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Shock adjustment help needed, launch video #3209388
01/30/24 11:59 PM
01/30/24 11:59 PM
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Minnesota
Hemi_Joel Offline OP
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Here's a video of my coupe launching. I have double adjustable afco shocks on all four corners. It is a manual transmission. Bias ply DOT slicks. Based on the video, what can I do with the shocks?

https://www.instagram.com/reel/C2tOMNaObib/


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
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I don't regret the things I've done. I only regret the things I didn't do.
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Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209410
01/31/24 06:08 AM
01/31/24 06:08 AM
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A shed in England
Tig Offline
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If the vid is posted on You Tube, there is an option to slow the video down to 1/4 speed. I couldn't seem to find that option on the above clip.


'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
Re: Shock adjustment help needed, launch video [Re: Tig] #3209415
01/31/24 07:54 AM
01/31/24 07:54 AM
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ksj Offline
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Send this video to Jeff McConnel who rides with Doc McEntire. He knows his stuff.

Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209416
01/31/24 08:02 AM
01/31/24 08:02 AM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline
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Joel, from what i can see, i think the rear axle is extending extremely fast, hitting the end of the shock travel, rebounding and repeating all in about 5 to seven feet.
If you can stiffen extension, i would be tempted to go extremely stiff, maybe starting as tight as possible. Also i would drop the launch rpm if you can some. If your suspension has a high and short instant center, that might be part of the problem.


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: Shock adjustment help needed, launch video [Re: gregsdart] #3209417
01/31/24 08:49 AM
01/31/24 08:49 AM
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dvw Offline
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Like stated if you put the video on You Tube it can be slowed down and stopped at spots for a more in depth look. I agree on tightening the rear. Both rebound and compression. The front has very little travel but tighten up the rebound there as well. Once the bounce is corrected it needs some wheel speed. Not being a stick guy my thought is raising the rpm at the start will allow that adjustment..
Doug

Re: Shock adjustment help needed, launch video [Re: dvw] #3209478
01/31/24 01:09 PM
01/31/24 01:09 PM
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Minnesota
Hemi_Joel Offline OP
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I'll try and get the video on to YouTube. Super busy in the throws of sick week. Maybe tonight will be able to get it up there.

Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209485
01/31/24 01:16 PM
01/31/24 01:16 PM
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Tightewn the extension to start on the rear....What is the rest of the rear suspension?


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: Shock adjustment help needed, launch video [Re: Al_Alguire] #3209526
01/31/24 03:04 PM
01/31/24 03:04 PM
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Byron, NY
W.I.N. Racing Offline
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Id consider freeing up the extension on the Front as well suggestion previously made on the rear...Let it get a little pitch momentum. twocents


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Re: Shock adjustment help needed, launch video [Re: W.I.N. Racing] #3209551
01/31/24 04:03 PM
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Plymouth, MI
Blusmbl Offline
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Should be able to play this at .25x speed



'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118
Re: Shock adjustment help needed, launch video [Re: Blusmbl] #3209560
01/31/24 04:35 PM
01/31/24 04:35 PM
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So. Burlington, Vt.
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fast68plymouth Offline
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I’m def not a chassis guy, but it seems to me that fundamentally it’s going to be hard to keep the suspension loaded properly when it sounds like there is an “almost” bog after you leave.
In my mind I’m thinking there is some relaxing of the suspension when that happens.


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Re: Shock adjustment help needed, launch video [Re: Al_Alguire] #3209567
01/31/24 04:40 PM
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JERICOGTX Offline
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Originally Posted by Al_Alguire
Tightewn the extension to start on the rear....What is the rest of the rear suspension?


The car has a 4 link rear.

I run my rear shocks on the Road Runner, at full stiff on both Extension, and rebound. The more RPM, and harder I hit the tire, the faster it goes.


