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Discussion Starter · #1 ·
I have been looking over the Hotchkis perfomance springs set up for our cars and they seemed reasonably priced (for Hotchkis anyway) w/bumper stops and isolators all for for $265.00.

I know that AutocroSSer frowns on progessive rate springs but these have greater initial rates than our stockers be it Impala SS or 9c1. With for the fronts at 500 LBS" vs 440 LBS" and for the rears 180 LBS" vs 160 LBS".

Two days ago I talked with Hotchkis' Product Engineer, Gary. He stated that he thought that the Herb Adams (or HO) rear bar is wwaaayyyy too stiff at 440% over stock for his spring setup. And would produce a very dangerous oversteer situation :eek: :eek: for our cars.

Let me say he was really spooked by the 440% :eek: !!!!

Can you guys please weigh in on this???
Any early experiences with the Hotchkis springs with the Herb Adams rear bars :confused: ??? (or even using the HA, HO, F-Body or Hellwig front bar)

What is your opinion about the possible oversteer :eek: situation??

Do you think that Gary's fears are founded or unfounded

Would the biggest front bar we can find be stiff like the HA, HO or Hellwig compensate for the HA rear bar and avoid the oversteer???

AutocroSSer I know you are out there
we need your help on this one :confused: !!
 
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Discussion Starter · #2 ·
I think it COULD work.....but Gary is right. You'd really want a MUCH bigger front bar (than stock or F-body) in order to even things out. I think Hellwig or Addco makes a 34mm solid front bar....that'd be a good start.


Hotchkis really designed those springs more to work with a setup of over/understeer balance as achieved by their swaybars.
 
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Discussion Starter · #4 ·
So what springs are recommended for a F-body/HA bar setup?
I ordered the Bilstein 1104/0929's today and need to pick up some springs!

TIA,
 
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Discussion Starter · #5 ·
Quote Autocrosser:

"Hotchkis really designed those springs more to work with a setup of over/understeer balance as achieved by their swaybars."

Ed, you lost me here?? Maybe I don't understand how Hotchkis bars are different from HO/F-body setup. What are their rates versus what you get with HO/F-body? TIA
 
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Discussion Starter · #6 ·
Here are the spring rates per this digest:

Stock SS Springs
Front: 444 lb/in
Rear: 154 lb/in

Eibach (per Rick at Eibach)
Front: 588 lb/in (linear)
Rear: 143 lb/in initial, 228 lb/in final

Hotchkis
Front: 500lbs/in.
Rear: 180lbs/in.


Here are Scott Muellers comments on the optimal setup for swaybars and their rates etc.:
IGBA article

In my experience I have got to agree with Scott Meuller on the swaybars. I have the Eibach springs front and rear. The Bilstien shocks #1104 front and #0929 rear. The Hochkis front and rear sway bars and the Metco centering lower trailing arms and adjustable upper arms.
I have autocrossed the car with this setup and had alot of understeer (plowing). I dropped the Hotchkis rear bar for the HO Enterprises rear bar ( the 440% stiffer bar) and LOVE the way the car handles. Same driver, same conditions, same Autocross track, very close to neutral. I could push the car to the point of oversteer ( breaking the back end loose), but it did not go there without significant coaxing. Depending on how you load going into the corner you can go either way under or oversteer. With the setup before I HAD to use the horses to get the back end loose, good show, BAD times.

Just my experiences., but you know what they say…
Opinions are like A$$holes, Everybody’s got one!

Jeff Hazen
'96BBB
 
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Discussion Starter · #7 ·
Hotchkis bars are VERY different in stiffness compared to the HO bars or F-body front bar.

(once again, as I posted in the other thread note that Hotchkis springs are PROGRESSIVE and NOT linear).

The Hotchkis front bar is STIFFER than the F-body front bar, and a little stiffer than even the HO or HA front bars.

