I just ordered a set of 2 inch superlift coils from my local performance shop. they sent me coils for a hemi. needless to say i didn't check the part numbers and i put them in. well they lifted the truck exactly 1 inch, not 2. this is when i discovered the part numbers are wrong.

If i leave these coils in there what's gonna happen over time? are they gonna sag like crazy?

it looks pretty good i may just leave it like it is, oh yeah and for those guys who want a levelin kit alittle less than 2 inches, these coils ride awesome. not at all like a boat-ride feelin, but they ride a ton better than stock.

 

they are probably straight 380 or 420# springs. you should have progressive or straight around 500#. ks

 

I would be interested to see if they would begin to sag... I doubt it tho, just think of our poor springs in the rears of our trucks, that see alot of weight often... they do ok. Still something to ponder tho! Post a pic!

 

I think your biggest problem is that they will be too soft. You will be hitting the bumpstops on every speedbump driveway curb, offroad etc. Did you replace the factory bump stops with the Superlift ones that came in the kit?

I had the Superlift kit on my 04.5 with the right springs and it rode great too. I would tell you to get the right kit.

 

I'd take them back. The HEMI is much lighter that the CTD. You need CTD springs so you have the right spring rates.

DT<*)))><

 

You guys are funny..... what is the "right" spring rate? Do any of you know how to calculate spring rates? My calcs come out to around 400 lbs as the optimum spring rate for the sprung weight of a 3rd gen diesel.

TopBanana, if you're happy with the ride height and quality, keep 'em. They won't fatigue or sag any sooner than the "diesel" coils.

If the Hemi coils are anywhere 20lbs either side of 400lbs/in. you'll like the ride. What you'll really need is a quality shock to back it up.

Most folks tend to overspring the diesels because of the weight......this just results in poor performance and a harsh ride. You don't need a 500#+ coil on these trucks.

To give you any idea, I run a 360# spring on mine. I've had them over 2 years and they haven't sagged yet.

 

thanks for all the responses guys.

i guess i'll give them a shot for a while and see what happens. it's not to big of a deal to swap them out later. they ride really nice with skyjacker nitro shocks.

i posted the pics in my gallery, pending approval. take a look!

 

harsh? i think my new 06 CTD rides to soft. specially the rear!

 

[QUOTE=Cowhand]You guys are funny..... what is the "right" spring rate? Do any of you know how to calculate spring rates?

I don't calcualte spring rates I measure them! Softer springs might be OK but this is a truck not a race car. If you change spring rates then you need to consider the rest of the suspension like shock rates, roll rate, and sway bar.

Lighter springs most often require more sway bar to keep from rolling or leaning over in corners. Adding height at a sofeter rate will only make this more prevelant. Add this to hauling heavy and you'll see a different truck completely.

It's definitly ok to run lighter but consired what you need the truck for and decide. If I never planned to haul with mine I would drop it down but I have a car already.

 

[QUOTE=Derek Timm]How do you measure them? Free height? Ride height? Height at coil bind? Gotta calculate the spring rate to find out how far the spring will compress at ride height and how to valve the shocks. I guess you could measure the wire diameter and count the number of coils, but that tells you what the rate is after the fact, doesn't it? I prefer to calculate the spring rate I need, then order the coil accordingly.

That's why I said back it up with a quality shock. I run a factory sway bar with a +6" soft coil. It rolls less now than it did with the OEM set up. Why? Little bit firmer compression valving in the shock. When I change the sway bar out, it'll be a little bit softer than the factory bar.

It's not a sports car, so I wouldn't be too concerned about calculating roll center. COG is too high to make much difference with a sway bar anyhow.

The purpose of the front spring is simply to hold the front end up and extend the shock after it's been compressed. Overspringing the front with a higher rate coil just overpowers the shock and doesn't let it do it's job.

Changing the spring rates is not rocket science. Going to a softer spring, as long as it's backed up with a GOOD shock, can make a pretty significant improvement in ride quality and performance without any adverse effects on handling.

 

[QUOTE=Cowhand][QUOTE=Derek Timm]

How do you measure them? Free height? Ride height? Height at coil bind?

Yeah all of the above come into measurement. I have acces to a spring rater at a friends race car shop so we can check all of the above. The main thing I was saying is a spring change can make other things happen with these trucks.