Rear Spring Comparison

[Spike 72]

I have a 72 GMC shortbed. I installed new 5" coil drop springs from LMC. They ride pretty well but the rear end is very spongy & I cannot put much weight in the back. Has anyone else had this problem? If so, what did you do to fix it? POL springs (Performance Online), Belltech, Hotchkis, these are all double the price. Is it because they are progressive springs & the LMC one are not progressive? or has anyone installed the airbag helper springs? If so, how do you like them & how did it change the ride? thank you for the help.

[Coley]

Given the 5" drop....it sounds like you bought and installed springs designed for looks and not load....so that is just the lay of the land at the moment.
Adding Airbags would give you the options on perhaps performing both functions.
All good
Coley

[Spike 72]

Thanks, I was curious if the springs from lmc are progressive, I wondered if that would fix it. what springs are you running?

[66clow]

What do you have regarding springs? Did you replace them?

[old Chevy guy]

Generally a progressive spring will have larger spaces in the loops near the bottom and get progressively closer near the top. That way the wide spaces close up first and the tighter coils carry more weight as the spring loads up. If the loops all look evenly spaced then the most likely are not progressive.

[Spike 72]

Thank you Old Chevy Guy. I will take another look at them, i believe i will try the air bag HELPER spring from the Airlift company. If i dont like that maybe go with the Hotchkis springs. if i dont like the ride etc. at that point, i guess i can look into bagging the rear.

[66clow]

Originally Posted by 66clow

What do you have regarding springs? Did you replace them?

Meant to say shocks

[Spike 72]

Sorry for the delay guys. yes new springs are from Lmc, the number ON the Spring itself is RC603-4 which is a CPP spring. I looked it up it should be a 4" drop spring. very soft. I did install new shocks at the time i installed the new springs. they are however NOT lowering shocks. Just a good brand shock. How important is a lowering shock? And or a shock relocator kit??

[Spike 72]

I also just Finished installing air "HELPER" bags today by Airlift 1000. its a universal kit so i did have to drill a hole at the top of frame by the bolt to feed the airline in. Not sure im gonna like this yet because by the time i get enough air into the bag to make it ride better it lifts the truck. So, will update after i get a few miles on this and see if i can find a happy medium. ( could drop it back down an inch with a lowering block)

[lolife99]

Personally I would run an air bag without the spring.
Use a 2500 or 2600 series bag with no top bracket.
Then add a 1.5" or 2" lowering block to help keep the ride height low.

But you also need rear shock relocators an adjustable pan hard bar and quality drop shocks.

[Shinysideup]

Summit carries the CPP spring made for a real truck, lowered but rides and carries a load without need for helper stuff.

Part # 603-4HD for a 4" drop

[Robznob11]

Originally Posted by lolife99

Personally I would run an air bag without the spring.
Use a 2500 or 2600 series bag with no top bracket.
Then add a 1.5" or 2" lowering block to help keep the ride height low.

But you also need rear shock relocators an adjustable pan hard bar and quality drop shocks.

I second this! Its the only way to go!

[Spike 72]

Thank you guys. I will look into the summit springs. if i go with the bags, What brand of bags do you like to use??

[Robznob11]

Dominator 2600. Air lift!

[lolife99]

Originally Posted by Spike 72

Thank you guys. I will look into the summit springs. if i go with the bags, What brand of bags do you like to use??

Slam Specialties re-7 or ss-7