Expert Advice Needed for Drive Line Angle Shims

[Healey]

Random thought: are the rear springs on the correct way around? Front to front and rear to rear. Is there a correct orientation? Might that make the rear pinion angle worse with the new (longer) rear shackles?
Does the vibration get worse with increasing vehicle speed (usually driveline angularity)? Or is it pretty much the same at all speeds (maybe some other cause)?

 

[78fj40mg]

Random thought: are the rear springs on the correct way around? Front to front and rear to rear. Is there a correct orientation? Might that make the rear pinion angle worse with the new (longer) rear shackles?
Does the vibration get worse with increasing vehicle speed (usually driveline angularity)? Or is it pretty much the same at all speeds (maybe some other cause)?

Hey Healey, The rear springs are OME and they have directional arrows and are correctly oriented.
The vibration increases with speed and is definitely due to drive line angle irregularity, that's what I'm trying to correct. The truck had a pseudo 3 inch lift from the PO but surprisingly it didn't have any vibration issues with the old springs.

 

[snaggletto]

If your aftermarket rear shackles are longer than stock then that would explain at least some of the angle difference. Be aware, as those new springs break in your diff angle will decrease as well. Then the 3 degree shim may be to much.... Before you shim it, load 500+ pounds (or a heavy trailer) in the rear and test drive and measure angle of the diff.

 

[78fj40mg]

If your aftermarket rear shackles are longer than stock then that would explain at least some of the angle difference. Be aware, as those new springs break in your diff angle will decrease as well. Then the 3 degree shim may be to much.... Before you shim it, load 500+ pounds (or a heavy trailer) in the rear and test drive and measure angle of the diff.

I appreciate your feedback and thanks for the useful information, I'll be sure to load the rear of the truck and recheck drive-line angles.

I'm using OME (Old Man Emu) shackles and springs, I was told they are similar to OEM shackles, however, the springs are beefier and that's where the 2 1/2 inch lift is established. Once the new springs break in and the pinion angle changes then I'll probably be looking at removing the 3 degree shims and replace with lesser degree shims if needed.

 

[cjgoode]

Put it on the ground and send some pictures. A lot of people, probably a majority have 2.5 or 4 inch spring lift with no problems, and OME is a very popular brand. I still would find it odd that this is the only installation that has a drive shaft angle requiring adjustment.

 

[78fj40mg]

Today I installed the rear spring shims to correct the drive line angles. Used 3* degree Belltech shims and I'm happy to report the drive line angles are once again pretty close to perfect.

Here are a few of before and after pics, used the exact same reference point for taking the before and after pics.

Before

After, sorry for the dark exposure

Before

After

Shim installed driver side

Shim installed passenger side

Belltech shims

Road test:
Unfortunately, I ran out of time since familial matters take precedence over work on the 40 and as such will have to re-schedule a test drive at another time/day to measure success or failure of this mod. The primary reason for the road test is to detect audible and mechanical vibration emanating from the pinion drive line area. I've been experiencing speed sensitive vibration since the OME springs, with a 2.5-inch lift, installation.

I'll report back with the road test results.

 

[drnekFJ40]

Looking forward to it...I still have to redone mine..I don't have vibrations,but it drives like a donkey and cant keep it straight..PO installed shims opposite way so made angles worst...CCOT has it written on their page wrong..Shims need to be installed opposite way -lowering pinion down instead up..

 

[78fj40mg]

Update: Road test complete and I'm happy to report the drive line vibration and noise is gone completely, the 3 degree shims worked great and my 40 feels brand new again!

 

[Blue77FJ40]

Those shims look like cast aluminum that can be brittle, and tend to fatigue or deform over time, and ultimately break. I'd recommend steel shims. I've heard Georg sells steel ones, but I know that Roger at 4Crawler Offroad Products who does Truck Tech on Toyota Trails has them.

 

[djcfj40]

x2 on the steel shim. Had a customer with an old blazer that we shimmed the front axle to get rid of death shake. A few years later the aluminum shim split and beat the crap out of the center bolt on the spring and the spring perch.
I'd personally get steel ones and oil or paint them over heavily once they are installed to keep the rust demons away.
Glad you got the vibration fixed. That stuff drives me nuts too.

 

[78fj40mg]

x2 on the steel shim. Had a customer with an old blazer that we shimmed the front axle to get rid of death shake. A few years later the aluminum shim split and beat the crap out of the center bolt on the spring and the spring perch.
I'd personally get steel ones and oil or paint them over heavily once they are installed to keep the rust demons away.
Glad you got the vibration fixed. That stuff drives me nuts too.

I will ultimately replace them with steel shims but for now I'm keeping eye out for any signs of wear. I don't use my truck for wheeling so I'm hoping the aluminum shims will last a bit longer, however at the slightest sign of wear they will be gone.

 

[Weber Sarge]

The aluminum ones are fine for a typical car - but with the heavy springs and far heavier tires on a truck they will fail whether it's wheeled or not .
Get with OrangeFJ45 , Georg should have a set of steel ones .
Sarge

 

[78fj40mg]

Thank You All for your support, great Ideas, and insight!

It's been quite a learning experience to say the least.

Mike