Frame Cracks

[JR74CJ5]

So I have a problem with my frame cracking after trips with heavy wheeling.

I repair them by grinding out the crack into a v groove and welding a bead. So far they are mostly all on the top or bottom of the frame, (not sides)

I know this is fairly common, but what can i do to minimize this? One day my frame is simply going to just break!

my body mounts seem to have issues as well... I've re-built a few of them now.

Is getting / building a new frame my only option?

Going to go check out oldguys build as another thread mentioned... For the custom build frame section especially...



~ JR

 

[Torxhead]

Frame cracks are quite common on a CJ. The front spring shackle hanger is a poor design and aftermarket versions are an improvement. Near the front spring eye on the frame is another location for cracks with high lift springs added. All the spring hangars are another and some guys add a plate there. The front crossmember goes on the list also and I am wrapping up that job right now. I think poor welds from the factory are one reason, poor design another, and just plain having fun with it will cause cracks also.

 

[IOPort51]

In a past life I was paid to make repairs of a number of conveyor systems and heavy equipment that were experiencing thermal and vibration stress cracks.

Ideally the solution is to "normalize" or "anneal" the parts by soaking them in a furnace at about 1500 deg for a given number of hours and slow cooling the part before re welding and in some cases reinforcing. I don't see the possibility of stripping the frame and heat treating it so we won't take that one any farther.

A couple of tricks for dealing with "work hardened" steel. Drill the ends of the crack to stop the propagation of the crack. there is something about making a clean square wall for the crack to run into that will stop it. Many times welding the crack it self never happened, it was just reinforced.

on the subject of welding. My personal favorite weld process for this is stick welding with heavy flux, slow cool rods. Solid wire MIG can very possibly put more stress on the part than the crack managed to relieve.

The design of a reinforcement is important, it is not best to cut a square plate and weld it on. Think blunt diamond!!

The trick is to let the weld stress follow a diagonal line and not cut straight across the frame. and do not join the welds at the point of the diamond. this is why you cut the points off the diamond.
Try to end up with 4 diagonal welds covering the crack.


Good luck Bud, I guess the bottom line is that we are dealing with a 30 something year old hunk of steel that we have beaten regularly in the interest of having a good time.

 

[coldair]

My 74 had a long chunk of strap steel on top and bottom stitch wielded. seemed to work really good streanthend the frame up alot. On the body mounts not sure about that.

 

[PaRenegade]

Can you say "TDK"? (Throttle Down Kustoms) :dunno:

 

[tarry99]

So I have a problem with my frame cracking after trips with heavy wheeling.

I repair them by grinding out the crack into a v groove and welding a bead. So far they are mostly all on the top or bottom of the frame, (not sides)

I know this is fairly common, but what can i do to minimize this? One day my frame is simply going to just break!

my body mounts seem to have issues as well... I've re-built a few of them now.

Is getting / building a new frame my only option?

Going to go check out oldguys build as another thread mentioned... For the custom build frame section especially...



~ JR

Hi JR
Yesterday Distributor Gears and today frames?

Take a few pictures and let me see what ya got.............

Is your frame boxed in the places you see the cracks?
Are the cracks more on the top rail? or bottom?
Are the cracks in any one area that is near suspension or engine & Transmission mounts.
Cracks are from stress in the chassis.............all chassis / frames have to move a little and not be totally rigid. Most times you need to look beyond the area that is cracked to find the real cause of the stress. Fix the cause of the stress and then the crack and the problem goes away............
Most of those Jeep frames are only .125 thick and Arc & Wire feed welding can if not done properly add other issues to the weld zone.
I would prefer Heli Arc / TIG over those other methods simply because you can control the heat much better.

 

[Sasquach]

Your early/mid CJ5 would have a channeled frame? Not sure exactly when 78 maybe they started boxing in the channel for more strength.

 

[JR74CJ5]

Yeah Tarry, I got issues! lol

I'll snap some pics tonight, but there are the normal spots mostly.

There's a "little" boxing done to the front portion, but not much...

And the cracks happen around it as well as on top of it.

Like I said ill get some pics tonight.

 

[IOPort51]

that is a nice frame!

there may be one of these in the future for all of us. think I will book mark this.

Can you say "TDK"? (Throttle Down Kustoms) :dunno:

 

[tarry99]

Yeah Tarry, I got issues! lol

I'll snap some pics tonight, but there are the normal spots mostly.

There's a "little" boxing done to the front portion, but not much...

And the cracks happen around it as well as on top of it.

Like I said ill get some pics tonight.

JR,

Just giving U a bad time!...........lets see if we can help U fix that chassis.

