View Full Version : My Front Pinion Angle
08-24-2008, 07:27 PM
My pinion angle is 4 degrees after caster correction. I am concerned that the DC drive shaft I am having built by Front Range will not be vibe free.
Does the pinion angle absolutely have to be an ideal zero for a DC shaft to work, even with the high-pinion diff?
08-25-2008, 09:01 AM
4 degrees might be pushing it, I assume you have full time 4x4? Check the angle of your front companion flange, you might actually be better off without a double cardan. Usually though that angle is way off, which is why the factory uses the DC/CV at least on minis.
08-25-2008, 10:08 AM
4 degrees will be too much, but you don't have to be a perfect match. you should be within a degree or so...i think the most i've gone was just under 2 degrees.
08-25-2008, 12:36 PM
Well I measured wrong. What a learning experience. At the pinion, the u joint is operating at 8 degrees and at the tcase it is 16 degrees (the driveshaft angle is 12 degrees). To make things worse, the DC taco drive shaft I got from the junkyard is bad. So needless to say, front Range is making me a whole new shaft with a DC that will operate all day at 22 degrees if necessary. I hope this works. I knew going into more lift, these things can happen.
08-25-2008, 12:58 PM
You still have that front pinion angle to worry about.
08-25-2008, 06:56 PM
how much is that shaft setting you back?
08-25-2008, 09:08 PM
4 bills. There goes my Bilstein money.
08-26-2008, 09:39 AM
To make things worse, the DC taco drive shaft I got from the junkyard is bad.
What was bad about it? U-joints (rare)? Or the cardan joint itself?
08-26-2008, 11:26 AM
The center pivot within the cardan joint has come apart and is binding.
I will remove the caster bushings and go back to stock if necessary to get a little more pinion angle if I get vibes with the new shaft. I really need to get a caster measurement done.
08-26-2008, 11:33 AM
Looks like the old cut&rotate is the best solution. I know you didn't want to hear that... but there is a local guy who will do it affordably and well if you gut the housing and pull it (no mean feat on an 80), and tell him EXACTLY what your angles are and what you want them to be. If removing the caster bushings works great (but doesn't steer great) I bet you could just take your measured caster vs. factory spec and he could make it happen.
08-26-2008, 12:03 PM
The steering linkage, i.e., tie rod behind the axle and possible interference with the control arms makes a cut and turn very hard, from what I have been told. The 80 is a different B^&%.
08-26-2008, 12:03 PM
Cut and turn does not work well on a 80 due to the tie-rod hitting the control arms.
So you say that you have 8 degrees in the front u-joint (at the diff). That does not sound right.
08-26-2008, 12:27 PM
I don't know what I am measuring anymore. My pinion flange is 4*. My t case flange is 4*. The stock shaft is at a 12* slope.
I am thinking either stock arms with the maf 4" drop brackets I have, or Slee arms by themselves. I think the blue bushings and the maf brackets are giving too much caster, but I need to measure it first. Will the Slee arms work with exactly 5" of lift up front?
08-28-2008, 02:31 PM
An update: I obtained another set of control arms with stock bushings from Irbis Offroad and pulled the current arms with blue bushings. I got the pinion pointed back up to where I have a .5* u-joint operating angle and the vehicle drives very well with just the 4" drop brackets (I will get a caster reading next week).
I also exchanged the bad Taco shaft for one that has even bigger u-joints adjacent to the cardan pivot ball. The bearing caps don't have the external snap rings, and they look much bigger than the previous shaft. Since the junk yard wouldn't give me a refund, I dropped this shaft off at the driveline shop and the owner said it was the perfect one.
Now I will have 2 shafts made and will sell one of them in the future. One will be brand new with Spicer 1310 joints and thick-walled tubing, and the other will be the re-tubed and shortened Taco unit with thick-walled tube.
I will find out on Tuesday how well everything drives.
Another benefit is that I can sell my old lift complete with arms that have caster bushings already installed for the buyer's convienience.
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