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Re: Setting up DA shocks [Re: Wirenut] #2817961
09/06/20 07:25 PM
09/06/20 07:25 PM
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Looking at both vids it looks like it is topping out the shock travel making the rear porpoise up ad down tsk
Did you compare the extended shock lengths on both sets of shocks? If not, if you can , do that now. If your new shocks are shorter at max extension than the old ones you may need to use shock extensions to help fix the extended length. If this is the case I might have a set of them, let me know if you need them or not up
Try removing the lower shock retainers and slip them off the lower shock mount and see how much more down travel you have on them, then try jacking the back of the car up with the rear end hanging down with jack stands under the rear sub frames and see how much rear shock travel downwards you have that way also. Please let us know what you find on this wrench grin
What does your rear spring shackle angel look like with the rear end hanging down all the way?
It ET better in the 60 before so you know it will do it again with the proper fixes up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Setting up DA shocks [Re: Wirenut] #2817983
09/06/20 09:02 PM
09/06/20 09:02 PM
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Fulton County, PA
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CMcAllister Offline
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Originally Posted by Wirenut
Thanks for the input . I truly appreciate the help .

They are ss springs (don’t know which ones) .

They are mounted inboard , via dc relocation kit. Front eye is as close to car as adjustment holes allow. Rear hanger is through frame fairly close to floor . Angle looks good .

Tires are 31.25

Just throwing this out there. I have had this car for a few years . Until last year it pretty consistently 60’ed 1.40 to 1.42 with an occasional 1.39 And an occasional 1.45. That was with 20 year old ce 3-way shocks .

Seems like I am having to go through a lot of change to only get back to where I started.



It happens. It's called "losing the rabbit".

Cab - I would bet a dollar that jacking that car up, putting jackstands under the chassis and leaving the rear hang, would not let it fall out any further than when it is on the ground. If there is so much arch that they are actually compressed, they need to be tossed.. Maybe need to be anyhow,


If the results don't match the theory, change the theory.
Re: Setting up DA shocks [Re: Cab_Burge] #2817991
09/06/20 09:32 PM
09/06/20 09:32 PM
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dvw Offline
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It appears to be bound up at full rebound. I agree with Cab see where the shock length is. Any reason for the tall tire? Too much gear? A 28" would lower the rear a ton. The bind needs to be fixed before the shocks can do anything. I'd like to see a pic of the rear shackle. Since its close up in the frame is it hitting the frame?
Doug

Last edited by dvw; 09/18/20 09:04 PM.
Re: Setting up DA shocks [Re: dvw] #2818012
09/06/20 10:40 PM
09/06/20 10:40 PM
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A smaller tire will bring the rear of the car closer to level, but won't do anything to get the rear up in the car higher if the springs are holding it out.

It does look like it's porpoising or bouncing out across the concrete. But if you look close, the tire is bouncing up and down. The suspension has no movement.


If the results don't match the theory, change the theory.
Re: Setting up DA shocks [Re: CMcAllister] #2818139
09/07/20 12:16 PM
09/07/20 12:16 PM
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Wirenut Offline OP
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About 3” of travel from at rest to hanging the axel.

Shocks have about 2.75” of travel beyond mounting point with axel hanging .

*****sorry don’t know why pics came out sideways and upside down******

37648529-9804-4463-88BF-15E25EE5033F.jpegE0D96241-91CF-449F-B91F-2C087058FEF5.jpeg5AC8ADCF-0BF1-4E12-80F6-278B746F5709.jpeg172BB484-8298-40D2-BDF2-42F7233FF966.jpeg
Last edited by Wirenut; 09/07/20 12:21 PM.
Re: Setting up DA shocks [Re: Wirenut] #2818176
09/07/20 02:21 PM
09/07/20 02:21 PM
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You need to have a lot more angle on the rear shackles so they don't rotate past center at max lift on the rear of the car twocents scope wrench
I would relocate the upper bushing hole forward two to three inches closer to the rear end to increase the shackle angle more, you can test where to put it by removing it and move the top part forward until you see what angle you like, it should be rotated forward while testing to see where you want it wrench scope
I'm thinking more like a 45 to 60 degree angle instead of 25 to 40 degrees work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Setting up DA shocks [Re: Cab_Burge] #2818182
09/07/20 02:32 PM
09/07/20 02:32 PM
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Originally Posted by Cab_Burge
You need to have a lot more angle on the rear shackles so they don't rotate past center at max lift on the rear of the car twocents scope wrench
I would relocate the upper bushing hole forward two to three inches closer to the rear end to increase the shackle angle more, you can test where to put it by removing it and move the top part forward until you see what angle you like, it should be rotated forward while testing to see where you want it wrench scope
I'm thinking more like a 45 to 60 degree angle instead of 25 to 40 degrees work


