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Discussion Starter · #1 · (Edited)
So there are several new dropout 3rds on the market within the last few years. We all know there has been some drama surrounding some of them, but I would like to set that aside for the purposes of this thread and stick to just the technical aspects of the various diffs and their benefits/detractors.

I'd like to compare the newer diffs to the more common 9" options.

The diffs I'd like to compare are:
JRat Sixty9(feel free to discuss the Jana 76 version of this as well)
SOLID 14
Torq Nodular 14
Torq Super-14
Toyota Tundra 10"
Spidertrax/Trophy Truck 10" 9
True Hi-9
Mega Hi-9
Standard 9"
Nodular 9"

Let's look at:
R&P strength(pinion size/spline count, ring gear diameter, R&P design as in where the pinion meets the ring gear)
Diff features(side adjusters, 3rd pinion bearing, etc)
Locker choices
Axle shaft diameter options(35 spline, 40 spline, etc)

Let's create an all encompassing discussion of these diffs, as the shafts/knuckles/ends/etc are pretty much all cross-compatible. I realize that much of this information exists out there already because the 14-bolt and Dana 60 are obviously not new diffs, but I feel that there is enough significance to the particular diff designs as well as improvements/advancements in the industry's offerings that a new conversation is warranted.

If I missed any diffs, please feel free to let me know and I will add them to the list.
 

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I hope this doesn't go too far off of your main topic.

I have been waiting to purchase a third from JRat but, understandably it is taking awhile. I wonder how a seventy9 and Rock Jock 70 compare to each other. I would plan to run the 35 spline 5.38 gear in either one.

This is for a front axle build.
 

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You've named a lot of the big boy axles. Does lightweight get any love?
Depending on application (portals)....

Ford 8" ...IIRC, isn't that what TJmark is using in his IFS/Portal Build?
Are we totally discounting the Toyota 8" as well?

If we're talking 1 ton stuff, then disregard...with exception of portal application (I guess).
 

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Discussion Starter · #5 ·
Tundra 10" drop out.
Good call, I'll add that to the list.

I hope this doesn't go too far off of your main topic.

I have been waiting to purchase a third from JRat but, understandably it is taking awhile. I wonder how a seventy9 and Rock Jock 70 compare to each other. I would plan to run the 35 spline 5.38 gear in either one.

This is for a front axle build.
While I'd like to stick to dropout tech, the gears available for the RJ70 would most likely be cross-compatible to the Seventy9, so I don't mind discussing their merits here.

You've named a lot of the big boy axles. Does lightweight get any love?
Depending on application (portals)....

Ford 8" ...IIRC, isn't that what TJmark is using in his IFS/Portal Build?
Are we totally discounting the Toyota 8" as well?

If we're talking 1 ton stuff, then disregard...with exception of portal application (I guess).
I'm a big Toyota fan, but I think the 8" tech has been well covered and is not comparable in strength to the 9/14/60.

My goal here was to create a discussion about the various diffs you're likely to find in a "standard" U4 build where high horsepower and 40" tires are the norm. It seems that 9"(and the 10" variants) have been dominating as the most common diff of choice, but I see that changing as more options come online. Hence the discussion.
 

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My goal here was to create a discussion about the various diffs you're likely to find in a "standard" U4 build where high horsepower and 40" tires are the norm. It seems that 9"(and the 10" variants) have been dominating as the most common diff of choice, but I see that changing as more options come online. Hence the discussion.
Understood. In solid axle form, no 8" diff will compare compare and doesn't even belong in U4 discussion...just wasn't sure if we were quite venturing out into portal land or not.
 

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Perfect timing as I am outgrowing my 8" toy thirds, some discussion on fabbed housings would be great as well but may need a thread of its own.
 

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You have the Nissan H233b differential. I think both Diamond and Ruffstuff are producing axle housings for these dropouts. Gears are expensive but they are D60 sized ring gears if memory serves me correctly.
 

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Stock 9" 3rd members:
Carrier bearings: 2.89" or 3.063"
Axles: 28 or 31 spline (1.31")
Pinion: 28 spline (35 spline available, but not necessary with factory 3rd)

Weak point: axle shaft diameters or the pinion support ripping out of the casting. Factory nodular 3rds don't have that issue.

Nodular Aftermarket 9" 3rd members:
Carrier bearings: 3.250
Axles: 35 or 40 spline capable (1.5" or 1.71" respectively)
Pinion: 28 spline (35 spline available)

Weak point: Well balanced failure points, start reaching the limits of the ring gear bolts and have them back out (check out Zukizzy's bridge locks to help retain ring gear bolts). 35 spline axles might be the first to go, serious shock load of both axle shafts can take teeth off the ring gear

Currie High 9" 3rd member:
Carrier bearings: 3.063" or 3.250" (early units had 3.063 available, now all produced are 3.250")
Pinion: 28 spline
Axles: 35 or 40 spline capable (1.5" or 1.71" respectively)

Weak point: This uses a HP8.8 gearset. The high pinion will be a strength bonus in a front application, but it lacks the 3rd pinion bearing of a true 9". I don't know it's true durability.


