GM A Body Suspension ?.....

Wade_Owens · 08-10-2008, 01:52 PM

I have a 66 Chevelle 283/PG combo. When the car leaves, it hooks good initially, then unloads and spins a little. It seems to spin as the front tires come back down, unloading the rear tires. Will pinion angle cause this on these cars? I do have adjustable top bars where I can fine tune this. I have Calvert shocks and Santhuff front springs. If the track is really good, it never does this. All of my previous race cars have been leaf or ladder bar stuff. Just not sure what the coil cars like......

Any and all help and comments are appreciated!

Thanks,
Wade O

Alan Roehrich · 08-10-2008, 02:10 PM

Pinion angle is the included angle in the rear u-joint, AKA the difference in angle between the drive shaft and the pinion centerline. Nothing more, nothing less. The only reason to adjust pinion angle itself is to get it to be about 2 degrees down under power.

Are you sure you're not topping out the front suspension? If the front tops out too quickly, it will unload the rear tires, especially on a lower HP car that cannot lift the front tires and carry them. On a really good track it'll still hook because you don't need as much weight transfer to maintain traction.

Jeff Goss · 08-10-2008, 05:04 PM

If this isn't a Stocker, put an anti-roll bar in it. This will plant the tires evenly. A 283 isn't making any torque, so this should sort things out easily.

Jeff

08-10-2008, 07:32 PM

How about a good 12-way adjustable front shock to control how quickly the front end settles back down? If you could "slow" this down and control it perhaps you could keep from unloading the suspension too quickly. I know Hal (QA1) makes a very nice one that I've used but not sure about your particular application.

Good luck.

Mark Yacavone · 08-10-2008, 07:59 PM

Wade, Are you using Air Lift bags? How much preload?
How about no hop bars on the housing?
How much ballast?
What technique are you using to leave the line?
I think we need more info here.

Good luck at Indy.

greg fulk · 08-10-2008, 09:25 PM

Wade my car dose the same thing on a not so good track! I have air bags on both side 30lbs passengers side 10lbs on the drivers. The car wants to leave with the wheels up then unload spin then go again?

Wade_Owens · 09-03-2008, 12:02 PM

Quote:

Originally Posted by Wade_Owens

I have a 66 Chevelle 283/PG combo. When the car leaves, it hooks good initially, then unloads and spins a little. It seems to spin as the front tires come back down, unloading the rear tires.

I ran Indy this past week and we found the problem. It wasnt suspension related at all. The sump on the PG was uncovering, causing the converter to get a gulp of air and flash. The tires do not spin. Thanks to Steve Decker for watching the car and William Belanger for the lead on the problem.

On to the next issue..........

Wade O

08-10-2008, 01:52 PM	#1
Wade_Owens Senior Member Join Date: Jul 2007 Posts: 578 Likes: 0 Liked 3 Times in 1 Post	GM A Body Suspension ?..... I have a 66 Chevelle 283/PG combo. When the car leaves, it hooks good initially, then unloads and spins a little. It seems to spin as the front tires come back down, unloading the rear tires. Will pinion angle cause this on these cars? I do have adjustable top bars where I can fine tune this. I have Calvert shocks and Santhuff front springs. If the track is really good, it never does this. All of my previous race cars have been leaf or ladder bar stuff. Just not sure what the coil cars like...... Any and all help and comments are appreciated! Thanks, Wade O

08-10-2008, 02:10 PM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,113 Likes: 1,571 Liked 1,827 Times in 414 Posts	Re: GM A Body Suspension ?..... Pinion angle is the included angle in the rear u-joint, AKA the difference in angle between the drive shaft and the pinion centerline. Nothing more, nothing less. The only reason to adjust pinion angle itself is to get it to be about 2 degrees down under power. Are you sure you're not topping out the front suspension? If the front tops out too quickly, it will unload the rear tires, especially on a lower HP car that cannot lift the front tires and carry them. On a really good track it'll still hook because you don't need as much weight transfer to maintain traction. __________________ Alan Roehrich 212A G/S

08-10-2008, 05:04 PM	#3
Jeff Goss Member Join Date: Nov 2001 Location: Burlington, WA Posts: 361 Likes: 1 Liked 0 Times in 0 Posts	Re: GM A Body Suspension ?..... If this isn't a Stocker, put an anti-roll bar in it. This will plant the tires evenly. A 283 isn't making any torque, so this should sort things out easily. Jeff

08-10-2008, 07:32 PM	#4
Gear Jammer '94 Guest Posts: n/a	Re: GM A Body Suspension ?..... How about a good 12-way adjustable front shock to control how quickly the front end settles back down? If you could "slow" this down and control it perhaps you could keep from unloading the suspension too quickly. I know Hal (QA1) makes a very nice one that I've used but not sure about your particular application. Good luck.

08-10-2008, 07:59 PM	#5
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,815 Likes: 2,904 Liked 5,121 Times in 1,952 Posts	Re: GM A Body Suspension ?..... Wade, Are you using Air Lift bags? How much preload? How about no hop bars on the housing? How much ballast? What technique are you using to leave the line? I think we need more info here. Good luck at Indy. __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers Last edited by Mark Yacavone; 08-11-2008 at 12:54 AM.

08-10-2008, 09:25 PM	#6
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: GM A Body Suspension ?..... Wade my car dose the same thing on a not so good track! I have air bags on both side 30lbs passengers side 10lbs on the drivers. The car wants to leave with the wheels up then unload spin then go again? __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"