Drag front suspension question...
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Drag front suspension question...
I've noticed in several videos (including my latest video) that my wheels come off the ground, then the car bounces and the wheels come off the ground again... Could this be because my shocks are set to 80/20?? If I'll switch them to 90/10, could the 2nd bounce go away??
http://www.corvetteforum.net/c3/gran...otowheelie.wmv
http://www.corvetteforum.net/c3/gran...otowheelie.wmv
Safety Car
Joined: Jun 2003
Posts: 4,640
Likes: 0
From: Sunshine State
Originally Posted by GrandSportC3
I've noticed in several videos (including my latest video) that my wheels come off the ground, then the car bounces and the wheels come off the ground again... Could this be because my shocks are set to 80/20?? If I'll switch them to 90/10, could the 2nd bounce go away??
http://www.corvetteforum.net/c3/gran...otowheelie.wmv
http://www.corvetteforum.net/c3/gran...otowheelie.wmv
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by Special K
Springs Oliver, think springs.
.. I went with '65 small block springs because they are the softest springs available... I first want to see if it'll make a difference when switching to the 90/10 setting..
Race Director
Joined: Oct 1999
Posts: 13,298
Likes: 14
From: Somers NY
I watched the video, & see what you mean.. but I don't think its hurting your ET or traction..
It might be serious if you were lifting the front 1-2 FEET and unloading the rear when it came down & bounced,, but it does not appear to be unloading the rear..
Do you think you are feeling the rear tires breaking loose when it bounces ?
It might be serious if you were lifting the front 1-2 FEET and unloading the rear when it came down & bounced,, but it does not appear to be unloading the rear..
Do you think you are feeling the rear tires breaking loose when it bounces ?
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by Red96Coupe
I watched the video, & see what you mean.. but I don't think its hurting your ET or traction..
It might be serious if you were lifting the front 1-2 FEET and unloading the rear when it came down & bounced,, but it does not appear to be unloading the rear..
Do you think you are feeling the rear tires breaking loose when it bounces ?
It might be serious if you were lifting the front 1-2 FEET and unloading the rear when it came down & bounced,, but it does not appear to be unloading the rear..
Do you think you are feeling the rear tires breaking loose when it bounces ?
However, I haven't launched with the transbrake yet.. Right now, I'm pulling the wheels 1 - 3 inches off the ground but once I use the transbrake, I expect to pull them a foot or so off the ground.... I don't really want to have a second 1 foot bounce
Looking closely at the video, the second bounce is almost as high as the initial lift of the front wheels...
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
I also noticed that my front stays up pretty high during I'm going down the track... Maybe I should go with not so tall front tires.. Right now I'm using 28 x 13.5 - 15 rear slicks and 28 x 4.5 - 15 front tires.. Maybe I should go with the 26 x 4.5 - 15 front tires.. That would lower the front and could reduce drag... but I'm not 100% sure...
Safety Car
Joined: Jun 2003
Posts: 4,640
Likes: 0
From: Sunshine State
Originally Posted by GrandSportC3
I also noticed that my front stays up pretty high during I'm going down the track... Maybe I should go with not so tall front tires.. Right now I'm using 28 x 13.5 - 15 rear slicks and 28 x 4.5 - 15 front tires.. Maybe I should go with the 26 x 4.5 - 15 front tires.. That would lower the front and could reduce drag... but I'm not 100% sure...
It will save you money over the long haul.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by Special K
One last suggestion Oliver. Take it to someone that knows what they're doing. Call Tracy and I'm sure he knows some good suspension people around there.
It will save you money over the long haul.
It will save you money over the long haul.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Good luck Oliver. Hope it works. 
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by vetteman9368
65 small block springs, QA1 SHOCKS...................trust me on this one
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
Isnt it rebound that is causing the second bounce?
I would think 70/30 would reduce the bounce.
And 90/10 would most definitly have the front riding high the whole track under heavy acceleration, thus 70/30 might level it out better but hurt your et with a loss of traction.
Can your shocks do 70/30? If so I would give that a try and watch the video of a few runs.
I would think 70/30 would reduce the bounce.
And 90/10 would most definitly have the front riding high the whole track under heavy acceleration, thus 70/30 might level it out better but hurt your et with a loss of traction.
Can your shocks do 70/30? If so I would give that a try and watch the video of a few runs.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by jd_v3tt3
Isnt it rebound that is causing the second bounce?
