CJ-8 Frame/ Body mount dimensions

I've just started posting here... but I'm not new by any means, nor new to Jeeps. It just took me almost 15 years to get my first Scrambler, and it was/is a rust bucket.

What I'm trying to do is get a plan together for putting a YJ frame under my new to me '81 CJ-8. My CJ frame is way wasted (like wet sheet of paper thin) in all those special CJ-8 spots, and I really don't want to cut the back 4 feet of frame off and try to get a CJ-7 frame to fit with modifications.

I've got two free YJ frames and plan on splicing them together.

I've seen this:

https://www.cj-8.com/index.php?option=com_content&task=view&id=18&Itemid=56

But if you compare that drawing with this one:

http://www.mesa4x4.com/tech_articles/frames/yjframe.jpg

And you look at it, you realize that the CJ-8 drawing on here is missing some specifics.

Specifically where I see the CJ drawing to be lacking is:

1) Dimension H- is the singular measured difference between the CJ-7 and the CJ-8. This drawing (as near as I can figure) doesn't show a 10 inch wheelbase increase. If I were to build a frame from this, I'd end up with a CJ7 with a really really long rear overhang and an extra pair of body mounts.

2) That (IMO) significant oversight leads me to question dimension S, which should be different and isn't on that drawing. And, if that's wrong, what else might be?

3) If you compare the CJ drawing to the YJ drawing the next thing that becomes apparent is that while the CJ drawing has the height of the body mounts, it doesn't have all of the center to center widths, nor does it have any of the for to aft measurements.

So, I'm sitting here with my drawings unable to even come up with a basic plan of attack for cutting the YJ frames up.

What I think I know is (from years ago looking at putting a YJ frame under a CJ-7 and other searching around on here and the web), is:

1) 2 of the mounts out of the 3 under the doors are different on the YJ frame and require relocation. Sure, no problem... but which two? Can't figure that out from the drawings, and I can't take my tub off my frame to try to figure it out. Even if I could, my frame is so hashed that only 2 of the 13 body mounts are still "O" shaped, not "C" shaped (from rusting out)

2) I'll need to add a set of body mounts (IIRC, like the normal front of the gas tank body mounts) to the frame. Location, unknown.

3) I think I will need to lop the front spring perch off the YJ frame, then lengthen it in that area about 10 inches, then put the perch back on according to what dimension "S" from the CJ drawing should be.

4) I think I'll need to cut the rear cross member off the YJ frame, add a 14-inch extension, and then build a new rear cross member (the stock cross members are crap, and hardly take a decent tug)

5) If I didn't build a cross member from scratch, I can see that the center to center width of the rearmost body mounts is about 43 mm different between the two. I think that the mounts will just clear the YJ frame width if I use the stock CJ spacing.


Anyway, sorry this is so long. I'm hoping that you guys can help me fill in the missing and wrong dimensions on that CJ drawing so I can push forward with planning. I don't want to cut anything until I've got a good grasp of what is different between the two frames.

PS- you'll notice I didn't mention the axles or springs or whatever. I know the narrow track axles won't work under the YJ frame (in the rear anyway... with the tires and rims I have). I'm torn on axles... I have a 44/9-inch that I could retube the driver's drop 44 and sling under it, or if I stumble across a free/cheap widetrack setup I'll toss that in. I'll be putting YJ springs under the front... and the long (63-inch) Chevy truck springs under the rear if I can. If not, I'll figure out rear springs... WCS will be stock YJ stuff. But anyway, that isn't trying to mate a modified frame to a stock body... that'll be way easier and I'm not worried about that.

Thanks

I have found that old blueprint/drawing is not accurate to my '81 Scrambler frame. Just so you know.

rreed said:

I have found that old blueprint/drawing is not accurate to my '81 Scrambler frame. Just so you know.

Click to expand...

Not good news, but not overly suprising.

We should get together on here, whoever's got frames laying around and redo the drawing.

I can do a drawing in CAD and export it as a .jpg or whatever, but I need accurate measurements to do so. I can get a lot of em off my -8, but a lot I won't be able to get since the body is on it still.

I have a bare frame if somebody wants me to measure it. It would be a couple of weeks though before I could get to it.

Truck

That would be great.

Let me see about getting a blank frame drawing done up and posted.

over2land said:

Not good news, but not overly suprising.

We should get together on here, whoever's got frames laying around and redo the drawing.

