Frame differences over the years.

[F Bill]

http://www.youtube.com/embed/1bL464GHLSc?


If that works, it will be a video by JPet over on the 2A page. He posted a pretty detailed video with the different features of the MB, GPW, and CJ2A frame, and even had a little 3A information at the end.

Here are some of the more basic differences between a WWII frame, the 2A frame, and a 3A frame:


MB and GPW use a bellcrank on the front axle instead of on the front crossmember like a 3A.

 Tranny crossmember is different than the 2a, and mounts completely different from a 3A. �

GPW uses a hat channel shaped front crossmember, which appears to be a square tube from the top.

Body mounts on the drivers side of the chassis are on the inside of the frame . This is due to the gas tank well occupying the space the tub mounts would be in on later models.

There is a round or oval plate on the crossmember behind the front seats, used to mount a machine gun on the WWII jeep. This plate gets in the way of the civilian tub so must be removed when a 2A or 3A tub is installed, as was done for some early 2A models that used the WWII frame.


MB, GPW, And CJ2A used strapping reinforcement spot welded to the top of the frame rails, of varying lengths at different times. �They also used front bumper gussets riveted and welded on to attach the front bumper. The strapping went away and a 3A style frame was used in 19999948, with non offset motor mounts. The 3A style frame used �thicker material and less boxing. Bumpers were bolted directly to the frame. Many including myself, feel these 3A frames are the ultimate stock frame for a flatfender.

The one thing Jeff did not include in his video is the offset motor mounts for the 3A, because of the different front engine plate and fuel/vac pump used. Also not mentioned are the 2 versions of radiator used and the presence of radiator mounts on the crossmember on earlier Cj3A jeeps.

While we are on the subject of frames, the DJ3A frame is basically a 3A frame with no rear bracing for the drawbar, etc. On a DJ3A the gas tank is in that location..

It is my understanding that a 3B frame is interchangeable with a 3A frame. �I have not done a side by side comparison yet so take that for what it is worth.

If you try to interchange a CJ5 frame you will find it is slightly longer, and the tub will show a few inches of frame out the back when mounted up so the fenders and grille fit. �

Suggestions and comments and especially corrections welcome.

[jpet]

That 3A frame had a lot of stuff removed .... Rear crossmember, engine mounts, shock mounts.  Perhaps someone with a good 3A frame can shoot some video and I can append it to my video.

[Bob W]

Bill, the CJ-3A bumpers are riveted on, not bolted.

Here is a link to The CJ-3B Page that shows a few more frame differences.
http://www.film.queensu.ca/CJ3B/Dating/DatingFrames.html
There are a few other minor differences in CJ-3A frames that have not been discussed but they are minor, a few holes and weld nuts changed.

[garage gnome]

I'll be taking the body off my '49 within the next month. I can take a video then.

[Bob W]

Here is a photo showing the offset motor mounts...

Don't tell anyone but that is actually an M-38 frame.

[F Bill]

I never realized the bumpers were riveted, as I am used to old jeeps where they have been changed, or the DJ3A  model with chrome bumpers....Do you know if a plain DJ3A would have been a bolt on or rivets?

I assume all rear crossmembers, which many call bumpers are riveted?

If you'd like to share the other minor differences over the years Bob that would be great... I will go visit your page and see what major mistakes I made.. This post is a work in progress, and once we get it hammered out I will delete the wrong stuff and reedit  for clarity.

Much thanks!!

[Bob W]

Don't really know much about anything after 1953 but I've got to assume regular DJ-3A front bumpers were riveted. Rear crossmembers were riveted. The minor changes, I don't have any solid information yet. The one thing that comes to mind is elimination of the weld nuts and then the holes for the left fender splash apron to frame attachment bolts. There are a couple other holes in question but I need to get a couple frames side by side to narrow it down.

[F Bill]

Here is an excellent page thanks to Bob W and Ken B on the major frame differences over the years of the civilian flatfender.

http://www.film.queensu.ca/CJ3B/Dating/DatingFrames.html

[Lee]

I will add, one thing I have noticed, a CJ3A rear cross member is riveted on with flat head rivits, as well as the late 2A.

Lee

[jpet]

Hi All,

Here is some more frame info on M38 frame characteristics:

https://www.youtube.com/watch?v=uu-4DmC3ieA&feature=youtu.be

[media]https://www.youtube.com/watch?v=uu-4DmC3ieA&feature=youtu.be[/media]

[Bob W]

Thanks Jeff for taking the time to make and post the great video!

Just a couple other items...
CJ-3As don't have the spacer inside the frame at the rear bumpstop location.
Only some CJ-3As have the inner reinforcement inside the rear frame crossmember. That reinforcement was part of other "kits" on a CJ-3A. On an M-38 it is welded in place.
M-38 shock bracket studs are threaded where CJ-3A studs have a cotterpin hole.
The front brake hose bracket is further forward on an M-38.