beepo

I'm using offset trailing arms and was looking for a shortened main leaf for my 9 x 2.5" leaf spring. I checked with Guldstrand but they no longer make it. I decided to cut mine, no problem but making the 7/8 holes prove to be difficult. What is the best method to make the holes, drill vs carbide bits? Or if anyone knows where I can purchase the shortened main leaf. Thanks for any input.

doorgunner

Buy some "Thread Cutting Oil" from the hardware store apply it to the metal while drilling the hole.
First......drill a 1/4" diameter hole through the exact spot......use a variable speed drill motor at about 50 to 60 rpm/veryslow (you can practically count the rotations of the drill(bit)!

Use the cutting oil to keep the metal wet.

Next........use the correct size drill(bit) to drill the finish-hole...use plenty of cutting oil.....you may have to use a slower rpm on the large drill. Once the larger drill(bit) is about to go through the spring, press lightly on the drill motor to keep the drill(bit) from "grabbing the metal" and spraining your wrists

Take your time....the spring metal will harden if you spin the drill(bit) too fast......and you will not be able to drill all the way through.

Plan B would be to take the spring to a small machine shop---they are more likely to do the work sooner and cheaper.

beepo

Thanks, I think I was running the drill to fast. I appreciate your advise.

chvet73

Slow slow slow speed is the key to it. I did mine and found that was the key. Cutting oil and a sharp drill bit will help too.

loup68

You might need to buy a carbide drill bit. Again, run at very slow speed and use oil. Lou.

hail to R3

Use a torch, oxy-fuel or plasma

PeteZO6

There goes the heat treatment in the spring. The spring will be softened where heated.
Pete

hail to R3

Only with the oxy-fuel, if your not careful

beepo

I used thread cutting oil and a carbide mason bit as well as a black oxide bit. After a lot of patience and a file it's all back together. Thanks for the advise.

redvetracr

I would think the spring (after being cut) would be stiffer on one side than the other, cutting only one side is not something I would ever do but it`s your spring...

beepo

I cut the spring equally on both sides which I did for tire clearance. I installed off set trailing arms at the same time. After I bleed the brakes and road test I'll post how it worked out.

68/70Vette

For my 68 and 70, I ordered a composite rear spring and ordered it 1/2 shorter on both sides for each car. the composite spring weighs 8 pounds, the steel spring weighs 42 pounds. Also, the composite springs are so much easier to install (safer). My 68 has a Tom's Differential rear end that is essentially stock..although with Tom's hardware and a VBP offset trailing arm. The 70 has what I'd call Tom's Super 10 bolt differential, 31 spline axles, large diameter U-Joints, Offset trailing arm made by Toms. Stainless Steel Brake Corporation aluminum calipers on both cars.