.
I can't give you any info on how it works yet, i still have to install all of it.
a related question, Im not sure what the stock springs are front and back for each model. I'm going to do suspension replacements and upgrades and I know I want some stiffer springs I dont know where to get anything as far as upgrades and I know not how to order them.
I suppose there is a spring rate (measured in pounds here in the USA) a spring inner and outer diameter measurement. and an overall uncompressed height...
please, someone correct and enlighten me if I'm wrong. and I believe I am at least partially...
a related question, Im not sure what the stock springs are front and back for each model. I'm going to do suspension replacements and upgrades and I know I want some stiffer springs I dont know where to get anything as far as upgrades and I know not how to order them.
I suppose there is a spring rate (measured in pounds here in the USA) a spring inner and outer diameter measurement. and an overall uncompressed height...
please, someone correct and enlighten me if I'm wrong. and I believe I am at least partially...
The stock spring rates for the 88's are 205 lb/in in the front and 143 lb/in in the rear (the different models just got different ride heights, all springs rates were the same in 88). The effective spring rate at the wheels is about 100 lb/in for the front (spring is about 50% of the distance between the lower a-arm bushings and the ball joint) while at the rear it is about 140lb/in due to the strut design.
Making some assumptions on the sprung weight of the car (I have a dedicated autocross car and the weights are less), using 250# springs on the rear would give you a natural frequency of about 1.7 Hz, which is about right for a sport/street car. 350# springs on the front would give you a natural freqency of about 1.4 Hz, which would be about right (the front should have a lower frequency than the rear). 300# springs on the rear would give you a frequency of about 1.9 Hz. You would want to match that with 500# springs on the front, which would give you a frequency of about 1.6 Hz. This is assuming the sprung weight of the front is 540 lbs per side, and the rear is 690 lbs per side.
Let me get a post in here before this thread goes to the archives...
I'm running 700# springs up front and 475# in the rear. I have custom Bilsteins up front and Koni reds in the rear set to full stiff (but they're not stiff enough).
This results in wheel rates of 175 lbs/in in the front and 293 lbs/in in the rear, and ride frequencies of 1.8 Hz front and 2.0 Hz rear. EDIT: I messed up these numbers. The numbers I posted were the ride rates, and the rear motion ratio was wrong. The correct wheel rates for 700# springs up front and 475# springs in the rear is 196 lbs/in for the front and 402 lbs/in for the rear, with frequencies of 1.8 Hz for the front and 2.1 Hz for the rear.
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Originally posted by fieroguru: The stock spring rates for the 88's are 205 lb/in in the front and 143 lb/in in the rear (the different models just got different ride heights, all springs rates were the same in 88). The effective spring rate at the wheels is about 100 lb/in for the front (spring is about 50% of the distance between the lower a-arm bushings and the ball joint) while at the rear it is about 140lb/in due to the strut design.
That's not correct... 50% distance = 0.5 spring motion ratio = 0.25 rate ratio. You have to square the ratio because the spring constant is based on deflection distance AND the wheel has mechanical advantage due to the position of the spring. So the wheel rate for 205 lb/in springs up front would be 51 lbs/in.
The actual motion ratio is 0.53, so the rate ratio is actually ~0.28 and the stock front wheel rate is 57.584 lb/in.
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Originally posted by bse53:
Making some assumptions on the sprung weight of the car (I have a dedicated autocross car and the weights are less), using 250# springs on the rear would give you a natural frequency of about 1.7 Hz, which is about right for a sport/street car. 350# springs on the front would give you a natural freqency of about 1.4 Hz, which would be about right (the front should have a lower frequency than the rear). 300# springs on the rear would give you a frequency of about 1.9 Hz. You would want to match that with 500# springs on the front, which would give you a frequency of about 1.6 Hz. This is assuming the sprung weight of the front is 540 lbs per side, and the rear is 690 lbs per side.
That sounds roughly right but I'm not sure what numbers you're using for unsprung weight; with my calculations the ride frequencies are lower for the rates you listed, but not far enough off that you forgot to square the motion ratio.
1.8 to 2.0 Hz works well for the front, with about 10% higher in the rear for level ride. I don't find this too harsh on the street, even in lightly padded racing seats. That said, I don't drive the car on the street much.
[This message has been edited by Steven Snyder (edited 11-22-2013).]
I have 12 inch 260 pound springs in the rear coilovers and stock front springs on my 88 with a 3800. I like how it rides and don't plan on changing it.
Originally posted by Steven Snyder: That's not correct... 50% distance = 0.5 spring motion ratio = 0.25 rate ratio. You have to square the ratio because the spring constant is based on deflection distance AND the wheel has mechanical advantage due to the position of the spring. So the wheel rate for 205 lb/in springs up front would be 51 lbs/in.
My error... I keep forgetting it isn't just a simple lever...