The Hotchkis rear bar is SOFTER (by a good bit) compared to the HO/HA rear bar. Hotchkis IS stiffer than stock in back, but not by a huge amount. The HO/HA rear bar is a LOT stiffer than stock (or Hotchkis).

Point being : with the Hotchkis springs, I think the F-body/HA bar combo will indeed be too biased towards oversteer. With their springs, I'd recommend EITHER a bar combo like theirs (more front, less rear compared to F-body/HA) or going quite a bit bigger than F-body (i.e. HO or HA) bar in front.

I honestly think that with the Hotchkis springs, the Hotchkis bars would make a nice and "somewhat" neutral setup. Ultimate handling probably wouldn't be quite as far out as MY combo, but it would be tons better than stock.

OK, I've probably sufficiently confused the issue now :D

Ed
 
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Discussion Starter · #8 ·
Whew!! I was off track. Thanks for the new info and refresher Ed and jhazen.

Really missed that Hotchkis springs are progressive!! Sounds like Hotchkis stuff (springs) needs to be matched with Hotchkis bars for one thing. I am sure Hotchkis wants it that way.


However, jhazen you are running Hotchkis front bar with HO rear. Relatively soft rear Eibach springs. And love it.

I'm still undecided what I want. :confused:
 
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Discussion Starter · #9 ·
Is there anybody out there who is running this setup? I have the HO rear bar/F body front bar and I was planning to go with the Hotchkis lowering springs (I just got in on the GP) with HAL adjustable shocks. Now, having run across this post, I'm afraid I might be making a mistake. Anybody?

If this would be a problem, is it something that could be corrected for by going stiffer on the front shocks? If so, what would be recommended settings for the front and rear shocks with this setup? Thanks.
 
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Discussion Starter · #10 ·
Hey Ed,
If the Hotchkis springs, HA/F-Body setup would give the car more oversteer, wouldn't having a wider tire in the back bring the car back into a more neutral setup? Reason I'm asking is I'm running 315/35's on the rear and planned on going to the Hotchkis springs.
Joe
 
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Discussion Starter · #11 ·
<BLOCKQUOTE>quote:</font><HR>If the Hotchkis springs, HA/F-Body setup would give the car more oversteer, wouldn't having a wider tire in the back bring the car back into a more neutral setup?<HR></BLOCKQUOTE>

Yes it would.

BTW, interesting side note : when BMW came out with the 6-cyl M3 in 1995, they had it set up quite nicely for over/understeer....a bit TOO nice for some though, as it could oversteer.

BMW's solution (a year or 2 later) : wider tires and wheels, but ONLY in back. Dialed the oversteer right out.

For a while at least, more than a few folks were going to the NARROWER (earlier) rear tires to get their oversteer back :D
 
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Discussion Starter · #12 ·
Let's assume for the moment that wider tires on the back are out of the question for me. There's a limit on how much I can spend on the car in any one season and still have a comfortable relationship with my wife. At the moment, my planned expenditures have gotten me pretty close. I'll hold this in reserve though.

So, what about using the adjustable shocks to either stiffen up the front or soften up the rear? It seems to me that this is also a way to deal with the problem, with the risk that the shock adjustments that work for handling might not give that great a ride. That's a risk I'm prepared to take. Never being able to get the car under control is not. Any thoughts? Thanks.
 
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Discussion Starter · #13 ·
The shocks MIGHT help....but aren't gonna do it alone.

They really do more to damp the springs than provide rate itself.

It's worth a shot, keeping in mind that the you might afterwards have to swap back to softer rear springs.
 
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Discussion Starter · #14 ·
Thanks. That's what I'm going to do. I'm getting a good price on the springs, so if worse comes to worse, I can always sell them to someone who can use them in good health. Alternatively, I might want to go to wider tires in back ("but honey, it's a safety issue"). Any idea how much wider they would have to be (like, could you squeeze a slightly wider tire onto a stock rim and get there that way or are we talking a whole new setup)? Thanks again.
 
