Spring Rate Suggestions for '68 Camaro

[Mkelcy]

Originally Posted by David Pozzi

I entered the measurements from my Morrison sub into the Ride Tech calculator. The Morrison sub is nearly the same as the 21'st century using the same lower control arm and nearly the same shock angle.

Ride Tech Calculator:
Cruiser/daily = 375
Perf driving = 425
Racing =450

Mary has been running the 350 rate since last fall.
James has 425 on OLC and it's doing very well. With the Ride Tech shocks set at mid-range, the car rides great on the street.

We had some indication of hitting the bump stops on Mary's car when she tried lower shock settings. So we will be trying some stiffer front coils. I think if you have a more streetable ride height, the 350's will work fine, but I'd turn the shocks up for an autocross.
FYI, Morrison runs/ recommends a 450 front coil on their 69 Camaro.

Thanks David. I ran the Ride Tech tool (nice job there, by the way) and came out in the low to mid 300's depending on shock travel. My car's not down in the weeds (my LCA's are essentially level with the ground), so I should be okay at those spring rates.

The 350 lb./in. springs came in today, as well as the nitrogen setup for the rear shocks. I'll get everything installed, drive it and see where I am. It's quite possible that a new set of front shocks are in the cards.

I have tell tales on the rear shocks, which are about 1" to 1.5" from bottoming out.

This car is primarily a long distance tourer that's supposed to be fun on curvy roads; it's not focused on auto-crossing or HPDE.

[bret]

Keep in mind that our spring rate calculator provides a starting point...rates can be tuned to satisfy a particular car, driver, tires, swaybar, shock set up.

We worked very closely with Hyperco to develop this tool. They've been building springs for awhile. We took their lengthy and complicated engineering algorithms and translated them into a tool that most of us can understand. We've found it works pretty darn well. If we get a car that is on the extreme fringe for weight or traction sometimes it can miss a little, but such cars are typically serious track units that are subjected to an appropriate amount of tuning anyway.

The other cool resource we've developed is the huge library of vehicle weights that we've gathered over the last few years. http://www.ridetech.com/tech/coiltech-2/

If you take a look at that library I'm sure you will find a combination that is darn close to yours. This will save you the trouble of finding a 4 corner scales for your own car. Then all you need is a tape measure and the discipline to use it!

[Mkelcy]

Originally Posted by bret

Keep in mind that our spring rate calculator provides a starting point...rates can be tuned to satisfy a particular car, driver, tires, swaybar, shock set up.

We worked very closely with Hyperco to develop this tool. They've been building springs for awhile. We took their lengthy and complicated engineering algorithms and translated them into a tool that most of us can understand. We've found it works pretty darn well. If we get a car that is on the extreme fringe for weight or traction sometimes it can miss a little, but such cars are typically serious track units that are subjected to an appropriate amount of tuning anyway.

The other cool resource we've developed is the huge library of vehicle weights that we've gathered over the last few years. http://www.ridetech.com/tech/coiltech-2/

If you take a look at that library I'm sure you will find a combination that is darn close to yours. This will save you the trouble of finding a 4 corner scales for your own car. Then all you need is a tape measure and the discipline to use it!

As I said, really nice job with the coil spring rate calculator. It's a great tool and a great service to the community. I also found the library of weights which was very helpful.

My biggest area of guesstimation was unsprung weight.

I used 70 lbs. for the front - Forgeline 10" x 17" wheel, Michelin Pilot Sport 275-45-17 tire, C5 rotor, caliper, spindle, bearing pack and LCA.

I used 120 lbs. for the rear - Ford 9" with nodular iron pumpkin, Strange axles, brackets, control arms & Watts link for the 3 link, Forgeline 11" x 18" wheels, Michelin Pilot Sport 295-35-18 tires, Wilwood 12.19" internal parking brake rotors and calipers.

If I'm off, I'd guess that I'm over on the front and under on the rear. That third member is HEAVY.

[David Pozzi]

Mike,
I happened to have the parts to my Morrison sub laying around.

Front:
14" brakes 25lb
half of coil over shock 7.5
Half of LCA 10
Hub, knuckle, steering arm 20
18" Forgeline wheel with 275 tire, 47 lb
Total 109.5 lbs Smaller brakes would be a little less.

Shock angle 57 degrees which isn't available on the calculator.

A Ford 9' weighs 195 lbs with 6 piston 14" brakes, not counting suspension links or shocks. A ford 9" floater weighs 220 with brakes.

[Mkelcy]

Originally Posted by David Pozzi

Mike,
I happened to have the parts to my Morrison sub laying around.

Front:
14" brakes 25lb
half of coil over shock 7.5
Half of LCA 10
Hub, knuckle, steering arm 20
18" Forgeline wheel with 275 tire, 47 lb
Total 109.5 lbs Smaller brakes would be a little less.

Shock angle 57 degrees which isn't available on the calculator.

A Ford 9' weighs 195 lbs with 6 piston 14" brakes, not counting suspension links or shocks. A ford 9" floater weighs 220 with brakes.

David, thanks for the information. I was low for both ends. I measured a shock angle of about 64 degrees but, as I said, my car rides a bit high.

I got the rear shocks gassed up, but in the process of doing so, saw that the driver's side rear wheel was rubbing the canister hose. Things get tight back there with the 3 link and the exhaust. Fortunately, I'd covered the hose with some plastic wire loom for just this reason, so the hose wasn't damaged. I'll jury rig a mount for the canister in a different location, and make fabbing something pretty a winter project. We definitely have a driving season up here in eastern Washington, and I don't want to miss seat time while I get the car sorted out.

[Mkelcy]

I've got close to 1,000 miles on the car since I got it on the road at the end of April (including one 300 mile trip and one 250 mile trip), and have concluded that I need to look at damping before I play anymore with spring rates. I can't dial the AFCO M2's down anymore and I still get a pretty good jolt over slow speed bumps. It's great on smooth roads, but that's not a great test of a suspension. I think the spring rates may still be too high, but the current principal issues seems to be damping.

I'll be calling Ride Tech on Monday.

[Mkelcy]

I put a set of the Ride Tech handling quality shocks (single adjustable) on the car, together with 300 lb./in. springs in front and 175 lb./in. springs in the back.

According to the Ride Tech spring rate calculator, those rates were recommended for performance driving, and I agree, while at the same time the car rides much better than it did over bumps and pot holes. Overall I'm very pleased.

One thing I'd mention is that the Ride Tech shocks come with bearings that have a 5/8" ID. They include adapters to sleeve the bearing down to the 1/2" bolt size I was using. With the adapters installed, however, the overall shock bearing length is about 1.25".

The lower front shock trunion I had was set up for a 1" long shock bearing, however Ridetech has a trunion that will work with their 1.25" stack height.

Unfortunately my top shock mount on the subframe also required no more than a 1" bearing width and there was no modifying that mount. I ended up having the Ride Tech adapters milled down to the 1" overall width I needed.

If any of you end up needing to do this, be aware that the adapters don't touch inside the shock bearing, so you need to install them in the bearing, and then determine how much to take off each adapter.