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Discussion Starter #1
Hey guys,

I have noticed that my 1994 Caprice has an uncertain feeling when it comes to road manners. It is factory equipped with the B4U handling package, and I have added the stock Impala SS wheels with BFG KDWS 255/50ZR17's. The car only has 43K miles, so I can't imagine that the suspension pieces are excessively worn. With the new tires I have noticed that it wants to follow bumps and ruts in the road, but even without that behavior considered, the car has a very vague feeling to it. When I was in college I worked for a used car lot that handled a lot of BMW's. Needless to say, I fell in love with the way they handled. My experience was limited to 3 and 5 series cars, and I never had the opportunity to drive an "M" car, but the feedback from the cars was amazing. Is there anything we can do to our cars to give us a more "sure-footed" feel? I realize that those BMW's were smaller cars, but BMW also makes the 7 series which are very similar in weight to our B-bodies.

Thanks,
Chris
 
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Discussion Starter #3
So the standard is BMW? High bar, but ,start with the body bushing modification. A search will give you all the details. BMW's perception of precision comes from a stiff chassis useing a moderatly sprung/aggressively dampened suspension philosophy, so to come close you may want to consider a stiff Bilstein set revalved for even more rebound and compression. You will have to talk to them to see how far they would recommend, but first you will have to chose which springs you want to use and what ride height. With your tires you'll also want to explore sway bar/ spring sets.Just to start.
 
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Discussion Starter #4
Thanks - I had planned to replace the idler arm with a Moog unit when I get my next alignment - I guess it's time!

scot - you mention new sway bars. It seems that the popular choices in this group are the HA/HO setup, or the 2nd gen F-body/HO setup. These are supposed to make the car extremely neutral - to the point of being affected by uneven loading, etc. Will these bars make the car really prone to "spinning out" if the throttle is released while going around a corner (excessive over-steer)? I consider myself to be a novice driver, but I am safe, and have a fair amount of common sense. I guess the bottom line is: I want a car that will handle well, but still be safe if my wife takes it to the grocery store with the kids.

Thanks,
Chris
 
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Discussion Starter #5
Originally posted by 94lt1Caprice:
Will these bars make the car really prone to "spinning out" if the throttle is released while going around a corner (excessive over-steer)?
Depends how fast you are going in the corner. During normal driving, or even "spirited" driving (normal person's definition), you won't have any problems. Now if you drive like a maniac (like me), you won't have any problem inducing oversteer by any one of the available methods.
 
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Discussion Starter #6
Chris,
If you want to check out how a car feels with the HO rear F-body front, shoot me an e-mail and we can meet up one of these weekends. You can drive one of my SS's to see if it is to your liking.
Joe
 
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Discussion Starter #7
Somewhat closer to neutral would be the hotchkis set, which will leave some body roll, or the HO front 1 3/8 and rear 1 1/2. Any 1 1/4 front with that 1 1/2 rear will incline to oversteer.
 
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Discussion Starter #8
So, the front (HO) bar being a little thicker helps to lessen the tendency to oversteer?

What is the real controlling factor for swaybars, and finding the right combination? Is it simply the camparative thickness of the two bars that makes the difference in behavior? Does the vehicle's weight have an effect? Why are the front and rear different diameters?

Also, the Hotchkis system really does appeal to me, but mostly because it is, in fact, a system. You call them up and then all the matching components arrive on your door step. No guessing, no experimenting. But I also know from reading the comments on this forum, that it is not necessarily the best.

If anyone reading this has the Hotchkis set, please chime in and give your opinion.

Thanks!

Chris
 
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Discussion Starter #9
Yes, the HO 1 3/8 front bar is far better choice for any use with the 1 1/2 rear bar if you are leaning toward understeer as a final bias. Springs will affect the outcome greatly as well. Up to a point stiffer front springs=more understeer; stiffer rear springs=more oversteer. gets tricky though when really stiff bars are added to even moderately stiff springs.Too stiff and you have vastly reduced adhesion as soon as the road get bumpy. Body bushing mod reduces understeer, raising the rear also reduces understeer. HO bars, relatively soft, full range of motion, springs, aggressive damping would be the closest approximation of the M series BMW feel.Hotchkis bars, with all else staying the same, would incline more toward underteer with more body motion and roll, little closer to standard 3 or 5 series car.
 
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Discussion Starter #10
Very interesting. When I bought my car I would say that “vague” would be an excellent way to describe how it tracked. After having Hotchkis springs and Bilstein shocks installed and the car aligned, the suspension felt stiffer, but tracking remained vague. Oh, did I mention that it also grabbed cracks and ruts? A couple months ago, I had my BFG KDWS replaced with RE750’s. After that, the car tracked very well, and it no longer grabbed and pulled with every crack, rut, and expansion joints on the road. In my particular case, the KDWS proved to be the problem.

BFG KDWS and SoCal freeways are a bad combo. Very uncomfortable feeling when a crack or rut makes a bid at pulling you into another car or a freeway divider. :eek:
 
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Discussion Starter #11
I have noticed that my 1994 Caprice has an uncertain feeling...
With about 55k, my SS started acting like yours is. In my case, the "vagueness" was a result of a loose steering box and a worn intermediate shaft, it would tire you out on a long trip. Adjustment of the box and replacement of the shaft fixed that. Ed Runnion recently posted a review of the Borgeson intermediate shaft and his procedure for adjusting the box.

