mommucked

I have 2" lift rear springs on my 84 truck now, some years on them but not much sag. They are NWOR springs. I am going to replace the fronts w Pro Comp 4" springs I have as my old 3.5" NWOR front springs are sagging. I have 2.5" angled blocks on the rear now and rear is too high. I plan to get 1.5" rear lift shackles, and ditch the blocks, to level the stance but assume i'll need shims to adjust the pinion angle for the 2" rear springs. What degree shims do I need for this setup? and where can I get them cheap?

dropzone

iTrader: (6)

check out 4crawlers website, he makes them.
I would also wait though to see what your pinion angle looks like after you do your spring swap

mommucked

I'm not swappimg the rear springs, I'm lowering the rear 3" by removing the lift blocks. Right now I have 2" rear springs and angled 2.5 or 3" blocks w shimming built into the blocks and it's not right. I get an audible/felt vibration at certain speeds 45-55mph when cruising on flat pavemant w little throttle. I thought it was the old 250k tranny/ tf case that was chattering, but swapped it and nothing changed but the chattering. I also swapped Rear diff,and Driveshaft, nothing changed, so i'm assuming its got something to do w the rear pinion angle that appears to be not turned up quite enough right now. I also have older NWOR traction bars that sit on top of the of the springs that may be part of the problem, and I intend to remove them and use lift shackles to improve axle wrap amplified by the blocks I've used to get rear lift more than the 2" springs. The traction bars eliminated the axle wrap or wheelhop wthe liftblocks, but also impede articulation. I the guess the simple question is how much shim degree for 2" lift rear springs on a 84 reg cab as I assume the rear 1.5" shackle lift will adjust it only slightly if any?

waskillywabbit

iTrader: (-1)

With so little lift pinion angle really shouldn't be an issue.

:wabbit2:

mommucked

Thanks for the advice, I guess the vibration, metal on metal, from the feel of it, is coming from the old traction bars. where the threaded front rod clamps through a bracket attached to the front spring hanger w old worn poly bushings and do'nt need shimming for the 2" springs lift? the fine threads on the bars are rusty and cannot be tightened anymore so the bar may be slopping up and down in the bracket causing my vibration problem.

4Crawler

iTrader: (3)

Measure and you'll know the answer:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1
- http://www.4crawler.com/4x4/CheapTri...l#Measurements



May not need any correction depending on the type of lift and the type of drive shaft:
- http://www.4crawler.com/4x4/CheapTri...FixingProblems

mommucked

I don't understand the parellel diagram? My stock axles have twist built into the equation by the placement of the spring perches. Front and rear pinions are pointed up towards the transfercase from the factory?.

4Crawler

iTrader: (3)

What kind of drive shaft do you have? Is it 1 or 2 piece and is there a u-joint or a CV joint at the top end of the shaft?

I was assuming you have a u-joint (single cardan) shaft as it is the most common setup from Toyota. If you have a CV shaft, then yes, you want the pinion flange pointed at the t-case:
- http://www.4crawler.com/4x4/CheapTri...n-Measurements

mommucked

It's a stock driveshaft w a slip yoke and u joints at both ends. The yoke is at the top end unlike the one in your pic. the truck was manufactured in Sept. 83. I have parts from an 86 includeing driveshaft and they are both the same. I thought the CV joints were for the parellel setup, opposite of your discription?

4Crawler

iTrader: (3)

CV joints need the in-line setup, u-joints NEED to be parallel. Why? See the animation below and read the web page and you'll see the 2 u-joint angles need to be the same to cancel out the non-uniform motion of each:

http://www.4crawler.com/4x4/CheapTri...ies/ujoint.avi

- http://www.4crawler.com/4x4/CheapTri...n-Measurements

In other words, if CV stands for Constant Velocity (as it does), then a u-joint is a Non-Constant Velocity joint. If you have the lower joint at 0 degrees, it'll run smooth but then the upper joint will vibrate since it is at an angle.

peow130

Wouldnt you actually want the pinion pointed about 2-3 degrees upward of the output flange?
I mean, once you put power to the rear, the spring wrap will point the pinion more towards the tcase.

