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Discussion Starter · #1 ·
Hi all,
I joined last year but have not worked on my impala until last month. So I have had my impala since 1992 and have kept it stock. Now I would like to improve the rear suspension components. I would to start with control arms upper and lower bushings and while I have them out possibly box them. Could anyone suggest which bushings are better than others ie. vendors, rubber vs poly I mainly would like to kept as stock as possible. Also I am on the fence as to box my lower control arms. Any opions may be some has done this already?
Thanks
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Welcome Tino,
Given your desire to keep things stock, I don't think you need to box your control arms.
If you had a built up motor, or big block, and were going to drive it hard or had plans for drag-strip runs sometimes, then I would say to box'em.
I did box my stock lower control-arms on my '66 because I do drive it hard, do burnouts, have an upgraded rear-end and sticky tires, manual tranny, etc.
The rubber vs polyurethane debate depends upon your budget, driving habits for the car, and maybe even how smooth your roads are and tolerance for a slightly firmer ride.
The poly bushings are superior in most every way - but they will transmit a bit more road-noise and harshness of bumps like we have on roads with 4 distinct seasons.
You would notice that more with low profile tires versus the stock-like tires with cushy, big sidewalls.
In my opinion, Rubber is fine. I personally leave the poly for my more performance oriented rides made to handle well.
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Discussion Starter · #3 ·
Thanks for your input. Yes this will mainly be cruiser not a 1/4 mile track car. With that being said, my biggest problem is the way the whole car rolls when I make turn like a boat. Since I will replace all the rubber bushing with new rubber, my question is will that be enough to eliminate the horrible body roll. That is why I was thinking, since I have the control arms out why not box them. My impala has two upper and two lower control arms and the pan hard bar(no sway bar).
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I would go stock on the bushings. To stiffen up the body roll, Add aftermarket sway bars.
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The body roll is a factor of the swaybar, the springs and to a degree the tire sidewall (roll-over) more than it is about the bushings. If you want to fix the roll, address those things primarily.
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Chevrolet sourced the rubber bushings that they used as OEM equipment back in 1965 from Moog. The parts made today meet OEM specifications for new cars but are softer than what Chevy used back in the sixties.
As to why rubber was used the answer is simple. Plastic was in it's infancy. Point in fact, one of the first successfully made plastic devices was the telephone. It was as hard as a brick, nothing would affect it chemically and unless melted or mechanically shredded every one that Ma Bell made is still in existence some where on or buried beneath the surface of this planet.
The way your suspension is hung there has to be some give in all three axis or the bushing will bind. That is why I don't recommend polyurethane bushings for all of your rear suspension control arms. At least one end has to be either rubber or a solid steel heim joint. on a tubular control arm. So I would stay with all new American Or Canadian made Moog replacement parts.
If you can weld then I would box in the stock control arms because the added weight is nothing compared to stiffening the member mechanically. All gain and little loss in my opinion.
Big Dave
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Discussion Starter · #7 ·
Ok, I understand your logic. So what if I went with new springs(1.5" drop in front & 2" drop in rear) with matching shocks and installed sway bars front & rear. Then install new bushings in the control arms with out boxing them? All bushings would be poly. I am just looking at my options and my pocket book.
Also I know something has to give\move ie. the bushings or the control arms and I have read how boxing the controls arms makes a big difference however also do sway bars. So what is going to eliminate my body roll; option A boxing control arms and installing new rubber bushings or option B installing front and rear sway bars with new springs and shocks and new bushings in the control arms all being poly?
Option A = $300
Option B = $600
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B And if your going to punish it, box the uppers as they tend to break, and pull through the frame.
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Bigger diameter anti-roll bars (sway bars) are auxiliary springs. They are only flexed when one side of the axle goes up or down more than the other. The bigger the bar the stiffer the spring rate.
