rebuilding a jeep

I am rebuilding my 73 cj5 304 v8,I have already rebuilt once,but I made the mistake of puting on a 78 cj frame.I found another frame for the years 72-75.Is this correct years a 73 cj5?.What I noticed is that the frame is not solid all the way around.Then it is only covered on 3 side from the tranny back is this going to be strong enough for normal wear and tear(no off roading). What is the difference between the 72-75 frame and the 78 frame. I have noticed that the back end is higher and the body does not fit properly.I also tooke off the carb off and found somenumbers.The firing order and a bunch of other numbers. Any idea what these mean

 

That is a stock frame, the early and intermediate frames where not fully boxed.

 

You should be good to go

 

there is a slight difference in the body mounts between 72-73 bodies and 74-75 bodies. You will notice the vendors sell two different body mount kits between the two. I believe the mount tabs on the frame are all in the same place so it is really no big deal.

 

Post 75 the frames are wider on the back. Thats why there is a difference when looking at bumpers. The C channel is used so the frame can flex as well. Can crack if flexed too much. If you have the ability to box it in, I would say do it. Over build now so you don't have to do it again someday. Kinda like you are right now But they did come from the factory with the C channel look.

High5

 

BOX IT IN FIRST!!! I wasn't planning on wheeling it that hard but it happened and now I'm having to replace the frame. I wish I would have known how weak the frame is the first time the jeep was in pieces. It's harder to backtrack than to plan ahead.

 

To box or not to box is plenty controversial. The frames on CJs are flexible, and that flexiness helps their off-road capability. Boxing means more strength but also more stiffness. Personally I'd be more in favor of selective strapping rather than boxing. I'd also recommend you do a search for old threads about frame boxing - here are some to start: http://www.earlycj5.com/forums/search.php?searchid=173973

Also look at this article on the CJ-3B page: http://www.film.queensu.ca/CJ3B/Tech/Frame.html - lots of other good info there, as well as on the front page of this forum.

 

I totally agree with you. But the excess frame flexibility has also caused me some problems with my clutch linkage. In order for us to compensate for the added stiffness since we do require articulation, we are doing a shackle reversal and 2 1/2" YJ springs. If we didn't offroad as much, we wouldn't need as much travel, so it wouldn't matter if it were boxed or not. I just wish I would have known I was going to want to push the limits before we built it so we wouldn't have to be re-doing all of this now.

 

Wouldn't strapping the frame just cause weak spots????

 

That's what happened to us. It just started cracking right next to the reinforced spots.

 

I never have bought the idea that they were built that way to allow flexibility...if I had to guess I'd say they were built that way to cut down on costs, and the result was more flexibility. In the early 60's I'm doubting anyone even said the word "Flex" very much. I think when the rock crawling phase started and "flex" became interesting, someone noticed that the old CJ's with open channel frames seemed to "flex" more. My two cents.

 

:iagree:

 

:iagree: X2

 

A disclaimer:

I completely agree with Tim Reese that the riveted, C-channel frame helps the flex on an old Jeep.

But I also agree with John that it's a happenstance, not a design element.

 

Mmm, dunno. Certainly the single center mount for the grille on a CJ-5 shows that the factory recognized the flex, and chose to accomodate it rather than fix it. Also, the '72 was delivered with a cable-in-sheath clutch linkage (some other earlier '70s models too?) in order to avoid the clutch pedal problems Jeep Gal points out - another instance of accomodation. Too bad it was such a maintenance headache that Jeep went back to bellcrank-style linkage in '73.

I also think you can't really say one way or the other, since the design was always a combination of available technology, limits of evolutionary changes (ie improving the existing model rather than a new model from the ground up), and price. When Bantam built the originals out of what they could get quickly and cheaply, I think they were surprised at the capability of the platform - and they went with it. The formula worked, and that established the basic design. IMO Jeep and the informed public came to recognize the strengths of the design, and that provided two good reasons to not change it - don't change what works, and give the public what it recognizes as an effective design.

 

:iagree:also