The other part of it though, the "tracking," was simply a trait of the tires I was running, BFG Comp T/As. This trait carried over to the KDWS and is one of many reasons for not liking that tire. My solution was replacing the BFGs with Kumho 712s. Another option is the Bridgstone RE750.

With 85k on the clock, the "vagueness," actually more of a "loose" feeling(doesn't tire you out, just has more play than I like), has come back, due to worn, all stock, front end components, but the car still does not "track." This with tires that are about 3/4 of the way through their life cycle. Over the next year I will be completely overhauling the front end, with the AC upgrade parts that Bill Harper has listed elswhere on the forum, to restore the car's stock traits.

While handling upgrades are great, attention should be paid first to maintenance and repair. After that, there are many options, some of which have been listed above that can make the car handle like a true sports car.

The car only has 43K miles, so I can't imagine that the suspension pieces are excessively worn.
I would do an inspection of the suspension and steering before assuming that.
 
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Discussion Starter #12
Another contributor to the BMW's feel is the close tolerances of the suspension components, so bring the Caprice steering and suspension to better than new. The heavy duty frame of the 9c1 and SS is not much more rigid than the civilian models, but for your ambitions any frame stiffness you could add would make the car more like the BMW. Boxing the open sections of the frame of my 94 SS did NOT make much of a perceivable difference, and probably NO performance improvement, and was a PITA.But I like welding.
 
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Discussion Starter #13
Boxing the open sections of the frame of my 94 SS did NOT make much of a perceivable difference, and probably NO performance improvement, and was a PITA.But I like welding.
Well, I'm glad you were able to share that knowlege with me, because I had seriously considered boxing the frame - and I'm a terrible welder!

I think I will go ahead and replace the idler arm with a Moog unit, and have the car re-aligned. Then I'll investigate the other suspension upgrades. I have also been planning to upgrade the bushings on the front end to Del-a-lums.
Chris
 
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Discussion Starter #14
I did the body bushings, moog idler arm and HAL shocks front/rear, air bags in the rear springs, cut a coil out of the front springs (lighter LS1 engine and battery relocation). I already had HA front and rear with metco ¾” extended rear control arms. The car feels like it lost about 1500 lbs! It did lose about 150lbs with the engine swap, but the handling is unbelievably better. The full coil out of the front was a little too much, so I am going to install Hotchkis springs to raise it a little and increase the spring rate. I need to align the front end, but overall I am very pleased with the outcome!

Bushings needed.

Qty----Part #--------Description
4------348080------upper bushing for position 1 & 3
2------330986------upper bushing for position 2
6------330942------upper bushing for position 4, 6, 7
2------488610------upper bushing for position 5
2------14085301----bolt (for #3 position only)
10-----457915------lower bushing for position 1,2,3,4, and 6
2------457917------lower bushing for position 7
2------472160------lower bushing for core support
2------377888------upper bushing for core support

I haven’t updated my site in a while, but there are a few pics here:
web page

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Forgot to mention that I tightned up the steering box as well.
 
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Discussion Starter #15
When I was in college I worked for a used car lot that handled a lot of BMW's. Needless to say, I fell in love with the way they handled.
SSh has just given you the parts list for the best first change to move in that direction. I'm still trying to fiqure out a frame/body stiffening modification that will change the overall perception of better handling as much as doing the U+L body bushings did.You'll be pleasantly surprised at how much better even relatively soft springs work when they are connected to a more rigid chassis.
 
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Discussion Starter #16
Scot - have you done any modeling to see what an x member would do for you? I considered a full tube frame, but this is my daily driver and I might as well build a car (AC cobra, 32 coupe...) if I am going to do that.
 
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Discussion Starter #17
SSh, I'll email you a couple pictures of my 98 Camaro, Full frame with jacking rail, deleted back seat for roll bar, floor, wheel well and shock tower braces,all welded to frame. Triangulated STB up front.Further description earlier in thread.
 
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Discussion Starter #18
Actually the Camaro info I refered to is in the thread REINFORCING THE FRAME??
 
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Discussion Starter #19
Actually the Camaro info I refered to is in the thread REINFORCING THE FRAME??
 
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Reinforcing the frame

A choice excerpt, for those interested:
The most effective way to keep things from bending and twisting is to use diagonal members oriented in a normal plain... Think of a square ... standing up with one side fixed to the ground. Now one top corner is pushed in so that the force is parallel to the top bar. The square has a tendency to become a parallelogram. One way to prevent the square from deforming would be to make it out of beefier material. However, it is far more effective in terms of weight penalty to add a diagonal member instead. Instead of a diagonal bar, diagonal cables (two cables since cables can only act in tension, not in compression) or corner braces could also be used.
Now lay this tubular square down flat and elongate it so that it becomes a rectangle... a simplified model of our frame. The forces ... don't tend to force it to become a parallelogram nearly as much as they tend to bend it and twist it... adding cross-members (whether perpendicular or diagnal) is not going to be very effective ... think of a ladder. A whole bunch of cross-members ... don't ... prevent the ... bending or twisting. This explains why boxing the frame or adding more cross-members does not do very much... add a second rectangle above the first one and connect the two together with vertical bars in all corners and at a couple of more places along the longer sides. (This second rectangle could represent either a roll cage or the body.) While the new structure is stiffer, it is not very efficient in terms stiffness divided by weight. Adding some diagonal members will significantly increase its ability to resist bending and twisting.
Basically, if the body does not have good torsional or bending rigidity, it will not signifficantly add to the torsional rigidity or bending rigidity of the frame regarless of what type of body mounts are used. The two will simply defelect and twist together.
 
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