CJ frame vs. YJ frame - Pirate4x4.Com : 4x4 and Off-Road Forum

redwrangler97 · 10-18-2005, 05:16 AM

How different are they? I've never seen the 2 in comparison and am wondering if you could easily put a YJ frame in a CJ and vice versa...

TIA

SPEEDCRAVIN · 10-18-2005, 05:26 AM

There is a bid differance. If you are going to buy one to build get the YJ frame. It is a lot thicker better built and the springs are a lot more flexable. They are a lot easier to find and because they are not as old they are usually in a lot better shape.

Personally I would not build on a CJ frame,if there was a choice.

JOSH

redwrangler97 · 10-18-2005, 05:36 AM

but could i replace my 79 CJ7 frame w/ a YJ frame? i know the body mounts will be a bit different, but is that about it?

Pyagid · 10-18-2005, 05:49 AM

yes you could do it, there is not much different, But the frame on a YJ is a little wider in the front so I dont think your stock Axle spring perches will line up here are spec sheets on the dimensions for each frame

Root Moose · 10-18-2005, 08:00 AM

It's fairly common for CJ7 people in the rust belt to replace their CJ tub with a YJ tub. This is basically the inverse of what you are talking about.

401ton · 10-18-2005, 08:14 AM

Quote:

Originally Posted by redwrangler97

but could i replace my 79 CJ7 frame w/ a YJ frame? i know the body mounts will be a bit different, but is that about it?

The YJ frame will almost fit on the outside of your CJ frame.

If you are using wider axles than stock CJ wide track, it will work better.

You will need to use a YJ steering box or do a lot of fab work.

You will need to fab engine mounts.

Fuel tank may be a problem, again unless you use a YJ tank.

Yes you can do it, but the more YJ parts you have the better.

It would be a better idea to get a YJ tub and frame, then add whatever CJ parts you have left to it. IMO

jeepinwhores · 10-18-2005, 02:02 PM

I know of a couple guys running YJ frames on their CJ's. If you want to keep your widetrac CJ axles, you will need 2" wheel spacers to keep the tires out of the inner fenders. Personally, I don't like spacers that thick but go for it.....and let me know how it works for you!

redwrangler97 · 10-18-2005, 05:22 PM

ok heres what i sorta got in mind: YJ frame on my CJ. swap out axles D60s maybe, SOA w/ YJ springs, fuel cell, then try to use everything else thats already on the CJ.

oh yea and the fenders will def be cut

redwrangler97 · 10-18-2005, 07:43 PM

jeepinwhores, can you get some more info from those guys you know?

SPEEDCRAVIN · 10-19-2005, 05:27 AM

Quote:

Originally Posted by redwrangler97

ok heres what i sorta got in mind: YJ frame on my CJ. swap out axles D60s maybe, SOA w/ YJ springs, fuel cell, then try to use everything else thats already on the CJ.

oh yea and the fenders will def be cut

Red, if you are going to do this, be prepaired for some work. The tub is very similar but it is alot of big differances. If you stay leaf sprung and use D60's you can use a kit that will be a pretty much bolt on from BTF. i have seen this kit installed and it is a great kit. I would start there. If you are going to use the YJ frame do use the YJ steerbox It is just a Saginaw 4 bolt box.
unless you move your axel back in the rear the fuel tank should work fine.

JOSH

redwrangler97 · 10-19-2005, 06:06 PM

im prepared for work just wondering exactly how big of a mess i'm gettin into so i can plan ahead, ya know?

SPEEDCRAVIN · 10-19-2005, 06:27 PM

Quote:

Originally Posted by redwrangler97

im prepared for work just wondering exactly how big of a mess i'm gettin into so i can plan ahead, ya know?

Plan on a lot of rusted bolts. Soak it down on all the bolts you can think of everytime you think of it untill you start the project. especially on the body mounts.

JOSH

redwrangler97 · 10-19-2005, 07:31 PM

Quote:

Originally Posted by SPEEDCRAVIN

Plan on a lot of rusted bolts. Soak it down on all the bolts you can think of everytime you think of it untill you start the project. especially on the body mounts.

JOSH

haha yeah im ready for that, rust is the reason im replacing the frame in the 1st place

CSP · 10-21-2005, 05:06 PM

So far nobody has addressed the fact that the wider frame will mean the springs are further apart, side to side. What difference does this make?

The springs run directly under the frame rails and the perches on the axles will not line up with them under a YJ frame. No biggie on the rear since it's easy to relocate them.

The front is a bit more involved since the passenger perch is cast into the center section. A '79 CJ is narrow track and there's not a lot of real estate between the center section and the knuckle to be moving the perch outward.

Of course nothing has been said about what axles will be used, so it may be a moot consideration.

redwrangler97 · 10-21-2005, 06:57 PM

im swappin in heavy duty axles. lookin at dodge 1tons. d70r/d60f

10-18-2005, 05:16 AM	#1 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	CJ frame vs. YJ frame How different are they? I've never seen the 2 in comparison and am wondering if you could easily put a YJ frame in a CJ and vice versa... TIA __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

10-18-2005, 05:26 AM	#2 (permalink)
SPEEDCRAVIN Registered User Join Date: May 2004 Member # 30432 Location: Dallas Texas Again! Posts: 1,640	There is a bid differance. If you are going to buy one to build get the YJ frame. It is a lot thicker better built and the springs are a lot more flexable. They are a lot easier to find and because they are not as old they are usually in a lot better shape. Personally I would not build on a CJ frame,if there was a choice. JOSH __________________ SHOP AND APPARTMENT FOR SALE [url]http://pirate4x4.com/forum/showthread.php?t=589523[/url]

10-18-2005, 05:36 AM	#3 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	but could i replace my 79 CJ7 frame w/ a YJ frame? i know the body mounts will be a bit different, but is that about it? __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

10-18-2005, 05:22 PM	#8 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	ok heres what i sorta got in mind: YJ frame on my CJ. swap out axles D60s maybe, SOA w/ YJ springs, fuel cell, then try to use everything else thats already on the CJ. oh yea and the fenders will def be cut __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

10-18-2005, 07:43 PM	#9 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	jeepinwhores, can you get some more info from those guys you know? __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

10-18-2005, 05:49 AM	#4 (permalink)
Pyagid Registered User Join Date: Jul 2003 Member # 21409 Location: CT Posts: 183	yes you could do it, there is not much different, But the frame on a YJ is a little wider in the front so I dont think your stock Axle spring perches will line up here are spec sheets on the dimensions for each frame

10-18-2005, 08:00 AM	#5 (permalink)
Root Moose Registered User Join Date: Dec 2001 Member # 8601 Location: ON, Canada Posts: 947	It's fairly common for CJ7 people in the rust belt to replace their CJ tub with a YJ tub. This is basically the inverse of what you are talking about.

10-18-2005, 02:02 PM	#7 (permalink)
jeepinwhores Registered User Join Date: Apr 2005 Member # 46402 Location: Morinville, Alberta Posts: 1	I know of a couple guys running YJ frames on their CJ's. If you want to keep your widetrac CJ axles, you will need 2" wheel spacers to keep the tires out of the inner fenders. Personally, I don't like spacers that thick but go for it.....and let me know how it works for you!

10-19-2005, 06:06 PM	#11 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	im prepared for work just wondering exactly how big of a mess i'm gettin into so i can plan ahead, ya know? __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

10-21-2005, 05:06 PM	#14 (permalink)
CSP Registered User Join Date: Aug 2000 Member # 1533 Location: Parker, CO Posts: 2,779	So far nobody has addressed the fact that the wider frame will mean the springs are further apart, side to side. What difference does this make? The springs run directly under the frame rails and the perches on the axles will not line up with them under a YJ frame. No biggie on the rear since it's easy to relocate them. The front is a bit more involved since the passenger perch is cast into the center section. A '79 CJ is narrow track and there's not a lot of real estate between the center section and the knuckle to be moving the perch outward. Of course nothing has been said about what axles will be used, so it may be a moot consideration.

10-21-2005, 06:57 PM	#15 (permalink)
redwrangler97 Registered User Join Date: Jul 2004 Member # 32870 Location: Huntsville, AL Posts: 32	im swappin in heavy duty axles. lookin at dodge 1tons. d70r/d60f __________________ 97 TJ- long arm, 35's, ARB's, armor all around '86 CJ7 project for sale - PM if interested

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