I can do a drawing in CAD and export it as a .jpg or whatever, but I need accurate measurements to do so. I can get a lot of em off my -8, but a lot I won't be able to get since the body is on it still.

Click to expand...

hey, what's up you jeepaholic! long time no see
sorry (well not really) for the hijack

GreatCJ8 said:

hey, what's up you jeepaholic! long time no see
sorry (well not really) for the hijack

Click to expand...

Hey Mike, how you been!?!?

I finally got me a Scrambler! After all these years. You still have yours?

IIRC, last I'd heard you'd just gotten another one? Even that was years ago... lol.

These dimensions were taken from a '82 with the front and rear spring mounts welded in place with no OEM pins visible, a previous repair that located them square and in line to the over all length and a '83 that is known to be true but I installed the Warrior SRS w/supplied front spring mounts welded onto frame. this said my reference to the G is more of a question that others could be more help with.

I mention the G which would be common to the 7 and another guess on my part same as all CJ's '76 up. The diagram is not clear to me as to where the forward reference point is actually located on the frame.
I found from the front spring eye to the rivet of the front cross member to be 42 5/8" and then 41 3/16" to the front most threaded nut and 45 1/2" to the front of the frame.
So I haven't a clue what the diagram listing of 40.61" is referring to.


'H' to the rearmost welded nut c/l has IMO a wide range, 60 1/2" up to 60 7/8". All four points on these frames were different.
I suppose that the nut isn't always easy to get, right?
Anyway adding 5/8" more length will be to the end of the boxed frame.

'M' should be 41 1/4"

'S' was 59 1/4" on the two and then rreed's frame may then show a dimension of 58 3/4" and presumably all other std. '81's since it's wheel base was 1/2" shorter at 103 1/2"

Okay for the lengths I recorded these from the front of the frame to the rear and found 9 3/4" to the grille mount and then #2 50 1/8"- 50 3/16", #3 is 73 1/8", #4 is 98 1/16 up to 98 1/4", #5 is 134 1/8" then 6 is 151 3/4" and seven at the rear cross member mount is 164 1/2" and you could add 1 to 1 1/4" to the rear end of box.


This may and then may not add up. Let me know how I may be of more or clearer help.
Good luck with the stretch

mcmud said:

These dimensions were taken from a '82 with the front and rear spring mounts welded in place with no OEM pins visible, a previous repair that located them square and in line to the over all length and a '83 that is known to be true but I installed the Warrior SRS w/supplied front spring mounts welded onto frame. this said my reference to the G is more of a question that others could be more help with.

I mention the G which would be common to the 7 and another guess on my part same as all CJ's '76 up. The diagram is not clear to me as to where the forward reference point is actually located on the frame.
I found from the front spring eye to the rivet of the front cross member to be 42 5/8" and then 41 3/16" to the front most threaded nut and 45 1/2" to the front of the frame.
So I haven't a clue what the diagram listing of 40.61" is referring to.


'H' to the rearmost welded nut c/l has IMO a wide range, 60 1/2" up to 60 7/8". All four points on these frames were different.
I suppose that the nut isn't always easy to get, right?
Anyway adding 5/8" more length will be to the end of the boxed frame.

'M' should be 41 1/4"

'S' was 59 1/4" on the two and then rreed's frame may then show a dimension of 58 3/4" and presumably all other std. '81's since it's wheel base was 1/2" shorter at 103 1/2"

Okay for the lengths I recorded these from the front of the frame to the rear and found 9 3/4" to the grille mount and then #2 50 1/8"- 50 3/16", #3 is 73 1/8", #4 is 98 1/16 up to 98 1/4", #5 is 134 1/8" then 6 is 151 3/4" and seven at the rear cross member mount is 164 1/2" and you could add 1 to 1 1/4" to the rear end of box.


This may and then may not add up may Let me know how I may be of more or clearer help.
Good luck with the stretch

Click to expand...

That's great info, thanks. Certainly enough to get me started on drawing it up.

I've never heard that about the 1/2 inch wheelbase change regarding dimension "S"... I thought the CJ-8s were the same throughout, although it wouldn't suprise me if Jeep made some changes after the first model year like they did on so many other Universal series Jeeps.

Is the body off the frame on either one of those?