69 GTX 68 Road Runner
Re: Shock adjustment help needed, launch video [Re: JERICOGTX] #3209659
01/31/24 09:39 PM
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dvw Offline
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Now that I can watch in slow motion. The rear looks to have no seperation (even squats a tad) but still appears to dead hook until it bounces. Also no wheel speed. My first thoughts woukd be it needs more rpm and less tire pressure to gain wheel speed. But the underlying problem may be a bog leading to the above issues. Not sure I'd worry much about the front until the rear is fixed.
Doug

Re: Shock adjustment help needed, launch video [Re: dvw] #3209674
01/31/24 10:52 PM
01/31/24 10:52 PM
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Minnesota
Hemi_Joel Offline OP
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Thanks for all the input. So if it has no separation would tightening the extension help it or hurt it? As far as the bog, there's nothing I can do about that for tomorrow's race. So I'll just have to live with that.


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
WM21J8A
I don't regret the things I've done. I only regret the things I didn't do.
"Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209690
02/01/24 12:17 AM
02/01/24 12:17 AM
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dvw Offline
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I would say yes as it may reduce the bounce back after the hit. It may like a looser comp setting to aloow it to squat. That might give it some wheel speed. It's possible the 4 link is way off as well.
Doug

Last edited by dvw; 02/01/24 12:22 AM.
Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209696
02/01/24 12:57 AM
02/01/24 12:57 AM
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Bend,OR USA
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Cab_Burge Offline
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Try stiffening all four up as stiff as you can them and the see what that does and go from their wrench scope
It may only need the rear only stiffer, tighter, but I would do both and then if that helps start softening the fronts a little bit at a time until you like it one way or the otherwrench scope up twocents


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Shock adjustment help needed, launch video [Re: Blusmbl] #3209707
02/01/24 08:15 AM
02/01/24 08:15 AM
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Tig Offline
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Very little suspension change front or rear in that video, everything looks way too stiff but then again I'm a Caltrac guy. How much travel does it have front and rear ? are you topping stuff out or reaching the limits of the suspension ? I know it sucks to have to use a race meeting for test and tune but I'd go looser on ext front and rear and see how the car reacts.


'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
Re: Shock adjustment help needed, launch video [Re: Tig] #3209717
02/01/24 09:59 AM
02/01/24 09:59 AM
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Tulsa OK
Bad340fish Offline
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One thing to consider is these tracks are super tight from what I have seen this week. I think that is one reason Lutz in his pro mod has had a hard time getting down and is 2nd overall to a Coyote Powered mustang on a drag radial(6.29!) Some of the stick cars are running radials now as well.

Joel you might need to loosen the clutch up some to get the bog out, the wheel speed might be hard to come by with the tight tracks. A torque converter would also be a good solution and it would get that pesky stick out of the way eek grin

Last edited by Bad340fish; 02/01/24 10:05 AM.

68 Barracuda Formula S 340
Re: Shock adjustment help needed, launch video [Re: Bad340fish] #3209753
02/01/24 12:18 PM
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JERICOGTX Offline
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Originally Posted by Bad340fish
A torque converter would also be a good solution and it would get that pesky stick out of the way eek grin


This is why no one will remember your name Claude...


69 GTX 68 Road Runner
Re: Shock adjustment help needed, launch video [Re: Hemi_Joel] #3209755
02/01/24 12:24 PM
02/01/24 12:24 PM
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Missouri
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jwb123 Offline
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I would agree stiffen the extension. Not suspension but what weight flywheel do you have? Many years ago 1980's I raced an Anglia with a four link, four speed, and it weighed 2,200 lbs with me in it. Ran low 10's high 9's Had a 30 lb flywheel in it, put a 15 lb wheel in it and it was so much easier to launch and drive. Light car does not need all the torque multiplication of a heavy flywheel.

Re: Shock adjustment help needed, launch video [Re: JERICOGTX] #3209764
02/01/24 01:34 PM
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ksj Offline
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Originally Posted by JERICOGTX
Originally Posted by Bad340fish
A torque converter would also be a good solution and it would get that pesky stick out of the way eek grin


This is why no one will remember your name Claude...
Savage reply. LOL.

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