# welding the rearend



## dany (Aug 21, 2001)

Welding a Rearend??

I have a 75 f-250 factory highboy with a 3inch bodylift. There is a burnout compatition down at the local ossipee fair and would like to weld a rearend togeather to make sure I get posi. I will be doing this on a spare rearend. How would I go about welding it? This would only be a one time event or if it works well i'll do it next year. What parts do i need to weld solid? Iam not going to put a detroit in till next fall when i get the money. Any help is apreciated.


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## Big Nate's Plowing (Nov 26, 2000)

Check out www.pirate4x4.com/forum and do a search on welding rearend, they have the best advice.~NaTe


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## Plow Meister (Oct 16, 2001)

Basically, you have to weld all the spider gears together. These are the four small gears in the middle of the carrier. Make sure to clean the inside of the housing very well! The oil can catch fire. Also, make sure to use an adequate size welder. An 80 amp / 110 volt welder from Menards will not be hot enough to penetrate the hardened steel enough to create a good bond.


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## Pelican (Nov 16, 2001)

I'd recommend you remove the pumpkin to do your welding, the slag and spatter will destroy your bearins in a heartbeat. I think we need 75 in here, I'm thinkin' you'll need to put the pumpkin in an oven to preheat prior to welding to get proper penetration. This will be tricky not to lose the temper yet get it hot enough to penetrate. Where's our expert?


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## dany (Aug 21, 2001)

Iam not realey familiar with rearends. Weld the spider gears to each other or? I was told you could use a mig and wouldn,t have to deal with the splatter or slag. At pirate4x4.com people have done this with a mig and been vary success with there "LINCOLN LOCKER''. I would almost always do it with stick. It is just a better weld. What rod should i use? 75 your our expert can you help me out?


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## 2401 (Feb 3, 2001)

Oops! Missed this thread, 'cause as a Chevy guy I don't venture into "enemy territory" very often. 

The "spider" gears are the 4 small ones that Plow Meister mentions, these are what actually provide the "differential" function. In a diagram I'm looking at in a Chevy (sorry!) manual, they are called the "differential pinion" and "differential side gear" - 2 of each - and the cross-shaped piece they are mounted on is called the "differential spider". They will be easy to identify anyway since they are the gears that drive the axle shafts.

I agree with everyone's advice here: A small 110 volt MIG machine will be a little small IMO.

In addition to the fire factor, oil on the parts makes it difficult to get a decent weld. Now, I don't know how much of a chore it is to disassemble the rear end as Pelican01 suggests but I agree it's a good idea if possible. Since it's a spare unit you will be using I'm assuming it's already in the garage.

Regarding preheat and which rod to use, first off a disclaimer: Welding up rear axle gears is something I _haven't_ done. That said, preheat is a good precaution to take. Good news is, an oven isn't necessary, it can be done with a torch. Yesterday I worked on a bucket gouging off and replacing a tooth shank. Because the cutting edge is hardened it's important to preheat. I used a propane "tiger torch". For the rear axle gears, a regular oxy-propane or oxy-acetylene torch will work fine.

How hot? Without a way of measuring the temperature it's kind of a guessing game, but basically you want to get the "chill" out of the gears. Cutting edges usually are preheated to around 400 F, I would think around 200 F to 300 F should be fine for your gears. This is well below where the metal starts to change colour: red-hot is too hot in this case!  If it feels hot through your welding glove I'd think you're close, 'cause that's how the bucket was yesterday!

The welding part: Since you're using stick, is your machine capable of DC and AC welding current, or AC only? (Most welders in home workshops are AC only) If you have DC capability, use 7018. If it's an AC machine, either 7014 or 6013 will work well. Since you're trying to get into a fairly small area - the gear teeth - I'd suggest using 3/32 diameter rod. Heat setting is usually around 90 to 100 amps for this size rod, but practice on some scrap first.

And once it's welded, one more precaution: Post-heat. This allows the temperature to come down gradually, reducing the chance of the weld or gear itself cracking. Put some more heat on the part right after it's welded, and let it cool down its own - *NO* quenching in water!

Let us know how you make out, and post some pics of the burnout competition!


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## CT18fireman (Nov 30, 2000)

I have seen it done once. Not sure what stick and such but I would agree with 75 on that.

I will say to make sure the parts are perfectly clean. When I saw it done they cleaned it in a parts cleaner and then sprayed brake cleaner and blew it off with compressed air. The oil is flammable and also will not allow for a good weld.

I would pull the housing and do the welding on a bench. Just easier that way.


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## dany (Aug 21, 2001)

75 Thank you 

I have acces to a 220 mig and both my weders at home have ac and dc capability. Since I have a 220 mig should i use that do to claness of the welds? By welding the spider gears togeather do u mean to each other or to something else? You guys always come through thanks.


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## 2401 (Feb 3, 2001)

Man, your home shop is better equipped than mine!  

If you can get access to the 220 MIG that should work well for you, I still agree that pulling the housing and doing the welding on a bench is the best way to go. Pre and post heat too.

Yes, you will weld the spider gears to each other. What this will do is turn the two axle shafts into the equivalent of one solid unit.


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## dany (Aug 21, 2001)

Thanks 75

Iam only 15 and been around machanics all my life. I have been suplied with great places to learn. I try to fix my own stuff when ever possible. I buy all my own gas for the mig and torches and all my rod. I have done quite abit of fabracating and will post some pics of my bumper, fathers flatbed trailer. Just cause Iam 15 doesnt mean i leach off my parents. I need to come up with a way to convience my father to build a bigger garage cause the 24 by 32 is a little jam packed right now.


WHY BUY IT WHEN YOU CAN MAKE IT!!!!!!!


