rear coil over tuning help needed
Moderators: David Lemmond, Dave Morgan
rear coil over tuning help needed
First off new here so hi to all.
I have a 4 link 5 speed stick car. We only get to the track 2-3 time a year, more hobby and family time then a competitive venture. We run a 6.18 in the 1/8 in full street trim, MT ET and full exhaust. Any way the issue I am struggling with has been poor 60'. At the moment of launch, instantly the rearend (not the rear of the car) compresses the tires to the point they actually bounce the rearend up and the tires unload. I only saw this once we started taping the launch and then watched it frame by frame. I know I have set up issue but was never sure of the correct adjustment for a given issue. We've changed anti squat up and down, tire pressure up and down, launch point up and down, slicks then DOT's, bought 4 link software, move weight front to back, tried most front single adjustable shocks settings. Most of what we have done has been 1 thing at a time. The end result is all 60' within .06 1.49-1.43 car runs well once it finally hooks about 60' out.
Then tonight I was reading through the tech section and found this article.
"Drag Racing Suspension Setup and Tuning using Digital Video
by John Heard with contributions from Mike Canter, Scott Smith & Pat Musi" The last paragraph of the article is the exact issue I've been chasing the last few years. Root cause looks like Loose shock settings.
My rear setup is Aldan coil over single adjustable shocks and 140 lb springs. No wheelie bars.
Based on the article I need to tighten my rebound up a bunch. Questions I have if this one adjustment doesn't control the launch then what? Different shocks? More- less spring? How does spring weight affect launch dynamics? I'm open for suggestions.
Thanks for any info.
Dave
I have a 4 link 5 speed stick car. We only get to the track 2-3 time a year, more hobby and family time then a competitive venture. We run a 6.18 in the 1/8 in full street trim, MT ET and full exhaust. Any way the issue I am struggling with has been poor 60'. At the moment of launch, instantly the rearend (not the rear of the car) compresses the tires to the point they actually bounce the rearend up and the tires unload. I only saw this once we started taping the launch and then watched it frame by frame. I know I have set up issue but was never sure of the correct adjustment for a given issue. We've changed anti squat up and down, tire pressure up and down, launch point up and down, slicks then DOT's, bought 4 link software, move weight front to back, tried most front single adjustable shocks settings. Most of what we have done has been 1 thing at a time. The end result is all 60' within .06 1.49-1.43 car runs well once it finally hooks about 60' out.
Then tonight I was reading through the tech section and found this article.
"Drag Racing Suspension Setup and Tuning using Digital Video
by John Heard with contributions from Mike Canter, Scott Smith & Pat Musi" The last paragraph of the article is the exact issue I've been chasing the last few years. Root cause looks like Loose shock settings.
My rear setup is Aldan coil over single adjustable shocks and 140 lb springs. No wheelie bars.
Based on the article I need to tighten my rebound up a bunch. Questions I have if this one adjustment doesn't control the launch then what? Different shocks? More- less spring? How does spring weight affect launch dynamics? I'm open for suggestions.
Thanks for any info.
Dave
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Re: rear coil over tuning help needed
Another good one to read
http://www.dragstuff.com/techarticles/P ... uning.html
http://www.dragstuff.com/techarticles/P ... uning.html
- John_Heard
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Re: rear coil over tuning help needed
Dave thanks for the comments on the article - it's good to know that it helped finding out what's going on with your car. You may find the Aldan's can't control the rear when tightened up, or that running them tight causes other issues down track like going over bumps. If that's the case and money is available I'd suggesting investing in some better shocks. On the high end Santhuff's are very good, mid range my nod would go to Afco - but talk to them about what valving you need for your application.
Let us know how you make out...
Let us know how you make out...
My 1971 X275 Nova | Facebook
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Re: rear coil over tuning help needed
Nothing wrong with Strange either...
Re: rear coil over tuning help needed
Thanks for the advice. I've talked at length with a couple shock manufacturers. They all have recommendations that should address my issue, should see quite an improvement. I will post vid of before and after shock upgrade.
Dave
Dave
- BillyShope
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Re: rear coil over tuning help needed
You say you've run different antisquat values. Have you tried to get as close to 100% as possible? Page 48 at my site gives you those 4link combinations which will work best. At 100%, there is no relative motion between axle assembly and the chassis, so spring and shock forces are not important. (Actually, there's a little "wiggle" in the first few milliseconds as the front springs extend, but this is minimal.)
http://www.racetec.cc/shope
http://www.racetec.cc/shope
- John_Heard
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Re: rear coil over tuning help needed
Billy you have an unhealthy fixation on antisquat values, you really need to get out of the house more often... lol...
My 1971 X275 Nova | Facebook
Re: rear coil over tuning help needed
John_Heard wrote:Billy you have an unhealthy fixation on antisquat values, you really need to get out of the house more often... lol...
LOL!!!!
That's what I was thinking. I didn't want to say it though.
ROTFLMAO!!!!!!!
Blackhoodmafia!!!!
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
- BillyShope
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- Location: Orlando, FL
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Re: rear coil over tuning help needed
Yes, I caught the disease during my schooling. All automotive engineers have the same problem. Antisquat is the only parameter which makes sense dynamically.John_Heard wrote:Billy you have an unhealthy fixation on antisquat values, you really need to get out of the house more often... lol...
http://www.racetec.cc/shope
- Mike Peters
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- Location: Wichita, KS
Re: rear coil over tuning help needed
Good thing racers aren't engineers then........BillyShope wrote: All automotive engineers have the same problem. Antisquat is the only parameter which makes sense dynamically.
"If winning was easy, losers would be doing it"
- Mike Peters
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- Joined: Wed Oct 12, 2005 1:48 pm
- Location: Wichita, KS
Re: rear coil over tuning help needed
Anyone want to buy my Afco's? I'm buying me some MonroesBillyShope wrote:spring and shock forces are not important.
"If winning was easy, losers would be doing it"
Re: rear coil over tuning help needed
Will they fit my Nova? LOLMike Peters wrote:Anyone want to buy my Afco's? I'm buying me some MonroesBillyShope wrote:spring and shock forces are not important.
Blackhoodmafia!!!!
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
- Mike Peters
- Posts: 930
- Joined: Wed Oct 12, 2005 1:48 pm
- Location: Wichita, KS
Re: rear coil over tuning help needed
Why waste your money on shocks? Haven't you been paying attention or are you just looking for style points?supernova wrote:
Will they fit my Nova? LOL
"If winning was easy, losers would be doing it"
Re: rear coil over tuning help needed
Mike Peters wrote:Anyone want to buy my Afco's? I'm buying me some MonroesBillyShope wrote:spring and shock forces are not important.
HAHAHAHAHAHA!!!!!!!
NOW THATS FUNNY STUFF RIGHT THERE!!!
"THE THROTTLE IS THE DEVIL" By Mr. Willis
"ALL I SEEN WAS HOOD!" By Mr. Heard
MAKO RS-1979
Sponsored By:
Total Removal Contracting-Tim Rogers
"ALL I SEEN WAS HOOD!" By Mr. Heard
MAKO RS-1979
Sponsored By:
Total Removal Contracting-Tim Rogers
Re: rear coil over tuning help needed
You know what they say, "If you can't make your suspension work like Billy's instuctions, at least look good doing it!!!!!"Mike Peters wrote:Why waste your money on shocks? Haven't you been paying attention or are you just looking for style points?supernova wrote:
Will they fit my Nova? LOL
Blackhoodmafia!!!!
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
1972 Nova SS
572 C.I. BBC
Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs
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