My swap was just completed...runs great.

with the added weight heres what Im looking for....

1...return to stock height
2...return to stock spring rate or a bit stiffer

If anybody has ideas...Im sure many of you have tested various set ups....my first instinct is coilovers...and would 300lb/in be a good spring rate?

Thanks

Coil overs yes. I've read somewhere here that stock spring rate in the rear is 350 lbs.

What were you swapping from. 4 cylinder or 2.8.
I had swapped from a 2.8 TH125 to a 3800 SC with 4T60e. In an 85GT
The added weight from the engine and transmission ended being around 72 lbs. Lost another 8 lbs by being able to get rid of the 2.8's huge starter.
With the gross weight change being about 65 lbs, the ride height only changed about 3/4 inch.
Now if you had originally had a 2.5 with no A/C in a coupe and then went to a 3800, I could see more of a drastic change. But you could always go to GT automatic with A/C springs.

I had 2.5 w/AC...so yeah I feel the weight...especially on the steering..I just want to level it out..and maybe a bit stiffer rate

quote Originally posted by FIEROPHREK: (snip) stock spring rate in the rear is 350 lbs.

That would be wrong.......

[This message has been edited by olejoedad (edited 05-23-2015).]

I started with a 2.8L auto and now have a 3800SC w 4T65eHD. I have not noticed any drastic change in handling or ride height but I do have the large front and rear Addco anti-sway bars. Traction is excellent with 225/45 x 17 tires in the rear.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

went from 2.8 /auto to 3800SC/4t65e-Hd, No ride height change, untill installed coil overs (250 lb rating).

I bought 10" tall 325lb Summit springs for my Fiero. My 3800 Series 2 Turbo with the 4T60-E trans is probably on the heavy side (weighing in slightly more than a 3800 Series 2 SC / 4T65-E conversion, due to the extra piping/turbo hardware). I lost no ride quality vs. OEM Fiero GT rear springs I had, but handling was much improved over the OEM GT springs.

Here's a great thread about the subject: https://www.fiero.nl/forum/Forum2/HTML/118751.html

-ryan

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