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'75 J series axles

5K views 27 replies 10 participants last post by  WillYJ 
#1 ·
Can anyone tell me point me to info on the axles and t-case under one of these trucks.

I have been told they are D44's. Is that correct?
What's the width?
Common gear ratio?
Spring perch width?
Offset?

Please help. I am looking to see if this would be a viable swap for my YJ.
 
#3 · (Edited)
Half ton J-trucks (J10):
Front- Dana 44
Rear - Dana 44
Gear ratios - 4.09 standard with 258 engine, 3.54 standard and 4.09 optional with 360, 3.54 only with 401.

3/4 ton J-trucks (J20)
Front - Dana 44
Rear - Dana 60 full floater
Gear ratios - 3.73 standard and 4.09 option if engine is 360, 3.73 only with 401.

Width is around 65-66" front and 62-63" rear. I can't remember exactly. Spring perch width (distance from one perch to the other) is 31.5" for the front and 42" for the rear. Both axles are offset to the passenger side. The rear is for gas tank clearance even if it used a centered tcase.

Gear ratios and spring perch distances come from my '75 factory service manual.
 
#4 ·
The J-truck axles are a decent swap into a YJ, if you want that much width, my experience has been that the fronts are more like 67" for six lug, and 69" with eight lug, the difference being in the hubs. If you wish to keep your driver's drop t-case (I would if I were you, the whole driveline is offset 1" to the pasenger side) then look for a '80 and up J-truck for axles, they have driver's drop front axles. You may be able to find a late model ('86 or '87) with a centered Dana 44 rear. Another option is Wagoneer axles, again, pre '79 passenger drop, post '80 driver's drop, and the Wagoneer's are around 61" wide, same as your stock YJ axles. All of these front axles have cast in spring pads in a SUA configuration, although SOA setup isn't hard. If running SUA they are nearly a bolt up, with either outboarding your springs 1/2" on either side, or moving / redrilling and grinding the axle pads. Yet another front axle option is the late seventies full size Ford Dana 44 from a leaf spring truck, F-250 or F-150 ex-cab, in either high pinion or low pinion. All of this has been covered in great detail at one time or another on this board, a little searching and you will be greatly rewarded.
 
#6 ·
Then one could assume that my head is up my ass and six lug J-10 dana 44's are 65" WMS - WMS, this all belongs in an axle chart, after confirming measurements have been taken by at least two different people.
 
#7 ·
Thanks!

Thanks for the link to Jeeptech. I remember when that info was on offroad.com, but that is blocked at work for me. I'll have to bookmark the jeeptech site.

The donor truck is a '75 J10. Those axles are W I D E! Not sure if I willl be able to get away with running them at that width. I'll have to look at gettting them cut down I believe. I'll probably center the rear diff when I do, and look at changing the front over to a driver side drop. I haven't even begun to look at the cost factor of all of this. I am also hoping that the diffs are housing the 4.09s, but with my luck I'll get the 3.54s. :) The good news is that I can score these axles cheap, making them work may be another story.

Thanks for the info.
 
#9 ·
I'll keep that in mind

I will need new wheels anyhow, so that is a better option, but I will still have to make it a driver side drop. My take on that is that I could grind of the plates, get the tubes pulled out and swap sides, then put reassemble. I'm not sure about the cost effectiveness of that, though.

There is a chance I could get the D20 t-case that is in it as well, but the crappy gear ratio scares me. I'm not even sure how much work it would take to adapt it to an AX-15, if any.

Man this is hard work.......and I haven't even started.
 
#10 ·
Sell that pasenger drop front axle and get one from an '80 and up J-pickup, driver's drop already, with spring pads that are 1" wider than your current YJ axle. Swapping sides isn't worth it on a Dana 44 when there are better options available. You best bet to use that passenger drop axle would be to score a Dana 300 out of an '80's CJ and use that, but then I would modify your motor and trans mounts to move your motor 2" to the driver's side for a 1" total offset.
 
#11 ·
True, I would be doing a lot of work when I really don't have to. I am just so amped about having decent axles for SOA and 36s. I am moving to Colorado in April and I want to play hard when I get there!

I doubt that I am ready to start swapping trannies and moving motor mounts. Lack of access to the proper tools keeps me from hurting myself!
 
