SPC/Slee 3* Knuckle Bearings - How will they affect pinion angle/driveline vibes? (1 Viewer)

[bryanb]

I'm trying to get caster back to "normal" for my '97 Landcruiser with 4" front lift, 5" rear lift (J springs and spacers) while avoiding driveline vibrations... aren't we all (at one time or another). I haven't yet installed any caster correction devices, it's just all stock with a lift. Steering is all over the place as was expected, and I have driveline vibes between 25-30 and 50-60... also expected.

I thought it would be trick to use the new 3 degree knuckle bearings offered by SPC and SLEE (since I'm planning to do a knuckle rebuild soon anyway) along with some 3 degree caster bushings (I have not yet installed these, still sitting in the garage). After a bit of reading around here, I am beginning to wonder if I will have uncorrectable driveline vibrations by correcting my caster by a total of 6 degrees while only changing my pinion angle about 3 degrees... since the knuckle bearings help the caster by 3 degrees, but do not change the pinion angle, unlike the traditional control arm bushings and plates.

I had purchased a landtank DC shaft (not yet installed) thinking it would cure driveline vibrations no matter the pinion angle, but I may be mistaken about that. Any ideas about what i can expect?

Thanks!

 

[BlueCruiser84]

The knuckle bearing won't do anything to your pinion.

I don't know nothin' bout a DC shaft. It's different on a case by case basis. Best bet is to get under there with an angle finder and figure out what you need , but basically if your pinion is pointing at the Tcase output flange you need a DC shaft.

 

[bryanb]

Correct, the knuckle bearings are unique in that they change the caster without changing the pinion angle, unlike caster bushings and plates. I'm wondering if that's a good thing or not.

 

[bhmmapping]

If you do the bushings + bearings you shouldn't need the DC shaft. That is what I plan on doing in the spring when I do a knuckle rebuild.

Since you have the shaft already, why not just use plates?

 

[bryanb]

If you're correct, that's great news! How did you figure out that the combo of bushings and bearings will not require a DC shaft?

If I don't have to use a DC shaft, that will save me along with not having to buy plates. Part of the reason I am hoping that knuckle bearings and bushings would work is that I have to replace the bearings anyway and I have heard that often the bushings have to be replaced due to wear. It would be great if I could replace the bearings and bushings and have caster dialed in (without a crazy pinion angle scenario) without have to do plates and a DC shaft. Right?!

 

[cruiserdan]

If you add the bearings on top of the caster bushings you may have contact between the tie rod and the control arms. That would require removing some material from the arms.

Race orientation is critical as well for a good outcome. If you are off the fore-aft axis you will affect camber.



Edited for clarity...

 

[bryanb]

If you add the bearings on top of the shims you may have contact between the tie rod and the control arms. That would require removing some material from the arms.

From what I have read around here, it sounded like you might be able to get up to 7 degrees of axle rotation before the tie rod contacts the radius arms. I was hoping that a total of 6 degrees would be safe. Hmmm, I'm guessing that since caster plates force the axle up above the arms slightly more than stock, if that permits another couple degrees of rotation before contact...

Also, I'm not sure what you mean by "shims", can you please clarify? Thanks Cruiserdan!

 

[cruiserdan]

Sorry I meant caster bushings.

Not every axle is the same. Some may get away with 7 when others may not. Some minimal grinding of the arm would probably not be a problem.

 

[bhmmapping]

PROJECT SNOWY building an 80 in another country [Aus owner-vehicle U.S]

 

[bryanb]

So... 3* knuckle bearings could be the key we have been looking for in terms of getting a 4" lift with pinion angles that should work with a stock drive shaft?

Which 3-4* offset bushings are recommended for flex and longevity (ha, I wan't my cake and to eat it)?

 

[cheddar bob]

Your pinion output flange needs to be parallel to the tcase output flange. That's how you avoid driveline vibes with a stock shaft. Caster bearings won't help with the rotation of the pinion flange downward. In other words, they're not going to help your vibes with a stock shaft.

 

[bhmmapping]

Not in the front of the 80. It is a broken back configuration so the pinion points up. As you correct caster for a lift by twisting the axle it will eventually point at the tcase, which isnwhynthe DC shaft works at that point since the angles are split at the DC joint.