Sway bar 101 - Chevy Impala SS Forum
 
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post #1 of 5 (permalink) Old 09-06-2016, 11:24 AM Thread Starter
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Sway bar 101

As written by my favorite GM suspension lunatic before the flood, the one and only Herb Adams: GM was terrified of law suits after Nader, especially on the suspension topic, so the mandate came down from on high: Oversteer is banished, even power on over steer is to be blunted by every means; our wonderful line of GM vehicles will henceforth understeer, a lot if at all possible, at least a little always. So was born the imperative for A- and B- and G- and D (you get the idea) bodies FRONT sway bars shall be of more roll resistance than REAR bars. Among other unfortunate choices. Oh, by the way, thinking about leaving out some front body bushing? OK if understeer is increased. Maybe a nice big heavier engine in your A-body. Give me that old time understeer. Old Herb thinks Hey! THere's a dumb idea I can play with. Maybe I can pump up the roll resistance on an F-body front bar, sure FEELS cool and flat, it might make people think it handles better too. Brass doesn't worry about bigger front bars. So then I can build up the rear one too ( WARNING!!) and what about that GTO? Hysterical conversation with GM brass ensues and flash forward until B-body production is ending and at least an 1/8" delta between F+R solid oem sway bars still holds. FE1, FE3 any and all different without a distinction WX3, 9C1. After market didn't fix it either, pointless jumbo front bars with the same roll resistance as smaller bars, the goofy delta F+R in roll resistance preserved. Finally I'm told someone makes a set of 1 1/4" F+R after market bars that finally incline (God only knows what springs some people have mucking up the works) toward neutral. So trust me (I'm not like the others. You can trust ME!) the OEM mandated and blindly mimicked by the after market delta in roll resistance deserved to die, long ago. So I wrote for the SVI cars 22 years ago and even here at least 15 years ago and as antediluvian as my advice is, everyone on this site will benefit from it: Any mix and match of sway bars that have the same roll resistance is the way to go. 1 1/16" solids F+R? yes. 1 1/4" solids F+R? yes...Same diameter F+R solids is the most obvious, but the Hellwig 1 3/8" hollow front has the same resistance as the generic 1 1/4" solid front and the 1 1/4" solid rear or the "new style" Hotchkis 1 3/8" hollow rear. Flame away only in contradiction to reality.
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post #2 of 5 (permalink) Old 09-06-2016, 03:05 PM
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I expect GM is as terrified as any other manufacturer of lawsuits. But your recounting of fear of oversteer might be over-simplified if the 1st Gen straight axle Corvair's propensity to flip over somehow found any application to stab bars on full frame RWD Front Engine design. Sounds like comparing apples and -- toenails.

I'm more after usable takeaways than anything else, and I can clean up the above quickly into usable bullets. From first experiments 30 years ago with an HA front and GM 'cop option' rear bar on an '82 Park Ave. Electra, I progressed to the severe lockdown affect of an F- front and HO rear on my SS. But, it's just a garage queen, and not that enjoyable after 3 hours on an interstate. I've read your prior reply on another thread regarding optimal setup for my 'new' '96 FWB, and I absorbed pretty much there as also above.

For my desired ride somewhere between the 'the blu-hair undead' FE-1 and full NASCAR I'm pretty much siding with the following based on my experience with my last Fleetwood. On that one I had transferred the stock bars off my SS combined with used SS coils and Bilsteins. The car still plowed more than my liking, but much improved responsiveness of course with less pushing. So I first tried adding the Cady rear bar to the SS, = meh. Then, putting 2 SS bars on back was quite a wake-up! It provided very gratifying control to reduce pushing and plowing. I noticed of course at a certain point it could tip into oversteer if not careful. More reasons not to drive tired or drunk I say. Win-win.

With my current Cady I'm pretty settled that regular SS bars will satisfy my base setup without having to buy anything aftermarket. I was offered an F- front but declined gracefully. And, instead of 2 rear SS rear bars I'm going to try an SS bar combined with the current FE-1 rear. Of course I've got no math to calculate the net positive delta as compared to the GM law of -1/8". I can't believe the stresses are simple arithmetic, more likely progressively exponential or geometric or something.

