What's the easiest way to swap closed knuckle for open?

SRT6 · Post by **SRT6** » Mon Jan 21, 2019 2:37 pm

Have a fun "new" truck in the fleet. 1972 J2000 360V8 4x4. Really liking it a lot. Trouble is the closed knuckles and making 10 point turns and not even dreaming about parallel parking. It makes regular trips to our small, old "downtown" and space is tight everywhere down there. It also makes it not real fun at the boat ramp and using it for work around the yard and picking up other projects. Research says I need to swap for open knuckle. What is the easiest way? Hoping there is a simple answer like "swap in the axle out of a 75-85 J-10 or wagoneer" or such. Thanks in advance for any and all help!!!
Matt

Post by **Stuka** » Mon Jan 21, 2019 2:46 pm

A wagoneer axle won't work. Need to be a 74-79 J-Truck or wide trac Cherokee front axle. But, these of course are going to be 6 lug axles. You can either swap in a matching rear J-Truck axle to be 6 lug on both. Or, you can swap on Ford outers onto the front axle to convert it to 5 lug. The other thing about a 74-79 front axle is they almost all had disc brakes, instead of drums.

The axle will need spring perches welded onto it if you want to retain the factory front springs. Or, you can swap in 74+ springs and weld on new spring hangers for the better ride that they provide.

So, nothing is super "easy", but its not a giant amount of work either.

SRT6 · Post by **SRT6** » Mon Jan 21, 2019 2:53 pm

Stuka,
Thanks for the quick reply. So If I find a cheap 74-79 J-Truck, I can swap the front axle from it in? Will steering still work the same or will I need to also transfer all of that over too. New linkages, tie rods, etc?

SRT6 · Post by **SRT6** » Mon Jan 21, 2019 2:54 pm

So assuming I can find a 74-79 4x4 J-Truck, is there any way to swap with no fabrication?

orionstarsin · Post by **orionstarsin** » Mon Jan 21, 2019 5:10 pm

74 and newer trucks have their front springs mounted under the frame instead of post mounted, so to use a newer axle, sadly you would have either get a hanger to mount under frame or move the spring perches on axle.

A little fabrication is required either way. I believe moving the springs under frame will also add some lift too.

orionstarsin · Post by **orionstarsin** » Mon Jan 21, 2019 5:17 pm

You might check out this thread too this guy just dealt with all this. Hope it helps.
http://www.fsjnetwork.com/forum/viewtop ... 44#p169719

SRT6 · Post by **SRT6** » Mon Jan 21, 2019 6:30 pm

Thanks guys!

Phils67 · Post by **Phils67** » Tue Jan 22, 2019 5:32 am

orionstarsin wrote:You might check out this thread too this guy just dealt with all this. Hope it helps.
http://www.fsjnetwork.com/forum/viewtop ... 44#p169719

That was my thread. Originally I was doing a disc swap on the closed knuckle, which I did. It was short lived though. Now I am building those J20 axles to swap in. I welded spring perches on the front prematurely and decided to go spring under frame, but that has not been done yet due to sub zero temps, massive amounts of snow here, and lack of funding due to financially rebounding from christmas still. If I recall, 66stepside did a spring under frame conversion on one of his builds with good results. After much contemplation, moving the springs seems like a bit more work but a better result. Just my 2 cents. Good luck!

44bz · Post by **44bz** » Tue Jan 22, 2019 9:53 am

80s dodge 4x4 front is also an option from what I’ve read over the years. You get open knuckles, discs, and retain the 5 lug bolt pattern.

However, with the tighter turning radius you risk hitting the springs at full turn if they remain in the post mount configuration.

It seems like a whole lot of work if you’re only goal is to improve parking and maneuverability.

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44bz · Post by **44bz** » Tue Jan 22, 2019 9:59 am

Here’s a quote from JoshD on IFSJA about swapping front axles and nicely outlines the work involved.

although this is about as easy as it gets for a much better axle into the early post mount trucks, it is not bolt in. A wide track FSJ axle will require basically the same work to swap, plus having to swap parts to get 5 lug, unless swapping both front and rear. Here's a basic list of changes/mods that have to be done:

1. Spring perches welded on (2 inch wide)
2. Shock mounts (I made some using channel and some universal shock studs)
3. Swap gears from old axle to new to match rear
4. Steering mechanicals (several ways to accomplish this. I used the tie rod and drag link from a '77 J-10. The Dodge used much smaller TRE's than FSJ's do, so I drilled and tapered the knuckles for the Jeep TRE's)
5. Brake lines (I used some stainless braided Goodrich lines for a CJ that matched up to both the early hard lines and the short rubber lines on the Dodge.
6. U-bolts (Dodge axle has nice 3" tubes like the later FSJ's)
7. U-bolt spring plates (I used ScoutII, because I had some laying around. These can be easily fabbed)
8. Disc/Drum master cylinder (My brakes were manual, so I used a disc/drum MC for a manual disc braked '78 CJ. It bolted right up!)
9. Brake proportioning/combo valve (Used one from a '77 J-10)

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Post by **Stuka** » Tue Jan 22, 2019 11:36 am

It should be noted that JoshD used a dodge front axle, not an FSJ front axle. This gave him 5x5.5 lug pattern, but it required extra work related to steering, shock mounts, etc.

