Stock rear springs loose when 70 GS convertible is on a lift

While reviewing various threads in regard to the rear springs, I have not read any comments about the rear springs being loose when a car is on the lift. Also, I replaced the upper and lower control arms (with new bushings) last year in the front, which raised the front end but as a result, lowered the rear. We double checked the control arms and they were adjusted correctly (all the way up on the ground). The good news is that although even lower than before, my 275/60 15’s are not rubbing in the back with the wheel well trim in tact!

My mechanic does not think the rear springs are worn out and the car virtually never has passengers or other weight in the back except for the spare (although they are over 50 years old). But he did say the Monroe gas replacement shocks may be too long when fully extended (car is off the ground). In addition to the top coil spring insulators, we added ones on the bottom that helped a little, but there is still a good amount of gap when on the lift.

I don’t know if this is a factor, but we also replaced all of the body bushings a few years back.

This week my mechanic will measure the shocks when the car is on the lift to replace my gas tank sending unit. I am considering the Eaton rear coil springs 1 - 1.5” higher than stock as I like a slightly higher rear stance over stock. I an also considering the AC Delco grey air shocks although they may not be a stock option on my ‘70 but I can adjust the stance where I want it. The car is virtually stock (except for the tires, shocks and battery) and only driven to shows and never raced. I was curious to get any members thoughts about the loose stock springs. Is this normal?

 

I'm going to pipe in and recommend against the air shocks. Your ride will suffer. I ran air shocks for years because that's what the car came with. When I finally redid the rear suspension I was amazed how much better the ride/handling is with regular gas (I used KYB) shocks.

 

Thanks for your all your input! Both sets of coil insulators are new. We will measure the shocks, as Larry and my mechanic suggested. Does anyone know if I go for the Eaton springs to raise the ride height 1 - 1.5 inches- would they help? I would like to raise the height in the back to give it a taller stance and forget the air shocks! CJay, are you suggesting 2 sets of insulators on the bottom in addition to 1 on the top?

 

The Eaton springs are $300 a pair! Moog springs are about $100, but you'll have to determine which ones will give you the extra lift.
I recommend contacting ESPO/Springs 'n Things and tell them what you are looking to do. They'll calculate what you need and pricing is competitive with the Moog springs.
https://www.springsnthings.com/

While I prefer replacing the springs to change the ride height, an option is to install a spacer lift kit.
https://www.ebay.com/itm/293599055227?hash=item445bde0d7b:g:OcEAAOSwlvBhY9It&amdata=enc:AQAIAAAA8HyKJCRyBeWJR/RL+8y/g8mqRqmIu4xprgYuFiS1a8eX7ff9Ce1MHe1qYZSwde4OzGqheGE1+TQpHwRtldINSaDhhHwkd6p1nnrO+dZrGol6BG4/78jMlqmcI1+XBwZ1ZsGrAlRpQPyXvd29B1Bt9H+knS66Nf5LLJnkIvHo1QmeRph0zGEbEY/oKrvapfvt4ms3iKRub+5H+EDK4oOarzeJixrdlSw9zzwqySs9wrgOIf6oegk0svc5RyyWQ0Co8oEcQ7q4rt6OdW2aASymeuvdSgSlwys6mi6x7ZfpSyqJXLuNud4BDFb9XLkXYBkwkw==|tkp:Bk9SR8aO2sGeYg

 

If it sits correctly leave it alone

 

Sounds like your mechanic knows stuff!
Most would say “ your springs are worn”

 

Guys, he's looking to increase the ride height. Some of you didn't catch that.
New springs are the best option, spring spacers (like I posted) would work, air shocks or coil over shocks would work (but not recommended) as would air bags.

The eBay spacers are $32, Eaton springs are $300, and Moog or ESPO springs would be in the $100 range.....That would be my first choice.

 

Guys, thanks for all your advice! Yes, as I read some of the comments on here, and talking with other GM A body owners, it is normal for the rear springs to be loose of the ground. My mechanic informed me yesterday that even if I go with springs that are higher in the back, because of the gap, they may not raise the ride height.

So my first concern is, as I mentioned in my original post, that the rear lowered to about the “normal” stock height only after replacing all four front control arms. (Before, I could see the top of the rear tires,) This is not the first time that I noticed when you make a change to the front or rear suspension it affects the other. The opposite occurred on two Ford Taurus wagons, when I put heavy duty rear springs on the rear, they wore out my front struts which had to almost immediately drilled out and replaced.

As a result, I’m thinking now that it might be best to replace all four springs since they are over 50 years old! I can always add the spacers later for the rear. (The additional insulators on the bottom helped although they are still loose.) I n front, I would like to keep the stock ride height; it’s just the rear that I want to raise a 1 to 1.5 inches. I’m not opposed to the Moog springs, but as Larry mentioned in a similar post about raising the rear ride height, the rear Moog springs have been discontinued for this application.

Does anyone have the correct Moog part number(s) for the front that are the stock equivalent? For the rear, besides Eaton, does anyone know of a stock appearing spring with a part number(s) that would raise the height that is still available? (Eaton, although pricier, would be my fallback position if others are not available.)

 

BTW, Larry stayed it was Moog part number 5399 that was discontinued.

 

Would the spacers alone raise the rear or are they simply just to fill in the gap of the loose springs?

 

They will raise the rear.

 

This is true, although many parts have been replaced over the years. So since the springs may be okay according to my mechanic, the spacers would be my first choice, but instead of the gold ones shown in this thread, I found some billet black ones from Supreme Suspensions on eBay that provide a 1” lift for $45. Although not stock, they will blend in better and even if they don’t lift the rear much, they will fill in the gap!

 

No gap when the car is on the ground. My springs had a little play when on a lift after I put KYB's in. They extended longer than the old ones.

 

As Larry said earlier and John just posted, the rear shocks are what limit the axle drop when raised. Different shocks will have different strokes, (length)...
I guess I need to say when raised on a lift with no axle support,