Here's a question, do the 10" gears for 9"s use the same 10 7/16" ring gear bolts as other 9" gear sets? I've seen some gearsets (but I cannot place the name) double drilled, with 10 7/16" holes and 10 1/2" holes. It would be sweet to drill a carrier to match so 20 ring gear bolts can be used. Should help increase the rigidity of things a bit I'd think!
 

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Let's look at:
R&P strength(pinion size/spline count, ring gear diameter, R&P design as in where the pinion meets the ring gear)
Diff features(side adjusters, 3rd pinion bearing, etc)
Locker choices
Axle shaft diameter options(35 spline, 40 spline, etc)
While we're at it, can we capture carrier bearing I.D. and O.D. also? That seems to be a limiting factor when transplanting bigger axle shafts. Been wondering if there's some opportunity there---notably with the new 14 bolt dropouts---to go bigger.
 

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You have the Nissan H233b differential. I think both Diamond and Ruffstuff are producing axle housings for these dropouts. Gears are expensive but they are D60 sized ring gears if memory serves me correctly.
These are pretty strong. I've seen them take loads of abuse under the big Nissan Patrols on 38"s

How about the HP Yotas, with reverse cut gears in a front axle application they're rumored to be 30% stronger than the LP 8".
I'm setting one up now with 30spl. longs for my Zuk.
 

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Here's a question, do the 10" gears for 9"s use the same 10 7/16" ring gear bolts as other 9" gear sets? I've seen some gearsets (but I cannot place the name) double drilled, with 10 7/16" holes and 10 1/2" holes. It would be sweet to drill a carrier to match so 20 ring gear bolts can be used. Should help increase the rigidity of things a bit I'd think!
Yes, most of the big pinion "Pro" gears are double drilled.
and
Hell, even the $65 31 spline Ford 9" spool I have is double drilled.

While we're at it, can we capture carrier bearing I.D. and O.D. also? That seems to be a limiting factor when transplanting bigger axle shafts. Been wondering if there's some opportunity there---notably with the new 14 bolt dropouts---to go bigger.
40 spline shafts will fit in any D60/70-14 bolt....How much bigger do ya really need?

These are pretty strong. I've seen them take loads of abuse under the big Nissan Patrols on 38"s

How about the HP Yotas, with reverse cut gears in a front axle application they're rumored to be 30% stronger than the LP 8".
I'm setting one up now with 30spl. longs for my Zuk.
No... HP8" is good in a front application, driving forward. Otherwise it is identical to a v6 diff. It's basically a HP v6 diff.

It may be 30% stronger than a low pinion going forward... but not 30% stronger overall.
 

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40 spline shafts will fit in any D60/70-14 bolt....How much bigger do ya really need?

Not a question of what I need, it's a question of what I can get away with later.

You sacrifice some carrier bearing snout strength when you bore it for 40 spline axles. You could accept that as "just the way it is". Or, if you're greedy (like me), you have to wonder what else is possible---like if you could have the 40 spline axles AND maintain comparable (or better) snout strength.

At some point 40 spline axles will become so commonplace that no one will consider them special anymore, and all the cool kids will be taking the next step up. I've personally had evil thoughts of 1.85" 36 spline axles (like from a Dana S110)---but that's another story....

Point is, if somebody's going to go through all the trouble of designing a new dropout now, bigger carrier bearings leave you more options for expansion in the future---unless the trend reverses itself and smaller axles become the thing to do, which I'm not expecting to see happen.
 

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Impeccable timing as I want to build 609's in the near future. I didn't even know there were 10" gear sets for the 9. I'll be sure to follow along. Thanks for the good information!
 

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Discussion Starter · #17 ·
these are all great links, i have read them all

and there is a ton more great threads im missing
Agreed. I have read all of them too. I spent some time re-reading a few of them last night and there's a lot of good tech/explanations in the Spidertrax 10" thread started by Randy from Jimmy's 4x4. I'll go back through that tonight and try to summarize it and pull it into this one.

Impeccable timing as I want to build 609's in the near future.
So do I ;)
 

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older stuff for comparisons sake?

Seems like you wanted this thread just to compare newer stuff to the 9" benchmark.

If you did want to include older stuff just for comparisons sake,
both the drop out Eatons, and the Dodge M37 style drop outs dwarf the 9's in size & strength.

M37's have limited aftermarket and weak for their size, coarse splined shafts
but huge pinions, available Air Lockers, and are usually cheap when you find them.

Eatons are the tough as nails grandpappys to the 14 bolts.

Oldsmobile & Chrysler also both made smaller drop outs with near Ford 9" strength.
(The Chrysler 8.75 now having decent aftermarket support, but almost no one uses them in trucks anymore)
 

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If parts and housings were more readily available I'd build a pair of Eaton ho72's . That would be killer! Not sure of the weight on those but assuming its a lot less than cast center 60/14.

I believe only the 72 had the load bolts. Thinking the other didn't.
 

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Not sure of the weight on those but assuming its a lot less than cast center 60/14.
I used to be of that train of thought on weight savings but I really think that less and less nowadays. I want to know what a bare stock 9" housing weighs PLUS the bare nodular 3rd member weigh combined, or aftermarket 9" housing with nodular 3rd compared to a stock 60 housing plus diff cover. I honesetly think the weight savings might not be as extreme as expected
 
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