Thanks Mr C

There is another hole forward of the current hole, but only on the passenger side . It’s like 1.25 more forward.

Will this creat more travel ?

Also what effect would unclamping the rear spring segment have ?

Re: Setting up DA shocks [Re: Wirenut] #2818187
09/07/20 02:39 PM
09/07/20 02:39 PM
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Unclamping the rear will make it, the rear half, separate more, not good tsk
Moving the upper hole forward to increase the rear shackle angle will allow the springs to move forward without going past 90 degrees, straight up and down on the shackles, and not pulling the back of the car down as it goes past 90 degrees scope
Now get to work fixing it wrench grin
Your car looks a lot like my old pump gas Duster but higher in the rear end. I had ladder bars with coil overs installed on it up
That car would hook up in a mud puddle in a rain storm whistling grin AKA aside, it flat hooked up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Setting up DA shocks [Re: Cab_Burge] #2818222
09/07/20 04:49 PM
09/07/20 04:49 PM
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robin hood country
deaks Offline
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9 PSI seems low to me, my 31x10.5 w hoosiers, wouldn't 60ft under 13 psi.


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Re: Setting up DA shocks [Re: deaks] #2818271
09/07/20 07:01 PM
09/07/20 07:01 PM
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Deaks, Hoosier is making a 31 !0.5W 15 slick? Didnt know they started making one, have to check that out.

Re: Setting up DA shocks [Re: deaks] #2818403
09/08/20 05:28 AM
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Originally Posted by deaks
9 PSI seems low to me, my 31x10.5 w hoosiers, wouldn't 60ft under 13 psi.


I have run them as low as 8 .

The 60 has typically been better the lower the psi

Re: **update w/ video** Setting up DA shocks [Re: Wirenut] #2818406
09/08/20 06:28 AM
09/08/20 06:28 AM
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Not gonna pretend I'm a 60' guru but if you slow the video down you have 5 almost 6 sidewall wrinkles. I've always been told 2-2.5 and any more the tire is wadding up and acting like a spring. If you watch, that's what I'm seeing, the tire wads up, and releases momentarily and initiates the bucking. Even as big as those are, I'd be going the other direction in PSI. I think you're trying to compensate some other issue by continuing to drop pressure.

Last edited by A39Coronet; 09/08/20 06:29 AM.

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Re: **update w/ video** Setting up DA shocks [Re: A39Coronet] #2818409
09/08/20 06:59 AM
09/08/20 06:59 AM
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Originally Posted by A39Coronet
Not gonna pretend I'm a 60' guru but if you slow the video down you have 5 almost 6 sidewall wrinkles. I've always been told 2-2.5 and any more the tire is wadding up and acting like a spring. If you watch, that's what I'm seeing, the tire wads up, and releases momentarily and initiates the bucking. Even as big as those are, I'd be going the other direction in PSI. I think you're trying to compensate some other issue by continuing to drop pressure.


Yes I tend to agree with you.

I will try and correct the rear shackle angle in hopes to create more travel or spring movement .

Re: **update w/ video** Setting up DA shocks [Re: Wirenut] #2818413
09/08/20 07:22 AM
09/08/20 07:22 AM
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Switch to sliders. It won't be that much more labor.