------------------ -Chris '85 V6 SE 4sp (SOLD) '88 GT - Series 3 SC3800 w/ 3.5" pulley, 1.8" rockers, 3" exhaust, 3.5" intake, 3.29 gearing. Installed and tuned by Sinister Performance '99 Kawasaki Vulcan 500, owned since new '03 Sentra SE-R Spec V (Prepping to sell) '09 G37x Sedan w/ Premium & Nav (wife's car) '13 G37xS Sedan (new daily driver)
I was putting the snows on for winter when I noticed the place that installed the snows onto the wheels had one mounted the wrong way. Directional tires. So.. I left the snows on the front-14" and installed the summer fronts (17 X 8) on the rear. Bled the brakes at the same time so I drove it down the street to test the brakes. It felt a lot smoother with the 17" on that with the huge 18". I think I found the source for the extremely rough ride. The 18 x 9's on the rear. Also the car is now level and is not putting more force on the front.
[This message has been edited by solotwo (edited 11-21-2013).]
On my '85 SE 2M6, I've got 375lb springs on Monroe struts. The front, by the way, are standard springs with one coil cut off, and KYBs. Works fine for me...
Bear in mind your wheel/tire choice will have a significant impact on the handling/ride - you can get away with some stiff suspension if you have floppy tires.
I have stock '87 GT springs up front with Koni shocks 1 turn from full soft with 215/55-16 tires I have 325# rear springs ('87 cradle) with Koni struts full stiff... The Koni reds were designed to work with stock spring rates, so they're actually somewhat soft for these springs. I have 245/50-16 tires on the rear.
Overall the combo has very neutral handling. Powertrain is Northstar/Getrag, so minimal additional weight vs. the 2.8.
The ride's certainly firm, but I don't feel that it's unreasonable at all.
[This message has been edited by Will (edited 11-22-2013).]
Well the winter tires are on. What a difference in ride from the summer tires, summer tires are mounted on 17 x 8 front, 18 x 8 rear wheels with yoko "s drive" tires, 255/45-18 rears. I know the smaller 14" tires will ride a little different. They are very tall tires but narrow. I used them on the 88 coupe I had. Looks like I find out where PO bought the wheels and see about getting some 17" for the rear.
[This message has been edited by solotwo (edited 11-25-2013).]
I have 12 inch 260 pound springs in the rear coilovers and stock front springs on my 88 with a 3800. I like how it rides and don't plan on changing it.
This sounds reasonable to me. I'll do similar when the time comes. I have the 3800SC, the HD auto trans, the 88 cradle, the red Konis, and 88 front springs. I plan to cut the front 88 springs to lower the front of my 85 and add the 88 cradle, etc. I will start with 275 lb springs or less.
To those wanting stiff or stiffer springs, how much available suspension travel do you have, how much of it are you using, did you set your coilovers by ride height only or did you consider pre-load and sag?
Jonathan
[This message has been edited by Boostdreamer (edited 11-23-2013).]
I have 350# springs in the rear with KYB's... Stock 2.8... It is fine at all times except large bumps so I avoid them
If you don't mind me asking, what do you have up front? I'm curious, because I'm in the middle of an '88 cradle swap in my '87 Fiero. I got 350 lb/in springs for the rear, and am wondering what to put up front. The Arraut Motorsports website suggests using the same spring rate front and rear with the '88 cradle swap, but I'm skeptical.
And FWIW, my Fiero is a weekend car. I also race it, on occasion. Ride quality is only a minor concern.
Rides: 86 Fiero GT, Blue, V8 " Snapperhead" 2013 Fierorama Best of Show Non-Stock, , 88 Formula White stock soon to be 4.9 met Blue like Snapperhead--- 10 Camaro, 99 K2500 Suburban, 04 Trailblazer
To those wanting stiff or stiffer springs, how much available suspension travel do you have, how much of it are you using, did you set your coilovers by ride height only or did you consider pre-load and sag?
Do the springs ever need to be any stronger that the bare minimum to keep the suspension from bottoming out? I understand that the less travel you have, the stiffer the springs would have to be. So that brings my next question, why would you want to reduce suspension travel by using the short coil-over springs such as the 7 inch ones? If the whole sleeve is threaded, couldn't you use the longer springs set lower on the sleeve and still have the same ride height and also have more suspension travel?
How much sag should the springs have? 1/4 to 1/3 the total travel? If you have a 7 inch spring, you've already lost 1.75 to 2.30 inches of available travel. You will need a REALLY stiff spring to keep from bottoming out on normal pot holes and such. If you hit a bigger hole, you're going airbore. Every time your tires leave the pavement, you have lost traction and control even if only for a split second. Why would you put time, money, and effort into causing yourself to be in a situation where you lessen the total time your car is under control?
Unless you have a dedicated track car that runs on a near perfect surface that is free of irregularities and holes, etc., you need a suspension that not only has available travel, but also a spring rate that allows the car to move up and down in a way that maximizes the usability of that travel. I agree that the spring and shock also need to be a matched pair. If either one is too strong, the other will be overpowered and the ride and performance will both suffer.
... what he said. It appears you agree now too. 
