Technical Quick change repair. Grind this weld?

A local shop fixed the magnesium quickie for my '33.



How much of this weld needs to be ground down to clear the ring gear?



Thanks, -Abone.

 

I'd assemble to see how little if any has to come off.

 

Yeah you need to assemble it to find out if any.

 

Wouldn't a spot like that also possibly need a bit of machining on the inside of the hole? Would it shrink smaller when welded?

 

It will probably need to be taken down a little. Some more weld might not hurt.
Here’s a couple for reference.






Sent from my iPhone using The H.A.M.B. mobile app

 

flame -

1. NOT a very strong weld on that center section.
2. DO NOT grind any weld material unless you really need to. ANY...grinding weakens the weld.

In this case, I actually would grind the "skin" off and have someone with better welding skills go over and do that again...correctly.

IF...it were mine of course..!

Mike

 

I think I would have welded it the opposite direction, and stop the weld on heavier part of the casting.

 

Amen to that. Was this a professional shop or a backyard?

 

would usually get those welded with the old pinion and bearing left in-it will crack again as soon as you drive it anyway,so don't worry about it.Crack in the pinion support does't seem to hurt anything,I've run the Halibrand centers with the whole pinion support milled out!Model"A" QC didn't even have a support

 

I agree with Mike, looks like a cold weld to me. If you don't need to grind it I wouldn't touch it.

 

Seems to me we had a discussion awhile back about magnesium wheels and how they can catch fire and not being able to put out the fire. If that's correct, how was someone able to weld on this magnesium casting without a fire starting ?

 

Retardant...

 

Remove the oxygen?

 

Because to get mag to catch fire , the air fuel ratio must be correct, so if there is a pile of mag dust shavings, it will light quicker because there is lots of air surrounding each partical

 

MIG/TIG with correct gas I would think.

 

Here is my experience with welding the nose bearing support.
If it is cracked or broken but no missing pieces, you can weld it similarly to Abone's. As Marty said, you want to end on the thick part of the casting. Then you need to clean the inside of the bore and weld it there also. If you don't weld in on both sides, the original crack will serve as a stress riser and it WILL break again. Then you need to remachine the bore, as alchemy suggested. Of course, that needs to be done locating off the pinion bore.

If there is a piece missing, you must build a bridge from both sides to the middle. Again, you will probably have to add material to the inside of the bore. Same with remachining on this one. I have never tried to add a filler piece as we don't really know much about he metallurgy of the castings and why introduce a third component to the mix? I think Abone's might have had a piece missing.

Leaving the old bearing in while welding prevents the rod from filling the root. I have thought about trying it with a brass or bronze plug with a flat on the crack side, but have never actually done it that way.

The ring gear side can be flattened with a small sanding disk. As others have said. you want to remove as little as possible. I put bluing on the weld and turn the carrier with ring gear to get a witness mark. Something else to consider it that the ring gear bolts should not protrude past the face of the gear. You need every bit of thickness you can get. A few thousandths clearance is enough.

The bearing is there to support the front of the pinion under load, which is greatest at launch. In most of our cars, it is not really necessary. If I were building a Quickchange for a drag car, I would definitely have the nose bearing in place. I would also likely look for an unbroken case. I have built a couple of QCs without the nose bearing. One was in a sand rail dragster. The other was used in a unit with a flipped case. Never a problem.

As long as we are discussing this; I use a roller bearing in virtually all my builds. The ball bearings do fail and then all hell breaks loose inside the case including breaking the pinion nose support.

I have the tooling to rebore the nose bearing support. With welding, the process usually takes about 5 hours start to finish. I work cheap but not free.

 

You were the guy I was waiting on. My plan is to assemble the rear and see what the clearance is. Hopefully, I can leave most of the weld in place.

Thanks, -Abone.

 

Can we see a picture of the bearing bore?

 

The ball bearing came apart and wedged broken guts into the pinion nose area, which cracked at the thinnest part. The guy who did the welding closed the gap about 95%, ground a V into the crack and hit it with the MIG.



There is no way to truly know until you are standing on the track picking up pieces.

-Abone.

 

That really needs to be welded from the inside. It probably won't cause a catastrophic failure, but it WILL crack all the way through and won't hold the bearing. The bearing will likely not spin because it will have less friction internally than externally. You can help this somewhat by using Loctite Green when installing the bearing. The magnesium will have to be clean and bright.

If you don't want to go to the expense of reboring the case, you might try grinding the internal weld just enough to be sure that there is no high spot. This would allow the Loctite to flow around the bearing race. The gap is closed and the bore can't spread.

Rotsa Ruck

 

I have two perfectly fine Winters mag centers, but I reeeally want to run that Halibrand. This is going under my supercharged '33 with slicks, so I know what I SHOULD do......

-Abone.

 

^^^Send it to that guy^^^