Crack in Diff axle tube
 

Help!!! Just found a crack in my axle tube on the horizontal axis betwwen the pumkin and the welded suspension link bracket. I've had a leak from my differential for the last year or so. Could never find it until this last weekend. Had it up on a lift and with a trouble light there it was a hairline crack about 6 inches long. See the pic attached. The crack is right where the black RTV stuff is. Did that as as a temporary fix.
Looking for suggestions on why this might have happened and how do I get it repaired? Mig weld? Does the rear end need to be removed?
Looking for help.
Thanks,
Jim

I tried enhancing your photo, but I'm still not sure about the crack's location.
http://www.erareplicas.com/misc/crack.jpg

I couldn't figure out where the crack was either. If Bob has spotted it, yes it can be welded and yes it must come out of the car and the carrier removed. You'd cook the oil and start a fire trying to weld it in place. Also the area to be welded needs to be thoroughly cleaned inside and out.

After welding, it should be stress relieved. I'd also look for other indications of fatigue in the housing while it is out. The crack you have is stress induced.

Could even be that replacing the housing would be a good idea. That wouldn't cost all that much. There are lots of 9" Ford housings around. I'd call that approach cheap life insurance.

Al

Heck I wouldn't replace it myself. A good weld over and it should be stronger than stock.

Ernie

Bob: the crack in under the Gray looking RTV smear. It is right on the center line of the axle tube, runnibg from the pumkin out tio the first welded bracket.
I really do not want to replace it. If I had to, and the RTV held, could or can I run it the rest of the year and make it a winter project. As long as I don't do any more full power launches like we did at DVSFIII. By the way the diff has been leaking for almost a year and a half now. Just never spotted the hairline crack.
Jim

Might be a job for JB Weld??

Roscoe

stress
 

The crack may be from stress, You probably should send the entire rear end on vacation.

Electric weld with the vent open.

Trularin

:3DSMILE:

The only thing to watch is if / when you have it welded that the tube doesn't bend do to the heat spread.
it is likely to believe me, an old trick on rally cars has been to deliberately weld an axle tube to cause bending to counteract damage type bending.

....winter project, now stop doing those hard launches until then.

Ernie

PNJSNAK Hi Jim Take the rear out of the car and find a guy with good welding skills. If you goto speedway or some of the 4-wheel drive mags. they sell a support kit for this rear because of hard abuse this happens. Try Currie engineering they are big in 9 inch ford rears. The support kit welds around the back of the case and under the bottom of the housing to stop twist. 1/4 mile racers do this. With this work done the housing will last the lifetime of the car. I was looking though some mags but don't see anything. If I fine it I will e-mail the info Go luck A good welder will have the weld stronger than the housing material. Rick Lake

Roscoe: What?????? Have you checked yours lately? I'm sure Joe got mine from the same source as yours. I've got a guy near by that says he can mig weld it on the car!!!! He is certified to weld nuclear reactors if need be. He said the gear lube in the tube will act as a heat sink. Don't need to take the diff out!!! Any comments by the forum? Took the car for about an hour good run on Sunday after 24 hrs of the RTV on the tube, no visible leakage. I think I might just wait unless this guy can convince me to mig weld it now. HELP!!!!!
Jim

PNJSNAK,,,,,sounds like a plan to me all right. I usually get in trouble around here for saying stuff that is "just to simple". The "Club" has very high standards and usually "leans toward" the absolute perfect way to get the job done.

Hey,,,,,you can never be wrong recommending the "perfect" and totally "proffesional" method of doing something.

,,,,,now if no one is looking I think I'll go weld the crack in my rear end. Uh,,,,,,did that come out right?

Ernie

PNJSNAK:

The area you put the silicone on is one of the factory welds where the parts are welded together to from the housing. With your lower link attached so close to the area where the tube goes into the housing, the twisting forces are concentrated in that area as the pinion gear attempts to climb up the ring gear. The harder the launch and stickier the tires the more this will be agrevated. As far as welding it in the car, I would caution against it. The area it is in will require a fair amount of heat to get a good weld and it may need to be checked for straightness when completed. The oil present will contaminate the weld.
Prior to actually welding it, drill a 1/8" hole at each of the crack to prevent it from continuing to crack then weld it with a good rod, and plenty of heat, being sure to get good penetration on the weld. When you have it out, if you decide to do it that way, it would also be a good idea to keep the gear housing assembly (pumpkin) bolted in the housing to aid in keeping it structurally correct.
I was unable to tell from your pictures but if you are not already consider using urethene mounts on the ends of the lateral links that locate the axle housing, they will absorb a minute amount of energy and could prevent this from happening again.

Rick..................

PNJSNAK Jim take the rearend out and remove the fluid. Get your weldind friend to weld inside and out. Do the job RIGHT, If you are not worryed about your life, think about the accident you could cause if that rear breaks or locks up when your driving or racing. Since you built your car I would think it will only take 2 hours to pull it 2 hours to put it in and bleed the brakes, and you can check the center section while it is apart. You have a lot of time and money invested in the car, what's another hour here or there.:) In the winter pull it out and by that time I will find you that support kit for the housing. I forgot about drilling the holes to stop the crack,that's a good thing to do. Rick Lake