Ok so I'm a bit stumped.

I've blown quite a few brain cells taking in ALL the information over at pirate 4x4 on putting rear toyota leafs up front.. Ok well I'm not going to do that when I SAS.. but.... Why are people putting chevies out back if they're putting rears up front????? Everyones adding leaf packs to the rears upfront, WHY can't we add leafs to the rear and get the same flex as we're getting upfront with the rears...

I just DONT get it... Besides, chevy (63") don't flex worth CRAP if theirs not enough weight on them... so WHY do we stick springs with high spring rates back there and stick are perfectly GOOD rears up front that flex amazing (upfront).

Ok, so heres what I know.. When they move them up front you lose the overload spring and people cut and match wagoneer or mazda springs to whatever ride they like... Ok so WHY can't we do that out back?

I've got an EXTRA set of 86-89 (48") Toyota rears to work with.

Can't I ditch the overload and add in a leaf or two to make a softer and flexier rear leaf pack?


SOMEONE please help me understand why I can't find any reasons why folks don't just re-do the stock rears? Ok I've found one guy who used rears all around but just one.. ...

Stiff, long crappy chevies or the already trail-proven adequate rears (used up front)???? ...
CONFUSED




***Stock rears with 6" shackles my springs actually flex out and stop at 22.5" shock length (eh, didnt measure frame to axle) ... but my shocks max extend to 22.5 and thats exactly how far the axle drops with stock rears and 3" shackles..[without shocks installed] Now I'm going to go to 2" shackles next month cuz I don't like the the rear rake and 3" is a bit much ... kinda makes me nervous a shackle bolt might snap heh.. unlikely but @3" over stock its gettn there on leverage...

anyways, if I can go back to STOCK shackles and just fix the rear leafs to flex more... i dont know, point and goal is to get as much flex out of a STOCK rear end without lifting the truck more than 2".

thanks =)

 

People do that because it is cheap.

 

my chevies in the rear flex amazingly. my limiting articulation in the rear is either my wheel wells or my front IFS

 

I always thought that people used 63" Chevies in the rear, and Toyota rears up front because they are respectively longer from eye to eye than stock. A longer spring can have a flatter arch, which ultimately makes it easier to flex.

 

LOL thanks I didnt know that

I'm looking to get more flex out of the stock rear-end. Eventually it's all getting replaced with aftermarket springs with the SAS but till then I'm looking for advice and meshing TWO sets of rears into one to get something more back there!

 

You got it. That is true.

However if you browse the pirate faq on rears up front the flex upfront is by far better than what you get out of stock springs in the back. But the mounts are the same .. To me if you got 48" springs upfront, shouldnt the same springs flex the same in the rear? Well, maybe not AS good because there is less wait but atleast the potential is there.. right now my stocks dont flex very much, better than IFS but not as much as I've see on some of these sas'd rigs with em up front..... Kinda see why im curious?

They remove the overload spring and add springs (thin 6mm-7mm) to get the flex or whatever they want..

i'm just wondering if you can do the same in the rear with similar results.

I'm asking from a stand of having NO spring building experience whatsosever... =)

 

The lenght of the spring affects the "rate".
Also the geometry of the spring changes as well with lenght and shackle lenght...

In the case of the 48" rears up front - thers alot more weight up front (engine) versus rear (empty pickup bed)

But the main reason for Chevy conversion is - its cheap...
Theres a ton of em in the junkyards.
They sell for not much
Ther are likely to be "pre-softened"

Notice that Dez Racers do a 63" conversion but do NOT use Chevy spring packs....

 

I think you have to also consider the position of the spring in relation to the axle.

Front spring perches are far more inboard, leaving more of the axle hanging off the ends. Doing the math, you can see how much farther the wheel will travel then with the springs at the axle ends.

Envision a teeter-totter. Move the fulcrum (spring perch) towards one end of the totter, your respective totter end isn't going to travel very far. Move the fulcrum farther away, and the teeter end is going to really going to cover some distance in relation to the fulcrum.

Thus... increased flex with the same springs... magic.

I have seen some rigs on Pirate move the rear springs in board to match the front, and in turn get monster flex at both ends. Of course, you are looking at a lot of body roll that way on road... but for trail dedicated, who cares.

 

You can add leaves to the rear, but there is a limit to the flex you can get with the stock length leaves and the free arch. Moved up front, you are putting a longer spring in there and you are moving the front axle forward 2". As noted, with the extra weight and with the more inboard spring location, you get a lot more flex:



In back, more flex usually means longer springs, I run 56" Alcans:
http://www.4crawler.com/4x4/4R_suspension-III.shtml

 

Bingo. That's why rears flex better up front than they do in the rear. They are farther towards the center of the truck. The spring doesn't have to travel as far to get more movement at the end of the axle, i.e. tire.

 

I have a question for those that have used Toyota rears for their SAS- how much spring lift do you get? When I SAS my rig I want to run 33's, every kit out there comes with 4" lift springs minimum, but I'd rather go for 2.5-3" of total lift, including whatever lift I get out of the front hanger and a decent shackle.

 

The lift you get from running rears up front depends on what donor springs you add to the pack when you build it. You won't be able to run just stock springs because they'll be too soft.

You'll need about 4" total lift (including the lift created by the spring hanger and shackles) in order to clear the hi-steer setup.

I'm running Trail Gar 3" springs, and with the hanger and shackles I initially had about 5.5" to 6" of lift up front. That's about 2" more than I wanted, and my springs have only settled about .5"