Putting Spring Back In Your Suspension

Your car’s suspension probably needs a good restoration and you may not be aware of it. That’s not surprising. Suspension systems wear slowly and evenly. Nothing dramatic happens. Then one day you realize that the old precision and sharpness has disappeared. It’s time to either restore it, or modify and restore it at the same time.

Restoring the suspension system of your car can make it drive like new again. However, there arc some concepts and precautions to keep in mind.

1.) Don’t make suspension improvements without replacing bushings and any other worn or damaged parts.

2.) Decide the end result that you want: stock, modified, or race. Consult the Moss catalog pages on suspension tuning to help you decide. But once you decide, stick with it. Don’t change your mind in the middle of the job or you may end up with an ill-mannered car.

3.) Deal with the same supplier throughout the job, especially if you are modifying your suspension. It’s hard to get your questions answered if you’ve picked up bits and pieces from different places. (No, I’m not a Moss employee. I’m only sharing my experience.)

4.) Have all of the parts that you need before you start. It’s usually too late to find a critical, but necessary part, once you’re really into the job.

5.) If you can’t afford to do the whole car at once, be a cautious driver until you are finished. A car with a partially rebuilt suspension can handle worse than it did before you began.

There are good reasons for these rules. First, you must remember what your suspension is actually doing. It insures that the outside wheel remains nearly vertical to the road when cornering: that the weight transfer, under acceleration, braking, or cornering is controlled; that the wheels are in nearly constant contact with the road; and that the front end of the car is always trying to stay in front of the rear.

The first three concepts are largely controlled by the designers of your car. You can restore your car to the designers’ specifications or you can “improve”upon them.

However, “improving” always means a trade-off. You can trade comfort for improved cornering ability by stiffening the springs and shocks. If you stiffen your suspension too much, you’ll compromise the principle of “keeping all of your wheels on the ground all of the time.” Watch a coaster-wagon rattle down a bumpy street. There are usually only three wheels on the ground instead of four. Your car’s designers had a pretty good balance of expectations in mind and you can’t improve upon them too much with out giving up a lot of things that made your car good in the first place.

The last rule, keeping the front end ahead of the back end. is the one that may cause you your grief during a long-term rebuild. Your car was built with certain spring rates, shock absorber settings, suspension angles, and ground clearance. Substitute new parts for old and you’ll upset the equilibrium into which your car has settled.

Here are some easy lessons that I’ve learned:

Lesson #1. I began my rebuild by replacing the rear springs. I did it for cosmetic reasons (I hated the sag at one rear corner). The car looked better with the new springs, but it had become a real handful to drive.

New springs had restored life to the rear end, but without new rear shocks to control the springs. I’d done more harm than good. The car was out of balance and the lively rear was trying to push the front end around.

Moral: If you have to drive a car with the suspension only partially restored, drive carefully.

Lesson #2. When I could finally afford to restore the front end, I decided I really wanted to “improve-on-the-original.” This was back when tube-shock kits and springs with modified rates weren’t too common.

My favorite shop was providing all of the pieces except the special parts. For those, I was on my own. I purchased a tube-shock conversion kit from a supplier that I’d used successfully for other modified parts. Then I succumbed to an ad from a different supplier for some really special front springs. I ordered them instead of buying new original specification springs.

The new springs were o.k., but nobody knew the answers to questions like these: if the front springs are stiffer, and if the tube shocks are also stiffer. Will the car tend to have only three wheels on the ground? Are the springs stiffer or just lower? If lower, would I need to re-arch my almost new rear springs in order to preserve the correct castor angle? No single question was a big problem. It’s just that I had no single source of information and I was beginning to realize that I was over my head. My phone bill for answers sent the project over budget.

Moral: If you’re going to need advice before the job is completely done, be able to get it all from one source. Don’t change doctors part way through the operation.

Lesson #3. The rebuild and modifications all came out,very well, almost too well. Although I’d not replaced the rear shocks, I began to test the new limits of the car’s adhesion. It didn’t take long. The front end was gripping better than It did when it was new, but the backend was less controllable than It had been before I’d started. It didn’t take me long to learn that I’d really made a mess. The rear end went wherever It wanted In spite of all of the changes that I’d made to the front of the car. I ordered the tube-shock kit for the rear end that very night.

Moral: Original equipment shocks have the half-life of a popsicle in the sun. They should always be among the first parts that you replace.

Lesson #4. Worn suspension bushings will make your suspension seem loose and imprecise. The big rubber bushings at the wishbone/crossmember joint of an MG are critical. When they deteriorate, your suspension will be sloppy and your steering can feel tight. It won’t drive like a sports car any more. All rubber bushings need to be looked after frequently, and they should be replaced with neoprene or metal substitutes.

Moral: Don’t even think about making modifications until you’ve made all of the moving parts factory new.

Lesson #5. Begin the restoration. One of the reasons that you chose a British sports car is that you wanted superior handling and control. It is always tempting to put your always too scarce money into things that “show”. It’s hard to get excited about buying arts that are never seen.

Moral: The only thing that really counts for “show” is the back end of your car disappearing down a curvy road. That’s the “show” to put your money in.

By Dick Hankinson