things nobody ever seems to address or consider it seems.

what is the spring rate of the chevy pack. is it a progressive rate or flat? what is the rate on a stock toyota?

also every time i have ever tried to use lift blocks bad things have happened. from broken ubolts to sheered center pins to spring wrap or even broken blocks. what is the preferd block setup.

what pinion angle do you get with no lift block? angle with a 3" lift block?

1) Don't know the spring rate, but they are VERY soft (not progressive) and don't hold a load well w/o the overload installed (sag w/ weight). I believe the stock Toy rate is 150lbs/inch and I'd guess the Chevy's are similar but they work MUCH better overall...

2) I've used 3" Procomp, 2" Trailmaster (currently), and the stock Chevy overload (~1") turned upside down. Use 9/16" or larger u-bolts, keep them tight, and you shouldn't have any problelms. I haven't anyway. Center pins should be good too if the u-bolts are tight. Use a torque wrench!
"Preferred" block setup would be to build your own into the perches on the axle, setting the pinion angle as needed while you're at it (see next).

3) I'm not sure what pinion angle you end up with matters as much as what you should set it at for your particular application after the swap is finished... (CV, no CV, how much lift, etc.).

Good luck, Camo. I think you'll be happy with this swap! ;)

LOL ya i am swamping out my 4 link coilover for junk yard chevys ....:flipoff2:


not for me but a friend is doing the swamp and i was curious.

besides the info needs to be added to the tech list.

so from your guys lack of replys i assume none of you junk yard engineers have actually run the #'s. you just run what the last guy did and hope it works?

all Leaf springs with shackles are progressive to a point as the sahcle moves up it is lowering the spring rate. so the rate of the spring varies to the shackle angle.
The springs I'm runing ( which is the shorter chevy springs from the mid 70s to mid 80s 53" long better departure angle and still flexs good) saged 1 inch less then the stock springs, which were wore out, with 200lbs on them.
As an eample of the varable rate be caus of the shacke angle I orginally set the shackles up with a 15 degree angle and drove the toy around a few days and the ride was very harsh. I then changed the shackle angle to 45 degrees and the ride improved considerablly. The only draw back to the steeper angle is it lowed the rear of the toy a bit but improved compression and drop.
I know this is not a direct answer to your ? but hopfully it helps.

I don't have any stock springs available, but these are the numbers I have for the 3 leaf chevy's I put on vs. the NWOR 3.5" springs I took off:

Chevy's: 145lb/in

NWOR: 358lb/in

The NWOR were the heavy duty springs for a 81 toy pickup.

I don't know what the best block is becasue I'm using a fabbed rotating perch that gives me around 2" of lift, similar to the ones made by bcbroncos (bcbroncos.com).

I will measure my pinion angle when it is done and on the ground, I haven't finished yet.

If anyone has a set of stock springs, the equation I used to calculate the spring rate I found in the dec. issue of petersens off-road:

W = width of leafs in inches
F = number of leafs
T = thickness of one leaf
L = length of spring

(W x F /12) x (1000 x T / L)^3 = spring rate

come on doesn't someone have any stock springs around. All you have to do is take 3 measurements and do a little algebra. If you really can't do the algebra just stick the measurements up here. I'm curious.

stock 91 springs= 182 lb/in
I'm getting 16" at each wheel with stock shackles

Originally posted by camo
so from your guys lack of replys i assume none of you junk yard engineers have actually run the #'s. you just run what the last guy did and hope it works?
that's right:confused: I saw allot of people running them and saying how good they were so I got some....same for the dual t-case,44044's,39.5 tsl's, lockers, ect.....:flipoff2:

Originally posted by camo
so from your guys lack of replys i assume none of you junk yard engineers have actually run the #'s. you just run what the last guy did and hope it works?

Yup :flipoff2: Why bother to reinvent the wheel, when there are several proven setups out there. I'd rather use something that is already proven, rather than having to jag around with it to get it to work well. Leaves more time to actually wheel! :D