I am going to replace the front springs in my 68 Cutlass S. I see that there are some poly isolators that are sold that go on the top of the springs. Do I need these? Looking at the assembly manual they only show a shim used on the LH side only for Wagons. I’m confused do I use the isolators or just the bare springs? Hope this makes sense. Thanks!

 

As you stated, a shim on the LH side for wagons only. The isolators have been available as an aftermarket item for many years. They are generally used to isolate noisy squeaks, etc. (if you get any noisy squeaks). Follow the guidance from the assembly manual, they are not needed, but it is your call if you want to install them - they won't hurt anything to install them.

 

Thanks thats what I was thinking. I originally put my springs on with the isolators and I think it sets to high in the front maybe using the isolators is part of the reason.

 

You mentioned neither the manufacturer or model number of springs you replaced nor the manufacturer or model number of the isolators you used. Let's not get too far down a rabbit hole, but both the manufacturers, and model numbers of each can make a difference on ride height and these are and can be installed to the preference of the owner. Most isolators are quite thin but others may increase the height - your decision(s). Again, I wouldn't go too far down the rabbit hole unless you enjoy removing & replacing springs.

 

Sorry I don’t have any part numbers but I did get the springs from Detroit Springs and they were supposed to be stock height. I used the isolators because they came up as a suggested accessory but I’m guessing maybe that added 1/2 to the height of the front end which I think is too high. I’ve seen were if you add 1/4” to the spring height it will add 1/2” to the ride height.

 

There are several, but the two most important are the size of the wire employed to create the spring and the compression of the spring. Via various manufacturers you will find various metals used for spring wire, size of spring wire, height of spring, coils of springs and rated compression of springs - I think you get the point.

Here is a rather good explanation from UMI Performance regarding springs. NOTE: These springs are for 1968 A-Body vehicles, but the description is generic enough to gain an understanding of springs in general.

https://www.umiperformance.com/home/...nt-spring-set/

A spring is a spring right? Wrong! When UMI chose to manufacture our own line of springs we went all out. Designed in conjunction with a leading Sprint Cup chassis engineer, these springs are the best in the business. UMI’s springs are designed to add modern handling and a crisp ride while maintaining the factory muscle car appearance. Our front springs are wound from 5160 CrSi premium wire and feature a linear 530 lb/in rate. The linear rate provides consistent handling characteristics which are important for Auto-x and Pro-Tour applications while the increase in stiffness reduces body roll and prevents the “floating” feeling so common with the A-body. These springs are suitable for Auto-x and Pro-Tour applications as well as corner carving and general cruising. The ride height is engineered to be level with standard SBC, Pontiac 400 and aluminum head/intake Big Block Chevy as well as LS power (lightened cars may require spring trimming). The front springs are also suitable for full weight Big Block applications when ¼” nose down rake is desired. They have a tough, black powder coat finish and UMI proudly manufactures these premium quality springs in the USA.

• Designed to maintain the factory muscle car appearance with today’s modern feel.
• Consistent rates and only the best materials (premium Chrome Silicon wire) ensure your cars sits properly for years to come.
• Linear spring rate provides a firm yet comfortable ride and incredible handling.
• No more floating feeling.
• Suitable for Pro-Tour, Auto-x and general cruising.
• Manufactured in the USA.

 

At the end of the day, good for you to replace the springs with new springs. Your 53 year old beast is going to love you for it and you'll love the ride.

More here >>> https://bimmertips.com/linear-vs-pro...ngs-explained/

 

There are no isolators on the front springs stock.

 

Thanks! No isolators it is.