SRT6 · Post by **SRT6** » Tue Jan 22, 2019 2:46 pm

So should I just sell the 72 and get a 75 or later?

tgreese · Post by **tgreese** » Tue Jan 22, 2019 2:56 pm

Stuka wrote:It should be noted that JoshD used a dodge front axle, not an FSJ front axle. This gave him 5x5.5 lug pattern, but it required extra work related to steering, shock mounts, etc.

How much work would the J-truck open axle save you over the Dodge? I understnd you can convert the 6-lug hubs to 5-lug using Ford hubs. That should not require any additional fab, just the right parts.

A '74 has an open knuckle front. Isn't the rear still post mount and the front the same as 1975 and later?

How far are you from Jake's? I'd expect there's somebody near ou that will do the fab work for you. Check your local Jeep/4x4 forums.

SRT6 · Post by **SRT6** » Tue Jan 22, 2019 3:13 pm

SRT6 wrote:So should I just sell the 72 and get a 75 or later?

Meaning is that the only way to get a steering radius that works for what I need without fabricating the major load points on my J2000?

Post by **Stuka** » Tue Jan 22, 2019 4:05 pm

tgreese wrote: A '74 has an open knuckle front. Isn't the rear still post mount and the front the same as 1975 and later?.

74 and 75 are both post mount rear. Box mount rear came in 76. But 74+ does have the newer front suspension.

Post by **Stuka** » Tue Jan 22, 2019 4:07 pm

SRT6 wrote:
SRT6 wrote:So should I just sell the 72 and get a 75 or later?
Meaning is that the only way to get a steering radius that works for what I need without fabricating the major load points on my J2000?

Well, I think thats a bit overboard for what is needed. Especially if the truck you have is nice otherwise. If its a rust bucket, then maybe finding another one wouldn't be such a bad idea. But if its nice, and its the truck you want, you can hire out the welding to convert the front to the later spring setup. Yes you could just weld perches to the newer axle, but the post mount springs will still limit your steering radius some as the tires rub the springs easier.

SRT6 · Post by **SRT6** » Thu Jan 24, 2019 12:35 pm

Stuka wrote:
SRT6 wrote:
SRT6 wrote:So should I just sell the 72 and get a 75 or later?
Meaning is that the only way to get a steering radius that works for what I need without fabricating the major load points on my J2000?
Well, I think thats a bit overboard for what is needed. Especially if the truck you have is nice otherwise. If its a rust bucket, then maybe finding another one wouldn't be such a bad idea. But if its nice, and its the truck you want, you can hire out the welding to convert the front to the later spring setup. Yes you could just weld perches to the newer axle, but the post mount springs will still limit your steering radius some as the tires rub the springs easier.

Stuka. Thank you sir. I will take it to a couple shops and see if anyone is interested in doing the fab work required to make the later Open Knuckle a Bolt in affair.

SRT6 · Post by **SRT6** » Mon Jan 28, 2019 2:07 pm

Will the front axle/suspension/steering from a Grand Wagoneer work the same as a J10? If so what years GW would work? They seem to be a lot easier to find and find nicer. Thanks.

tgreese · Post by **tgreese** » Mon Jan 28, 2019 3:34 pm

No. Stuka covered this in his first reply.

Cecil14 · Post by **Cecil14** » Mon Jan 28, 2019 5:58 pm

Another option not mentioned so far is a complete frame or chassis swap. If your body is in good shape (rare for these), you can likely find a J-10 or J-20 frame and running gear from a later model truck and just swap everything over. You may need to play around with body mounts a bit, but other than that you should be pretty set. The 360 was more or less the motor of choice (by sales figures) in the later years, so you should have little trouble dropping your motor onto a later frame, and the trans is just the cross member. If you decide to look into this route, keep in mind that the front axle went from a passenger side differential to a driver side from 1980 on.

A frame swap is a lot of work, but it's less custom work and more factory than have brackets fabricated and welded on.

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