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I'm helping my father on his 78 SA that he bought new and has a renewed interest to drive. The rear of the car sags and I was looking into options for replacing the rear spring. I now know that in 1978, the spring went to 2 1/2" wide with 7/16" bolts and his has the 7 leaf HS suspension. I cannot find a replacement anywhere. Does anyone know who might have one? The 2 1/4" 63 to 77 springs are available but no one has been able to tell me if it will fit. I assume it would need spacers.
If you like to work on these kind of things, you might try to rebuild the spring. Take it all apart, clean it up, repaint it with gray galvanizing paint, add the leaf spring liners. This could lift it a little bit. If they are not to sagged out, you can adjust the spring end bolts or add a little longer bolt. Have some fun and save money.
Here is what I THINK I know based on my conversations with suppliers:
In 1978, GM went from a 2 1/4" spring with 9/16" mounting bolts to a 2 1/2" spring with 7/16" mounting bolts. All 63 to 77 cars had the narrower spring. The 7 leaf was the HD option and the 9 leaf was the standard option. I stiff have yet to find a supplier for the 2 1/2" wide 7 leaf spring. There is not one listed on the Detroit Spring website. No one has yet to say if you can use the narrower spring on the 78 and if you would need spacers.
78s and 79s that had factory gymkhana springs used a 2 1/4" wide spring in the 2 1/2" carrier and shims front and rear.
If your 78 originally came with the gymkhana spring the shims should be there.
Altho when I purchased and drove my white 79 home 1100 miles I found this!!
Ahhh! This is coming together then. The car does have the Gymkhana suspension and it does have the shims. So Eaton does have the correct spring as part number ML715 2 1/4" width, 7 leaf stock ride height.
Ahhh! This is coming together then. The car does have the Gymkhana suspension and it does have the shims. So Eaton does have the correct spring as part number ML715 2 1/4" width, 7 leaf stock ride height.
Thank you!
stock was 6 leaf gymkhana..eaton will be 7..note my link and see how mine fit, had to remove one plate. Watch bolt length…you need spacer plate too if yours is still there on 2 1/4…or not…pic of center of spring.?
stock was 6 leaf gymkhana..eaton will be 7..note my link and see how mine fit, had to remove one plate. Watch bolt length…you need spacer plate too if yours is still there on 2 1/4…or not…pic of center of spring.?
Here is a picture. It does look like 6 springs but I wasn’t sure if the 7th was on top and out of view.
stock was 6 leaf gymkhana..eaton will be 7..note my link and see how mine fit, had to remove one plate. Watch bolt length…you need spacer plate too if yours is still there on 2 1/4…or not…pic of center of spring.?
which leaf did you remove? I understand on the bolt lengths. I’ll make sure the new ones match the old ones. I was told they are 9/16 bolts on 78’s.
I'm helping my father on his 78 SA that he bought new and has a renewed interest to drive. The rear of the car sags and I was looking into options for replacing the rear spring. I now know that in 1978, the spring went to 2 1/2" wide with 7/16" bolts and his has the 7 leaf HS suspension. I cannot find a replacement anywhere. Does anyone know who might have one? The 2 1/4" 63 to 77 springs are available but no one has been able to tell me if it will fit. I assume it would need spacers.
I may have a brand new one 7 leaf, I will check when I get home if you are still interested
not new but very lightly used
195.00 shipped
Thanks, grant
Last edited by grantstigers; Mar 3, 2023 at 04:34 PM.
I may have a brand new one 7 leaf, I will check when I get home if you are still interested
Thanks, grant
Now I’m thinking that I need a 6 leaf that is 2 1/4” wide since that’s what it came with. I’m thinking that the original 6 leaf gymkhana setup isn’t available any other. So I have to use a 7 leaf that might be a tad wider and eliminate one spacer.
Now I’m thinking that I need a 6 leaf that is 2 1/4” wide since that’s what it came with. I’m thinking that the original 6 leaf gymkhana setup isn’t available any other. So I have to use a 7 leaf that might be a tad wider and eliminate one spacer.
buy the 7 leaf..noone makes a 6..even gm replacement was 7.it is NOT wider..same 2 1/4, the 9 leaf is 2.5
Use both spacers for 2 1/4 wide
see link
78 Rear Leaf Spring Problem
