Leaf Suspension Tech - Planning for my 04' Tundra

[E.Roy]

Stock 2001 Tundra access cab springs are 56.25" and 56.38" center to center in free state. These were used for almost 15 years.

I didn't measure free arch, but I will soon to help out your geometry investigation.

Great, thank you. I know that the center to center distance from front hanger bolt hole to shackle hanger pivot hole is 59.5". Given that info, the stock shackle should lay pretty flat at droop.

 

[dyogim]

Leaf spring I-2-I (with no load) is 57.75".

 

[E.Roy]

The reason it's not drooping any further is because of the leaf spring itself are too stiff. The front part of the leaf spring has no where to go in order for the shackle to move down in an arc. Imagine the rear of the leaf pushing forward as it's being pushed down in the arc. Softer springs will bend more allowing it to travel along the arc with less force. Plus, if you let the shackles go past a certain point/angle, they won't cycle back up. That's why the mount has a lip to stop the shackles from cycling down any further.

Post#98^^ Mike, I think you are right with this info, but I think I can add a little. I would guess the stock springs are a high spring rate, with low arch, probably for load capacity to keep the sag/pound ratio low as it gets loaded. This compromises wheel travel, both up travel and droop travel. A lower spring rate, softer spring with greater arch is more flexible as you load it, it has a higher sag/pound ratio. You can get both springs to support an unloaded truck at the same height, but one moves much more and also will sag further with the same additional load that a high spring rate will support with less sag. That is why you have to compromise, unless you add an adjustable spring device like an air ride system

 

[WillBeck]

You might be right that a shackle flip may not help much with the same length or stock shackle. I'm happy with being honest about the facts on this, I guess we can wait and see in a few weeks or so, Addison's kit is en route. Member Cam-shaft on his 2005 Tacoma stated he got better droop travel with a shackle flip and they are similar beasts. I spoke with Deaver Spring and they schooled me and pointed out that the 2nd Gen Tacoma and 1st Gen Tundra are difficult platforms to address because of the spring over axle arrangement (if you stay with that), for this reason: the springs are very flat. Spring designers (besides Toyota) do not consider going past flat into negative arch as useable range, and a tidbit I picked up is that the axle starts moving back toward the engine in that range (not really bad). However, the Tacoma and Tundra are perfect candidates for conversion to spring under, large gains in wheel travel come with it. SUA allows you to go from flat springs to much more arched springs all without lifting the truck much. SUA brings a large gain in bump travel because of the distance from normal ride height (significant acrch) to the condition where the spring is compressed to flat (the accepted max compression point).
Most of Expedition Portal members aren't focused on uptravel, they want flex and load capacity. I am game to offer parts that really help owners achieve their goals, that's why the shackle flip idea needs to be tested

Can someone with a loose set of stock springs laying around measure the exact eye-to-eye length? I have a feeling the free length of stock springs are what is limiting droop with stock hanger. Then I can do some figuring and drawings to help see what's really going on.
Eric

Spring under is an excellent option as well. More setup cost, but ultimately a great way to go if you have the coin.

 

[toyotech]

Spring under is an excellent option as well. More setup cost, but ultimately a great way to go if you have the coin.

I see this option more for long travel desert jumpers.


Sent from my iPhone using Tapatalk