FormulaGTArs

I have a 91 formula pushing around 400hp. The front raises quite a bit when I launch and it’s cornering is not the best.

Along time ago I had a 89 gta ws6 and I remember it handling and cornering much better. Almost seemed to pull your body into the inside of the corner not outside.

What’s the best way improve my 91’s suspension / get it closer to what my 89 was?

Currently my formula has sub frame connector and kyb shocks and struts of which were on the car when I bought so I don’t know the condition or quality.

Will switching to stiffer springs and the addition of a wonder bar be enough? (I don’t want to lower the car any). Does changing out components like the pan hard bar to tubular make a noticeable diff? Bigger sway bar in back maybe? I’ve read some user say a bigger rear sway bar can be a bad thing. Does someone know “thee” struts and shocks to go with? Any other ideas. Looking at spending around a grand.

QwkTrip

iTrader: (22)

Just to make sure we understand, it's totally stock with the exception of subframe connectors and KYB shocks? How old are shocks and tires, and what kind of tire?

FormulaGTArs

Tires are front 245/40-18 rear 285/35-18
i bought the car a couple years ago with no motor no trans. I built a motor and trans. Put it in. I know nothing of the age or condition of shock, struts or springs. Only aftermarket component suspension wise is sfc and kyb’s of which again I know nothing about.

oh and tires are basically brand new. Rears may be a little worn

QwkTrip

iTrader: (22)

Kind of got to know what you're starting with so you don't accidentally buy the same thing twice.

Look up the RPO codes in the center console and see which suspension came from the factory.

Put a caliper on the front and rear sway bars and get those measurements of diameter.

Car looks like it could be slightly lowered. Check those springs over really good for some printed text on the coil identifying what it is. Even knowing if they're painted a certain color helps.

And it's super important to know if your shocks are functioning or if they're worn out. That could be most the problem right there. Unfortunately, shocks are pretty darn expensive.

Other option is to do none of that and just say I want _____ and go buy it. But you might end up keeping some of what you've got if you just verify what it is.

FormulaGTArs

I’m getting 30mm on front sway and 18mm on rear.

As far as shocks and struts rock auto has gas filled ac delco’s for a very reasonable price. They even have performance adjustable kybs for around $100/piece. I’m not too familiar with the ins and outs of struts and shocks and how much of a diff they can make.

I don’t auto cross this car or drag. It’s not a daily driver. I’ve upgraded a lot of things and made them much better then they were in 91. I wanna improve the handling as much as one can without going drastic. Like c4 rear and full k member front etc

It seems like there’s more body roll then there should be for this car.

I read reg coils are like 330# and ws6/iroc coils are 575# anyone know the coil wire thickness of each so i can see what I got?

FormulaGTArs

Rpo says fe1 but I have no idea if I’m the second owner 3rd 4th etc. the car had a 383 that was pulled and sold before I bought. Was an original 305tbi. Odometer says 150,000 miles but who knows if that’s even the original odometer. What I’m saying is who knows if theres original stuff or not. I’d guess coils are original soft ones with maybe some cut off.

So I’m leaning towards 36mm front and 24mm rear sways, wonder bar, new shocks and struts (prolly just ac delco gas) and stiffer stock height coils. Sound good? Anything else?

QwkTrip

iTrader: (22)

There were a ton of springs offered in order to achieve proper ride height given different vehicle options (varying front end weight), but it seems to whittle down to 5 different groupings of spring rates of 300, 345, 420, 700, 750 lb/in.

Posts #1583 and 1584. (Please don't post in that thread, keep the conversation here in your thread.)
https://www.thirdgen.org/forums/ltx-...ml#post6404837

Stuff like Hotchkis lowering springs is in the 600-ish range, so you can see some of the factory offerings got pretty stiff. On the other end of spectrum, Moroso drag racing springs are somewhere in the 250-ish range. A serious autocross car might be in the 800 - 1200 lb/in range. That kind of gives you lay of the land.

QwkTrip

iTrader: (22)

Well, that would be the soft ride suspension.
http://www.austinthirdgen.org/mkport...tents/rpo.html

FormulaGTArs

Thanks Qwk! You’ve been a lot of help! I have a direction now. (Yes I said direction)

QwkTrip

iTrader: (22)

My advice....

Springs without good shocks is a baaaaaad outcome, so I'd get good shocks first. Things like springs, bars, "wander bar" brace, etc. can be purchased used at a big discount.

* Shocks are where it's at. Koni yellow are the product. Unfortunately it's almost your whole budget. I know it's hard to stomach spending that much on shocks but it's the most important item for keeping wheels in contact with the pavement.

* Make sure all suspension bushings are in good condition. Replace as needed.

* Get that Wander Bar. It'll make steering feel better, but more than anything it will help prevent front subframe from cracking around the steering box.

That'll use up your budget. If you want to go further then I'd do sway bars next, and springs last.

Although, you're kind of in a weird spot because you have tires with decent grip and that makes springs compress more in the turns. Normally people would up the spring rate as their traction increases but your budget won't allow that. You'll just have to make that judgement call for yourself as you feel out the car with each modification.

Drew

iTrader: (58)

That's a base Firebird, not a Formula, and 90% of why it doesn't handle like a GTA. Everything was better on a car with WS6, from the steering box to the sway bars, bushings, springs, etc.

You could get all the hard parts from a junkyard car for not a lot of money and they'd make a big difference. But any way you cut it, it's going to cost money.

FormulaGTArs

really? So a formula was not available with the fe1 option? It did have the 305tbi. I’d almost think a base bird would have a v6 but idk. Someone just slapped formula stickers on it damn. Is there a rpo for formula?