#12 · (Edited)
WillYJ said:
I doubt that I am ready to start swapping trannies and moving motor mounts. Lack of access to the proper tools keeps me from hurting myself!
If you aren't up to either of these tasks you have no business even dreaming about retubing an axle.:rolleyes: This isn't a slam either, just stating the truth. Not many are up to the retube thing.
 
#13 · (Edited)
TRUE> I wasn't gonna be the point man with this. I'm still learning as I go. That's what friends are for. The most extensive work I have done thus far is my lift, clutch work, and installing lockers. I never let a shop do my work, though. I like to be taught as I go. Most likely none of this will be done until I PCS to Colorado and join a good club with knowledgeable folks.

P.S. How far is Parker from CO Springs...and what kind of tools do you have?? :beer: :beer:
 
#14 ·
Parker is about an hour north of Colo Springs. I would never attempt to retube a Jeep axle. There are just too many of either passenger or drivers drops to bother with it. I would retube a high pinion Dana 60, but my work would have nothing to do with the actual retubing part. Some things are better left to a shop with the right tools and know how.
 
#15 ·
So I guess you are up near Denver.

Actually the easiest route for me to take is to swap in a D300...but I was putting it out there for info. Then...all I would have to do is shorten the axles (unless I can get away with full width), center the rear diff as part of the slimming proces. Set the axles up for springover. Since the knuckles will be off as part of the slimming process, the proper caster can be setup for SOA at the same time. Lastly, shortening the axles down to a standard D44 size to allow common axle shafts would make most sense. Did I leave anything out?

Oh yeah...regearing and lockers........

Now...maybe I can deploy for four months so that I can pay for all of those mods. Let's get Saddam!! :usa:
 
#16 ·
Here's what I did

I bought another front Dana 44, driver side drop. Gonna swap the flat-top knuckles from the pass side drop axle over to the front.

Surgery begins Wednesday.

Keith Strong-- any leads on vehicles that would have the proper backspacing. The cheap aftermarket wheels (steelies) come with 3.75 BS. I am guessing something closer to 5" will work better in my situation...trying to tuck those tires in.
 
#18 ·
I know that you got a drive drop front alxe but why did you not just swap in a d300(I am thinking that you have a yj with stock tranny/t-case) then you could of just keep the passenger side drop and gotten a better t-case.
 
#19 ·
kyrel69-- I really don't have a good argument either way. The 231 hasn't blown up yet is the only thing I can think of. Regardless, if it does let go I can swap in a D300 at that time and flip it to match my driver side drop. I guess for now, it's just one less thing to change out.

CJ-Jeeper-- Thanks. I'll get back to you when I wade through the 795 threads the search brought up. Hopefully, I can find a 6-lug set that addresses the exact problem I have. If I'm not back in 10 minutes, just wait longer...
 
#23 · (Edited)
payton said:
umm didnt su j serise trucks come out with a dana 53?
The early J series 3/4 ton trucks had the Dana 53 in them. kaiser put that axle in rigs up until 68. The 64 J-300 I just parted out and made the bed into a trailer has one in it.

Jeep axles
 
#24 ·
I have parted out several wagoneers and J trucks and also have a 93 wrangler. Most of the 70 series J trucks that I have seen have a Quadratrac transfer case in them not a dana 20. That is the reason for the offset rear axles. I converted my wrangler over to a 360/TF727/Dana 300 with a set of 79 Cherokee Chief axles. These are the same width as a J truck Wagoneer axles are narrower by about 3 inches. If I were you I would look for a Dana 300 and put in the passanger drop axle. By doing this it eliminates the need for a slip yoke eliminator for your current transfer case ($400) and you will get a stronger case with the correct drop. As far is backspacing if you backspace too much it will interfer with your high steering and will hang the hub way out there for snagging on rocks and things.
 
#26 ·
jeepinblackdog said:
As far is backspacing if you backspace too much it will interfer with your high steering and will hang the hub way out there for snagging on rocks and things.
All valid reasons to swap to D300. I chose not to take this route.

I stumbled upon the BS problem already. Now it looks like 3.5" BS is the MOST I can run anyhow. I didn't think about the hubs sticking out there...since they are a foreign object to me thus far, after all I am used to vacuum actuated hubs. I can't wait until I get to actually engage the Warn premiums...that will be a first!
 
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