Rear end bouncing after shock change? Updated 9-30-2012
#1308727
09/22/12 12:34 PM
09/22/12 12:34 PM
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Joined: May 2004
Posts: 617
Corvallis,OR
540CUDA
OP
super street
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OP
super street
Joined: May 2004
Posts: 617
Corvallis,OR
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I had a leaking rear single adjustable QA1 shock so I replaced both rears. The new shocks have more adj clicks so I was guessing at the setting. The old shocks were at set at 9 (1-15 clicks) I set the new ones up at 11 out of 18. Now the car keeps bouncing in the rear pretty much all the way down the track, which is very noticeable in the video but it just felt like I was loosing traction during the run. Are they just set up to hard? It also shot to the right on launch slightly so a little more preload on the right ladder bar is in order, yes? Opinions please. 
Last edited by 540CUDA; 09/30/12 04:41 PM.
PRH 540,T-ram,-1's tagged and insured. 9.24et 146.13mph 1.30 60'3300#s
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Re: Rear end bouncing after shock change?
[Re: 540CUDA]
#1308729
09/22/12 01:48 PM
09/22/12 01:48 PM
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Joined: Aug 2003
Posts: 43,230
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,230
Bend,OR USA
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The only set of single adjustable QA1 I had where fronts, they where 90/10 on extension and the compression was what was adjusted by the knob, not the extension   What are your ratio  on the extension?
Last edited by Cab_Burge; 09/23/12 01:33 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Rear end bouncing after shock change?
[Re: Cab_Burge]
#1308731
09/22/12 03:56 PM
09/22/12 03:56 PM
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Joined: Mar 2003
Posts: 9,100
Rogue River, OR
Jeremiah
master
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master
Joined: Mar 2003
Posts: 9,100
Rogue River, OR
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Quote:
The only set of single adjustable QA1 I had where fronts, they where 90/10 on extension and the compression was what was adjusted by the nob, not the extension What are your ratio on the extension?
Not trying to be smart but how can they be 90/10 if we are talking about extension? I am not following.
I was looking at some other QA1 shocks that were here in the shop and had some concerns and the tech at QA1 (nice guy, very smart) told me to install the shocks and tune them on click at a time in the front until the front end stayed up long enough to get the car moving/weight transfer. He said keep the rear in the middle setting during that test. The next step was to tighten up the shocks in the rear until the car started to loose traction off the line. Those were instructions for a base line on a new set of shocks. This is for a leaf spring car.
I have talked to several guys with ladder bar or four link cars that have not had much success with single adjustable shocks and prefer double adjustable. That is not my direct experience just hearsay.
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Re: Rear end bouncing after shock change?
[Re: 540CUDA]
#1308732
09/22/12 03:58 PM
09/22/12 03:58 PM
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Joined: Mar 2003
Posts: 9,100
Rogue River, OR
Jeremiah
master
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master
Joined: Mar 2003
Posts: 9,100
Rogue River, OR
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Quote:
I had a leaking rear single adjustable QA1 shock so I replaced both rears. The new shocks have more adj clicks so I was guessing at the setting. The old shocks were at set at 9 (1-15 clicks) I set the new ones up at 11 out of 18. Now the car keeps bouncing in the rear pretty much all the way down the track, which is very noticeable in the video but it just felt like I was loosing traction during the run. Are they just set up to hard? It also shot to the right on launch slightly so a little more preload on the right ladder bar is in order, yes?
Opinions please.
Question : Is there a reason why you did not have the QA1's rebuilt? I think there is a place in sac that is a QA1 authorized rebuilder with a shock dyno, etc. If you want the number it's floating around my shop somewhere.
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Re: Rear end bouncing after shock change?
[Re: 540CUDA]
#1308733
09/22/12 04:04 PM
09/22/12 04:04 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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First I would wonder if the shock is bottomed out going down the track or if its topped out(put a tie rap on it to see whats happening)... with the different shocks its loading differently so thats why its going to the right... correct the shock issue first and the loading might be right again
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Re: Rear end bouncing after shock change?
