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Ok another perdicumant  , went to install front springs with isolators ,the isolators dont look like there the correct size for the spring that came out of the car .S ummit says they are the correct isolators. anyone know the correct diameter and length of stock coil spring for the front of 70 ss 454? thinking mabey someone switched springs back in the day.Also dont remember any isolators that were there when I took the springs out.

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There were 10 different springs (each identified by a two-letter code) that were possible to include in a 1970 Monte Carlo at assembly (see table photo below).  The proper spring was "computer selected" based on the weight of that particular vehicle (including all factory installed options).  If you have a build sheet for your '70 SS, it will show the front spring code in Box 13.  My '70 SS was moderately optioned and was still built with the strongest/heaviest of the ten springs available which was spring code GQ.  Assuming yours was also built with that spring, here are the specs:

Part Number = 3952813

Cutoff length = 149.85"

Wire diameter = .621"

Total coils = 11.22

Deflection rate  = 275 pounds/inch

Free height = 18.13"

Working height = 11.7"

Preload force = 1760 lbs (18.13" - 11.7") x 275 lbs/inch

It is entirely possible that your original front springs have already been replaced, usually during a front suspension rebuild.  If so, the Moog 6331 is a very popular replacement spring since the original part number springs are no longer available.  When I rebuilt the front suspension of my '70 SS, I discovered it already had that Moog 6331 installed (the spring number is stamped near one end of each coil).  You can google that spring for its specs.

As others have said, there ae no isolators used on the front coils (only the rear coils).  However, there are two very important things to observe when re-installing the front coils on a '70 Monte:

1. The top of the coil must be correctly positioned/centered around the tabs that stick down up inside the frame's spring opening.

2. The bottom of the coil must be correctly indexed/clocked so the end of the coil rests between the two small drain holes in the lower control arm.

There are several possible ways to safely install the front coils but I have found using a quality internal spring compressor (carefully positioned on the spring to both compress and shape it) worked best for me.  Good luck!




'70 SS Front End Rebuild 207.JPG

'70 SS Front End Rebuild 198.JPG

'70 SS Front End Rebuild 218.JPG

FGMC Spring Specs.jpg

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Wow ,thanks for the wealth of info ,really helps .I find it crazy that summit and jegs  say that spring isolators are needed in front top of the spring ,wasted over a hour yesterday on the phone trying to find a answer. I should have posted here first,nothing like experience . These  sights would have been handy 30 years ago when you had to find your answere in a motors manual . Once again great info . Thanks to everyone

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