9 Inch Ford in a 3B

My ’54 cj3b is already heavily modified with a 302 SBF/toploader among other things, and needs an overhaul of the suspension and axles to keep up. Plans include a D44 front axle and Holbrook springs. I am contemplating a 9 inch Ford to replace the stock rear axle. Tires will be limited to 31-33 inches and selectable lockers on both ends. Plans for the distant future include a hefty step up in power once the 302 is done. The jeep has been in the family for a long time and has a special place as a bit of a hot rod, so I plan to keep the build in that spirit while maintaining off-road worthiness.

I’m not interested in the weight and bulk of a D60, and have settled on a JK44/D60 hybrid or a 9 inch Ford in full float configurations. The 9 inch with an aluminum 3rd member is getting the most consideration right now due to the light weight & high strength relative to cost. Going to a high pinion 3rd member puts the cost comparable to the JK 44/D60. I understand the low clearance and low pinion nature of the 9 inch relative to a D44. What I want to know is if anyone has any actual experience putting a 9 inch in a SWB jeep and been successful dealing with driveline angles, particularly with ~3 inches of lift? Would the angle be more than a double cardan shaft can overcome? I have searched past discussions, but no one has discussed real world experience with this type of combination. It seem to mostly be used in longer wheel based models.

Duffer’s past posts on axles and 3B’s have explored a lot of the aspects I’ve been considering. Duffer, have you come to any firm conclusion on what axle configuration works best in your 3B?

Thanks

 

80 inch wheel base I assume?.............What Transfer case and is it offset? The D-44 up front is fine......no need to go Hi Pinon up front with only a 3 inch lift spring under as the front drive shaft angle and room between the motor on a Pass side drop may give you fits............nothing wrong with a 9 inch or the Hybrid 60 in the rear but both will have to be cut to fit , but since your only going to run 33" tires really no need for it.........also using the 1.750" wide long leave Holbrook springs with the extra un-sprung weight of either of the larger rear ends........... axle spring wrap even while mounted spring under would be a problem for those light flexy springs to control the weight........High Pinion in the rear is weaker so I would stay away from it.............due to the short wheelbase I would probably be looking at using a D-20 Transfer case offset using the D-18 2.43 gear set........ that would lessen the drive shaft angle to both front and rear axles and using a D-44 offset flanged axle in the rear.....Those axle's have 30 spline axles already and can be upgraded or floated if you want and plenty strong for 33" tires.

Your kinda caught in the middle of your desires versus what will fit and be compliant......

 

Thanks Tarry. I agree that wanting what just may not work may be the case here

I do plan on a traction bar in the rear for the reasons you indicated. The transfer case is an offset "super 18" (D-20 case/D-18 gears). I already accept a custom axle housing is necessary. I agree a 30 spline D44 would be plenty strong, but the strength per cost ratio in a 9 inch is better (I can just get more for my money). And it would seem the potential weight savings over a heavy duty D44 housing would seem to be significant...depending on how it is built. The alternative would be a D44 with JK gears (Currie RockJock or standard housing with JANA kit).

Yes, a standard D44 could serve quite well, but if I can get some extra beef without a weight penalty then I would like to if its possible.

 

Might not be that big a difference in weight between the 9 inch and D-44.........Don't get me wrong I like the 9 inch package been running them for years in the race cars and will be using them in my CJ-6 build but I'm also running 37" tires.......but along with the axle upgrade , brakes & tubing size & wall thickness upgrade and a back brace they can get heavy........the lower pinion is not and issue to me as it still has more clearance than a D-60 with no weight & bulk penalty and the 5 bolt lug pattern...........but the best thing about the 9 inch and the lower pinion over the 60 is the fact that it always has 3 teeth engaged with the ring gear while the 60 only has a little over 2 ....I still think you should find a 70-71 offset D-44 flanged axle , already cut to size. I may know where one is at in California.

 

It's your Jeep, do what you want. At least you are not going to an AMC 20.

 

Hey hey .... I have a AMC 20 IN MY 73...

 

I've rebuilt a few '20s. They are OK unless you do something stupid with them like trying to get big air off of a hill, they aren't quite as stout as a 44.
Put some flanged axle shafts in to replace the tapered shaft set up.
The last 2 later era jeeps I worked on we put Eaton electric lockers in. Actually we did front and rear lockers on both of them.
One of the guys could break anything.
The son of the other guy isn't too kind to the Jeep either.
Both of the Jeeps are still doing fine.
I'm really happy I have a flanged 44 in my Commando now.

 

Hey Josh, I'm in nearly the same position. My rear axle project will likely be a year down the road but will be watching this to see what you come up with. Almost certain I'm going 9".

 

Perhaps a few more details might open up the discussion. The options I’m considering for this application include:

9 Inch

• Custom housing/triangulated center with 3” tubes: would minimize the weight and would likely be strong enough without trussing

• Third member:

o If a low pinion would work (preferred) you can get it in aluminum (light weight, affordable, maintain low pinion strength in a rear application).
o A high pinion from Currie or Hi9 would weigh more but correct driveline issues. As I understand Currie uses 8.8” gears where Hi9 is a true 9”. Currie rates theirs at 400hp (no torque rating given) and I would expect Hi9 to be a
higher rating.

