diffy Problem With Differential Installation

[Mark Maras]

 Any theories? The little I know about u-joints, axles, and prop shafts is the installed angle at the u-joints should be the same on both ends.

[Patcon]

10 minutes ago, Mark Maras said:

 Any theories? The little I know about u-joints, axles, and prop shafts is the installed angle at the u-joints should be the same on both ends.

I guess I would start with the differences 4cyl versus 6? Less HP and torque? Shorter drive shaft, maybe? what others?

[Mark Maras]

30 minutes ago, Patcon said:

I guess I would start with the differences 4cyl versus 6? Less HP and torque? Shorter drive shaft, maybe? what others?

  I don't believe that half shafts spin fast enough to have a vibration problem and I've seen steeper prop shaft angles (which spin 3 1/2 - 4 times faster than the half shafts) on V-8, 4 wheel drive pick-ups. What was the official reason for the squaring up the angle? I can't bring myself to believe it was u-joints or vibration.

 

[Zed Head]

3 hours ago, Mark Maras said:

 Any theories? The little I know about u-joints, axles, and prop shafts is the installed angle at the u-joints should be the same on both ends.

Doesn't the 510 use a different type of rear suspension?  Besides the fact that it was designed to be an inexpensive passenger car, not a sports car.  Lower expectations?  No offense intended.

[Patcon]

[240260280]

The rear wheel always seemed too far forward to me... not just the differential.

Look at the wheel well gap leading edges.

 

 

 

 

 

[w3wilkes]

4 hours ago, 240260280 said:

The rear wheel always seemed too far forward to me... not just the differential.

Look at the wheel well gap leading edges.

Are you saying it's more of an aesthetics thing? My car has had no issues with anything in the all original drive line for over 100,000 miles that I'm aware of (build 12/70).

 

[240260280]

12 minutes ago, w3wilkes said:

Are you saying it's more of an aesthetics thing?

 

Yes.  Look at the profile.  It sticks out like a sore thumb.

[Namerow]

4 hours ago, 240260280 said:

The rear wheel always seemed too far forward to me

And adjusting the hub position to help correct the early design's leading-diff/trailing-hub situation would have made the tire sit even further forward inside the wheel opening.

I've heard it explained (source?) that the S30's differential was pushed forward late in the design cycle when Nissan's engineers became concerned over meeting the new US FMVSS requirement for rear impact.  The explanation was that they wanted to move the differential further way from the front of the fuel tank to reduce the liklihood that it would puncture the tank when the rear of the car folded up.  I don't think this was guess work.  They must have observed a potential problem or else they wouldn't have taken such an unnatural design path.

There was a lot of confusion and uncertainty within the industry over what form the actual FMVSS rear impact standard would take when made into law (impact speed and fixed vs. moving barrier were still being debated).  I wonder if Nissan decided to take an extra-conservative route to begin with and then relaxed the design back to 'normal' when they felt more comfortable?  It's all very curious.  A lot of parts had to be changed, at enormous expense, and giving back the crash safety margin in the process.  This would not have been done unless Nissan felt there was a major problem with offset design.

And yet modern-day owners of Z's with the offset design never seem to complain about the expected issues (which are: 1) drivetrain resonance at cruising speed, and; 2) premature halfshaft U-joint wear).