Caster correction, double cardan pinion angle

[satchel]

I've done some researching but not sure I am finding what I'm looking for. I'm new to the 80 world, more familiar with 60's, and have an 80 that needs caster correction for a 3" lift. I keep hearing of people adding a double cardan (possibly not needed with just 3" of lift) to limit vibrations after the caster correction is used.

If the caster correction is moving the axle back to it's stock geometry causing the pinion to point back down to stock angle, and then a double cardan shaft is used to fix the vibes, wouldn't that cause more vibes using that driveshaft?

My understanding of how a pinion should be pointed with a double cardan is that it should be directed straight to the output of the transfer case, such as is shown here. That's the point of doing a cut and turn on a sprung over 60, to allow caster at the ends of the axle, yet have the middle pointed toward the tcase.

I'm sure I'm missing something somewhere but didn't see much when searching for it.

 

[cjmoon]

Your from the outside world, so am I follow your instinct correct your phase on the yoke and you should be fine. The real problem is toyota set the standard 80 shaft and pinion angle set up backward for some reason which works on stock heights. Know lots of lifts with correct shafts and castor correction running just fine

 

[satchel]

yeah I doubt I'll need a double cardan, my question is more hypothetical for those that do need it. For a double cardan to not have vibes, my understanding was that the pinion should be pointed to the tcase but that does not sound like the case for people in the 80's world for some reason I'm not sure of. Just curious if there was something that makes the 80 special...

 

[-Spike-]

When you lift an 80 over 4 inches and return the pinion (and caster) to the stock angle, it does begin to point straight at the transfer case. Generally it's very close to perfect at 6 inches of lift. The 80 comes from the factory with the front driveshaft in a broken-back configuration, meaning the u-joints are at the same angle, where the typical config has equal but opposite angles. There's a good explanation of driveshaft geometry and broken-back config about a third of the way down this page, with a diagram. Because of the odd factory geometry, the angles behave differently when lifted than typical setups.

Some folks with 4 and even 5 inches of lift have no issues with using a standard driveshaft, so the chances of you needing one at 3 inches are low, as it sounds like you know.

 

[satchel]

I figured the only way it could work was that it was somehow pointing towards the tcase after a lift so that makes perfect sense. Was not aware this was the case, makes the 80 a little more special I guess. Thank you for that explanation.

When you lift an 80 over 4 inches and return the pinion (and caster) to the stock angle, it does begin to point straight at the transfer case. Generally it's very close to perfect at 6 inches of lift. The 80 comes from the factory with the front driveshaft in a broken-back configuration, meaning the u-joints are at the same angle, where the typical config has equal but opposite angles. There's a good explanation of driveshaft geometry and broken-back config about a third of the way down this page, with a diagram. Because of the odd factory geometry, the angles behave differently when lifted than typical setups.

Some folks with 4 and even 5 inches of lift have no issues with using a standard driveshaft, so the chances of you needing one at 3 inches are low, as it sounds like you know.

 

[Nay]

It’s either a stroke of luck or a stroke of genius that you can convert the front to a DC and have perfect caster due to the stock driveshaft design.

It makes the 80 extremely easy to lift and 4” is a real sweet spot in geometry.

 

[BlueCruiser84]

I had vibes with OME 2.5" springs and no CC. Vibes with J springs and no CC. Vibes with J springs and CC. Finally installed a DC shaft with J springs and Slee plates and it's fine.

On my other cruiser I have had everything from 2.5" to some custom ~4.5" springs. Sometimes with CC and sometimes without. Never any vibrations.

It's weird how different each cruiser is.

 

[COYS]

I recently went from OME 2863 to 2860s in the rear to level it out better as I run stock bumpers, zero added weight. I’m noticing vibrations or light shaking at hwy speeds say 60-70mph. Not excessive but perceptible.

I have the wits end D cardan on order. Hoping this resolves.

 

[RevFZJ80]

How’s the wits end drive shaft? Thinking Of getting one.

I recently went from OME 2863 to 2860s in the rear to level it out better as I run stock bumpers, zero added weight. I’m noticing vibrations or light shaking at hwy speeds say 60-70mph. Not excessive but perceptible.

I have the wits end D cardan on order. Hoping this resolves.

 

[COYS]

How’s the wits end drive shaft? Thinking Of getting one.

no complaints. just make sure it's even available.

80 Series Double-Cardan Front Drive Shaft

LANDTANK 80 Series Double-Cardon Front Drive Shaft (DCS-1)

absolute-wits-end.com

 

[RevFZJ80]

Just messaged them to see if they’re going to restock.

 

[lasoundguy]

I have texted @NLXTACY a few times on that exact point but haven't heard back yet...lmk if you get a response.

In the meantime going to try new U-joints (supposed to show up tomorrow so hopefully have some results soon.)
@RevFZJ80 how much lift and caster correction do you have?

 

[RevFZJ80]

I ordered some OEM Toyota u joints as well lemme know how that goes. I have Icons w Delta arms and prototyping some bushings, im at 5.2 castor with 3ish lift.

 

[landtank]

finding and getting used cores to make a DC shaft is getting harder and harder each day. I'm currently looking for more cores and will hopefully have some coming in next week.