 

[Purple77CJ7]

I have plated my frame at the motor mounts and at the shock mounts on the front portion of the frame. On the rear I have plated by the rear leaf spring front hangers. All with 3/16" steel plate that is diamond shaped as stated above. On the rear frame end at the top I welded some flat strap to the top to streghten it. Sounds like everyone has done basically the same thing in the same areas to some extent. My frame is boxed almost all the way and still cracked. Every thing I have fixed has never broken or cracked again. Life of a Jeep and Jeepers.

 

[tarry99]

I have plated my frame at the motor mounts and at the shock mounts on the front portion of the frame. On the rear I have plated by the rear leaf spring front hangers. All with 3/16" steel plate that is diamond shaped as stated above. On the rear frame end at the top I welded some flat strap to the top to streghten it. Sounds like everyone has done basically the same thing in the same areas to some extent. My frame is boxed almost all the way and still cracked. Every thing I have fixed has never broken or cracked again. Life of a Jeep and Jeepers.

Purple77

I'm glad to hear you have had some success in fixing these cracked area's. Point is no matter how its fixed there is always potential for it to crack again.......Just the nature of the beast when your dealing with twisting and work hardening an object on a daily basis.
The only goal hear is to make a repair that perhaps last longer and keeps with the structural integrity for which it was designed.
I get involved in my business making frame repairs to Trucks , Trailers and Heavy off road equipment all the time.

 

[JR74CJ5]

JR,

Just giving U a bad time!...........lets see if we can help U fix that chassis.

Oh i know . No "butthurt-ness" here lol. I ended up fixing the gears tonight and actually taking her for a spin tonight . Felt great!

 

[tarry99]

Cool

 

[PaRenegade]

that is a nice frame!

there may be one of these in the future for all of us. think I will book mark this.

I bought one last Aug. It's all modded and painted, sittin' under a tarp waiting for me to move it back into the garage and make it a Jeep. Beautiful welds on the thing. It's the only remaining Jeep frame manufacturer out there. Jeremy, the owner, used to work for Advanced Frame Works, which he bought out and created TDK. Matkins was another manf. but has gone out of business.

 

[Torxhead]

Now go finish that Rubicon trip.

 

[JR74CJ5]

Man I wish!

Heading to Tahoe this weekend...

Guess I "could" take take the CJ and then the scenic route back...



Did not get a chance to grab the pictures of the cracks. One is near the spring hanger / clutch mounting plate on the drivers side, and looks to have been (badly) welded up by the PO. One in each side of the front near the cross plate / winch plate I built. (that part is boxed...) I forget if and where the others were but think there were at least 2 more new ones...

None of the ones we welded up already since having it have re-cracked though so we're either just spreading the breaking / stress point out, or ?

But I'll get those pics up in the next few days for this.

 

[paparooster]

Well i'm joining the crowd on cracked frames. I've been doing a lil research on dj5 frames , heared that they are way stronger , has anyone done this switch on frames. Here is a few pictures of the crack , the crack started at where the previous owner ended the boxing in the frame , the top of the frame was strapped and it also cracked .

 

[project74]

JR,
I was cruising Craigslist in the southeast areas and came across a CJ5 frame for sale, already set up for spring over, looked good in pics but didnt call to check on it??? I dont remember exactly where in S.E. it was but should be in the Ga., SC, NC or Tenn listings. It might be a good (cheap) replacment for your tired frame...just a thought.
Ed

 

[tarry99]

Well i'm joining the crowd on cracked frames. I've been doing a lil research on dj5 frames , heared that they are way stronger , has anyone done this switch on frames. Here is a few pictures of the crack , the crack started at where the previous owner ended the boxing in the frame , the top of the frame was strapped and it also cracked .

Papa,

Lets face it these Jeep frames no matter what variety you have all do a good job but will all crack sooner or later ........no getting away from it.
Going over rocks,up hills, twisting and turning , big tires, big horsepower Metal bends , stretches , work hardens and cracks.

Never going to change that unless you leave it home.

Clean the weld zone up on both sides V the crack and weld the crack with a method that you or your welder are most familiar with.

I like to TIG weld it when possible as I find it much easier to control the heat.

When I have an exposed crack where there is access inside I will weld the crack up grind it flush and plate both sides with the plate extending away from the crack in both directions on both sides. Stitching the weld is a better method on the plating than welding a full pass.
You can even box that area when done if you like.

Inspect you chassis on a regular basis...........a small crack is much easier to deal with than something left unattended to grow.

Have a beer , go wheeling and watch for the next one.