Topic: Spring wedges

[Bounty Hunter]

Nevermind, will post more later.

[Bounty Hunter]

Can you take a similar pic of the front axle, showing the relationship between the pinion and driveshaft?

[Bounty Hunter]

Your rear pinion is too high, it should be below the driveshaft about the same amount that it's currently above it.  It will then rotate up to parallel under acceleration.  I'd bet this accounts for some high speed vibration.

[jfrabat]

Can you take a similar pic of the front axle, showing the relationship between the pinion and driveshaft?

Sorry, posted the wrong one; I took it already, so here it is...



Now, I know it looks wrong with the pinion pointed up like that, but if you look at the TC, the angle is the same (hard to see here, but I checked):



And here you can clearly see the angle (seems to be about the same 5* I have of difference in the front axle) of the TC vs the frame:



Now, the RE did come with the TC drop kit, but since I got the CV Shaft, I never installed it.  Maybe I can use the same spacers to push the TC up?  There is enough space on top...  I checked today the motor mounts, and there does not seem to be any lift (I looked at night, but would have to measure the mounts to be 100% sure), but the engine itself seems to be tilted as well...  And the rubber on the driver side looks pretty shot.

Your rear pinion is too high, it should be below the driveshaft about the same amount that it's currently above it.  It will then rotate up to parallel under acceleration.  I'd bet this accounts for some high speed vibration.

Should also be fixed if I tilt the TC, right?  I mean, in that case, the rear yoke would be pushed up and the front down, right?

[jfrabat]

I put the picture of the TC and frame in AutoCAD, and calculated the angle...  Lo and behold, it came out to 86* (remember the shims were 4*?).

Here's the pic with the angle:



Here are the measurements again with the AutoCAD calculated angle (the pics are a bit blurry) for reference; turns out, the difference is 4* as well...

Angle at TC



Angle at Axle:

[aw12345]

From the look of the picture it will run perfect with a cv shaft

[Bounty Hunter]

This pic shows just what I suspected, your front pinion is pointed up past being parallel with the driveshaft.  It should be pointed below parallel, pointed more toward the rear axle than the engine.  This is the source of your vibe, removing the front shims will be a step in the right direction.
 The Tom Woods pic showing a non-CV driveshaft, shows the TC output parallel with the pinion.  Your pinion is pointed sky-high compared to what it should be.
 I think you're putting too much thought into figuring the angles, and forgot the basics as the Woody diagrams depict.

[Bounty Hunter]

From the look of the picture it will run perfect with a cv shaft

Yes, close to perfect, but at the expense of proper caster.  A CV shaft isn't the solution for the front of a YJ, proper caster and pinion angle requires the pinion to be pointed downward, nearly parallel with the ground.

[Jeffy]

The stock transfer case IS at an angle even stock.  One reason is to give the rear driveshaft a better angle.  This isn't usually a problem because your front driveshaft doesn't normally turn BUT now it does.

The way Jeep fixed this with the TJ was to use a front CV shaft.  They also balanced it.  Actually, early TJ's had some vibration issues because they didn't balance it at highway speeds.

Easy to check though is to get rid of the wedges and disconnect the front driveshaft.

[jfrabat]

The stock transfer case IS at an angle even stock.  One reason is to give the rear driveshaft a better angle.  This isn't usually a problem because your front driveshaft doesn't normally turn BUT now it does.

The way Jeep fixed this with the TJ was to use a front CV shaft.  They also balanced it.  Actually, early TJ's had some vibration issues because they didn't balance it at highway speeds.

Easy to check though is to get rid of the wedges and disconnect the front driveshaft.

I did run it without the wedges and without the front DS; there was no vibrations...

[95 Lowbuck]

I have a 95 yj with the same lift and had the same problem.
The only difference was I run a Trutrac in the front which also
makes the front driveshaft turn all the time.
The front of the transfer case points up and the pinion yoke points up.
Not good for a non cv driveshaft.
I had a choice of keeping the stock driveshaft and running a huge shim, (really screwing up my castor)
or going to a cv driveshaft and running a small shim. (2 deg. was about right).
I went with the second option and had good results without messing up my steering.
As been said make sure you use a steel shim what ever way you go.
P.S. Not running any T.C. drop or Motor lift.

[Bounty Hunter]

I have a 95 yj and the pinion yoke points up.

But it doesn't point up, it points down (in relation to the driveshaft) in stock form and after most lifts.  If a spring lift alone points the pinion up, the springs are designed wrong or the shackles are too long.

I'd bet you would have no vibes with no shims, and stock shackles.  If you do, they're likely found elsewhere.

[jfrabat]

I think I'm gonna try lifting the TC just a bit, and removing the shims, and seeing how that goes; it's probably gonna fix both angles with one fix...

[95 Lowbuck]

My front pinion even with stock springs and shakles pointed up.
I did not care how it lined up with a stock D.S,
I was concerned how it lined up with the T.C.
It was a total of 7 deg. off and I was not willing to shim that much.
With a CV D.S. it was off 2 deg. and that's what I shimed.

[jfrabat]

I think I'm gonna try lifting the TC just a bit, and removing the shims, and seeing how that goes; it's probably gonna fix both angles with one fix...

So, just to be sure before I go and screw it up again, this is a good idea?