How do leaf springs provide lift?
 

So as I understand it, MC's springs are 46.5" long, measured from eye to eye along the top spring and all of TG's springs 3,4,5" are 47" ....

What I'm not getting is how each spring can be the same length but provide more lift yet require the front hangar to be positioned further forward.

For example, the 3" TG springs (that i have) I have my hangar substantially further back compared to what you see and my shackle is moved slightly forward of where TG reccomends it be which is cenetered in the body mount, vs mine which is slightly forward of that (Wish it was even further forward eh)

I mean if all the spring packs (regardless of what they say the lift is) have the same number of leaves and the top leafs are all the same AND spring rates are same, wouldnt the direct eye to eye measurement be less and less (as you move up the lift chart 3,4,5") ???

:saw:

So my question is, what exactly is the difference between the spring packs?

=/ . . .

anyone have any input?

I also have the 3" springs and realized the same thing... I want answers! just curious tho really...

Im no spring expert, but i would guess that the lift that a spring gives depends on the arch of the spring and also the length of the shackle that you use.

springs are measured EYE to EYE, NOT along the spring itself...stretch a piece of string from eye to eye and measure it...that's how they measure them.




I BELIEVE?

Nope.

They are measured eye to eye along the length of the spring as if it were flat.

TG springs are not all the same length. Nor are All-Pro or Marlin's.

The 3" TG springs are significantly shorter than their 4" springs or 5" springs. Usually around 2" shorter which is why the OP had to move things where he did.

The lift height is based on spring arch for the most part.

Also, the amount of lift you get is not necessarily 3",4", or 5". You actually get a lot more lift than that. In fact, on a recent 4runner build that I did, the lift was actually around 7" of actual overall lift compared to stock when it left the shop. The kit used was a 4" front/5" rear kit. Now, it will settle around 1-1.5" overall after a few months.

Just an FYI.

aww now i feel stupid...LOL:chairfall:spank:

Well ya thats how they are measured. My questions is why sacrifice the length giving me a horrible shackle angle? Mix up the spring pack a little differently... I dunno

Man, why the heck does all their sites list ALL their springs at the same lengths?

From TG,
"Our front springs feature a full military wrap on the front and the 1/4 wrap on the rear. Spring rate is 220 lbs per inch. Leaf pack is 6 leaves.

Springs are 47" long as measured along the top leaf.

Pin to center of front mount is 22" and pin to center of the shackle mount is 25". New poly bushings and left side spring pad are included with springs."

I figured they HAD to be different lengths. If you increased the arch on my 3" TG springs you'd have to move the the hangars closer together, it's pretty obvious geometry! I just wish the mfg's actually listed details on each spring pack they sell, guess if i want specifics ill have to contact them directly.

I was considering changing over to MC 4" packs but wanted to get an idea of how much ill have to move the front hangar forward. Right now my hangar is 3/4" from flush IIRC which is "far back" by most SAS standards but the 3" packs just must be really short ive never measured mine. My axle is moved 1" forward on the the perches and this seems to work great for clearing 37's and getting a low stance with a shorter spring.




anyhoo thanks Scotty for the info!

You put your front hangar flush and now you have a near vertical, if not completely vertical shackle sitting level?

Basic rule of thumb ive found with doing a SAS is to shuv the rear shackle tube as far forward in the body mount as you can. I wish i had known this before i did mine, i did move mine almost all the way forward but theres still some room left. But i ended up moving my hangar back 3/4" so the shackles operating like it should now for full up and down travel of the spring.

To get the axle further forward I moved it forward exactly 1" on the perches.

You don't mount all front hangers the same and not all frame tubes go in the same spot, nor do you use the same length shackles for every kit...for optimal performance. It takes some experiential knowledge to know what springs work best mounted in different ways. Slight differences make big differences.

While these are certainly DIY kits with all the parts supplied, you still should tack together and test fit for the best angles before welding out.

:guitar: