1971 J2000 build on Jeep JKU Frame

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Copper204
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1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Building a 1971 J2000 on a 2017 Jeep JKU 4 door Rubicon.

1. Will be using fully built trussed and gusseted axles, with 3 link front and rear.
2. Rock Krawler 4.5 inch lift Long arm kit.
3. GM LS LY6 6.0L aluminum block fully built with 21/218 .550 lift and 112 LSA cam. Running LS3 Heads
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Stuka
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Stuka »

Welcome to the forum.

The JKU frame is stronger than the stock frame, so good starting point. It will need to be lengthened behind the rear axle unless you are bobbing the bed. You should be able to stretch the wheelbase to work pretty easily with just lengthening the control arms. I don't think the RK arms will extend that far though as you need to make up roughly 4 inches.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

sansabarJ
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Re: 1971 J2000 build on Jeep JKU Frame

Post by sansabarJ »

I m not at all sure about that statement on a late model frame on most vehicals produced today .
My J4000 really is only heavier due to the flat steel the be Tory welded to the bottom of the frame between front and rear leaf springs . I've yet to hear or see any post or other comment regarding weak frames . The FORD Raptor Chevy Colorado and others use thinner light weight frames and while we are talking a JKU I'd look at it and see the differences in the steel thickness number one that is heavier gauge. Second most all late frames have holes in them to lighten them up .
So Again I digress the JKU frame is in no way stronger .


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sansabarJ
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Re: 1971 J2000 build on Jeep JKU Frame

Post by sansabarJ »

I'm you g to add here , this does not mean you cannot perform your conversion. The J trucks are far heavier than anything late model built today . Heavy steel body's and beds . Lots of weight .
Consider this when deciding to change out a vehicals designed frame onto another vehicals been
Built as a complete AS designed vehical . Guys do put dodge frames under these like a Cummins platform and similar . Those frames are designed for heavy engines and payloads and are more appropriate for such a conversion . At your own risk on all of these modifications though .
Consider this as well .

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Stuka
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Stuka »

sansabarJ wrote: Wed Mar 17, 2021 12:58 pm I m not at all sure about that statement on a late model frame on most vehicals produced today .
My J4000 really is only heavier due to the flat steel the be Tory welded to the bottom of the frame between front and rear leaf springs . I've yet to hear or see any post or other comment regarding weak frames . The FORD Raptor Chevy Colorado and others use thinner light weight frames and while we are talking a JKU I'd look at it and see the differences in the steel thickness number one that is heavier gauge. Second most all late frames have holes in them to lighten them up .
So Again I digress the JKU frame is in no way stronger .
A JKU frame is fully boxed with seven cross members. I have owned both a Cherokee, J-Truck, a JK, and a JKU. And I have been all over all of them. While J-Truck frames were stronger than say, GM c-channel frames of the 70-80's (Which were notorious for flexing and cracking), the J-Truck frames are very much inferior to trucks made today, which all use boxed frames except for the Tundra.

A JKU Rubicon also weighs more than an FSJ. Which makes sense as it has to pass safety standards, and durability testing is much more stringent now.

There have been posts here of J-Truck frames (no cab/bed) on three jack stands with a weight on the fourth corner, showing how much the frame flexes. And then show the same test after boxing the FSJ frame.

A JKU frame has almost no flex until it is put under extreme forces. With my Cherokee, if the suspension was crossed up, and you opened the tail gate, good luck closing it. Because the whole body and frame would twist. This is not the case with a JKU. Boxing a frame and giving it a lot of cross members makes a GIANT difference.

sansabarJ wrote: Wed Mar 17, 2021 1:03 pm I'm you g to add here , this does not mean you cannot perform your conversion. The J trucks are far heavier than anything late model built today . Heavy steel body's and beds . Lots of weight .
Consider this when deciding to change out a vehicals designed frame onto another vehicals been
Built as a complete AS designed vehical . Guys do put dodge frames under these like a Cummins platform and similar . Those frames are designed for heavy engines and payloads and are more appropriate for such a conversion . At your own risk on all of these modifications though .
Consider this as well .
J-Trucks are definitely lighter than almost any full size truck made today (2wd, single cab short bed F150 is a bit lighter, but its also aluminum). A new Jeep Gladiator weighs more than a J-Truck, it tows more than a J-Truck, and it uses a frame that is partially based off a Wranglers with some Ram bits tossed on in back.

While early FSJ's used thicker sheet metal than later FSJs, it was not enough to greatly change the weight.

Anyway, we all love FSJs. They have amazing style and character. But they were never really known for amazing build quality. Kaiser and AMC did what they could with what they had. And if they could take a short cut, they did. Even if it did lead to things like dash fires.

So again, I think Copper204 going with a JKU frame is a fine idea. Its strong, TONS of parts available for it, and he will end up with a nice riding, capable Jeep with modern brakes, power train, and suspension.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

Topic author
Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Well, being as Bill Cosby ( not actor) has already done this conversion. I am not re-inventing anything. As far as making it fit not a problem. My current 2017 JKU is 118 inch wheel base. The J2000 is 119 inch as measured. Not my first go around. I have been building Jeeps in one for or another since 1980. And luckily own a shop that we build them for others. Also on Instagram I go by @copper204. I have been documenting my build process on Instagram under @1971_gladiator_build If anyone wants to see my direction I am going?

We completely flipped one of these JKU’s at KOH in 2020. It was accidentally launched off of my JKU. The rig barrel rolled twice and flopped on it’s side. We replaced the windshield frame only. And it has been back on the road since. Even checked the frame on a frame jig. So yea I believe these frames are extremely robust.
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Stuka, this build is going down at Auto Tech swing by one day. Going This coming Friday to get frame from buddy Tommy. Waiting on Rock Krawler to send me the rest of my kit.

My daily is the big Purple Rubicon running around town in Sonora, Ca.

Just. We’d o figure out how to load pictures? Is there something like the old Photobucket I need to use?
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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rocklaurence
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Re: 1971 J2000 build on Jeep JKU Frame

Post by rocklaurence »

Looking forward to the build and make mention of the details to mount the body on the frame.

oregonphil
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Re: 1971 J2000 build on Jeep JKU Frame

Post by oregonphil »

Copper204, yes, you will need to sign up at one of the photo sharing web sites. The basic versions are free. I have been using https://postimages.org/
it took a little time to figure it out. They all probably work about the same :
Image
Image
Image
Image
77sj 401 warmed over
72 Commando basically stock
07 Siena should last forever
76 FLH just for fun

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

You guys are correct. I do not like it. But will be adding a 10 inch section to rear of frame. Do not want to bob bed. But have welder and metal. So will get it done. Looks like first order of business is to get frame built up on suspension and wheels. Then place cab. And determine mounts and rise for bed. Then after that is configured. Plasm off the JKU body mounts. Then tack on cab mounts. Good thing about having a full shop. Means I have 5 2 post to pick from for the build. Wifey is prepared for the long nights ahead. She usually works a 12-14 hour day. Guess it is my time. Anyone have an issue if I start a build up with pictures on engine and transmission? Do not want to upset anyone on so many postings? But would love to document the work someplace.

And a huge shout out to: oregonphil For showing me how to get pictures up...
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Image


Let’s see if it works? This is my truck
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Image


The purple is my daily. Titan is one I have worked on and helped build. Hopefully I have enough skills? As far as toughness of JKU frame.

We launched the gray one off the purple one in a horrible accident. This was at KOH in 2020. All that broke in the high speed double barrel roll and end over was a busted windshield and track bar bracket. The frame was checked on a frame jig and found to be within 1% degree of deflection. Not a way I ever want to see or do. I still have nitemares over it occasionally. If I had not had the rockslide engineering steps. It probably would have tore through my Jeep and possibly killed me, Brad from Trail Recon and Richard from Rig Times.

We build em tough and lots of research or at least try. I am not re-inventing the wheel. This was done before by Bill Cosby (not actor) you can see his rig on Magna Flows website. It was featured in about 2017-2017 in several 4 wheel drive magazines. I am just build a little more powerful engine wise. And using a fleet side instead of bobbed box.

Image
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

So again. I want to make sure it is ok to document the building of engine and transmission on here? I know it will possibly fill up the feed. But if no admin against it. I would love to post it.
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Stuka
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Stuka »

Copper204 wrote: Sat Mar 20, 2021 11:00 pm My daily is the big Purple Rubicon running around town in Sonora, Ca.
Oh, I met you once at that get together the local Jeep dealer did a few years back. I have a Chief Blue JKUR.

As for photos, you can use a photo hosting site, you can use Tapatalk (a free app to connect to the forum), or you can attach the photos to your post (You have to use the full editor button instead of the quick post). Although you may have to shrink them down a bit as I limit the size of the images.

I can't recall offhand how long you can make the RK arms. You might have to move the mounts back to get the extra wheel base? But like you said, this has been done before. And its an easy way to get a modern driving J-Truck.

The one other thing to be aware of is J-Truck frames get very wide in back (much wider than a Cherokee or Wagoneer). So the bed mounts won't line up with the JK frame. You will have to fab up some mounts to make up the width difference.

Should be a really cool project.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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Stuka
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Stuka »

Copper204 wrote: Sun Mar 21, 2021 9:57 pm So again. I want to make sure it is ok to document the building of engine and transmission on here? I know it will possibly fill up the feed. But if no admin against it. I would love to post it.
You can post anything in this thread that is related to your build. The more data the better for anybody else that tries it down the road.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

So this is the engine I am building/built for the project.

2008 GM LY6 6.0L

Originally with VLOM/DOD ie;

Variable
Lifter
Oil
Management

Displacement
On
Demand


I deleted both on this engine. As it can/will cause a camshaft and lifter failure.

In this case it destroyed the cam, and ticked like a bomb.


Image

This was the engine I started with after cooking it in my aqueous parts washer. And honing cylinders and verifying with bore gauge. Love LS engines ...like perfect after 90,000 miles... except cruddy cam...
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

This is the garbage VLOM lifters. You can see the collapsed lifter. It is the one with compressed spring. Of course with LS heads have to come off.

Image
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Crankshaft cleaned and policed and mic’d and checked. New brings.

Image
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Piston all back in. New rings and bearings. All cleaned up.

Image
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

Jeep nut

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Copper204
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Re: 1971 J2000 build on Jeep JKU Frame

Post by Copper204 »

Rebuilt heads on. With new beehive springs and seats. Valves lapped in and verified. New camshaft with 212/218 duration and .550 lift and 112 LSA from TSP Stage 2 . New LS7 style lifters. New factory head bolts and head gaskets.

Image
1971 J2000. 1981 CJ-7. 1989 XJ x3. 1989 MJ. 1990 YJ x3. 1972 Jeep Commando V-8 304 , Biggest baddest Purple 2017 JKU Rubicon in Tuolumne County

Follow me on instagram- @copper204 @oh_that_1_other_dude and @1971_Gladiator_Build

Jeep nut
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