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?
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?
With factory rear springs and Monroe Sensa-Trac Struts, my GT rides nicely.... ------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
[This message has been edited by Vintage-Nut (edited 10-23-2024).]
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.
Thank you for the advice. I installed these struts about 8 months ago. I would say they have less than 2500 miles on them. I can’t say I remember them even having bump stops on them though.
The stock rear strut has 7" of travel. At stock ride height, there is about 3-4" of suspension travel. You can gain and extra inch in compression by flipping the strut hat.
You can gain and extra inch in compression by flipping the strut hat.
I've done that with both of my lowered Fieros, but I'm surprised that flipping the strut hat might be required on a Fiero with unmolested factory springs. I'm just wondering if something else is going on with the OP's rear suspension that's contributing to it bottoming out?
[This message has been edited by Patrick (edited 10-27-2024).]
EDIT: Can you check on the model of GR2 rear struts you brought? I can only find Monroe or KYB Excel-G rear struts for a '88 and not KYB GR2 rear struts......
[This message has been edited by Vintage-Nut (edited 10-27-2024).]
Phils88GT... I have a pair of these, unused, brand new in the box (both) with everything.
I decided against using them because the factory ones were still in great shape in my 1985 Fiero 2m4 SE, so I opted to re-use those. If you would like the ones I have, you can have them for free. I will mail them to you in the next couple of days, and then you can just PayPal me whatever the shipping cost is. PM me your mailing address and I'll send them out to you. I debated whether to sell them on eBay, but I just don't want the hassle and it's not worth it. They are brand new...
I've done that with both of my lowered Fieros, but I'm surprised that flipping the strut hat might be required on a Fiero with unmolested factory springs. I'm just wondering if something else is going on with the OP's rear suspension that's contributing to it bottoming out?
Not required, but is an option if he is concerned that his car does not have adequate suspension travel.
they might be doing what we did on our 88 which was using 84-87 rear struts which do bolt right in. the no bump stop thing is absolutely their problem though. the kyb struts tend to not get much stiffer compression as they travel unlike Monroe or different kyb models. so they do like to bottom out quite harshly even with bumpstops installed. the solution is to use new bumpstops or steal the kit from a 90s to 2006 grand prix which comes with a progressive bump stop designed to be loaded all the time. usually its in the sport trims/HD suspension. I know it is for our 95 gtp
the kyb struts tend to not get much stiffer compression as they travel unlike Monroe or different kyb models. so they do like to bottom out quite harshly even with bumpstops installed.
That tends to agree with how I felt when I compared the two brands of struts. From ten years ago...
I used Monroe Sensa-Trac shocks and struts in my lowered and stiffened (cut springs) '84 for daily driving and autocross for four years. Love the way that car feels.
I now daily drive and autocross an '88 Formula. When I first got the car a year ago, I put new Monroe Sensa-Trac shocks and struts in it with the stock springs. Car felt okay, but I didn't like the soft stock springs. A friend gave me a set of four '88 lowering springs along with near new KYB shocks and struts. Since I now had shocks and struts made by both companies in my hands (literally), I compared them. I wanted to use the stiffest ones, the ones with the most resistance to both compression and rebound. You might be surprised at what I found.
The KYB shocks were stiffer than the Monroe Sensa-Trac shocks. No surprise there.
However... the Monroe Sensa-Trac struts were stiffer than the KYB struts.
So I now have KYB shocks on the front of the Formula, and Monroe Sensa-Trac struts on the back.
The Formula feels pretty good, but I'm still not satisfied with the lack of stiffness in the front. I'll be removing the '88 front lowering springs and replacing them with a pair of cut '84-'87 front springs. I'll continue to use my current choice of shocks and struts (and rear lowering springs).
And I did replace the front lowering springs in the Formula with cut '84-'87 springs. The front suspension was then quite a bit stiffer, and I much preferred the feel at autocross.
Ok, so I went to Rock Auto and looked up the struts I bought back in March of this year. They are KYB Shocks & Struts 234005 - KYB Excel-G Gas Shocks and Struts. As it would turn out, they don't list these for the 88 Fiero GT, but they do list them for the 87 Fiero GT. I guess at the time I was so dead set on getting KYB's for all four corners that when I went to Summit Racing, because I couldn't find the KYB's on Rock Auto for the 88 GT, Summit Racing listed them (KYB # 234005). But now, I am looking and they don't have them listed for the 1988. I guess I am up a creek and will have to just suck it up and get the Monroe's from Rock Auto.
I didn't find KYB / Monroe Compression and Rebound Rates.
KYB Valving / Dampen: "based on each vehicle’s specific manufacturer specifications"
Monroe OESpectrum Valving / Dampen: "known for their smooth ride quality and feature proprietary ASD (Acceleration Sensitive Damping) technology allowing them to adapt quickly to changing road conditions, which helps to maintain ride comfort"
So, get the boots / bumpers and try them before buying Monroe struts....
------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
[This message has been edited by Vintage-Nut (edited 10-29-2024).]
Ok, so I went to Rock Auto and looked up the struts I bought back in March of this year. They are KYB Shocks & Struts 234005 - KYB Excel-G Gas Shocks and Struts. As it would turn out, they don't list these for the 88 Fiero GT, but they do list them for the 87 Fiero GT. I guess at the time I was so dead set on getting KYB's for all four corners that when I went to Summit Racing, because I couldn't find the KYB's on Rock Auto for the 88 GT, Summit Racing listed them (KYB # 234005). But now, I am looking and they don't have them listed for the 1988. I guess I am up a creek and will have to just suck it up and get the Monroe's from Rock Auto.
This sucks! What a waste of money! :-(
Again, your issue is the lack of bump stops... Buy 2 of these: https://www.summitracing.com/parts/URO-008941 They are a lot cheaper than new struts, which will have the same issue if the bump stops are left off again.
There are lots of people using the KYB 234005 on the 88s w/o issue. Monroe Sensatracs name/model has been retired and the only Monroe rear strut is the 71814 OE Spectrum. It is listed for all years of Fieros.
It has probably been 2 decades since the 88 Fiero had their own unique rear strut.