More on the 1LE rear sway bar change after '93

[John_D.]

This is from http://www.fbody.com/members/safbody/genfaq.htm

Apparently, the decrease in the rear bar was not because it was too big. According to this, GM moved a portion of the suspension stiffness from the bar to the springs... Downsizing the bar and upsizing the springs at the same time.

So our bar size selection should ideally factor in spring rate too.

Given this, a bigger bar with our stock softer spring, might not be so bad after all, assuming that the following information is correct.


Here's the text from the site:

The 1993 1LE cars had the same springs and deCarbon shocks (but with much stiffer valving) as on the stock Z28s and Formulas.

Initial 1994 1LE cars received the same set-up, but sometime during model year (between Dec 94 and Mar 95), the 1LEs received stiffer (higher/variable rate) springs and the shock valving was slightly reduced (but still considerably stiffer than the stock deCarbon valving).

Due to the stiffer springs and modified valving, the 21mm rear sway bar was dropped in favor of the 19mm bar (which was the same as on the stock Z28s and Formulas).

[ March 04, 2003: Message edited by: John_D. ]</p>

[V6Bob]

"Given this, a bigger bar with our stock softer spring, might not be so bad after all"

Sorry, no offense intended, but you have to consider the front springs and the rear springs relative to each other, not total spring rate. The spring/bar interaction involves opposite ends of the cars. The big _rear_ bar requires stiff _front_ springs.

With (compared to a V8) the relatively soft front springs on the V6, and the less soft rear springs (especially the 98-ons) the big rear bar is _worse_ a choice than it was for the 1LE race cars of 93-94.

[ March 04, 2003: Message edited by: V6Bob ]</p>

[Dominic]

V6bob you're right, however worse depends on who is driving and what they want from the car [img]smile.gif[/img] . I still like my 32/21 setup personally and have taken it to the edge many times and it hasn't felt unsafe or done anything squirrely. The thing to remember as well is we cannot put down the power of a V8, and so the rear is less likely to fishtail at speed than something with a considerable amount more cornering force.

I don't think you can have an incorrect swaybar/spring combo, unless you go insane with it, but you can make things better and worse... How much so depends on how you drive, where you drive, and how much of a change you make.

Bearing that, you must keep in mind V6 cars handle differently than V8 cars no matter what the gross weight may be. Their center of gravity is more centered due to engine placement, the tires generally aren't as wide, the spring setup is softer in the front but yet the same in the rear, etc...etc...etc... So is there a true final "This is the way to go, this is best" answer? No. [img]smile.gif[/img]

[img]graemlins/fluffy.gif[/img] Ahh another day in the suspension forum...

[V6Bob]

"I don't think you can have an incorrect swaybar/spring combo, unless you go insane with it"

I strongly disagree. A guy above was inquiring as to simply increasing the size of the rear with no other changes. Supposed you just slapped a stock V8 rear (19mm) on a 98-up V6 with stock springs. Is that insane? It surely is incorrect (and downright unsafe). Someone sells a 35/25 combo. Insane? I dunno. Incorrect for a 98-up V6 on stock springs? Absolutely.

"Their (V6) center of gravity is more centered due to engine placement, the tires generally aren't as wide, the spring setup is softer in the front but yet the same in the rear"

Totally agree. All of the above suggest that a _smaller_ rear bar than on a V8 would be better. That's why GM puts a smaller rear bar on.

"So is there a true final "This is the way to go, this is best" answer? No."

Strongly agree. It's why I won't recommend swaybar changes, but I will point out incorrect ones.

IMHO, 32/21s on stock V6 springs are incorrect. My reasons why are: They were rejected by GM on V8 racecars with relatively stiffer front springs. Expert autocrossers think that setup is incorrect (even with stock V8 springs). And I've tried them.

[Dominic]

Well Bob you pointed out an insane combo, 28mm front with 21mm rear, yeah thats very insane, hence I'm still right on that point [img]smile.gif[/img] .

[ March 04, 2003: Message edited by: Dominic ]</p>

[FirebirdGT]

http://tech.firebirdv6.com/1le.html

http://tech.firebirdv6.com/suspensio...F-body_Springs


I'll explain this one MORE time:


1993
1LE Front 32 mm Stabilizer Bar (GM p/n 26032907)
1LE Rear 21 mm Stabilizer Bar (GM p/n 10021221)
Stock V8 Front Spring (292 lbs/in)
Stock V8 Rear Spring (114 lbs/in)


1994-02
1LE Front 32 mm Stabilizer Bar (GM p/n 26032907)
Stock V8 19 mm Stabilizer Bar
1LE Front Spring (360 lbs/in, GM p/n 22132887)
1LE Rear Spring (130-170 lbs/in, GM p/n 22132889)


Note that with the change in rear spring rate, the front was also changed.

[John_D.]

<blockquote>quote:</font><hr>Originally posted by FirebirdGT:
I'll explain this one MORE time:
1993
Stock V8 Front Spring (292 lbs/in)
Stock V8 Rear Spring (114 lbs/in)

1994-02
1LE Front Spring (360 lbs/in, GM p/n 22132887)
1LE Rear Spring (130-170 lbs/in, GM p/n 22132889)
<hr></blockquote>

Thanks for the info on the spring rates, both front and rear, to help clear up what happened there during the transition.

You have a lot of good info on the tech database. :D

I just hadn't made the connection between the spring change and the sway bar change before...

[V6Bob]

The spring rate change was pretty small, in terms of balance. The fronts went up 23%, the backs (on average, the progressive springs make exact calculation impossible) 32%. That's a pretty small change to the balance. The rear swaybar stiffness went down 49% while the front bar was unchanged. That was the big change, and showed that there was just too much rear bar for speed.

BTW Dom, in my post I suggested a change to _28/19_ with the stock springs was both incorrect and downright unsafe. Are 28/19s on stock springs insane in your book? ;)