4Crawler

iTrader: (3)

No, you want the pinion flange 1-2 degrees below the ideal angle since axle wrap causes the pinion to tip up under load. Since it is somewhat inconvenient to lean out of the truck and measure the shaft angles at 65MPH, you set the angles a little low to allow for the up-tilt:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1

And axle wrap seen below:
- http://youtu.be/0qfrxsm3iJg

mommucked

This is starting to make sense to me. Before the blocks and 2" springs were added, I had lift shackles in the rear and 1.5" blocks made out of the front bumpstop raisers that came w the original Rancho 3.5" lift and 1.5 degree shims. Laugh but it worked ok for years! till I broke a leaf on the old stock rear springs. When I installed 33 15.50 15 Swamper SXs years ago axle wrap became a big problem w all the traction. I drove sensibly on the road, but offroad the truck ocassionally bucked like a mule, hillclimbs and loose rocky paths. I got the traction bars and all was well. The swampers are long gone now. When I installed the 3" blocks and returned to stock shackles it was 5" of rear lift. I was going to add 5" front springs,35s, but changed my mind shortly after. I lowered the tranny 1+"s w washers stacked between the transmission crossmember/frame and longer bolts, and it worked ok for years. But the vibration started about 5 years ago, only briefly at coasting or low throttle cruising on asphalt. I added weight to the back of the bed to lower the rear and it worked fine, no vib. I removed the crossmember shims when I changed out the tranny this summer and the vibr. got worse even w the weight in the back. I'm gonna fix it right this time. The ujoints are ok but are obvoiusly worn and thats were the vibration must be comming from. I think leveling the truck w/o the weight should add more weight to the rear anyway and improve the onroad ride also. Thanks for the advice .

mommucked

4crawler, your advice was spot on. I compared the tilt of the trans and diff, visually w a 4' level kneeling, from about 10' beside the truck. The angled blocks that came w the Pro comp lift have turned the snout up too far. It looks to me if I simply add flat 1.5" blocks under the 2" springs the angle of the pinion will be parellel, just like the factory suspension would be. Lowering the axle/lifting truck vertically, should not change the angle at all in theory. I never knew about the parellel issue before and assumed the more the truck was lifted the more the pinion needed to turn up. I verified this by putting more weight in the bed and sure enough as the rear of the chassis lowered, they became parellel. A test drive w the extra weight showed vast improvement in smoothness and no noise/vibration whatsoever. Thanks for all of your replies and help w this everyone, and thankyou YOTATECH for a fantastic forum I wish I had joined a long time ago!

4Crawler

iTrader: (3)

Correct, with a simple spring or flat block lift and a u-joint shaft, just think of a parallelogram formed by the two flanges the the top and bottom of the shaft. Move the axle end up and down all you want and the angles at the top and bottom remain equal. Now if you had a CV shaft, a spring or flat block lift will affect the angles, so it all depends on what type of lift and what type of drive shaft you have, all detailed in a table below:
- http://www.4crawler.com/4x4/CheapTri...FixingProblems

peow130

unless i'm mistaken, when you give your truck gas, the pinion angle tips down so instead of being | it's like \ that.

mommucked

You're mistaken unless your in reverse! Thats why dragsters do wheelstands, the axle is trying to twist the front up.

4Crawler

iTrader: (3)

X2, pinion tips up, click on the youtube video above and watch for the wrap at about 0:25.

mommucked

It just gets better. I've driven more miles, and 4 wheeled in some slick holes and my truck feels and steers better on the road w stock steering, and feels softer flexing offroad. I believe the slight camber change from having the rear lifted too high before, has improved the steering. And the extra weight is giving more traction in the rear than before. Leveling the truck should put more weight on the rear w/o the cinderblocks I'm using now. I'm looking forward to fixing the rear suspension soon.

peow130

That was some epic derpy mode when i wrote that. The pinion tips up because the wheels are moving in the opposite direction... Hence the force causes the axle to wrap up