High Pinion Rear Axle?

I understand that most fitment issues come from the shorter length in these old jeeps but has anyone done any high pinion rear axles? Thinking it could give Vetter angles a bit on the short length...

Would this force the gears to ride on the coast side or could a reverse rotation gear set be used as in the front?

 

Options are out there for high-pinion rears... it just depends how much you want to spend on a custom unit, or how creative you plan to get with parts-mixing with front HP carriers and custom tubes.

This has been on my wish-list since I started my project. Give this a read.
TrueHi9 - Home Page

 

Hi 9 would be sweet but it's more money than I have into my jeep...

Also saw portal axle conversions today for the first time... maybe a 5" lift with stock driveshaft and angles... But then again, I'm too cheap...

 

I have a Ford 9 inch rear axle with a Currie high pinion in my 76 CJ, it’s been trouble free for about 8 years with plenty of highway and trail miles. The axle was cheap from the junkyard and it was less than 200 bucks to have the tube shortened and the axles re-splined. The high pinion unit with an air locker, 4.11 gears, shipped to my door was $1,800.00. Pretty pricy but I saved up for it because I wanted a really sensible driveshaft angle for long highway trips. I later added disc brakes.

The gears do ride on the coast side of the gears but Currie claimes their high pinion unit will support up to 37 inch tires.

 

I saw your rear in a different thread and almost asked what it was, but I didn't want to derail the thread. I was going to bet Toyota, but the high-pinion 9" makes more sense in retrospect. Cool stuff.

 

Thanks ITLKSEZ, I had forgotten about that picture.

 

I have a custom HP offset 44 in the back of my Flatty. No issues in the 4 years that I wheeled it hard. It's just about back on the road.

 

Whadja do, MC? Flip a front 44 carrier and weld in tubes or something? Looks like an upside down 44. Curious. Interesting.

 

You can't actually do that right? Wouldn't you just have several gears of reverse?

 

Oh, flip a front and put it in back, got it.

 

Take a HP front, from say, a Ford, and press in new tubes.

You can't "flip" an axle. It will spin backwards. That's why the HP axles are "reverse rotation".

 

So.....dumb question. A HP center section actually different than a LP center section, right? You can't just flip a LP and add reverse rotation gears?

 

Nope. If I remember correctly, the pinion is on the other side of the ring gear, so the direction of the cut in the gears is backwards.

Also, since they are mainly designed to be run up front, running them in a rear application makes them spin backwards, and some issues may arise with oiling deficiencies to the pinion bearings. These issues have been supposedly worked out with the hi-9.

 

I'll agree with the oiling issues and I know nothing about how gears are cut and rotate in a HP vs a low but, here's a story for ya........ I swear it's true and it was a long time ago but it's happened. A friend built this crazy "lawn tractor." Made a frame, put a 302 and a c4 in it, tacked on whatever sheet metal from an old Pennsylvania Quality (?) lawn tractor, threw a seat on it and a rear axle out of something. Yes. This fella was a little crazy.

So, when he finally fired this death machine up, he pulled 'er back in D and went backwards. Put in R, and he went forward. He had 3 gears in reverse and 1 in drive. He pulled the axle out, flipped it and the problem was solved.

I have no idea what the rear came out of or why it would have spun backwards but it did. Maybe some tractor rear axle or something. There were no springs. Solid mounted to his frame.

He wasn't driving the thing down the road. Just up and down his dirt lane for a few minutes at a time. So, you can flip an axle but, it likely won't last long in real service. BTW, my friend is passed on now. Not as a result of the death machine, though.

 

To be honest, I'm not entirely sure what my axle guy did. I had an angle issue like many do with that much lift. I started talking with Gary Marshall (axle guy) and told him my issues and what I wanted. He said no problem. I'm not sure what the center section is other than HP Dana 44. I had him build it the same width as my narrow track Dana 30 front, and offset it for my Dana 18. One of these days he'll let me pick his brain on it and actually tell me what he did, but he hasn't so far. I bought the gears thru him as well, and then had one of the techs at ARB assemble everything in the center section on the then new 2 piece Air Locker. It runs 30 spline flanged shafts.

I've done plenty of highway driving on this axle as well as some pretty heavy wheeling with no issues in the approximately 4 years it was on the road in this configuration. I'm just about done making the fuel injected 5.0 run in it, so it should be back on the road and trail this winter sometime. I'll still be using this rear end.

I've also got a friend with a centered version of this axle in the back of his flat fender built by the same guy. As far as I know, he's never had any issue with his either. His sees more street time than trail these days. His has a chevy small block and auto trans.

 

I remember reading there is a modification you can make to the housing to divert oil to the bearings, but what it is... my memory is mush. If your axle guy has secrets, that might be one of them.

 

Gary Marshall is probably the best gear guy to ever walk this planet. You can hand him a stack of shims and he will tell you to the .001 how much is there with his fingers. I have been very spoiled to have him live a few minutes away from me.

 

Regarding oiling issues with a high pinion unit, my Currie unit came with a metal tab that mounts in the housing directly next to the ring gear. This tab scrapes gear oil off the rotating ring gear and directs the oil to the pinion bearing. The tab doesn’t ride directly on the ring gear but close enough to pick up gear oil and splash it forward to the pinion bearing. Pretty simple but effective.

 

That doesn't surprise me really. The difference in pinion height on the LO vs. HI with a 9" is far more drastic than with a 44. 9" LP has a really low pinion, which when flipped, leads to a really high pinion and potential oiling issues. The 44 doesn't go as high so less of an oiling issue.