Re: **update w/ video** Setting up DA shocks [Re: Wirenut] #2818436
09/08/20 08:56 AM
09/08/20 08:56 AM
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Mt Morris Michigan
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Not a pro here either, but I think the rear is too high and the tire too soft. I have a 67 Barracuda and i like to keep the upper wheel well lip about 1" above the tire. I use Vikings doubles on the front at 1 or 2 clicks rebound and 12 compression. Calverts on back at 5, but next outing i will try 7 on rear because i get a ton of extension. At 1 click rebound i was pulling 1 foot wheelies, 2 clicks tamed it down alot to 5" wheelies. I use a tubular upper control arm as well. My drag radials hook like glue. One other thing, put some 12" extensions on your headers, you might find some power there. I think your porpoising my be the soft tire, because when you pull up i see the car bouncing from the soft tire.

Re: **update w/ video** Setting up DA shocks [Re: mopar dave] #2818463
09/08/20 10:12 AM
09/08/20 10:12 AM
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Romeo MI
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I didnt see where you said the total weight as you leave the line.. any tire will run best with a certain
pressure for a given weight.. my car is light and I run 6.5 to 6.75 PSI and above that it spins.. you should
start with GOOD tires not some set thats been on it for 10 years.. you would be using that as your
zero point which could be wrong to start with.. tires dont last as long as people think.. on mine
the tire is pretty well shot at a 100 passes then the 60' starts falling off.. I could tell by the 60' numbers
the side walls would be shot.. that was with tubes to help stiffen the side walls.. to look at the tire it
looked fine and had plenty of life let in it.. I use to sell them off.. my 60' would range from 1.19 to 1.22
then I got a new set.. there is no reason for a big burn out.. that just burns up the tire.. just needs
to get a light bit of smoke to clean and warm them up.. so start fresh and dont waste your time
trying to tune the suspension which comes next
wave

Re: **update w/ video** Setting up DA shocks [Re: mopar dave] #2818468
09/08/20 10:28 AM
09/08/20 10:28 AM
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Have you tried more air pressure? In the photo with the shackles is the drivers side almost vertical? As already mentioned if you have to move the top shackle mounts in the frame I'd go ahead and install sliders, it'll be a much easier job.

Not a chassis tuner so take this with a dump truck load of salt. In the videos I see three things, one it appears just as the drivers front tire comes off the track the rear tire unloads. Two, there is almost no movement in the rear, separation or compression. Three, the rear tire needs more air. I'd add some air to the slicks, slow down the rebound in the front and loosen both the compression and rebound in the rear. In that order.

The above and $1.75 will buy you a cup of coffee in some places.

Re: **update w/ video** Setting up DA shocks [Re: justinp61] #2818476
09/08/20 10:37 AM
09/08/20 10:37 AM
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Originally Posted by justinp61
Have you tried more air pressure? In the photo with the shackles is the drivers side almost vertical? As already mentioned if you have to move the top shackle mounts in the frame I'd go ahead and install sliders, it'll be a much easier job.

Not a chassis tuner so take this with a dump truck load of salt. In the videos I see three things, one it appears just as the drivers front tire comes off the track the rear tire unloads. Two, there is almost no movement in the rear, separation or compression. Three, the rear tire needs more air. I'd add some air to the slicks, slow down the rebound in the front and loosen both the compression and rebound in the rear. In that order.

The above and $1.75 will buy you a cup of coffee in some places.

iagree I have to agree w/ all of this.


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Re: Setting up DA shocks [Re: Wirenut] #2818479
09/08/20 10:41 AM
09/08/20 10:41 AM
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Connecticut
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Originally Posted by Wirenut
Ok thank you both.

Unfortunately I don’t have anyone to video

Man! I was there that day. I will be at LVD sat and sun on 9/12-9/13. If you are going back, stop by and I will video the cars launch for you. This is my car.

67409210-6D34-4130-AB87-3E531AF9879F.jpeg
Last edited by FurryStump; 09/08/20 10:42 AM.

best of 11.39 at 117 mph 1.60 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: Setting up DA shocks [Re: FurryStump] #2818484
09/08/20 11:00 AM
09/08/20 11:00 AM
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Connecticut
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Not sure why removing the rear leaf spring clamps and gaining more body separation would be a bad thing. Then let the shock do its job of controlling the axle.


best of 11.39 at 117 mph 1.60 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
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