* A comparable sized R&P is the Dana 50 which is rated at 5000 ft lbs torque so I would expect the 9 inch to be a bit higher because of its pinion support. Most sources point to a 20% decrease in strength when gears run in
reverse so the hi pinion 9 inch should still be stronger than a standard D44 (rated at ~3500 ft lbs torque).
* Down side to a Hi9 is the custom gears: seem to be made by Richmond only for Hi9.

• The Schreiner full float kit is a great value: you can get all the outer components, brakes (minus calipers) and 31 spline axles for ~half the cost of assembling a comparable Dana FF kit.

o Down side is the components are proprietary and junkyard scrounging for replacements parts would be minimal.

JK 44/60 Hybrid

• Although I couldn’t find any torque rating specs on the JK gears, Jantz suggests their size and design improvements should put them in the same ball park of ~5000 ft lbs.

• JK gears would require a custom center section (Currie) or the use of the JANA J4 kit (http://www.jantz4x4.com//jantz.php?p=detail&pro=jana_k4). The JANA K4 it looks interesting but I have some reservations.

• To use ready-made or junkyard parts (i.e. D60 spindle and 14 bolt hub) would require 3 inch tubes.

o Ruffstuff spindle flanges, D60 spindles, 14 bolt hubs (machined junkyard pieces or Solid Axle components), flanged FF axles (custom or re-splined D60 shafts).
o Options for a 2.75 “ tubes exists too, but are not bolt on ready, would take work to fit 30+ splined shafts thru the spindle, or use internal splined hubs (double splined FF shafts and internal drive flanges = more $$). Not many
junkyard 3” tubed D44s to be found, and would likely require re-tubing anyways. Which points back to a Currie housing (already has 3” tubes).

Regardless of axle, a double cardan shaft and traction bar will be used. The current drive shaft is stock length and will not change with any future engine swaps. Lift will be limited to that provided by Holbrooks. The overall drivetrain is intended to deal with off-roading with high engine torque but not necessarily rock crawling with large tires. The overall goal is light weight strength.

All this is to say a low pinion 9 Inch would be ideal if it can be made to work. If I can get over the negatives of a Hi9 I might be convinced to pay the extra cost. Anyone with thoughts/experience with any of these approaches, particularly in a SWB jeep, please chime in.

 

• Custom housing/triangulated center with 3” tubes: would minimize the weight and would likely be strong enough without trussing.


Depends on the 9" Housing your going to use........since it will have to be "Offset" due to the Offset D-18 TC the banjo size of most 9 " housings start to become an issue on the short side, which leads to the next issue which would be , the length of the axle Tube engagement into the housing and or whether or not a bulkhead inside the housing along with a back brace would also be needed to insure against flex. This would all depend on what axle width your thinking about? On a standard 53"width axle you will run out of room on the short side quickly.


• Third member:


o If a low pinion would work (preferred) you can get it in aluminum (light weight, affordable, maintain low pinion strength in a rear application).


The Aluminum 3rd member is OK but would require a skid plate due to the potential of rock or clearance damage......the real weight savings versus keeping your weight at the lower COG is a trade off where perhaps that money could be better spent elsewhere............Also due to the bulk of the aluminum 3rd members internal bracing.......inner bulk heads in the housing to grab the inner portion of the axle tube may be at issue.



• The JANA K4 it looks interesting but I have some reservations.


If I was going to use the larger JK gear set I would also use the conversion Currie housing



Regardless of axle, a double cardan shaft and traction bar will be used. The current drive shaft is stock length and will not change with any future engine swaps. Lift will be limited to that provided by Holbrooks. The overall drivetrain is intended to deal with off-roading with high engine torque but not necessarily rock crawling with large tires. The overall goal is light weight strength.


A CV type joint off of the Transfer case would work while adjusting your pinion angle / housing up say 4-6 degrees ???..........the Holbrooks will probably net out to about 2.5-2.75" of lift once setup depending on shackle angle.........that in itself may not equate to even needing and advanced joint in the drive-shaft.
That area can also be further complicated with pinion offset to the Transfer case not in the vertical but in the horizontal plane due to what I mentioned above about the larger Pumpkin & banjo of the 9" housing and how close you can get it to the spring hanger on a narrow 27-28"+/- Center line frame of that early CJ chassis.............Notwithstanding doing a traction bar back there may negate any real benefit of even having the flexy Holbrooks.


All this is to say a low pinion 9 Inch would be ideal if it can be made to work. If I can get over the negatives of a Hi9 I might be convinced to pay the extra cost. Anyone with thoughts/experience with any of these approaches, particularly in a SWB jeep, please chime in.[/QUOTE]


Joshh , All great Ideas , I hope some of the things I mentioned helped you.

 

I think you'll run into less driveshaft issues with a custom 44 vs a 9". A HP 9" might solve those but, as Tarry99 mentioned, you may not be able to get the center far enough over for a straight shot to the yoke and you're running on the wrong side of the gear. Some misalignment won't hurt but enough can prove disastrous. How much street time is this gonna see? The 9" can be built to do what you want, but you'll be using a lot of proprietary parts to do it that will significantly add to the cost and if something were to break, you're stuck with one option to fix it that may take some time to source parts. If you're starting from scratch, I'd start with a JK44 center and tube it how you want. Run 30, 33, or even 35 spline shafts if you want depending on the carrier you use. You'll have a lot better parts availability and options that way.