So James, you obviously prefer a Dana 60 over a Ford 9". Other than possible (likely) cost savings, any other reasons? I realize this has been beaten to death for decades and I could just search, blah blah. But I'm interested in your take. Ground clearance isn't a big deal to me, for the way I use my Bronco (much off highway travel but not Rubiconesque trails). Unsprung weight does matter. Strength and cost matter.
For the record I have an approximately 2005 vintage 31 spline ARB in my 9", Richmond 4.56 gears, Currie clone of a Daytona case, a no-long-available heavy duty Currie housing and Explorer brakes. I was eyeing it yesterday, wondering how much longer the third member might last. Have probably 100k+ miles on it now, mostly connected to my previous 5.0 but now my 408 with double the torque. A 60 like you described might be an attractive and potentially more affordable option.
Ah yes…the Classic “junkyard axle” riddle! It’s my favorite! I have no particular love for the D60. But in the arena of competing priorities, the 60 wins in a number of use cases. The whole discussion starts and ends with lug nuts.
As soon as you are willing to have 8 lug nuts, the 60 falls out of contention, and the GM 14 bolt is the clear winner. But not for the reason that most people think. It’s because of the availability of the lunchbox Detroit for $200, or free from the M1009 CUCV.
So once we decide that we must have 5 lugs, (or 6) but basically a 5.5 bolt circle…the full float solution space is no longer available. There are exactly zero low cost full float 5.5 bolt circle floaters out there. Even though my picture above shows one.
A. Are we in semi-float solution space?
Now to lockers. The selectable locker is the single most expensive component of any axle build. If you are willing to put up with poor handling, and strange noises, the full Detroit, or a spool makes a HUGE DIFFERENCE. If you can live with a spool, the 9 inch is not only a great contender…it actually dominates.
For years, nascar teams made cheap Detroits available for the 31 spline 9 inch. $200 all day long. A Detroit or spool is the only traction Device that can withstand the durability of the 9 inch ring and pinion. An ARB is close, but the spatial limitations do not allow for adequate travel of the engagement coupler. Since the coupler can’t travel, and since you need a lead-in chamfer to enable shifting…it ends up running on the chamfer, and requiring huge application pressure to stay engaged. So they slip. Once they slip a little, they go on to slip a lot. You can imagine if I only let you shift your transmission halfway into gear. It’s the same effect. ARB “fixed” it by telling you to increase application pressure. But that has proven inadequate. So their ultimate solution is a $2k “comp” unit…which is default engaged, and air unlocked. It works well enough…but it violates the “low cost” requirement. ARB has done an admirable job of marketing, so nobody knows there’s a problem. Except for competitors at KOH, who all know it’s a problem.
B. What kind of locker do you have?
The Dana 60 has no such constraint. The available space within the ring gear is cavernous, and all problems are solved with mass. I think the ARB for the 60 weighs 53 lbs, and the 9 inch is 30 lbs. it looks like the 60 carrier swallowed and ate the 9 inch.
As with all competent design criteria, the failure modes need to be considered. Not so much when it will fail, but how does it fail? What breaks first, and what breaks never? Too many engineers do not consider test to failure. Too many enthusiasts consider only “use to failure.”
C. What have you already spent?
If you already own a 3.25 inch big bore Nodular case with gears and a 35 spline carrier, and axles…you are already committed. But if you own a c7aw-e 2.891 inch grey iron case with 3.50’s and a 28 spline open diff…totally different story. I only recommend the 60 for people starting from stock. The price of a custom case, a trussed or fabbed housing,a locker, and a set of axles, and a pinion support take you WAY past the cost of a junkyard 60.
I used to try to find the 66-68 5 lug Ford 60 just to get the 4.10’s and the power lock posi. Even with 30 spline axles, they were unbreakable. 8 lug full float drum brakes are heavy, and unnecessary. So there’s that.
The biggest problem with the 9 inch is the bench race morons that look solely at ring and pinion strength and declare it “as strong as a 60. Maybe stronger”. Yeah, probably. But as soon as you put a differential in it, (other than the Detroit) it turns into junk.
In your case, you are “pot committed”. Your set up is good for at least 500,000 miles with minimal maintenance. A couple of $2.00 o-rings rings, and You are good for another 500k after that.
