Strange looking D20 gears

Viperwolf1 · Jan 31, 2014

I'm putting together a D20 and was supplied these sliding gears. They are the same size of T style gears and have the T style Dana numbers. They also have some features I've only seen on the late '76-'77 J style gears. The machine work lots much finer on these than any Dana gear. Anyone ever seen these before? I'm thinking they might be O'Brian gears.

Last 2 pics are Dana gears.

DirtDonk · Jan 31, 2014

Just signing on to see what you come up with.
Wouldn't Jack's gears have been a different ratio, and there fore a different tooth count than the ones you pictured? Or was the change in other gears to get the lower ratios?
And while they do look nice, weren't they some more exotic materials as well? Different material, or different heat-treating for strength perhaps.

But would any of that have made them look noticeably different anyway?

Paul

Viperwolf1 · Feb 1, 2014

I know Jack has made several different ratios. He could have made some stock ratios. But even the stock J and T sliding gears have the same tooth count. The cluster gear has a different count and the sliding gears are slightly different diameters.

The material does look different but I can't tell what it is. There are almost no marks on them where they would have been machined. Very smooth and fine grain looking.

treihesse · Feb 1, 2014

Jacks gears are purchased like this.
1. Buy only the unique gears to the reduction. $1700 (2 gears I think)
2. Buy all 5 gears including the sliding gears and the ones that reduce the ratio. $1900 ish dollars. .
3. Buy gears, output shaft and his install stuff. $2400
I could buy a atlas

I called and spoke with jack and he said with all his gears and output shaft the dana 20 would be stronger than a atlas 2.

treihesse · Feb 1, 2014

Phil he did tell me one thing he did different is the machines them again after thru hardening to take the warp out of the gear which dana and atlas dont do

bmc69 · Feb 1, 2014

Viperwolf1 said:
it is. There are almost no marks on them where they would have been machined. Very smooth and fine grain looking.

A sintering process maybe? I've noticed in recent years that a lot of the large locking nuts and similar parts that we buy from SKF have taken on a smooth and polished appearance very similar to those gears. No longer any evidence of machining from stock or a traditional forging as before. We assumed they are using a different very sophisticated forging process that might include some type of sintering as well.

treihesse · Feb 1, 2014

Im really just glad the mystery gears are going in my case

broncodriver99 · Feb 1, 2014

I do see the DANA diamond stamp on the one gear. I wonder if they could be Omix-ada stuff. They are really cranking out the jeep stuff lately and Jeep ran the D18 and D20 for a long time.

I rebuilt a 4 speed last spring and one of the replacement gears was an omix gear as Jeeps ran the Ford/Tremec 4 speed. It was surprisingly a very finely machined gear. Slightly better than the stock Tremec gear that came out.

treihesse · Feb 1, 2014

Well since I got these ive compared them to tera low, advanced adapter, novak, and omix. None of them look similar. The only one I cannot find a pic of anywhere and obviously Phil cannot either is jack Obrien gears. I dont know either Phil but they are pretty....

Viperwolf1 · Feb 1, 2014

broncodriver99 said:
I do see the DANA diamond stamp on the one gear. I wonder if they could be Omix-ada stuff. They are really cranking out the jeep stuff lately and Jeep ran the D18 and D20 for a long time.

I rebuilt a 4 speed last spring and one of the replacement gears was an omix gear as Jeeps ran the Ford/Tremec 4 speed. It was surprisingly a very finely machined gear. Slightly better than the stock Tremec gear that came out.

The Dana stamp is on the stock Dana gear.

Jeep D20s have one very important difference. The front sliding gear has a reduced size collar for the smaller shift fork that they use. These sliding gears don't have that. This was one of the first things I looked for. Here's a pic of some Jeep TeraLows and Bronco forks to show the difference.

treihesse · Feb 1, 2014

They have to be jp rock eater gears. There is only three people I know of who made a bronco dana 20 gear. Tera low, Jack Obrien and dana spicer...

kntr · Feb 1, 2014

Does Jack Obrien still do gears?

treihesse · Feb 1, 2014

gears

kntr said:
Does Jack Obrien still do gears?

Spoke with him this month. Quoted me around 2400 to 2700 for a complete dana 20 tc. Hes a little long winded. I will buy a Atlas before I spend 2700 on a d20.. luckily I live a few blocks from the best dana 20 mechanic so we will see how long it lasts with 40s and lots of horsepower

Viperwolf1 · Feb 1, 2014

treihesse said:
luckily I live a few blocks from the best dana 20 mechanic so we will see how long it lasts with 40s and lots of horsepower

Send that guy over my way. I could learn a thing or two.

I should be done with your D20 tomorrow.

treihesse · Feb 1, 2014

Dont rush the broncos are playing

bronco italiano · Apr 19, 2014

-O'Brien's gears are all made by LFW mfg in Stockton. That guy is one of the best gear Mfg's in the world.

-His stuff is perfect and you get what you pay for.

-The gears are far better in quality/craftsmanship than what atlas can offer.

BI

bmc69 · Apr 20, 2014

VT_Don said:
Photos are most likely 8620 forgings media blasted after carburizing.
.

Or sintered..like so many are these days.

bmc69 · Apr 20, 2014

VT_Don said:
Most likey another hack.

Hmmm.....

http://www.lfwmfg.com/experience.html

bmc69 · Apr 20, 2014

This article is pretty old...

http://www.geartechnology.com/articles/0995/Comparison_of_Surface_Durability_~_Dynamic_Performance_of_Powder_Metal_~_Steel_Gears

....might be out of date, considering how fast things evolve. We didn't have the ability to produce our large titanium structures in '95..for example.

Strange looking D20 gears

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