Picking Out Leaf Springs?

70mustanguy

New Member
Jul 14, 2010
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Well I have broken leaf springs and just gonna buy a new set. But when searching they give me the options of ether 4, 41/2, 5. I am thinking of going with the 41/2 and cutting the difference between a stiff ride and too soft. But will A standared eye keep the car stock height or will I need to go to a mid eye or other to get the car lowered in the rear by ''1. I'm looking to lower it in the rear just by 1 inch. Opinions???
 
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4 1/2 mid eye is what I have, it lowered my rear probably just a little bit more than an inch. I got the grab-a-track brand. I put some 620 springs out front and cut 1/3 of a coil off of them and now it is nearly perfectly level...26" from the top of the fender lip to the ground.
 
Don't get the idea that 4-leaf springs are soft. The 428 Super Cobra Jet, and even the mighty BOSS 429 NASCAR had 4-leaf springs. Sounds like you need a 4-leaf mid eye. Fine tune with the shocks. Something like the Kayaba GR-2 for GT-type stiffness, or for something firmer, the Kayaba Gas-A-Just.
 
Don't get the idea that 4-leaf springs are soft. The 428 Super Cobra Jet, and even the mighty BOSS 429 NASCAR had 4-leaf springs. Sounds like you need a 4-leaf mid eye. Fine tune with the shocks. Something like the Kayaba GR-2 for GT-type stiffness, or for something firmer, the Kayaba Gas-A-Just.

I put 4-leaf mid-eye Grab-A-Traks on my '66 coupe with KYB GR-2 shocks. I was looking for a soft, but controlled, ride for daily commuting. I definitely got the soft part, but w/o the control. I'm now deciding whether to change shocks and see if it helps enough, or just go ahead and change springs again.

BTW, with the mid-eyes out back and 1" lowering springs and a Shelby drop up front, the car sits perfectly level.
 
I have 5 leaf on my '70 because I had them laying around..... They're way too stiff for most street applications, and I'd suggest you go with the 4 , or the 4-1/2 leaf. Keep in mind the Spring rate you're getting is one of the important factors. For example, A 1970 Boss 9, or Boss 302 only had a Spring rate of around 153#, a standard model had around 85#, and a Mach, or 428 had around 138 #....

Check these guys out....... http://www.eatonsprings.com/index.html
 
Do not buy springs from Laural Mountain, they are junk. I bought the 5 leaf high performance and they lasted 2 months before sagging worse than my old worn out 4 leaf. Customer service sucks.
 
I used Maier racing 4 1/2 on my fastback form Mustang depot. Very stiff for street (165#). Great spring design though. No traction device needed. I added fays2 watts link and Bilistein shocks and it was like a cat on the carpet.
The ride quality of the car is mostly controlled b the rear spring. If its ride that's important, Becareful not to put to stiff a rear spring in. You can stiffen up a rear with shocks and if you don't like it , there easy to change. My 65 convert has new stock GT 4 leafs with KYB gas shocks (not KYB GR2) and it just perfect for a cruiser. The guy at Mustangsplus (where I bought the springs) said the shocks were way to stiff. But they compensate for the softer spring rate and put me right where I want to be. I did use 1" lowering blocks with this set up as I have struts up front that lower the car and I wanted to keep everything level
A good compromise might be 4 1/2 mid eye with the GR2 shocks
 
Alright thanks for the opinions. I have ordered a set of 4 1/2 springs. Ride wasn't the ultimate concern for me really, but primarly this car will be a cruiser with the odd drag racing or autocross weekend in the summer. But it's primary function will be a cruiser first since it will recieve the most milage and use as a cruiser. Just didn't want a ride that would be beating me up on hour long trips or be too soft for any occansional track use. Idealy I do like my car to handle a fair bit. But after talking to some guys at the shows, since most of them are runnign 4 1/2 and 5 inch springs. I decided to cut the difference and and just go with the 4 1/2 spring since the 5 will primarly just beat me up on long strips anyways.
 
I have 5 leaf mid-eyes and GR-2 shocks and the ride is quite nice, and certainly light years better than my stone-stock '88 GT. By comparison, a friend has 4 leaf stock replacements and KYB's and his car rides like a logging truck.