1966 3/4 ton front coil spring rates.
 

Looking for some knowledge folks. My 3/4 ton 1966 gmc pick up is getting front end rebuilt. I called eaton springs and was told the stock spring is thier ML 2022 spring which is rated for about 1018 lbs spring rate. Now when compared to the same year chevy c20 version that spring is considered heavy duty for a chevy c20. Same year in c20 the standard spring is listed as ML1766 which is listed at around 722lbs spring rate, this spring is standard for both c10 and c20.

So question, is does anyone have any knowledge of GMC using heavier duty springs as standard springs? I'm debating going with the c20 version of standard to get a more plush ride, since the standard in GMC is heavy duty version according to Eaton springs. Hopefully someone knows about this or have ran across this at some point. Thanks in advance.

Re: 1966 3/4 ton front coil spring rates.
 

Your V6 engine (assuming that's what you have) weighs 200 to 300 pounds more than a Chevy engine. If you go with a lighter duty rated spring, you risk bottoming out the suspension on potholes, speed bumps, etc.

Re: 1966 3/4 ton front coil spring rates.
 

Have a small block 350 in it now.

Re: 1966 3/4 ton front coil spring rates.
 

Oh no!
:ahhhh:

Re: 1966 3/4 ton front coil spring rates.
 

Go with the Chevy springs.

Re: 1966 3/4 ton front coil spring rates.
 

I think they are using P/N 3817997 std. for the Chevy truck I6 230 63-65, 250 66 and 3817998 HD for the small block V8. GMC used the same springs for their I6 only in 65-66. They change the springs in 67.

The I6 230 and 250 are about 440lbs. The Chevy V8 350, 283, 327 are about 575lbs. GMC 1966 V6 305E-795lbs and V6 351-860lbs. P/N 2436529 std and 2440323 HD. They would be special order.

I would go with the MC2022 spring. The ML1766 iare for the I6.

Now the spring rate (spring deflection rate) for the ML1766 (3817997) is 173 and load rate is 1018lbs. MC2022 (3817998) spring rate 239 and load rate is 1152lbs.

Call again and check, I could be wrong.

Re: 1966 3/4 ton front coil spring rates.
 

I think they are using P/N 3817997 std. for the Chevy truck I6 230 63-65, 250 66 and 3817998 HD for the small block V8. GMC used the same springs for their I6 only in 65-66. They change the springs in 67.

The I6 230 and 250 are about 440lbs. The chevy V8 350, 283, 327 are about 575lbs. GMC 1966 V6 305E-795lbs and V6 351-860lbs. P/N 2436529 std and 2440323 HD. They would be special order.

I would go with the MC2022 spring. The ML1766 is for the I6.

Now the spring rate (spring deflection rate) for the ML1766 (3817997) is 173 and load rate is 1018lbs. MC2022 (3817998) spring rate 239 and load rate is 1152lbs.

Call again and check, I could be wrong.

1966

Re: 1966 3/4 ton front coil spring rates.
 

Those numbers I got straight from eaton springs. They stated ML1766 is 722lbs spring rate. And ML2022 being heavy duty rated at 1018lbs.

But since I went to the sbc350 I lost about 300 lbs of weight from the original v6 351. It felt very bounce as if the spring was to hard to compress so trying the ML1766 and if that don't work I'll go back to stock.
I'll watch to see if I bottom out with a lower spring rate which hopefully it doesn't happen. Many chevy trucks use the lower spring rate and have swapped in sbc350 and have been fine. I'll report back next week after putting some miles on.