Rear Axle / Leaf Spring Wedge / Pinion Angle?

Hey,
I don't know a lot about pinion angle but I do know that the pinion on my van was more or less horizontal before I had my leaf spring bushings replaced. As soon as I picked up the van I knew something was wrong with it as it had picked up a pretty hard vibration at about 2500rpm. I started looking around for a loose drive shaft or something and all I could find out of place was the rear pinion angle, now it's angling uphill to meet the driveshaft, it was horizontal before.

From what I gather, the total variation from trans to rear should be 5-7 degrees and no more, other wise it strains the u-joints and can causes vibration at speed and early failure.

There were no shims or blocks under the rear springs that I can remember and the shop doesn't recall seeing them either. I just talked to a driveline shop and emailed them the picture below and they seem to think that the shop that did my bushing work put the springs together backwards.

I'm going to take some measurements when I get home today from the spring perch fore and aft and also for the wheel base and see if it's changed...

Is it possible that the springs were put together backwards with the shackles and installed? Would it cause this? As a quick determinign factor, which end of the rear leaf spring is bigger in diameter? (the front if I remember correctly).

Thanks for the help!

Ya, That doesn't look right to me. And mine lines up with the drive shaft.

killakans wrote:Ya, That doesn't look right to me. And mine lines up with the drive shaft.

mine did too until they changed the spring bushings.... looks like Im going to miss the car show Sunday because my rig is down.

Ok, this is definitely the problem, I just don't know how it got so far out of whack.

The shop manual says (page 16:4) the bearing yokes on the trans and rear chunk should be at 90 degree angles to the floor (with the vehicle leveled).

i.e.
"rear axle misalignment will cause propeller shaft vibrations as the horizontal parallalism of the universal joint is affected"

I dont know how it got jacked up but it is.

On the drivers side rear spring the measurements are:
from centerline of the spring perch forward to CL of the bolt: 21"

from centerline of the spring perch aft to CL of the shackle bolt: 27.5"

center to center between the front and rear wheels is 89.5"

from the front edge of the rear wheel well to the front of the rear wheel: 2.25"
from the rear edge of the rear wheel well to the rear of the rear wheel: 3"

Are the rear shackles pointing up or down? The eye of the spring rides above the shackle mount I think.
.

my best guess is there was a tapered shim between the axle and the spring. usually made out of a white metal that does turn to dust if disturbed but you should have some pieces of it to be sure.the spring bushings are round on both ends of the springs and you can't put the spring on backwards. mabey i should rephrase that. you would have to work at putting them on backwards and the wheel wont be centered in the opening if you did. did you do a spring flip to lower the van?? the perches are welded on wrong if you did. did they take the springs apart for a new centerbolt or anything else?? i'll bet the shim was there and now its a new kia or something like that.

get us all some pics of the spring mounts to shacle / frame-and the axle to spring mount

Digz wrote:Are the rear shackles pointing up or down? The eye of the spring rides above the shackle mount I think.
.

Can you confirm this?

see the picts of mine as they sit now please.

Twinpilot001 wrote:get us all some pics of the spring mounts to shacle / frame-and the axle to spring mount

here you go:
front of the rear spring:



rear shackle of the rear spring:



I don't have a pic of axle to spring mount but it looks fine to my eye, well seated.

Somebody can correct me if Im wrong But I think the shackle is on upside down,, spring should be on the top ?

Very Possible - also maybe the springs?? Need reversed if different on the ends form one another??

digz you are correct the spring should be up top and the shackles come down to the body mount.

I was pretty sure that was a dodge thing, Havent been under mine since last fall so wasnt going to bet on it. lol, that would or should make a big difference in the pinion angle I would hope, not a real easy fix tho , jack up body remove the front bolts and roll and flip?

worse things in life has happened !!!!!!!

dix wrote:digz you are correct the spring should be up top and the shackles come down to the body mount.

You guys are right! I googled the web looking for picts and the spring shackle goes up, not down, I'm taking it back in 1st thing tomorrow morning to have it fixed.

Here's a pic of one I found on a '69 Sportsman:

Just blew the rear u joint on the way back to the shop to get it fixed. Waiting on the wrecker to show up now. :/

i hope the shop is fliping the bill on this one. from the pic's it looked new. if not i would change both.. i sent you a p.m.

Yeah they covered the wrecker and repairs, I'm on a blackberry at the moment, when I get to my pc ill answer the pm


"BOOM" WTF?


going on the wrecker:


AT least I had company while I waited:

man, I'm going to have to check mine now~!

Mine is that way too!
Gotta figure out what to do....

Would lift blocks act the same way? I have used 2" blocks on at least 4 diffrent A's over the years. The only problem I had was on the 65. Trunion ujoint didnt like it! Felt like I was driving with four flat tires!

RodStRace wrote:Mine is that way too!
Gotta figure out what to do....

Get some axle shims from an offroad shop and get the angle back under six degrees

slowflapper wrote:

RodStRace wrote:Mine is that way too!
Gotta figure out what to do....

Get some axle shims from an offroad shop and get the angle back under six degrees

Yeah, I like the rake and figure if I flop the shackles it will drop at least 3 inches and I'll have tire clearance issues.
It does explain why it feels a bit tippy, it's gotta change the roll center big time, and this doesn't have a front sway (I did grab one from the JY). Another thing is that the tires are forward in the wheel wells now, not centered. Showflapper's is too, look at the photo of it on the tow truck.
I do still have the blocks from the 100 I pulled out. Guess the right thing to do would be to get new U-bolts, swap the shackles and add the blocks.

are the springs you used the same ones that were on the van???
were they something from a salvage yard,or
are they something you bought and were told were correct.
the reason i ask is i can't see how flipping the rear shackels move the centerline that much forward and change the pinion angle that much.
the van MUST have had shims and they did not replace them.

jkr, mine as I got it, no idea what's been done before...

Moving the end of the spring 6" with a short front section and a long rear section is going to move the axle down and a bit forward. Mine isn't that much forward, maybe an inch.
The shot on the truck looks like it's more optical, since the POV is roughly inline with the back or the front door. I think that the tire is normally slightly forward in the wheel well anyway. It's a designer trick to make it optically 'faster'.
Here's one from the net that looks like it's stock height and close to the same perspective.