I would think 70/30 would reduce the bounce.
And 90/10 would most definitly have the front riding high the whole track under heavy acceleration, thus 70/30 might level it out better but hurt your et with a loss of traction.
Can your shocks do 70/30? If so I would give that a try and watch the video of a few runs.
I would think 70/30 would reduce the bounce.
And 90/10 would most definitly have the front riding high the whole track under heavy acceleration, thus 70/30 might level it out better but hurt your et with a loss of traction.
Can your shocks do 70/30? If so I would give that a try and watch the video of a few runs.
Pro
Joined: Jun 2005
Posts: 543
Likes: 0
From: East Lyme CT
I also experience the bounce with my '70 big block. I run the CE shocks on 90/10 to keep the weight transfer maximized. I also have the long bump stops in the rear.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by markshaw70redBB
I also experience the bounce with my '70 big block. I run the CE shocks on 90/10 to keep the weight transfer maximized. I also have the long bump stops in the rear.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
Don't even know why he bothered asking??? 
Racer
Joined: Jul 2004
Posts: 332
Likes: 0
From: Geneva Ohio
Originally Posted by markshaw70redBB
I also experience the bounce with my '70 big block. I run the CE shocks on 90/10 to keep the weight transfer maximized. I also have the long bump stops in the rear.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
I've been consulting with Tom's Differentials for several years to get help improving the launch. I can get a 1.36 60' time when I leave at 4000 rpm using my full shot of nitrous. I can carry the front wheels about 12" off the ground all the way past the tree. (9.81, 140 mph). It lands smoothly and doesn't rebound back up. That's a launch I don't do all the time. More often, I leave at 3800 rpm, hook perfectly and leave straight. When I watch the video in super slo mo I can see the bounce after the front tires lift about 3 inches for a few feet.
Tom's advice is to add leaves to the rear spring until the transfer doesn't drive the bump stops down on to the top of the trailing arms. I have added two additional leaves (total of 9 now) and use QA1 shocks dialed all the way up. Even then, I notice the 2nd bounce but I don't think I'm unloading the suspension energy.
Keep us posted on your results. I'm curious what will happen if you dial 70/30 instead of the 90/10.
We are looking at that 9 second pass with nitrous big block but with 27" tire and 4.33 gears I don't know if we'll have enough RPM to go that speed.
Thanks
Drifting
Joined: Jun 1999
Posts: 1,874
Likes: 1
From: Garden Grove CA
Check out
http://www.geocities.com/kdslaby/Tec..._Glossary.html
Most likely you will need more shock rebound not less, or you need to find some way of increasing front end travel to avoid the snap unload (when your front end drops too quickly it is actually decreasing the load on your rear tires). What you want is a more controlled lift and slow drop. Alternatively, you may find improved results by limiting the front wheel travel and converting the lifting motion more efficiently into forward motion.
Thomas
http://www.geocities.com/kdslaby/Tec..._Glossary.html
Most likely you will need more shock rebound not less, or you need to find some way of increasing front end travel to avoid the snap unload (when your front end drops too quickly it is actually decreasing the load on your rear tires). What you want is a more controlled lift and slow drop. Alternatively, you may find improved results by limiting the front wheel travel and converting the lifting motion more efficiently into forward motion.
Thomas
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by The Green Rocket
Check out
http://www.geocities.com/kdslaby/Tec..._Glossary.html
Most likely you will need more shock rebound not less, or you need to find some way of increasing front end travel to avoid the snap unload (when your front end drops too quickly it is actually decreasing the load on your rear tires). What you want is a more controlled lift and slow drop. Alternatively, you may find improved results by limiting the front wheel travel and converting the lifting motion more efficiently into forward motion.
Thomas
http://www.geocities.com/kdslaby/Tec..._Glossary.html
Most likely you will need more shock rebound not less, or you need to find some way of increasing front end travel to avoid the snap unload (when your front end drops too quickly it is actually decreasing the load on your rear tires). What you want is a more controlled lift and slow drop. Alternatively, you may find improved results by limiting the front wheel travel and converting the lifting motion more efficiently into forward motion.
Thomas
I might try 90/10 and 70/30 setting and will see what happens.. The 90/10 setup should allow the wheels to come off the ground higher and should dampen better when coming down...