spring rate suggestions

[GTP091]

I'm one email away from ordering a rear coil over kit for my GTP. I'm almost set to go with 200 lb springs but was wondering if you guys have any opinions or feedback for those that have done it. 200 seems a good compromise but maybe 225 is better. I think 250 would be to hard... suggestions??

[walterdude]

Years ago I bought a set of rear FFP coil-overs. Michael was shipping them with 250lb/in, said that was close to stock... I went with 275s. Myself, I am very happy with them, glad I didn't go with the 250s. It is a bit stiffer but not uncomfortable or incompatible with the stock fronts.
Just my opinion tho...
Tom..
PS: my car is a 93 Z34.

[GTP091]

right on thanks for the reply! good to know the stock leaf is about 250 as a spring rate. I dont want it any softer than stock so I may up the rate to 250. anybody else before I order??

[mfuller]

Are you just looking for something that "feels" stiffer, or are you looking for the proper spring rate which will help to increase your cornering power? Because that involves getting your car corner-weighted and doing some math.

[GTP091]

im not going nascar style or anything I just want it as close to stock as possible.

[walterdude]

Well, here is a cut and paste of a couple of comments Michael (Fast Forward Performance) sent to me in e-mails:

"Springs.... they are available in 25# increments, so there is nothing
between 250 and 275. The 275s aren't all that harsh. You can tell it's
not stock, but I haven't had anyone ask me if I just took the springs
out."

"As for spring rate, I usually ship them out with 250 #/in springs. That
seems to be pretty close to the stock GM FE3 suspension (stock on GTP
and Z34). I have gone all the way up to 300 #/in... that's right on the
edge of overpowering the damping of the KYBs. 275 is noticeably stiffer
than stock suspension and the ride tends to be a little on the choppy
side."

Hope this helps,,,
Tom...

[GTP091]

Thanks for the feedback guys. I ordered the kit today! I will take pictures of the job and post a walkthrough when I get time to put it in so we have something on here and not just the wbody forums.

[GTP091]

The parts came in Wednesday. I picked them up after a trip to Vancouver. Everything looks good now I just need a warm day and some time off to put it in. I'd like to get a rear suspension bracket that the lateral lnks bolt to but GM has discontinued them and said they listed for $750. Good ole dealer pricing. Looks like I will just buff mine and Paint with spray on rock guard. The ones I find at the JY are always rustier than my own.

[d.o.h.c]

haha 275lbs. I am going to be running 500lbs Hypercos on Konis race. Should be a very sweet set-up when done.

Mark-OEM

[GTP091]

haha 275lbs. I am going to be running 500lbs Hypercos on Konis race. Should be a very sweet set-up when done.

Mark-OEM

500lbs each side? that's gonna ride like a lumber wagon.

[d.o.h.c]

I was running 475 on my B&G kit on my sunfire that weights like 800lbs lighter than this car. Also I am gonna be running Koni's so the ride will be awesome.

Mark-OEM

[RedZMonte]

500lbs each side? that's gonna ride like a lumber wagon.

OEM introduces the NEW Lumina Z34 1 Ton Edition! Lol

Than is going to be FIRM... Scratch that... Stiff.... Hard... something just doesn't sound right with what i just said.... LOL what i ment to say is its not going to feel like Grandpa's Cadillac.

S

[mfuller]

It will likely be very stiff. Consider the motion ratio of the strut-type suspension....what works on the track does not necessarily correlate to a street car.
FWIW, several years ago I ran 300# F/200# R Eibach ERS race springs on my Alero (about 3200 pounds) with custom-built Koni double-adjustable dampers (done by Truechoice Motorsports in Hilliard, OH). They were fab on the track but on the street, it was like Mike Tyson punching me in the kidneys.......so uncomfortable that I didn't enjoy driving the car. That was a bad thing.

But to each his own.

[kwhauck]

It will likely be very stiff. Consider the motion ratio of the strut-type suspension....what works on the track does not necessarily correlate to a street car.
FWIW, several years ago I ran 300# F/200# R Eibach ERS race springs on my Alero (about 3200 pounds) with custom-built Koni double-adjustable dampers (done by Truechoice Motorsports in Hilliard, OH). They were fab on the track but on the street, it was like Mike Tyson punching me in the kidneys.......so uncomfortable that I didn't enjoy driving the car. That was a bad thing.

But to each his own.

glad to know that is what i'm looking forward too!! althought i'm still not sure how to adjust the dampers....

[GTP091]

Do you guys know how much of a whore it is to get the 4-bolt main rear suspension bracket unbolted from the car?? I'm thinking an impact should do it. It's a pretty important main piece so I imagine its torqued on pretty good.