In any case, the wimpy oem Cady bar and nicely sized SS bar will be a good fit considering my general satisfaction with 2 SS rear bars previously. I already have the front and rear SS bars waiting, now just $750 more to go for KONIs and poly LCAs. And maybe a little frame gusseting. And Airlift 1000s again. And maybe a 1/3-1/2 coil off the fronts, you know for rake and 50# harder spring rate. And----

\'96SS SOB: SSRI, Herter Tune, Tri-Y II, , 3000 Edge, F/HO bars, METCO extendeds with CV MMC, Bilsteins, currently Vredestein Ultrac Sessanta (315/35 rear). Finally, wait for it... LT-4 knock module!
\'96FWB BUW-Butt Ugly White: PCMPerformance tune, HDFA w/ swissed filter, 1/2 SLP s.s. catback with H- and Flow Super 50s, oem opti rebuilt 3 times, SS Bars, METCO LCA, Airlift 1000, Monroe SS, PowerTrax No-Slip, CTS wheels with +1 rubber. Finally, yes again... LT-4 knock module!
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post #3 of 5 (permalink) Old 09-06-2016, 03:41 PM Thread Starter
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That's funny

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Originally Posted by 96 Black View Post
In any case, the wimpy oem Cady bar and nicely sized SS bar will be a good fit considering my general satisfaction with 2 SS rear bars previously. I already have the front and rear SS bars waiting, now just $750 more to go for KONIs and poly LCAs. And maybe a little frame gusseting. And Airlift 1000s again. And maybe a 1/3-1/2 coil off the fronts, you know for rake and 50# harder spring rate. And----
Well, maybe it was really funny. If I understand all the info I deleted from your (or it you're) post and you have the WX3, FE3, 9C1 front + rear bars (unlike the same code springs, the bars are all the same) and you already have a FE1 front bar, so you have both 1 1/16" solids with almost identical roll resistance, so I encourage you to try them together (well F+R) Free experiment, worst case you waste an hour and you just might be pleasantly surprised. You can even fine tune the front bar with and without poly bushings.It will behave very differently with Cadillac FE1 springs than your previous car with SS(lower)WX3 springs. If you've never driven a B-body with F+R sways matched in roll resistance you are in for a treat. Even ignoring the effect of various spring sets on neutrality (that's a Swiss word) the matched roll resistance bars make for a dynamic positive. I give you facts, not my opinion.

PS " But your recounting of fear of oversteer might be over-simplified if the 1st Gen straight axle Corvair's propensity to flip over somehow found any application to stab bars on full frame RWD Front Engine design. Sounds like comparing apples and -- toenails."
Herb Adams swore it true none the less, and he lost countless battles with the brass with science on his side. Oversteer was the terror. FWD, RWD 4WD or rear engine, How the oversteer reared it's ugly head was inconsequential.The lawyers, the suits, the ad men and others lived in dread of a media accusation that the product was '"unsafe at any speed" because of the child killer and granny murderer; over steer. Stupid but fact.
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post #4 of 5 (permalink) Old 09-06-2016, 05:27 PM
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OK, I'll try just the FE3 rear before changing out the FE1 front then. I'll even try poly endlinks on the stock front. But, I will disclose I am religiously pre-disposed toward that nice FE3 bar on front. If that wins out then it'll have to be the combined FE1 and FE3 in back to get to the + side of neutral.

By the way, I had a total of 4 Corvairs, but all were Gen 2 split shaft rears. I never could get any of them to roll over, and I tried.

\'96SS SOB: SSRI, Herter Tune, Tri-Y II, , 3000 Edge, F/HO bars, METCO extendeds with CV MMC, Bilsteins, currently Vredestein Ultrac Sessanta (315/35 rear). Finally, wait for it... LT-4 knock module!
\'96FWB BUW-Butt Ugly White: PCMPerformance tune, HDFA w/ swissed filter, 1/2 SLP s.s. catback with H- and Flow Super 50s, oem opti rebuilt 3 times, SS Bars, METCO LCA, Airlift 1000, Monroe SS, PowerTrax No-Slip, CTS wheels with +1 rubber. Finally, yes again... LT-4 knock module!
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post #5 of 5 (permalink) Old 09-06-2016, 05:48 PM Thread Starter
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Facts are our friends

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Originally Posted by 96 Black View Post
OK, I'll try just the FE3 rear before changing out the FE1 front then. I'll even try poly endlinks on the stock front. But, I will disclose I am religiously pre-disposed toward that nice FE3 bar on front. If that wins out then it'll have to be the combined FE1 and FE3 in back to get to the + side of neutral."

Sounds very smart.
2 bars in the rear confounds any attempt at prediction because how they are mounted to each other, if a spacer is used between them, and of what material and even if after market or oem LCA's are used are just too many variables. It will be less rear roll resistance than a jumbo solid bar and more than just an FE3 but fuzzy math dominates beyond that. For predictability the FE3 front bar and any solid 1 1/4" rear bar would incline just a touch toward over steer, if even noticeable at less than very aggressive driving. Any talented driver would like it.


"By the way, I had a total of 4 Corvairs, but all were Gen 2 split shaft rears. I never could get any of them to roll over, and I tried.
Of course. Nader was, in perfect hindsight, a well intention and sincere but ultimately duped media phenom. Science came second to PR. As old Herb reported the GM brass position was "Don't confuse me with facts, my mind is made up". Old Ralph learned from the masters.
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