Convex or Concav - Front Springs

[Stage1]

The front springs on 1986 1 ton 4x4, what were they when new convex bowed down or concav bowed up? Currently they are concav, bowed up about 2 inches from the center line of the spring eyes.

thanks,
Les

[Dieselboy]

My suburban came with the heavy duty three leaf suspension, and had a negative arch. I've not seen a factory spring pack except the two or three leaf variety - both of which had negative arch.

A positive arch might mean aftermarket or re-arched springs.

[Stage1]

Additional information on condition of origional springs, the wheel well opening height at the wheel center is front 37.5" and rear 38". This is with the origional Firestone tires worn about 2/3s. How much have the springs settled? Also if getting new springs should the front axle be moved forward about an 1 inch for more tire clearence?
thanks,
Les

[Stage1]

David,
Thanks for the information, these have three
springs, at 23.5 inches center to eyes both front and rear.
thanks,
Les

[Stage1]

David,
Thanks for the information, these have three
springs, at 23.5 inches center to eyes both front and rear.
thanks,
Les

[84 Convert]

My K30 dually has negative arch front springs, however, my k2500 has positive arch springs that came from some sort of gov't special order truck, the rear 9-leaf springs have a matching amount of arch (no lift blocks). These are the only "stock" springs I have come acrosst that are positive arch in the front. I think you could re-drill the hole for the centering pin 1" forward to get the result you are looking for. You may have to sharpen the drill bit a few times, and a drill press is highly recommended with steel that hard. Also, use plenty of cutting oil it sure makes things work better. Good luck!

Gregg

[Dieselboy]

If you're looking to run a larger size tire (33"+), then moving the axle forward will gain you some decent clearance. The rear part of the front fender is always the first to make contact with a tire while flexing. My 35s have a way of self clearancing the fenders. :D

I would avoid redrilling the springs themselves since spring steel is usually hardened to 47 HRC! That would eat through a drill bit or three not to mention that you increase the likelyhood of cracking the spring around the former center pin holes. Instead, Offroad Design makes a 1" zero rate add-a-leaf (http://www.offroaddesign.com/catalog/Zero%20Rates.htm) that allows for you to move the axle forward 1-1.5". I've installed some, and the quality is top notch with a reasonable price.

PS: the actual spec on the front springs is 48" eye to eye. Rancho 44044 4" lift springs are the best all around at 48" if you're looking in that direction.

[G. Gearloose]

I concur the rancho 4" front leafs are nice stuff, I've had two.

Thanks for sharing the link on the 1" add-a-leaf-block-thingies.

I have a K5, and with the 6.2 and 8' Fisher, its just a little front-heavy, I think that inch will help the balance.

I need to lengthten the front propshaft anyway, so good timing, thanks.