Leaf Spring Rate

[SuperCab]

Hey guys.

Any suspension experts here?

Whoever had my sig truck before us put a huge set of springs out back. IDK what they had back there, but it was more than the carpentry tools we have in there now, and they beefed it up big time to carry it all.

So how do I know how many springs I need back there? The truck weighs about 7,000 lbs. It has like 8 or 10 leaves; it looks like they just took the springs from 2 F250s and stacked them all in.

I know it needs less then it has because it's crazy hard to control; almost like it's straight welded to the axle.

Does anyone know how many springs I should keep back there or have any info that can help?

Thanks in advance guys.

 

[jr32560]

I ain't no expert on nothing but my brother in law had a 73 250 and the springs on the back of that thing were like 6" thick with a set of overloads to boot-rode like a hardtail Harley! no bounce-they were some stout trucks!

 

[SuperCab]

Yeah, it's rediculous. Hopefully someone can help...

 

[Skandocious]

I seldom see a stock spring pack thicker than about 4-5 inches MAX. You've got WAY too many leaves on there. Some of the newest ford trucks only have 2-3 leaves.

Just head to the junkyard and find some stock springs from a comparable truck. That's the ticket

 

[john112deere]

I seldom see a stock spring pack thicker than about 4-5 inches MAX. You've got WAY too many leaves on there. Some of the newest ford trucks only have 2-3 leaves.

Number of leaves isn't the only relevant factor in determining what springs work for your application. Thickness plays a role, too, and newer trucks seem to use fewer, thicker leaves.

Can you post a pic of your springs, SuperCab? Might make it easier than trying to explain what you've got...

*Also, trucks, especially heavy duty trucks, especially old trucks, and more especially old heavy duty trucks, DO bounce bad on rough pavement and are harder to control. Even a Ranger with the heavy service springs will hop sideways on bad roads if you hit the bumps too fast...it's part of driving a truck, and part of why many people prefer Buicks.

(Also, adding weight is probably easier than changing springs...throw 200 lbs of sand back there or something if your tools aren't heavy enough.)

 

[SuperCab]

I know there's more to it than number of springs.

I'll try to post a pic if I can.

Also, I know some old trucks do hop a little, but there's not that much of a load on this truck; if it's hopping this bad, it just doesn't need all the spring it has.

A few hundred pounds of sand would probably help, but the mpgs are just that much worse then.

I wouldn't be caught dead in a buick, or at least not for about 60 years.

 

[SuperCab]

Bump...

Someone must know somewhere to point me or something...

 

[smokey]

the older f250's had 6 or 7 spring ply's IIRC.

 

[SuperCab]

What do you suppose the GVWR was for those f250s?


Edit: I just went outside and looked. It has 8 leaves on each side; they're about 1/4 inch thick. Hope this helps.

 

[SuperCab]

Bump...

Hoping the right person will see this and be able to give a definitive answer...

 

[smokey]

Should be either a 6 or a 9 pack
Either some one added 2 or you missed one.
Being a supercab I would guess it is the 9 pack
here is a link to the parts
http://www.lmctruck.com/ICATALOG/FC/full.aspx?Page=111

 

[SuperCab]

I'm thinking after looking at your link and elsewhwere, that I need to lose 2 or 3 springs and it should be perfect.

Finally we're getting somewhere! Thanks Randy and others and any more help is still appreciated.