Tech Question - Drilling a Spring

Mike,

I just bought a new pair of springs from you folks for my 62 Falcon. I don't have a warranty because I have a stroker motor installed. I installed the springs on my Falcon and noticed a decent amount of slop between my spring perch and the leaf spring center pin. I took the axle back out of the car and measured the hole. It was way bigger than the pin that came on my springs. I'm not blaming you guys, there's a chance that the rear end in the car isn't stock. Anyway, I know that it is very important for the spring and the rear end to be firmly mated together without movement...

Here's where I may have screwed up:

I went to my local supply house and got a new spring locating pin with the proper OD. to FIRMLY locate my rear end. The problem was that it was 3/8" OD. where it goes through the spring and my stock pin was 5/16" OD. Using my trusty Dewalt and a little bit of WD40 I punched out the holes in my springs to the desired 3/8" size. With the new pins in place, my rear end set very firmly over the pins and everything went together nicely.

That's when a buddy of mine (into 4-wheeling) told me that I probably destroyed my springs from the heat caused by the drill. I used a little WD40, but not a lot. It did get hot, because it ruined the drill bit. He told me that if the heat from the drill didn't cause the springs to break, the stress risers caused from drilling a hole would (he told me the stock holes are punched and drilling a hole creates a stress riser). I spent $500 for these springs and if I ruined them before the vehicle has even been on the ground I'm going to be sick. What are your thoughts?

Thanks - Corey

Fear not young man, you have not damaged your springs. Now that I have relieved your fears, let me tell you why.

All '62 Falcon springs, and there were 8 different factory springs, use a 5/16 center bolt. This size center bolt has a head that is 1/2 Inch diameter. So based upon this your axle has either been changed or the hole in the spring seat was drilled out.

Drilling the holes in each leaf did absolutely no damage to anything except the drill bits. Spring steel is some mighty tough stuff even when it is not heat treated. This is one reason why we punch the holes. The other reason, and the main reason, is speed. As you know, it took you a lllloooonnngggg time to drill the holes larger. Imagine how long it would take us to drill several thousand holes a month?

As for heat, it takes 400 degrees to start softening spring steel and believe me, drilling the holes did not even come close to producing this much heat.

Finally, it takes a nick or a gouge or weld splatter to cause a stress riser in a spring leaf. A round hole will not. So go forth and enjoy your ride. - Mike