[Re: MR_P_BODY]
#1308734
09/22/12 08:43 PM
09/22/12 08:43 PM
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Joined: May 2004
Posts: 617
Corvallis,OR
540CUDA
OP
super street
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OP
super street
Joined: May 2004
Posts: 617
Corvallis,OR
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Thanks for the replies guys, It was easier to get QA1 shocks than a kit,plus I can use them on my truck later. Theyre not bottoming out, but that had crossed my mind. I should have mentioned I completely rebuilt the rear end housing and brackets so it was a baseline adjustment that got me to this point-zero preload and then one flat on the right side. I guess it needs more preload to go straight. And after looking at the pics and videos Im killing the tires at the line with 7psi, so multiple issues I guess. I'll post some pics when I can.
PRH 540,T-ram,-1's tagged and insured. 9.24et 146.13mph 1.30 60'3300#s
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Re: Rear end bouncing after shock change?
[Re: 540CUDA]
#1308735
09/22/12 09:23 PM
09/22/12 09:23 PM
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Joined: Dec 2005
Posts: 1,495
Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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Reading between the lines you have a caltrac system????? If that is the case then that is not the right shock. That shock cannot control that system enough.
JAKES AUTOMOTIVE
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Re: Rear end bouncing after shock change?
[Re: JAKE68]
#1308736
09/23/12 12:35 PM
09/23/12 12:35 PM
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Joined: Mar 2003
Posts: 9,100
Rogue River, OR
Jeremiah
master
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master
Joined: Mar 2003
Posts: 9,100
Rogue River, OR
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Quote:
Reading between the lines you have a caltrac system????? If that is the case then that is not the right shock. That shock cannot control that system enough.
What would be a good rear shock on an application such as this?
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Re: Rear end bouncing after shock change?
[Re: MR_P_BODY]
#1308738
09/23/12 06:11 PM
09/23/12 06:11 PM
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Joined: Dec 2005
Posts: 1,495
Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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Either the calvert shock or a step up would be a afco dbl adjustable.
JAKES AUTOMOTIVE
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Re: Rear end bouncing after shock change?
[Re: JAKE68]
#1308739
09/24/12 11:49 AM
09/24/12 11:49 AM
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Joined: May 2004
Posts: 617
Corvallis,OR
540CUDA
OP
super street
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OP
super street
Joined: May 2004
Posts: 617
Corvallis,OR
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Its a ladder bar system that went 1.30 on the old QA1 shocks. It just started the bounce with the new untuned QA1's. Next weekend I'll try more tire pressure and preload and stiffen the shocks if it needs it after that.
PRH 540,T-ram,-1's tagged and insured. 9.24et 146.13mph 1.30 60'3300#s
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Re: Rear end bouncing after shock change?
[Re: 540CUDA]
#1308740
09/24/12 12:10 PM
09/24/12 12:10 PM
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Joined: Dec 2005
Posts: 1,495
Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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Now with more info I have another question.Did you change anything on the front end? Ya you should be at least what it was before!!!!
Last edited by JAKE68; 09/24/12 12:11 PM.
JAKES AUTOMOTIVE
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Re: Rear end bouncing after shock change?
[Re: JAKE68]
#1308741
09/30/12 03:10 PM
09/30/12 03:10 PM
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Joined: May 2004
Posts: 617
Corvallis,OR
540CUDA
OP
super street
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OP
super street
Joined: May 2004
Posts: 617
Corvallis,OR
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http://www.youtube.com/watch?v=0CQHLzN_lHE&feature=channel&list=ULVideo of the bouncing last weekend. I made some runs yesterday after adding more preload,softened the rear shocks, upped the tires to 9psi and went up 2 jet sizes. It responded with a 9.30 at 145.13. Launches are straight and no more pogo action. Video of that run soon to come.
Last edited by 540CUDA; 09/30/12 03:32 PM.
PRH 540,T-ram,-1's tagged and insured. 9.24et 146.13mph 1.30 60'3300#s
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