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Old 11-20-2009, 04:12 PM   #1
55Designs

 
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Rear Suspension Squatting and Bouncing on all videos with Tuned setups why?

I have seen just about every single video on the Camaro and regardless if the car has Pedders, springs, Pfadt, KW everytime the car is hammered the back end squats so much and on the tarmac it tends to bounce in the rear.

Even through an autocross I see the car bouncing yet the front is flat and stable with no roll. Its an up and down bounce.

Look on Hennessey website of the Yellow video launching how the car is so sloppy taking off.

Now why cant this be solved via the valving on all these coilovers or what?

I understand drag cars need to load up so that makes sense but the rear end bounce just sucks because it does this in stock form and when your going through turns that have a slight dip in the road it can get scary at high speed along with the wiggle from the subframe.

Vette doesnt bounce eigther does a Porsche or any other sports car.

I dont want the bounce i want it tight and planted.

Comments guys?
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Old 11-20-2009, 04:16 PM   #2
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i agree with you very much. We will be doing some testing at Road atlanta on the same issue next weekend. Haven't changed the shocks out yet simply because we haven't found the best yet. All the new coilover kits out right now simply don't resolve that very issue. Hope to have some more knowledge after Road Atlanta.
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Old 11-20-2009, 04:48 PM   #3
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Now we are talking Lawdog. I sold my first coilover kit because the dampening was not making the bounce go away and in NY is almost felt worse.

I have springs and I sent my shocks for a basic revalve they feel realy good and to be honest I have less bounce now than ever but it still pops up and annoys me.

This is why I think a custom valved coilover or a serious race shock is required.
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Old 11-20-2009, 05:10 PM   #4
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The KW suspension system does not bounce and is smooth all of the time.
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Old 11-20-2009, 05:37 PM   #5
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John does the yellow car in the road test on your website have the KW? Yes or no and if so what settings because the video did show some bouncing.
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Old 11-20-2009, 05:49 PM   #6
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Hmm, I wonder if anti-squat is adjustable?
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Old 11-20-2009, 11:57 PM   #7
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Coils and shocks or coilovers alone will not stop a ZETA chassis from hopping on a hard launch. It is a matter of harmonics. Wheel hop or wheel tramp is the result of a reverberation through the drive line or suspension that explodes as the vibration grows. Squat is effective in allowing the weight of the vehicle to transfer weight and power to the rear. The real problem lies in the foundational bushes in the Camaro. In this instance it would be ths sub-frame bushes and differential bushes as primary with the remianing rubber bushes in the control arms contributing. Add to this negative camber and running on the inside edges of the tires and you have wheel hop.

A well setup ZETA chassis will have virtually no wheel hop. We have been working with the ZETA chasssis on the G8 for almost four years in AU and the USA. We have numerous ZETA vehicles running high RWHP and launching well. Most will be able to run with sub-frame bushes and an alignment with ZERO negative camber. This gives you a solid / square up tire to pavement orientation and limits the movement of the IRS. As you add RWHP you can add additional upgraded bushes, coils and dampers.

No single solution exists to make a perfect launch. It is a series of upgrades, tires and adjustments including alignment. Don't sell positive camber short as a solution to this. Not only will it imporve your launch, it will reduce understeer.
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Old 11-23-2009, 11:51 PM   #8
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I think it is easier to control the front than the rear due to the weight of the engine. The rear is a lot lighter the front. If you apply the same amounts of control, then hitting the big bumps you will go airborn. Now looking at the Optima Challenge video in full screen, the Pedders Camaro has a huge amount of control side to side and fore/aft. The back end needs to be softer than the front so the back end does not get launched in a rebound mode. But I think on hard accel for example, it is good to have the back end drop just a little for launching. If it does not, then you will do nothing but spin tires and go no where.

Here is the Pedders Optima challenge video. Look at it in full screen and look at the balance front and rear. It is quite controlled. Paul Tracy said he wanted nothing changed after his practice laps. Who is going to deny him his opinion?


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Old 11-24-2009, 07:26 PM   #9
Aaron Pfadt
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Quote:
Originally Posted by 55Designs View Post
I have seen just about every single video on the Camaro and regardless if the car has Pedders, springs, Pfadt, KW everytime the car is hammered the back end squats so much and on the tarmac it tends to bounce in the rear.

Even through an autocross I see the car bouncing yet the front is flat and stable with no roll. Its an up and down bounce.

Look on Hennessey website of the Yellow video launching how the car is so sloppy taking off.

