Having some suspension work done on my '66 and would like to change the spring rate on both the front and rear leaf springs to attempt to make the ride less harsh. The current setting is one step away from the softest (which VBP claims would be equivalent to the stock springs). AFAIK the suspension may have been like this for 10 years. Would changing the spring rate now cause any problems with the springs? Anyone have any experience doing this?

Regards,
Jerry

 

I'm not sure i understand the use of settings with regard to springs. They are what they are. you can change settings on adjustable shocks but springs are whatever the spring rate is. Stock spring rates with good stock dampening shocks is a pretty good ride.

 

Jerry,
You have to understand how the VBP spring system is set up. There are multiple mount points for the bracket as shown in the pic. The closer to the center of the car the thru bolt is the lower the spring rate. Mine is currently in the second hole from the center.

Regards,
Jerry

 

I have VBP monosprings front and rear. I set them at second stiffest setting 16 years ago. I recently moved them to the next inboard (less stiff setting). Other than having to change the spring bolt lengths to get the ride height back where it belonged, I haven't noticed much difference. It's too early to tell if doing so will affect the life of the springs.

 

So moving one hole did not make much difference in the ride?

Regards,
Jerry

 

Just curious, what spring rate does VBP tell you they are for the different settings?

 

Per the installation manual for the rear spring:
Going from the inner points to the outer points, respectively, the holes correspond to the following approximate spring rates: 325, 350, 375 and 400 lbs./inch. For maximum handling, balance your car’s rear spring rate with the front spring rate.

I don't see anything for the front spring.

Regards,
Jerry

 

For reference the '63 base rear spring is about 162 lb/in and 305 lb/in for the HD spring, which is about 140 and 270 at the wheel. At the front the base spring rate is 260, 80 at the wheel and 550, 170 at the wheel with the HD springs. So the HD spring ride rates are about DOUBLE the base spring ride rates. (The '64-'67 variable rate base springs average about the same as the '63 fixed rate springs.)

So whatever adjustment these VSP springs allow, the ride rates are greater than the OE HD springs, and you need a lot more rebound damping to control excess rebound with such stiff springs.

Like Jerry said, the base springs provide a very decent ride, and with a set of rebound adjustable shocks, soft compound high speed rated tires and some judicious alignment tuning these cars can generate close to 1g on a skid pad and still have a comfortable ride.

There have been several VSP threads and most installations appear to be disasters. For the life of me I don't understand why guys invest hundreds or thousands dollars on this stuff. And then most of them are riding on rock hard, low speed rated "van tires" that are lucky to generate 0.75g on a skid pad - about the same as a modern low end small sedan - no matter what you do to the suspension!

One problem is that most car owners have zero understanding of vehicle dynamics and suspension tuning. But the bigger problem is that most of the outfits that sell this stuff are just as clueless. Back in the nineties when I went to SEMA every year I talked to most of the aftermarket suspension vendors at one time or another, and when I started asking questions about ride frequencies, roll stiffness distribution, and camber gain, they just went catatonic.

Duke