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## 2401 (Feb 3, 2001)

When you've got the axle on the bench, if it has a separate rear cover like my Dana 60 (I don't speak "Ford" too well so I'm not sure what the rear end in yours looks like) take a look at the inner workings before you start burnin'. You'll have a better idea of how the spider gears work if you watch things turning in there.

By all means post some pics in the Welding forum of your projects, there's a thread in there called "Pics of projects" just for that purpose.


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## dany (Aug 21, 2001)

Has any one else had any exsperience with LINCOLN LOCKERS?


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## dany (Aug 21, 2001)

I just saw a drawing of the spidergears on hot rodding tv. The spider gears form a square patter right? At every joint where each gear makes contact with another, is that were iam supposed to weld? Sorry about all the questions I only want to do it once and not have any thing mess up on me.


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## Plow Meister (Oct 16, 2001)

*Only weld the gears to each other.* Not to the housing. This way in the future if you want to make your diff "open" again, all you have to do is pull the cross shaft and slide the welded gears out and put new ones in. Or, if you want to remove the spider gears and install a Powertrax locker later on in life.


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## 2401 (Feb 3, 2001)

Plow Meister is right: Only weld the gears to each other.

And that reminbds me of something I forgot to mention in my earlier post: When you go to weld them, make sure you ground to the part you are welding rather than just to the axle housing. This way the current can't travel through something you don't want it to - like the bearings.  

If it's not feasible to clamp right to the gears, you can tack a piece of flat bar to them and put the ground clamp on that.


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## dany (Aug 21, 2001)

Can i use a mig? I think there would be less of a mess if i were to do so. The machine is 220, will that do the job?


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## 2401 (Feb 3, 2001)

*Yes, the 220 MIG should work OK:*



> If you can get access to the 220 MIG that should work well for you, I still agree that pulling the housing and doing the welding on a bench is the best way to go. Pre and post heat too.


Quoting myself here from an earlier post in this thread! 

Remember to ground to your workpiece, regardless of what type of welder you're using.

On something like a loader bucket, grounding to the bucket, working on that for a while and then starting to weld on the lift arms without moving the ground clamp means the current passes through the bushings - which has the potential to turn into an expen$ive mistake.


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## Pelican (Nov 16, 2001)

Now that the welding's covered, I'm curious about the motor that's gonna spin this thing. How about it?


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## dany (Aug 21, 2001)

Its only got a 390BB with a four speed tranny. That happens to get great fuel milage at about 4-6 mpg. Ive only got till early to mid july to do this. Iam gettin a little excited about something that will last 5 minutes. OH-WELL


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## Big Nate's Plowing (Nov 26, 2000)

I myself have done it. (burnout contests and welded rear end) with a 220 mig, it held up allright but after that I broke 2 axleshafts (thank god I hade spares) and sold the truck. if you are doing a burnout contest with a stick... well any vehicle I would invest $50.00 in a line lock for the front brakes that way you dont have pressure on the rear shoes/drums when you are going spin crazy, another thing to touch on is the fact that tires in a burnout contest last longer when spun @ 30 mph then tires spun @ 50-60 they smoke just as bad, what kind of rubber are you going to run?


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## dany (Aug 21, 2001)

The compation at the fair has a cement pad with two colums cemented into the ground. They chain you vehical to the colum. There is no need to use your brakes. Line locks are on my order list anyway though. Iam not sure what i ahould run for tires though. I'am going to run a worn set of 33x12.50 mud tire or a skinnier tire that is only run on a 6 or 7 inch, 8 bolt rim. I will probally use the 33's. They have abou .25 tread left and the truck will spin them just as fast as the skinnier tire. Do they make a rubber softener or I have heard of bleaching your tires also? Which works best?


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## mud_man93 (Mar 5, 2002)

I would go up the road to "k-mart" and grab as many rear ends as i could and weld one with stick one with mig and see how they work.


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## dany (Aug 21, 2001)

mud_man93 are u who i think u are? I knew it the minute you said "k-mart up the road". only a few people ne about that great big wonderful 73-79 (mostly) salvage yard.


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## John DiMartino (Jan 22, 2000)

Dany,good luck at the burnout contest,I always wanted to hook up an antifreeze nozzle to the carb inlet under the air cleaner,and use the windshield washer resoivor to squirt a small amount of antifreeze into the motor ,give it a few hits when its screaming for more smoke!! anyone who has ever seen a car smoke with a blown headagsket knows how you can cover a city in 5 minutes with a blanket of fog.Your contest didnt specify it had to be tire smoke?Once the tires are smoking real bad,your not going to be able to tell where its coming from anyway!!I agree with plow kid,smoke em too fast and they'll blow sooner,you have enough weight to make the smoke real good anyway.


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## CT18fireman (Nov 30, 2000)

John I heard on the old James Bond cars they used to use a small amount of tranny fluid to get the smoke from the exhaust for a smoke screen. Not sure if this would have bad affects to the motor or exhaust. Then again I doubt he cares.


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## dany (Aug 21, 2001)

This contest has two rules. If you start to move around to much with the wheel chucks you get chained and if you catch on fire you have to stop. Last year a mustang caught the plastic panel right behind the tire on fire. Another person has a 70's camero with a 383 stroker. He hit nitrous and just hydroplained through all the gears. They spray watter down on the pad. I think if i put bleach on the tires befor hand and during the burnout I rig up a line going to the rear tires filled with tranny fluid or oil.


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## mud_man93 (Mar 5, 2002)

we found out last night that the old ford with a 390 with 33's will burn the tires great in about 5 seconds you could not see any thing there was so much smoke!!!


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