Can you check dimension "N" "K" and "J" for me too? It would be useful to have measurements from two Jeeps... the more numbers we get, thanks to bending, warping, wed vs fri builds/ whatever will help me make my drawing more accurate Also on that drawing we are referencing, it looks like the center to center dimension across the frame for body mounts #4 and #6 could be the same as for #7, which is dimension "J" on the drawing, but nothing is mentioned of it, and #4 and #6 definately look to be further apart than #3 ("M"), which you gave me.

What is the diameter of the body mount holes? I don't have any that aren't completely rusted to a different size.

Thanks!

Sorry about my omit on these N= 37 3/4", K = 29 1/2" and J was 43 1/2" on one and 43 5/8" on the other.

The four, six and seven are the same, as J at either of those dimensions but I think that it better fits into the 43 5/8" range.

The holes are 1 5/16" all.

Neither have a tub but the engine/suspension/axles are mounted on the one.
EZ access to either.

Are they in good shape? Mine is so rust scaled... or just plain rotted through... I have problems making heads or tails of some things on the drawings. Like the two crossmembers in the rear on the drawing... i've only got one, and its mostly rusted through. Anyway, I was wondering if you could put up a couple pics like from the "top view" drawing so I can get a better idea what I should be looking at in that drawing.

Thanks again.

CAD drawing of CJ8 frame

Hope I'm not intruding but I am new to the Scrambler and I am glad to see that I am not the only one that had trouble finding a Scrambler with the rusty frame. Let me know if there is anything I can help with on creating the CAD drawing for the CJ8 frame. I would like to replace mine eventually but like you guys need a solid frame drawing to start from.

Franko

frank613 said:

Hope I'm not intruding but I am new to the Scrambler and I am glad to see that I am not the only one that had trouble finding a Scrambler with the rusty frame. Let me know if there is anything I can help with on creating the CAD drawing for the CJ8 frame. I would like to replace mine eventually but like you guys need a solid frame drawing to start from.

Franko

Click to expand...

Frank- do you have AutoCad?

My plan was this: re-draw both the CJ-8 and the YJ drawings in autocad seperately, and then import both drawings into one drawing so I can kind of combine the two using "construction weight" lines.

Just saw your post, sorry didn't post sooner.

I need something else: I'm having issues with the whole dual welded C channel of the CJ-8 frame. Also, I know the section height varies down the length of the frame. Can anyone get me measurements for inside and outside "C" at the various points it is different?

Here's what I'm talking about.

I kinda guess on these dimensions, but I think you guys get the idea.

I know this changes at least three times on the frame. Where? And to what?

Are there more changes? Thanks.

Having gotten laid off in November I've been working on mine quite a bit lately. I've found more and more that old drawing is not accurate to my '81 at all. Maybe it is to the '82-up but not to mine. Mine are a bit more like mcmud's.

If you can be specific about which areas you're trying to measure maybe I can help. There's a lot of area on a 14' long frame. I'm working on the rear section of mine right now and need some help fabbing up pretty much everything from the axle hump-back from scratch.

Me too!

I am very interested in this thread as I am about to do the same thing with my Scrambler. I have found the same drawings that you guys talk about and they are bad to say the least. My frame is in great shape it's just that I want the YJ frame for it's strength and room to build. I was going with a BB454 but have since decided that in the long and short run the LS1 will be every bit the power and tourqe with way less work and not as pricey or hard to find parts for. Please keep me posted.

CAD Drawing

Has anyone run acrossed a CAD drawing of a complete scrambler? I'm preparing to build a roll cage from my 82' and since it's a little slow at the office thought it would be nice to actuallyl draw it up since i'm on autocad all day long! Sure would be nice to have the base already done!

Just in case someone may be in need of these dimensions

And these

I'm only chimming in on this because I have both CJ-7 and YJ frames, CJ-7 and YJ tubs, and 2 CJ-8s (one off the frame) in the yard. I found two CJ-7 frames. One was damaged in the front and the other was damaged in the rear. I used 2x4 3/16 steel tube as the inner bracing and spliced the two frames together to make a CJ-8 frame for a buddies project. It turned out GREAT. Yes, it was a little bit of work, but it was worth it. The plus side of dealing with the CJ frames over the YJ frames is the YJ frames have 4 of the rear mounts off set, compared to the CJ -7. The CJ-7 compared to the 8 has 2 side mounts off set. Either way, you have to move the ones second from the rear on the new 8 frame. After all the cutting and welding, We taped up all the holes but one on each rail, and poured in Rustoleum rust encapsulating paint. We lifted and turned the frame ever which way so its fully coated inside.