Also the stiffer the spring rate the greater the forces applied to the mounting mechanism. On my front bar I went to the biggest solid steel bar available from Affco and it ripped loose from the frame on a sharp turn. The factory used only four quarter inch sheet metal screws to hold the pivot points to the frame.
I recommend Hotchkiss hollow sway bars as they save weight and are stiffer than a solid steel bar (and a tad more expensive). They also use custom mounting hardware to hold the bar in place.
By the way the difference was night and day with the bigger sway bar front and rear as my '85 Impala cornered like a slot car. Of note is that the "before" was the heavy duty suspension found under a police car, not you average stocker, so it was already handling better than most.
Now for around the back I would box the rear control arms and use poly urethane bushings because you have two parallel control arms that swings in a simple arc. You also have a Panhard bar to control side by side (lateral) movement that is adversely affected by lowering the car. Because of this you will need to buy an adjustable aftermarket Panhard bar to center the rear end under the car.
http://www.hotchkis.net/6570_chevrolet_bbody_panhard_rod.html
Big Dave
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Discussion Starter · #10 ·
Thanks! for your help Big Dave.
I have on order new shocks to go with lowering springs 1.5" in front and 2" in back also an adjustable panhard bar and front and back sway bars.
So, what about my upper control arms? When I removed them, there where some shims. Will I need to replace the control arms with adjustable ones, because I am lowering the car?
BTW, Big Dave I took your advise on a previous thread about ordering the $12 manual from amazon it has helped out a lot. Thanks!
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Adjustable upper control arms are for use in adjusting the pinion angle which will change when you raise or lower the car (think of the last sky high 4x4 pick up truck you saw with the 45 degree angle on the drive shaft). If the pinion is not rotated to reduce that angle the universal joints will not last long (in this case days not years).
Additionally there is a tremendous vibration crated as the universal snaps past center every 90 degrees of rotation. The vibration in the drive line is why they sell adjustable upper control arms. It is also why Cadillac and expensive luxury cars use constant velocity joints instead of universal joints. It will cut vibrations in the drive train in half.
Check out this Wikipedia article about universal joints that shows how the forces on a universal can create a vibration in the drive shaft that your car's cabin will form a sound box to amplify the noise (like living inside an acoustical guitar as the strings are strummed.)
http://en.wikipedia.org/wiki/Universal_joint
Big Dave
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Discussion Starter · #12 ·
Arrrgh, When I was removing the bushing form the upper control arms, I ruined one of the outer shells from the upper control arm. Does anyone know where I can get a replacement? All the bushing kits(polyurethane) I have looked do not come with outer shells, help. I have looked at moog for original and did not find one. Help....
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I dont think anyone makes the outer shells. If your in a pinch I can remove one from a extra arm I have.
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I make Swiss Cheese out of the rubber bushing with a quarter inch drill bit. Once it is mostly air I attack it with a Jig Saw to separate the rubber from the outer and inner shells. I can then press the outer shell out of the arm on a 20 to ($200 Chinese import) hydraulic press I have. You can then pull what is left of the rubber out with pliers and a screw driver as it offers very little, to no resistance.
I don't recommend attacking it with an acetylene torch like I used to do as you have little control. Might add that the burning rubber will stick to your legs as you are holding the flaming bushing and are trying to blow out the fire.
Big Dave
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Discussion Starter · #15 ·
I pressed the bushing and metal shell out of the control arm oops. I thought the bushing would come new as one unit rubber and shell. I can do what you suggest for the lower conrol arms.
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Discussion Starter · #16 ·
Well I finished installing the rear suspension poly graphite bushings in the arms and installed new shocks and new 2" lowering springs oh and added a sway bar and adjustable pan hard bar. I must say the rear end is tight, when I make a turn it no longer feels like a boat. Now it's time to start on the front suspension , I already have new shocks, 1.5" lowering springs and a 1.25" sway bar. I am thinking of going OEM rubber in the front.
Source: https://www.impalas.net/threads/1965-impala-ss-rear-suspension-restore.17385/
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