I need to replace my rear springs on my 1975 vette. Any recommendations on where to purchase them? And do I need to be aware of any special adjustments needed when installing a new set of springs?

Hi, Are you interested in staying O.E.M. or going with a aftermarket product? Do you want a softer or more firm ride? Are you going to use the car for competition in any way? Lots of info to be determined before purchase. 

I would suggest looking at the factory service manual for instructions on removal as removing compressed springs incorrectly can be hazardous to your health. 

You need to clamp a block of wood to the underneath side of the spring about 8" inboard from the bolt. This will keep the jack saddle from sliding up the spring as you let the jack down. Then you need to place the jack under the spring near the bowl and just jack it up enough to remove the pressure on the nut. Once the nut is removed, you can lower the jack slowly. And then repeat for the other side. I found that on doing this on my friend's '66 Corvette that I had to buy a new 450 ft-lb IMPACT wrench to get the for mounting bolts loose. My old Harbor Freight 300 ft-lb impact wrench would not cut it. Yes, we did use a lot of penetrant and heat and it was still about all the new torque wrench could handle. The reason I recommend using an impact wrench is because I've heard many stories of people putting a breaker bar on the bolt and breaking the ear off the differential housing. That's a lot more expensive than buying the torque wrench. 

You can buy longer end bolts if you desire to lower the car in the rear. 

I want to keep the car as stock as possible with a smooth ride and just have a nice ride on a beautiful day in Hawaii.

I’ll look into the OEM repair manual on the procedure to r & r these rear springs. Thanks for responding…

Years ago I replaced the rear spring on "The Toy".  It wasn't a particularly difficult project, just took some time as I was being careful (sprung steel isn't something to take lightly).  When you're reassembling things be careful to get the center bracket bolts started smoothly.  You don't want to cross-thread them.  Don't ask how I know that!  🙄

Back in about 1990 we changed the original metal spring (there is only one remember) on our '78 for a composite TRW item.  It's one of the best things we ever did!  An improved ride and a whole lot lighter.  And, it's also proved a lot easier to deal with when doing work on the rear, trailing arms, bearings etc, anything that needs the spring being "un hooked' from the T/As.    I'm afraid I can't tell you poundage I went for as its a while ago, but I do know that it is pretty soft, definitely not a track or harsh one. 

You do of course need better shocks with a composite spring and I went with Koni adjustables all round, which have worked really well.

The swap was easy enough, just care needed when torquing up the new spring.

One thing I would certainly consider is replacing the original rear cover with a new HD one. It's right there and you might thank yourself in the future. 

Mine broke while re-assembling the spring in the car after re-furbishing with new liners and paint. . I probably did not do the assembly correctly, so it busted off one of the perches while tightening everything down very slowly evenly. 

The iron they used must become weak over the years and taking it apart and re- assembling finished it off. 

Not too expensive but it is a bit messy. Adding new lube and posi additive won't hurt either.....