I have an 88 GT with factory everything. Last year I changed out the worn our rear struts with KYB GR2's and the front, along with all ball joints, tie rods, etc. Weird thing is, the rear suspension, when hit just the right bump or dip in the road at just the right speed, feels like it is bottoming out. Not sure what to do about this. Anyone else have similar issues?

thanks

And this is with factory (non-cut) springs?

Even with lowering/cut springs in both my '84 and Formula, I've never had the rear suspension bottom out on either car.

The 88 rear springs are quite soft at about 145 lb/in, so the rear bump stops are pretty important. Did you replace those when you swapped struts?

They are uncut factor springs in the back. I will have to check on the bump stops. Been a while since I have been back there really to look at anything.

Is there anything out there in the way of stiffer springs that don’t lower the car a ton?

KYB GR2 Vs. Excel-G Shocks: A Comprehensive User’s Guide
https://glennsaid.com/kyb-gr2-vs-excel-g-shocks/

88 rear springs recommendations by jc8367
https://www.fiero.nl/forum/Forum2/HTML/134933.html

Get your '88 spring rates here (long, but accurate) by Doug Chase
https://www.fiero.nl/forum/...050119-2-054238.html

With factory rear springs and Monroe Sensa-Trac Struts, my GT rides nicely....
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 10-23-2024).]

Is there any way to stiffen up the rear suspension of the 88 GT without much lowering? It just seems far too soft, causing my bottoming out issues...

IMHO

With uncut factor springs, I bet your suspension issue is your KYB GR2 strut choice and not the springs.

This is called suspension dampen {Compression and Rebound} that control the energy generated by springs.

*Compression rates depend on how quickly the shock/strut compresses the spring
High compression compresses slowly / Low compression compress quickly

*Rebound rate is how fast it returns to its original, uncompressed state
High rebound allows for a softer ride / Low rebound is for stiffer.

KYB GR2 has less dampen
KYB Excel-G has more dampen

------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

New bump stops would likely fix the issue. The springs rates don't change significantly, so strut wear and bump stops are the likely cause.



Some of my customers switched to coilovers to get stiffer spring rates while keeping the ride height stock, but that is much, much more expensive than just replacing the bump stops.

Listen to fieroguru - he is in the Fiero Suspension Business!

And especially if you didn't replace the bump stops when you {or the shop} installed the new struts...........