Getting the Rates Right

The importance of the right springs was discussed last year. David Parkinson backs up the theory with a practical tale.

At the start of this year I was particularly hopeful, in a guarded sort of way, of my chances in the championship. Ewen Sergison and Geoff Fern had both moved out of the class and my car had been rebuilt after its losing argument with the Armco at Snetterton in the last race of last year. Ewen had fitted a very professional undertray and diffuser and his fabricated rear wing was far superior to many of the second hand lash ups I’ve had in the past.

The car seemed more stable at Snetterton this year but my fastest lap was somewhat slower then my best lap last year. I put it down to not being in the car for six months. At Anglesey the car again seemed quite stable but as at Snetterton the track appeared bumpier then previous. I got the same impression at Mallory. Although doing quite well my lap times were slower then my previous best in spite of having a better car. I must confess that I was beginning to think that it was an age thing.

Then, in two separate conversations, both Peter Bragg and Ewen Sergison advised that the rear end of the car was bouncing too much on entry into the corners. Ewen had already told me that in his opinion the car was too soft on the back end. With Peter Bragg’s assistance I had increased the spring rates at the rear end last year until at the final round at Snetterton it felt perfect.

I couldn’t understand it as the broken dampers had been replaced with exactly the same type and the same 550 rated springs had been retained. But after three meetings, being a bit slow on the uptake, I had to acknowledge that the rear end was too soft. I blamed the dampers. They were supposed to be the same but obviously weren’t. Ewen took the car and apart from various odd jobs was going to look at replacing them.

Ewen rang me. As a precaution he’d checked the spring rates on a tester. They were clearly marked as 550s but the tester illustrated that one was 475 and one was 500. Problem solved. New 550s have now been fitted. Although I’ve had a problem in the past with springs being incorrectly stamped I don’t think that this was the case in this instance. I believe that the rates were 550 but the stress impact from the crash caused some molecular amendment to the rates although no visual damage was apparent.

I’ve always said that the gap between the fastest and slowest cars on the grid is generally caused more by the set up differential than the skill of the driver. Maybe a more correct statement would be that if some of the slower cars were set up better they would be substantially faster.

The moral, if there is one, is when the car has been in an incident, get things checked even if they are visually acceptable. If Ewen hadn’t thought to check the spring rates I would have carried on convinced that the springs were correct and the slower times were due to my ever advancing age.

David Parkinson

A spring testing machine (Wagner company)