A-Body Lowering ??? School me....

[FlatBlack4Life]

I'm trying to do some homework on lowering my 1970 Buick Skylark. I'm not too familiar with the geometry of lowering w/ consideration to weight of the car and performance. Skylarks weigh about 3400 to 3500lbs like most chevelles. Can anyone offer some suggestions to a nice suspension setup, ride height and wheel/tire combo that works for an A-Body too handles daily driving very well??.....Thanks....

[USAZR1]

Originally Posted by FlatBlack4Life

I'm trying to do some homework on lowering my 1970 Buick Skylark. I'm not too familiar with the geometry of lowering w/ consideration to weight of the car and performance. Skylarks weigh about 3400 to 3500lbs like most chevelles. Can anyone offer some suggestions to a nice suspension setup, ride height and wheel/tire combo that works for an A-Body too handles daily driving very well??.....Thanks....

How much do you want to lower the car? What diameter wheel do you want to run?

[FlatBlack4Life]

Originally Posted by USAZR1

How much do you want to lower the car? What diameter wheel do you want to run?

I would like to see what a 2 inch drop would look like w/ an 18 inch rim.

[TravisB]

Originally Posted by FlatBlack4Life

I would like to see what a 2 inch drop would look like w/ an 18 inch rim.

Thats easy......you can either cut your existing coils or order drop springs and cut them to desired height! 18's are no problem!

[Blown353]

Originally Posted by 67 Camino

Factory front GM A body springs range from 15 to 18 inches free height. You don't want more than about 500 psi for a street car or it will be too stiff.

Just for the sake of clarification: spring rate is in lbs/inch, not psi.

Also, 500 lb/in is actually pretty darn soft on these cars. I was running 550 lb/in on my small block which was *too* soft. I'm now running 625 lb/in springs, and they're still too soft; I'm going to step up to 750 or 800 lb/in and see how they feel. The ride with the 625 lb/in springs is firm but not jarring, but they're still too soft and the car "porpoises" a bit on fast right/left transitions. If you aren't abusing the car in the corners they're just fine, and probably a little bit firm by many people's definition, but they certainly do not provide a harsh ride. Pairing them with decent shocks is also very important, a lot of cheaper shocks out there don't have adequate rebound control.

If you're just going to cruise the car with some occasional spirited turns and want good smooth road manners, I would suggest running about 500-550 lb/in springs for a SB car. I can't comment on good spring rates for a BB car. Rear spring rates between 150-175 lb/in are where the A-bodies seem to function best.

Also, an easy way to lower the car and also be able to adjust your height WITHOUT cutting coils is to hit up a circle track supplier and buy Afco spring jacks that sit up in the frame and then use Afco springs. You can get the springs in a wide variety of rates (cheaply, too) and then adjust the height via the springjacks.

Troy

[Derek69SS]

I don't have them installed yet, but I went with AFCO 5"x9.5" 700lb springs, and the taller height adjusters from speedway.

[Derek69SS]

Originally Posted by 67 Camino

Once you add poly bushings the ride is even stiffer.

I'm putting solid bushings on all 16 control-arm locations ...this is for a car that will be 95% street, 3% drag, 2% road course.

[Derek69SS]

It may be too stiff, it might not be... I won't know until it's together and I'm driving it.

I'll post a full testimonial in June when I get back from driving it from Rochester, MN to Nashville, TN with the wife for our honeymoon. A little vibration might be a good thing

I will be running solid bushings in front with 700# springs and a small (if any) sway bar, and spherical bearings in the rear with 175# springs and no sway-bar. I'm currently driving on stock springs with big sway-bars and it handles OK, but not great. The ride way too stiff in the rear from the poly-bushings in the quadra-bind C4L. I'm actually anticipating a smoother feel, the bumps will feel sharper, but not as big.

[sinned]

Originally Posted by 67 Camino

Factory front GM A body springs range from 15 to 18 inches free height. You don't want more than about 500 psi for a street car or it will be too stiff. The wire diameter and spring height determine the spring rate.

Relax guys, I'm going to be nice because he obviously both new to the site and to cars in general.

Camino, if you are going to post technical spec or pretend to speak tech jargon you must first learn a little bit about what you are speaking of. Spring rate is calculated using number of active coils, wire diameter, and mean diameter. Free height never factors in to rate. As already stated, springs are rated in lbs. in.; not psi. 500lbs is pretty weak for most cars, even factory springs in newer cars are over the 500lbs. in. mark as manufactures have figured out that heavy rates do not equal harsh ride. I run a 750/175 combo and am going to up to 1000lbs. in the fronts (yes, I drive it everyday on city streets). Lastly, the two schools are not light springs/big bars and big springs/big bars, they are light springs/big bars and big springs/light bars.

Derek, you are going to need at least a 7/8" bar up front, the 700# just aren't enough by themselves.

[67 Camino]

I outta here. Go blow smoke up someone elses ass.