Need front spring height advice - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**RenoKeene** · 11-19-2010, 02:23 PM

I have a 70 GMC factory BB402 that I put 2-1/2" drop spindles on with new stock height big block springs and new 3/4 ton shocks all from American Classic. I am transfering every thing to a 67 short bed chassis and I want to lower it only 3/4" more. I think I can do this by cutting maybe 1/8 of a coil off or less. I need some advice so I don't go too low and ruin the springs. Any help would be apreciated. Would 1/2 ton stock shocks help? Also if anyone has a part # for the front sway bar mounting plates for lowered trucks, that would be great. Thanks

**RenoKeene** · 11-20-2010, 05:53 PM

Any opinions on this?
Here is what I'm thinking
1 coil eq. 2 to 2-1/2"
1/2 coil eq. 1 to 1-1/2"
1/4 coil eq. 1/2 to 3/4"?
Posted via Mobile Device

**N2TRUX** · 11-20-2010, 08:33 PM

I think you are on the right track with your formula. Getting "exactly" 3/4" is going to be more luck than science though. If you want to be conservative then cut a 1/4 coil and run it for a bit to allow it to settle.

Personally, I think I would be tempted to cut 1/2 a coil and see what happens.

raycow · 11-21-2010, 04:41 PM

Keep in mind that the relationship between the amount you cut and the amount you drop isn't linear. This is because the spring gets stiffer as it gets shorter. If you think of the spring as a torsion bar wound into a coil this might make more sense.

Ray

**RenoKeene** · 11-22-2010, 10:43 AM

Thanks everyone. When I do it I'll let you know how it turns out.

Any help on the front sway bar mounting plates for lowered trucks? I saw them in a build thread in here somewhere, I searched....and searched.....and.... can't find it again, should have taken notes!

11-19-2010, 02:23 PM	#1
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	Need front spring height advice I have a 70 GMC factory BB402 that I put 2-1/2" drop spindles on with new stock height big block springs and new 3/4 ton shocks all from American Classic. I am transfering every thing to a 67 short bed chassis and I want to lower it only 3/4" more. I think I can do this by cutting maybe 1/8 of a coil off or less. I need some advice so I don't go too low and ruin the springs. Any help would be apreciated. Would 1/2 ton stock shocks help? Also if anyone has a part # for the front sway bar mounting plates for lowered trucks, that would be great. Thanks __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

11-20-2010, 05:53 PM	#2
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	Re: Need front spring height advice Any opinions on this? Here is what I'm thinking 1 coil eq. 2 to 2-1/2" 1/2 coil eq. 1 to 1-1/2" 1/4 coil eq. 1/2 to 3/4"? Posted via Mobile Device __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

11-20-2010, 08:33 PM	#3
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,021	Re: Need front spring height advice I think you are on the right track with your formula. Getting "exactly" 3/4" is going to be more luck than science though. If you want to be conservative then cut a 1/4 coil and run it for a bit to allow it to settle. Personally, I think I would be tempted to cut 1/2 a coil and see what happens. __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

11-21-2010, 04:41 PM	#4
raycow Registered User Join Date: Mar 2003 Location: San Francisco, CA USA Posts: 2,454	Re: Need front spring height advice Keep in mind that the relationship between the amount you cut and the amount you drop isn't linear. This is because the spring gets stiffer as it gets shorter. If you think of the spring as a torsion bar wound into a coil this might make more sense. Ray __________________ Live more responsibly. Eat lower on the food chain. Eat vegetarians.

11-22-2010, 10:43 AM	#5
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	Re: Need front spring height advice Thanks everyone. When I do it I'll let you know how it turns out. Any help on the front sway bar mounting plates for lowered trucks? I saw them in a build thread in here somewhere, I searched....and searched.....and.... can't find it again, should have taken notes! __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394



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