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Discussion Starter · #15 ·
Looking at this a little more, it doesn't seem like the Hotchkis springs should make all that much difference. Using the specs listed above for the stock SS springs, the ratio of rear spring rate to front spring rate is 0.35.

The Hotchkiss springs are progressive. From their website:

Front - 500-630 lbs/in
Rear - 180-240 lbs/in

leading to ratios of .36 and .38, respectively. The differences don't seem that dramatic. The Hotchkis is a bit stiffer in the rear but not all that much. Am I missing something? (Not unlikely).
 
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Discussion Starter · #16 ·
Yes : even a little increase in rear rate makes a pretty dramatic difference in how the car handles.

A swap from 160 lb-in to 180 lb-in will be QUITE noticable, no other factors changed....
 
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Discussion Starter · #17 ·
Good to know. I guess I'll do my test drive in a big empty parking lot. ;) It won't be for a couple of months, but wish me luck. I'll post results from home or hospital.
 
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Discussion Starter · #18 ·
Crap. I just ordered those springs. Hopefully they have not shipped yet and I can cancel the order. If that is the case what springs are recommended? My current setup is the F-body front bar/HA Rear bar and soon to be HAL shocks. Also the suspension in the next month or so will be redone with all new parts including a-arms from Bill Harper. What is a recommended spring that is good for autocrossing? Maybe Ed or Andy can help out on this one. Thanks John
 
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Discussion Starter · #19 ·
I'm interested in this information too, since there's a good chance I'll be swapping the springs back out and I've never quite been able to get a fix on what springs would be best.

Also, does anybody have any suggestions about what kind of maneuvers I should try under controlled conditions before I just start driving the car around (example, 90 degree turn at x mph, 45 degree curve at x mph)? I'd hate to think I'd tested it out adequately and find out the hard way that I should have tried something else.

If it's any incentive to provide suggestions, whatever I do, I'll do a full write-up and post my results. I might also see if somebody local would be willing to try a side-by-side comparison to see how my car with Hotchkis springs and HA/F-body swaybars compares to their setup. Like yohinan, I'm planning to go through the whole suspension: Navy Lifer control arms w. DelAlum bushings and new 9/16" ball joints, Moog the rest of the front end, HAL adjustable shocks, energy suspension body bushings and the Hotchkis springs (I already have the swaybars and BMR LCA's on). I'm also going to put in a new steering gear box, because I need it. This could be a great opportunity to do some real world testing, but I need input on how that should be set up. Thanks.
 
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Discussion Starter · #20 ·
Erik, you'll want to test a number of suspension loading (transient and static) conditions before taking to the streets with confidence. Here are all the ones I can think of.
1) Brake oversteer. Get going as fast as you can in a big parking lot, turn as sharply as you can, reasonably, and hit the brakes. Hopefully, you won't instantly swap ends. Learn to control this slide because going to a more neutral setup will introduce this phenomenon (I've experienced it with bone stock suspension and tires).

2) Lift throttle oversteer. This is harder to test in a parking lot since they're generally not very smooth (unless they're new) and it requires a bit more space and finesse. But the proceedure is the same. Get going at a good clip in a gear where the engine can be turning 3000rpm when you let off the gas (2nd should be good for the 3.08 LT1s). Now let off the gas and turn sharply at the same time. Note oversteer, if any. Try slightly different combinations of this like a static turn where you suddenly let off the gas, -or- constant deceleration (engine braking, an extreme case for an auto) where you suddenly turn.

3) On throttle oversteer (aka the fun oversteer). This is easy to test for...I'm sure you can figure it out. Try it at all speeds available to you on your skidpad of choice.

4) Transient loading. Try some back and forth handling stuff to make sure you're not suseptible to snap oversteer while slaloming. If so, learn to control it because emergency situations happen on the street.

Generally, a stiffer anti-roll bar setup will produce less surprise events, i.e. a slide SHOULD be progressive, not snappy because nothing is loading or unloading with extreme force (as it would with the stock suspension).

Everyone feel free to add to or correct the above.
 
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