Thread: Welding brackets to axle tubes without bending them

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I have built a few rods with brackets welded to the rear axle tubes, and have never had a problem with warped housings. I believe that the secret to doing this is to design the axle bracket as a full 360 degree style, that goes all the way around the axle tube. And no, I don't take the rear axle apart to slide them over the tubes---I just cut the bracket into 2 peices, slide the 2 peices over the tube from each side, and tack them back together. I then position them correctly for pinion angle, etcetera, and tack them into position. Then pull the axle assembly out of the chassis, stand it on end, crank up the welder, and go. I start in one spot, and weld about 1/4 of the full diameter, then immediately jump over to the other side of the axle tube and weld 1/4 of the full diameter directly accross from the first weld. Let it cool for a half hour, then repeat on the two remaining unwelded quarters. My theory is this---when you heat the axle tube in one spot, it expands, and then when it cools, it shrinks, but it always shrinks a bit more than it was before any welding started.---this is what causes the tube to bend----If you can weld on two opposite sides of the tube almost at the same time, (as in no "wait time" between opposing welds), the shrinkage factor will now be more or less evenly distributed about the centerline, and will effectively cancel each other out.----after the welds are completed fully around the axle tube, weld the 2 halves of the bracket (which were previously tacked together) solid ------Thats why you need a full 360 degree bracket.---I believe that its all about even heat distribution.

Brian, in your experience, would you say that welding a simple inch and a half bracket to the top of the axle tube for the brake line fitting would create enough heat to cause a misalignment between the axle flange and the axle tube flange? The axle was fully assembled and supported during welding.

No, I don't think that would do it.---Brian

Thats sounds good if the bracket can be made to wrap around the tube ,but thats not always the case.I was thinking I could make some 12"X12" by 1/4" thick sqaure plates one for each side.They should be attached to the rear end.Then I could measure each corner to corner ,across the rear end .This should tell me if the ends are out of square.How do you guys check for straightness?You would also need to use a heavy bar the inside diameter of the tubes and run this through the legth of the tube?

Originally Posted by BigTruckDriver

Thats sounds good if the bracket can be made to wrap around the tube ,but thats not always the case.

On the contrary, that is always the case if you make your own brackets. Even if you use someone else's brackets, you can finish making them 360 degrees around the tube like Brian is saying.

Ya ,but say for instance sway bar atachments .That might look a little funny haveing the bracket wrap around the tube,maybe a bit over kill also. The axle saddles ,you would you wrap them around the tube?

Suit yourself.
If you are good at using a torch and a cold, wet rag to move hot metal around and get it straight again, then disregard my post.

No matter what scenario I come up with, there is always someone ready to step up to the plate and say "Ya can't do that"----And your right---In your world, probably you can't. However, in my world, I generally can. And I have. And I will keep on doing it, because I am a smart old S.O.B. who has been doing these things successfully for over 40 years now. I post things that I know---not things that I speculate, or have heard other people talking about, or have read about somewhere.---If ya don't want to take my advice, thats all right too.

Any one would be a fool to do something "because the guy on the internet said to do it".The beauty of this place is that you get different points of view,and maybe you see something you didn't see before.Don't take it as a insult to your intelegnece because someone(I) questions you.You should always keep your mind open for new ideas .Just cause you did something one way for forty years doesn't mean theres no room for improvemnet ,theres always room for improvement.I question because I want it explained to me,not to insult you.For me I take information I get here analize it ,and make my own conclusion.I would be sad for someone to not have any ideas and just take your word for.I am not trying to insult anyone ,but I do have my own questions.Isn't that what this place is supposed to be about?Now back to the rear end (brackets)thread its a good one ,keep it going.


I am questioning also becasue I am currently deciding on going to a 9" rear end instead of the 12 bolt.I am going to have to cut all the brackets off of the ford rear ,and install chevy brackets.So I question.

Two things are indisputable:

1) Welding heat warps and pulls steel

2) The PERFECT way to weld stuff on to a rear axle is to mount it on a jig, and then true it when done.

Now, that being said, I think Brian has a point. Although I am not a great welder, I have welded spring perches, shock mounts, etc onto various rearends over the years, without using a jig, or retruing the rear axle. I have yet to have a bearing failure or significant misalignment problem because I weld a little, then stop. Then I move to the other side, and stop. By doing so, the heat doesn't build up too high, and warpage is minimumized.

There is always the perfect world and the real world. The things we do in our home garages are sometimes not ideal, but work. That, I think is the point Brian was trying to make. I am not so sure even factory housings are dead on, especially after bouncing down the road for years. They have to deflect somewhat and deform.

JMO,


Don

no stock stuff is way out some times .i have a jig for doing the fords 9 s and have cut them down the best way to do it is weld the housing down to some heavy steel tubing this will be for a back braces weld all brackets on let cool then when done put in a jig and weld the axles ends back on if you weld all on the front part of the tube you may want to heat the tube and let cool before cutting it loose

I've also done quite a few different brackets - including ladder bars and a new spring cup/mount on a Ford 9" in my pickup. I did the same thing with a 4-bar on my A-bone. Never trued either, and never had a bearing failure. However, I used the same technique - moving from side to side in a cris-cross pattern. Doesn't make it right, but it worked.

I've seen recommendations for removing everything, then putting a steel bar jig through the axle tubes to hold them true. I've never believed that would work. If you heat the tube unevenly, it will still try to warp, but instead of moving, it will go under tension. It won't move until you remove the jig. Of course, it's been a long time since my mechanics of materials course, so I could be wrong.

Originally Posted by Henry Rifle

I've also done quite a few different brackets - including ladder bars and a new spring cup/mount on a Ford 9" in my pickup. I did the same thing with a 4-bar on my A-bone. Never trued either, and never had a bearing failure. However, I used the same technique - moving from side to side in a cris-cross pattern. Doesn't make it right, but it worked.

I've seen recommendations for removing everything, then putting a steel bar jig through the axle tubes to hold them true. I've never believed that would work. If you heat the tube unevenly, it will still try to warp, but instead of moving, it will go under tension. It won't move until you remove the jig. Of course, it's been a long time since my mechanics of materials course, so I could be wrong.

the bar will not stop it from moveing this get the ends on the same plan with the pig that is it . do not ask how i know

For anyone wondering what the alignment tooling referenced looks like here are a couple pics of the most typical kind.

The alignment tool is designed to align the housing ends, not hold the axle housing in place when welding. I like the 360 degree brackets on my ladder bar and 4 bar brackets for a drag car, not just because of the welding process but because of their inherent strength. For other brackets, the weld a bit and let it cool process works fine. I do check all the housings I weld on with the alignment fixture when I'm done welding. A large press and the appropriate fixtures will straighten a slight misalignment.