Help me tune my Koni shocks on the 72 - Team Camaro Tech
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post #1 of 8 (permalink) Old Sep 11th, 12, 10:08 AM Thread Starter
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Question Help me tune my Koni shocks on the 72

I picked up a 72 RS/SS recently. The car has Hotchkis front coils and Hotchkis rear 3 leafs, Hotchkis subframe connectors and had KYB gas-a-just on all 4 corners. The car had zero lean, great for track but I did not like how it handled of the street. Too much rattle and all potholes were really pronounced. I have replaced the very stiff KYB's with adjustable Koni's. While I had the KBY's out I compared them to the Koni's. Even with the Koni's set at the stiffest setting they were still very soft compared to the KYB's. I got the Koni's installed. Front is set at the softest setting while back is set on the hardest setting. The ride has really changed in a very good way. The car has a little lean to it around corners and much less rattle and friendlier potholes. I really like it a whole lot better now. Had a chance to drive the car quite a bit more on the highway at higher speeds yesterday. I think I need some tuning on the Koni’s. It appears there is a settle but consistent bounce (one long up and down movement) to the car when driving at higher speeds over the highway long “dips”. Dips being elongated up and down slopes in the road. You can feel a single long but smooth bounce in your body when driving over these long dips. If your body fat percentage is not 5% or less then some parts on the torso tend to move up and down. It also seems that when talking and driving, your voice tends to “bounce” along with the car. When doing the fender press test, the front seems to be softer while the back is still pretty stiff. No multiple bounces but rather a single bounce/recoil. Should I stiffen up the front or soften up the back? Does tire pressure matter? When I got the car the tires were running 45PSI. I got them down to 30PSI. The fronts are 275/40/17 while back are 315/35/17.

Matt

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post #2 of 8 (permalink) Old Sep 11th, 12, 10:49 AM
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Re: Help me tune my Koni shocks on the 72

Since the front bears a major portion of the weight of the car I would think you would want those shocks set stiffer than the rear. Why not try stiffening up the front and loosening up the rear?

I have my Koni's set at medium at all 4 corners and have never adjusted to test ride difference. I guess I should one day try the front at the stiffer setting or something.

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post #3 of 8 (permalink) Old Sep 11th, 12, 11:22 AM
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Re: Help me tune my Koni shocks on the 72

http://www.koniracing.com/autocrosstune.cfm

http://ls1tech.com/forums/suspension...-1st-time.html

http://www.chevyhiperformance.com/te...s/viewall.html

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post #4 of 8 (permalink) Old Sep 11th, 12, 12:05 PM
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Re: Help me tune my Koni shocks on the 72

From my own experience with Hotchkis springs and Koni classic shocks on my 1st gen convertible the bouncing you are describing is not shock or spring related. Sounds like an out of round tire or tire balance issue to me. If you were really at higher speeds, then maybe your front end was lifting but I don't think lifting would giggle body parts, the steering would just feel light!

As for the Koni settings on the street, I ran mine on the soft setting both front and rear and only changed the front to medium after installing the rear swaybar. I tried them on the firm setting and didn't care for the ride quality and even setting the fronts to medium made the ride a touch harsher then I'd prefer but I really like the way the car corners the way I have it.

My recomendation is set the shocks to the softest setting and go drive the car as hard as you plan to on the street and decide if you want to step on the ride quality by making the shocks stiffer. If you stiffen up the shocks at all go find a washboard corner and try to go around it fast. If you can't because the bumps cause the car to crab walk or drift sideways the shocks are too stiff for the street...

...Dennis

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post #5 of 8 (permalink) Old Sep 11th, 12, 12:13 PM
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Re: Help me tune my Koni shocks on the 72

I have run Koni red classics since day 2 along with 500# GM off road factory coil springs, .750" wire.

Years later I thought the KBY's were the thing as I had them on my Trifive but quickly realized the differance. I put the Koni back on . All are set in medium slot with 5 leaf rear springs. Doing all the powertours I can say that Koni is the best shock for me.
Car hugs the road as well as the C5 vetts I followed on the GM proving grounds in Detroit this year, I didnt think the car would handle curves and banks well but I was behind them all the way to the exit.
If you ever get the chance, you need to try this track out. I think its some 40K acres of roads .

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post #6 of 8 (permalink) Old Sep 12th, 12, 08:03 AM Thread Starter
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Re: Help me tune my Koni shocks on the 72

Dennis, I don't think it's a out of balance tire issue as something like that would be constant at higher speeds. It's more of onetime up and down on the car part and a couple giggles on the body part as the car travels over elongated dip in the highway. This does not happen when driving on a straight non-dippy portion of the highway. Perhaps this is seat related. I remember I had a similar issue on my 68 with the stock seats that had soft springs. After having them redone, the issue pretty much went away and now that I have the ProCar seats (pretty hard/tight seat) the issue is non existent. The 72 has buckets out of a Fiero. They are very comfortable and surprisingly the springs do not seem soft or at least there isn't that much of a give to them. Sounds like the consensus is that I need to harden up a bit on the front shocks and soften up on the rears. Perhaps my next setting should be 50% on front/back and see how the car handles. Also, I have a rear sway bar for the car but the previous owner took it off as he felt he had less traction with it on. If there was a rear sway bar traction issue, could it been related to the super hard KYB's he had on there? Can someone explain to me what a rear sway bar is supposed to do for a car?

Matt

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post #7 of 8 (permalink) Old Sep 12th, 12, 10:18 AM
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Re: Help me tune my Koni shocks on the 72

Quote:
Originally Posted by zlek131 View Post
Sounds like the consensus is that I need to harden up a bit on the front shocks and soften up on the rears. Perhaps my next setting should be 50% on front/back and see how the car handles. Also, I have a rear sway bar for the car but the previous owner took it off as he felt he had less traction with it on. If there was a rear sway bar traction issue, could it been related to the super hard KYB's he had on there? Can someone explain to me what a rear sway bar is supposed to do for a car?
I am still gonna say go to the softest setting on front and rear to set a baseline. My money says on the street you'll end up back there after trying other settings.

Just like a front swaybar the rear helps control over and under steer. Oversteer is when the cars back end breaks loose before the front and understeer is when you turn and the car plows or the front end pushes and the car wants to keep going straight.

Ideally you want both the front and rear to break loose at the same time in a balanced drift but having the front start pushing before the back breaks loose is a safer handling trait. If your backend is already breaking loose first in a hard corner you wouldn't want to add a rear swaybar. If the front end pushes real bad a rear sway bar will help balance things out by transfering more of the cornering load to the rear tire.

...Dennis

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post #8 of 8 (permalink) Old Sep 13th, 12, 07:55 AM Thread Starter
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Re: Help me tune my Koni shocks on the 72

I'll play around this weekend and will baseline the shocks at softest setting in all four corners and then go from there. Thanks for all the input.

Matt

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