Determining the correct 5-leaf springs - 69 SS 396

[nuch_ss396]

Hi all !

I need to solicit some help from members here regarding the
selection of the correct front & rear leaf springs for my
69 SS 396 Camaro. I am nearing the completion http://www.yenko.net/ubbthreads/images/graemlins/naughty.gif
of my restoration and now I have to look into selecting the
right springs.

While doing some preliminary research, I have come to learn
that there may have been many different factors that went
into the spring selection on big block Camaros. Was this
true for front and rear springs, or just the front springs?

I've see posts ( on several forums ) that dealt with the
problem of one end of the car sitting too high, or too low
after springs were rebuilt/replaced. How does one avoid
this problem?

So, what I really want to know is this: Is there some type
of formula that Chevrolet used back in the day to determine
the correct springs for a particular application and does
anyone know the formula or an alternate way to select the
correct spring combination? http://www.yenko.net/ubbthreads/images/graemlins/dunno.gif http://www.yenko.net/ubbthreads/images/graemlins/confused.gif

Steve

[Jonesy]

Here's a spring calculator:

http://www.chevynova.org/69_12437_L34_L35_L78_Springs.htm

Springs were selected based on the weight of the options on the car.

[Fhakya]

Jonesy: That is a cool calculator..new to me.

After punching in a couple of different configurations it occured to me that there had to be 'ranges' available to the line workers. My logic being that there wasn't a spring custom built for every car. There had to be some quick way for the production worker to know things like A/C + 396 = XXX spring etc etc..

Anyone know how that took place in the production setting?

[Hotrodpaul]

My 69 Camaro L-78 had YP front springs and 5 leaf BK code rear springs.

Paul

[rpoz11]

Wasnt the 4-leaf and 5-leafs in 69 factory predetermined?
Not aware of different rated 4-leafs & 5-leafs that year...
http://www.yenko.net/ubbthreads/images/graemlins/confused.gif

[Hotrodpaul]

Small blocks such as Z-28's and SS's etc usually had 4 leaves, where big blocks had 5 leaves. I guess it depended on the type of suspension and options ordered.

Paul

[70 ls6 convert]

69 z28s used 4 lief springs,69 ss used 5 lief, and heavy duty front if you orderd a big block,

[bertfam]

Kris,

That's not quite right. Taken from the "Ask CRG Archives" (http://www.camaros.org/askcrg-archives.shtml) (question #121):

[ QUOTE ]
121. Is there any difference in ride or handling between the 4 or 5-leaf springs? Why did GM put the 4-leaf springs on Z28 instead of 5-leaf springs? Is there a difference in ride height?
Dave McBride, 18-Jun-1999

[This was asked on the Camaro Institute (CI) and answered by us there. Since CI has no archive and we felt this question was important to others, we repeat it here.]


1. There was not a five-leaf spring. There is an entire family of five-leaf spring designs (in 1968-69, only monoleafs were used in 1967). The family covers different spring rates, arch heights, and different maximum load design points. Springs were selected to create an equivalent vehicle position or stance in the loaded condition, depending on the gross weight of the vehicle. The one exception was the G31 spring series, which, as Heavy-Duty (HD) springs, were specifically designed with a higher arch and a higher unloaded ride, allowing them to deflect more on loading - resulting in a higher loading capacity. The G31 springs purposely cause a vehicle to sit up higher in the back until it is loaded with extra weight. However improper vehicle stance will also occur if the wrong spring is installed.

2. The (1968-69) Z28 was not limited to the four-leaf spring, nor was a (1968-69) non-Z28 prohibited from having a four-leaf spring. We have documented five-leaf Z28s and documented 4-leaf non-Z28s in our data, and the factory spring tables confirm that this was intentional. In particular, the F41 option on the 1968 L30/M20 resulted in the four-leaf spring being applied to a non-Z28. The 4-leaf spring was lighter but also with reduced resistance to wind-up and decreased damping. If the weight of options so warranted it, the Z28 was equipped with certain five-leaf springs.
A detailed CRG Research Report is in preparation but it is coming along slowly due to the enormous amount of time required to do it right, and due to competing needs from other projects and from the CRG web site.

[/ QUOTE ]

Ed

[Steve Shauger]

In addition, the same can be said for big block camaros, because both 4leaf and 5 leaf came in those as well. It boiled down to the weight of the car, the ride height and handling package ordered as to what spring rate the car received. A good example of a 4leaf in a BB is Jeff Boone's rs/ss L78 and a 5 leaf is my rs/ssL34. Both survivors and shown in members rides. From a weight perspective mine weighs more based on the fact it has a cast iron intake manifold and deluxe interior. I would speculate that is why mine has the 5 leaf compared to Jeff's cars 4leaf.
If you look in the Chevrolet parts manual you will see a spring chart which is used so that the correct spring is used based on the options(weight of each). I have not reviewed it in years, but I believe it basically like this:

Select suspension rpo car is equipped with first. Then based on the options the car is equipped with and using the weight chart add/subtract weight of each option as it relates to the front and back springs. Finally take the sum of the options (burdened by their weight factor) and select correct spring based on the chart.

BTW, back in the late seveties I tried to buy springs based on the chart from chevy, and basically they gave me a generic(superceded) spring back then, which gave my car incorrect spring height. There is a guy who I have had great success with coilsprings.com he know what he is doing. There is nothing more frustrating than having to repeatedly replace coil spring to get correct ride height ...I know.

[Mark_C]

Try this for a Z28:

http://www.chevynova.org/69_RPO_Z28_Springs.html

Then check out the part numbers here:

http://www.chevynova.org/1969_Spring_Chart.html

GM serviced all of the available Camaro springs with about 3 different sets of front springs and about the same number of rear springs based on the part numbers in the 69 Camaro Master Parts catalogs.

[Nova Research Project]

[ QUOTE ]
There had to be some quick way for the production worker to know things like A/C + 396 = XXX spring etc etc..

Anyone know how that took place in the production setting?


[/ QUOTE ]

Yes, the total weight of the car was calculated based on the options purchased. The computer selected the spring needed to handle the weight and printed a 2 letter code on the Chassis Broadcast sheet. The assembly line worker looked at the sheet and grabbed the corresponding spring from the rack. The Assembly line worker did not have time to calculate just grab and go.

Greg R.