High Pinion Rear Diff

Could I run the FJ High pinion front member 3rd in the rear axle?

Trying to get the driveshaft up high - like NASCAR

Heard they use a little Power Steering pump lookin thing to feed oil to the pinion.

Lets hear some clever ideas, failure pics, units in action, etc.

 

I might be wrong, but doesn't the ring gear from the front diff turn the opposite direction? If you put it in the rear wouldn't your truck drive backwards when you're not in reverse? So you'd have to flip the diff to make it the correct direction, making it a low pinion...

 

You're over thinking it.
Rotations are proper.

Roll your hands in a motions and visualize your perspective moving around it.
John Moses Browning used this basic physical concept to invent countless designs.

If you feel like some mental Yoga,

Consider the Audi driveline turns opposite (CCW relative to the car) and their rear diffs are cut opposite,
Low pinion with the Ring gear on the RIGHT side. This is a result of the AWD transaxle.

Swap an LS+American trans in an Audi rear axle and you are going backwards.
Put a Nissan diff in the Audi and you are going forward again.
Flip that upside down along the diveshaft axis, and you are going backwards again.

In the Subaru system, the output shaft is reversed via a final reduction gear, usually 1.0 or 1.1 ratio.

Biggest issue is lack of splash lubrication at the pinion, and using the reverse cut gear profile leaves the force applied to the "coast" side of the tooth, which can be mitigated via thrust blocks, or a symmetrical tooth R/P

Marlin Crawler did it twice.
They never made a proper R/P, or did anything about the oiling.
Now we have 10,000 morons saying it cant be done, despite 100% of NASCAR doing it.

Really shows the level of intellect around here.
(Very Low)

 

You are a poster child for what not to do within an established forum/community. Abruptly enter, assert you possess superior intellect while throwing out dumb idea after dumb idea, and then follow up by insulting the community. Solid work.

If marlin did it twice and it didn't catch on, there is a reason. Probably that the gain is not worth the effort involved.

 

Ok I understand what you are saying and I already read up on the high pinion diffs on the Landcruiser. They are identical front and back so they can actually swap them if needed.

What I don't understand is your remark about the level of intellect around here being very low. You made a very basic post about being able to run a high pinion diff in a rear axle (assuming a tacoma here since we are on tacomaworld). I did preface my post saying I might be wrong, and I was. If you say people have a low intellect you will not get far here.

 

Isn’t it preferred to have a high pinion front, low pinion rear for strength purposes?

 

well I’m pretty sure the FJ front diff is small, weak, and an entire clamshell housing that driveshaft bolts to a flange. And uses CV axles coming out the side because it’s IFS. So no.

are there rear ends out there that go in from the top and not bottom? Yes.
They’re also heavy, expensive, bigger, wider, use different brakes, and a lot of work to fit.

if NASCAR put a driveshaft entry at the top off the diff, and majority weight at the bottom, they did so to put weight low for handling. They also have a different budget.

Audi and Subaru rear diffs are sealed units with CV axles that have limited travel. Light weight street cars compared to a truck, generally open diffs (at least Audi most years) not designed to climb walls.



portals would allow for less suspension lift, gear reduction, and higher propshaft

for $20k+.

 

like this?

 

Don't do drugs kids...