Now why cant this be solved via the valving on all these coilovers or what?

I understand drag cars need to load up so that makes sense but the rear end bounce just sucks because it does this in stock form and when your going through turns that have a slight dip in the road it can get scary at high speed along with the wiggle from the subframe.

Vette doesnt bounce eigther does a Porsche or any other sports car.

I dont want the bounce i want it tight and planted.

Comments guys?
I would argue that the the rear bouncing on most of these cars is due to the tight packaging space of the rear dampers on this platform. The dampers control the amount of travel and the stock dampers are pretty long. This means that you operate at near the limit of the travel of the damper even with stock springs. With drop springs you have the shock compressed even more.

If your shock travels into even a cut down bump stop, the increase in spring rate will overwhelm the rebound damping of the factory dampers. That is why we cut our bump stops with our drop springs. That said, if you are using the car in a competitive environment, you will be traveling into the bump stops some and there will be some amount of under-controlled motion. The only true solution to that is using a shorter strut or coilover that is designed to operate in that travel region.

Keep in mind that this is not a big problem, the car with stock struts will work very well in most cases and be only slightly compromised in cases of large compressions. I ran our car at the Optima Challenge (at Spring Mountain which is arguably a very bumpy track) and was very competitive with cars of significantly higher HP with only our Pfadt drop springs and sway bars. Would we have been faster on coilovers, certainly, but the car was extremely capable as equipped.

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Old 12-02-2009, 02:30 PM   #10
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Cutting a bumpstop generally removes the progressive portion of the stop leaving a blunt butt end. That can lead to chatter as the coil and supsension rebound off the blunt end of the stop under hard launches or cornering. In a Pedders installation, there is no need to cut bumpstops. Our drop coils are designed to work with the OEM bumpstops and our Xa coilovers adjust height by screwing into or out of the lower mount which maintains full jounce travel regardless of ride height with incredible stability. The confirmation of this can be found in multiple videos of the fastest Camaro running on a track with skilled drivers pushing the car at the limits.





In the first video you see there is minimal squat on a hard launch and no bouncing of any kind on the track. This is true even though we are running -1.2 rear cambers which without great suspension would create axle tramp / wheel hop on the hard launch. Follow the video and watch the tires as the drivers jump corners and you'll see just how stable the vehicle remains. It is Chevy built like a rock stable.

When the Hennessy video of the yellow car was taken, the car had been lowered in their shop while I was there. Unfortunately, the alignment machine was not operational. The alignment was done at a different shop and the OEM rubber bushes were not timed to the new ride height. The OEM rubber bushes, the resistance created when they twist, were out of time and created the bounce seen in the video. The next day at the track, the same car was completely different. On day 1 the driver rated it a 2. On Day 2 the driver rated it a 9. The video is from Day 1.

Suspension setup is critical with a vehicle like the Camaro. The IRS is best in class while the front is good, but far from equal to the rear. This creates balance issues with the IRS being far more competent than the front suspension. This creates understeer, the biggest issue we have with the Camaro. Finding ways to make the front stick better and ways to allow the rear to come loose in a controlled oversteer are the keys to setup along with careful attention to the foundational bushes.

Pay attention to the details as you set up your Camaro:
  • Minimal Positive or Zero Negative Rear Camber
  • Zero Toe
  • Bushes timed to the Ride Height
  • Tire Inflation

These are all things you can do with your OEM Camaro and not have to purchase any parts. The most important is launch technique. Take the time to make these changes to your Camaro BEFORE you buy any suspension upgrades. You may find that in full OEM trim your Camaro does what you want it to. People are still learning how to best launch their 5th Camaro. That makes it very difficult to document any 60' or other strip metrics. The darn drivers keep getting better at launching and driving down times.

If you want a shopping list, we could provide a rather long one. To keep it short remember that any modification you make to your Camaro must compliment the other suspension components or it will become unbalanced. Using Pedders EP1201HD Delryn for the street sub-frame bushes and nothing else makes little sense. Your sub-frame is now far stronger than the next weakest element. If all you are going to do is address the sub-frame motion Pedders EP1200 inserts would be a better balance to the rest of the components. If you are on a budget and want to start with the Delryn for the street like EP1201HD knowing you are building then it is a wise choice. Choose the right part for your vehicle knowing the hardest, biggest or baddest isn't always right for you.

Put a plan together with a well thought out strategy to modify your Camaro into the car you would like to drive. You'll save a lot of money by following a well thought out strategy and end up with a well balanced and great performing 5th Gen.
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