Rear Spring Comparison
 

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.

Re: Rear Spring Comparison
 

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

Re: Rear Spring Comparison
 

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

Re: Rear Spring Comparison
 

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

Re: Rear Spring Comparison
 

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.

Re: Rear Spring Comparison
 

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.

Re: Rear Spring Comparison
 

Meant to say shocks

Re: Rear Spring Comparison
 

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??

Re: Rear Spring Comparison
 

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)

Re: Rear Spring Comparison
 

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.

Re: Rear Spring Comparison
 

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

Re: Rear Spring Comparison
 

I second this! Its the only way to go!:agree:

Re: Rear Spring Comparison
 

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??

Re: Rear Spring Comparison
 

Dominator 2600. Air lift!

Re: Rear Spring Comparison
 

Slam Specialties re-7 or ss-7