Pinion Angle Bone of Contention?

[TJ Edge]

One of the mechanics at ORW suggested that having a pinion angle such as shown below may "starve" the pinion itself from sufficient lubrication because all the gear oil is sitting below the pinion in the differential housing.

Whatayall think about that?

Originally posted by BlackJeepOfTheFamily:
http://plaza.powersurfr.com/RJOTF/driveline.jpg

http://plaza.powersurfr.com/RJOTF/rearshaft.jpg

[dh-king]

For sure. You can overfill with a gear oil that has D4 so it won't foam. How you over fill is a mystery to me. Maybe disconnect the driveshaft and upper control arms to tilt the pinion down...

Any other suggestions to this starvation problem?

Tony

[Chris S]

.... How you over fill is a mystery to me...Tony

Drill and tap a new fill hole higher in the cover.

[Deanster]

What I think ....... I doubt it seriously.

[Jerry Bransford]

What is D4? Some kind of additive?

[BlackJeepOfTheFamily]

No Worries guys'

It seems the panic over this issue was based on the gross exaggeration and poor excuse for a drawing I slapped together.

I was trying to show a newbie the difference between a stock shaft and a SYE/CV shaft.

In order to emphasize my point, I made it look extreme, fact is the actual Jeep is no where close to that. I suppose I should redraw that with a little more care and take measurements so I can re-produce a scaled drawing if other people are gong to use my words....er sketches...out of context.

sorry for the confusion

[BlackJeepOfTheFamily]

Here's a photo from a TJ with an S3T and dropped t/c compared to my S4T with BellyUp ....the angle at the bottom of the pumpkin isn't that much different

http://plaza.powersurfr.com/RJOTF/s3t.jpg
http://plaza.powersurfr.com/RJOTF/rearshaft.jpg

It's more the length of the new shaft 16" over the stock 11" that make the biggest difference.

The new fixed output yoke is substantially shorter on the SYE jeep allowing a much longer driveshaft.

[TJ Edge]

OK. So with a radical pinion angle on a lifted TJ with a Belly-Up, the pinion points up so much you may starve the pinion bearings for lubricant because it's all in the pumpkin below, especially when going up steep inclines.

Here's the situation: the pumpkin filler is located too low on the housing to allow you to fill it with sufficient oil.

Solution: Take off the breather tube and pump extra gear oil in through there! Viola! Just don't fill it too much, or you may get leaking seals.


BJOTF: I believe your drawing, while not to scale, is still valid. Take a look at your photo above. Look at the angle of the street below the Jeep. Now tilt the picture until the ground is horizontal. *Now* look at the pinion angle. It's enough that when you go up a hill, if you don't have enough oil, it's sucking air.

[BlackJeepOfTheFamily]

First of all the street cannot be used as a reference, because it is only visible in one photo.

But.... just for you I've rotated both pics to show the body line level.(indicated with black line

http://plaza.powersurfr.com/RJOTF/as3t.jpg
http://plaza.powersurfr.com/RJOTF/as4t.jpg

still not convinced?

http://plaza.powersurfr.com/RJOTF/bs3t.jpghttp://plaza.powersurfr.com/RJOTF/bs4t.jpg

The measly few* difference will not "Starve" the pinion??? The pinion does not need to be fully submerged in fluid to survive....It won't be a fish out of water. How do you think High pinion diffs work?

A brief up hill climb will not grenade a pinion gear because of lack of fluid....I can garantee you the stuff still slpashes around enough inside to lube everything.

In 20 years of Wheeling , this is the first I've heard of a *starved pinion*. Not trying to be rude Edge, I just don't buy it ;)

[Chris S]

I think high pinion difs have a different oiling system than regular difs (at least currie's anyway), but I agree with BJOTF. I know a few guys who have had dif angles worse than his on their rigs for 10 years with no ill effects.

[The Man with the Plan]

There is some truth to that, but it isn't a big deal. There are basically two issues, one is that you cannot get as much oil in there, the other is that the oil is in bad location for proper lubrication.

Pouring oil through the breather tube sounds like a cool idea! A guy I used to 'wheel with a lot had another idea. He took a 90* elbow of conduit (or plumbing pipe?) that had the same threads as the drain plug. With the elbow pointing up, he was able to add significantly more oil to his diff. The only problem I forsee is hitting a rock while going in reverse.

But, as also mentioned above, the difference between the stock pinion angle, and a lifted jeep's pinion isn't that much. Don't sweat it.

[TJ Edge]

Originally posted by BlackJeepOfTheFamily:
<snip>
The measly few* difference will not "Starve" the pinion??? The pinion does not need to be fully submerged in fluid to survive....It won't be a fish out of water. How do you think High pinion diffs work?

A brief up hill climb will not grenade a pinion gear because of lack of fluid....I can guarantee you the stuff still slpashes around enough inside to lube everything.

In 20 years of Wheeling , this is the first I've heard of a *starved pinion*. Not trying to be rude Edge, I just don't buy it ;)



BJOTF,
Here are at least two reputable companies who have addressed this problem with their Hi-Pinion diffs. Gee, I guess it really is an issue after all! :p

Originally posted by Harry Brosofsky:
Better yet, have Dynatrac build you axles and get the 0 hi pinion oiling option...basically guarantees oiling up to 20 degrees.


Originally posted by DippStick:
Like the Curry HP 9" do too.



BJOTF, I can't say *for sure* that our diffs are being starved. I was just suggesting that they *might* be starved if the angle were high enough and the oil level were low enough; and I was just throwing it out for discussion. I imagine that splashing oil and only limited time in an uphill situation would probably never lead to any problems. But, hey...isn't it fun to talk about this stuff? Especially with pictures and drawings. I can't wait to get my camera so I can join in the "graphic" fun, too!

Beat. Beat. Beat. Dead horsey. Dead. :D

[BlackJeepOfTheFamily]

That's Cool Edge ;)

I enjoy the information exchange, I sometimes come off as being overly sensative to critisism ...I just tend to defend my position enthsiastically...no flames perceived or intended.

Good debate!:)