bad_idea

I installed an SYE and 8.8 together last year this time. I set the pinion 2 degrees down in relation to the driveshaft. At the time I had shackle relocation brackets, 7" shackles, and a worn bastard pack - all together netting 5" of lift.

I recently replaced the leaf pack with a set of OME Medium duty leafs. With the relocation brackets and long shackles I was up around 7" or so. No bueno. I pulled the relocation brackets and swapped the shackles for a pair from a Ranger (4 1/2" long, 1" longer than stock). I am happy with the height, but not the shackle angle. Will have to address that in the near future. Will likely use a set of no lift shackle relocation brackets.

NOW, on to my question for anyone still reading. My pinion angle is now 5 degrees down in relation to the driveshaft. I took it out for a spin, got it up to 60 and didn't notice any vibes. Should I shim the axle to get it back to 2 degrees? Will I eat u joints, pinion bearings, and transfer case with it at 5 degrees? What is an acceptable tolerance for the pinion angle with a SYE?

I searched the subject extensively when I installed the SYE, but never found a tolerance for the pinion angle. Everything just said set to 2 degrees.

aka"dude"

sorry man I dont think anybodies going to be able to give you the magical shim* to make your setup work. All I can say is pointing the pinion at the output yolk on the t case when using a double cardan type drive shaft has been close enough for my to keep the vibes down to a reasonable level under say 70ish mph. Good luck

bad_idea

I'm not looking for the correct shim to realign the yoke to the driveshaft, I can measure that. I am looking for an allowable tolerance on misalignment. For example, +/- 2 degrees. Currently it is 5 degrees down and I notice a slight harmonic sound at 60 mph +. Not sure if that is enough of an issue to cause excessive component wear.

SteveMongr

Deviating farther than 2* could overwork the u-joint. When suspension droops the pinion angle also increases.
The purpose for 2* is when torque is applied, pinion raises to near zero.

bad_idea

I was afraid of that. I'm scouring the inter webs now for a good brand of shim at a fair price. I am leaning towards the IRO steel ones now. They are $30 and come with new center pins. Looks like steel is the ideal choice. Looks like bolted with leaf pack via center pin is ideal. Any recommendations?

SteveMongr

Most shims are not branded, except for Tuff Country. I would not worry about that aspect.
If it comes with bolts that is a plus because you will need them anyway. And when ordering these bolts separately, you must know the size of bolt-head and diameter of bolt.

That you notice a harmonic vibration is a red flag. That vibration must travel through the suspension and/or motor mounts to be noticed and felt. If it has to travel that far to be felt, than how bad is it as the source..
The propeller shaft (drive shaft) spins ridiculously fast at highway speeds, 3.5 turns for one revolution of tire (stock). It must be 'in phase' and properly aligned.

bad_idea

I don't feel it at all. I hear it. Vaguely. The jeep is so blasted loud though, it may be louder than I think. But again, I can't feel it. I will identify shim thickness needed to rectify issue and order this weekend, hopefully on Amazon. I have read steel are preferable, other than that are there any features to look for? I know it's a simple device, not trying to overthink it too much.

freegdr

Post some pic of angles possible ?

bad_idea

I don't have any pictures, but I have the angle it is at. The pinion is 5 degrees down in relation to the driveshaft currently.

Jeepin'_Aint_EZ

so much this

I'd shim it and get that pinion angle back up. C-clamps are your best friend for installing shims. Get em nice and tight, remove u bolts and lower axle, remove center bolt from pack, install shim and new center bolt, tighten nut, remove C-clamps etc etc etc......... done and done.

bad_idea

Simple enough. Now, as far as measuring for shims....

I plan to loosen the u bolts and drive a wedge in between the rear of the spring perch and the spring until the desired angle is reached. Then order a shim in that degree. I understand the driveshaft angle will change as the pinion is rotated, so I won't quite need a 3 degree shim to get back to -2 degrees (currently at -5). I am thinking will likely end up with a 2 degree shim as it appears they come in 2, 4, 6, or 8. Are there 1 or 1.5 degree shims? I'm used to dealing in precise increments, seems driveshaft angles are a little more roundabout-ish.