Welding a back brace on a 8 3/4, any advice??

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flyfish

flyfish

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I’m about to try welding a back brace on my 8 ¾ and I need some advice. I’ve done some reading, and most folks agree that the right way to do it is to use a jig to keep it from warping the housing. Well….I’m a backyard mechanic, so I don’t have a jig…but this was my thought.

What if I tack weld a piece of angle iron on the opposite side of the housing from the back brace, and leave my axles and spool installed…would this be enough to keep the housing fairly strait if I space my welds (to not build too much heat) and work my way slowly around welding the brace?

Also, dose the brace need to be fully welded all the way around?

Any and all advice is appreciated,
Thanks in advance

Edit: Forgot to add...and when finished (obviously) cut the angle iron brace off the front.
 
I could be slam wrong on this, because it is something I have never done. BUT, I know welding and I know as long as you weld in small sections at a time, you are less likely to warp anything. I'd weld like 1" sections at the time maybe letting it cool a bit every other weld and I bet you'll be fine.
 
Well, this is what i did, be it right, wrong or indifferent. I took jack stands and placed them on my work table. I laid the housing face down on the stands (one one each axle tube and then one in the opening of the housing) and used ratchet straps to secure it from the very ends so as not to burn them when welding. I then proceeded to weld the brace on using very short bursts and moving from spot to spot. I continued stitch welding it until I had it welded solid. If you spend too much time in one spot it will start making a popping sound, if/when it does move to a different area.

As you're welding it will more than likely want to pull the axle tubes back as it gets hot, that's why I did it the way I did.

I made my brace for about 5 bucks of scrap steel I picked up from a local steel shop, just cutting and fitting until I had it where I wanted it and then welded it up.

It seems to work fine, slow and easy is the recipe.

A pic of after the brace welded on and primed and another of the completed project.
 

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I'm just thinking outloud here, so if you i'm off base just let me know:-k

I've never held a seperate brace in my hands before so i'm not sure how structural/stiff they are alone. My thought is if it's fairly stiff you could massage it to fit snug in the center and towards the ends. Then weld both ends and the center a bit and let the brace itself help hold things in line while you finish the remaining welds.

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Since i wrote the above a few hours ago i've been googling and reading other forums and i haven't found 1 case where the housing didn't have to be straightened or the ends cut and rewelded on. Since Badsport got good results on his i'll have to say that's probably the best way so far.
 
Put it in a Press to counter any pull. Otherwise, cut the ends off and start over.
 
Keep your ground close ! You don't want any arching, think about your bearings and gears.
 
Badsport said:
Well, this is what i did, be it right, wrong or indifferent. I took jack stands and placed them on my work table. I laid the housing face down on the stands (one one each axle tube and then one in the opening of the housing) and used ratchet straps to secure it from the very ends so as not to burn them when welding. I then proceeded to weld the brace on using very short bursts and moving from spot to spot. I continued stitch welding it until I had it welded solid. If you spend too much time in one spot it will start making a popping sound, if/when it does move to a different area.

As you're welding it will more than likely want to pull the axle tubes back as it gets hot, that's why I did it the way I did.

I made my brace for about 5 bucks of scrap steel I picked up from a local steel shop, just cutting and fitting until I had it where I wanted it and then welded it up.

It seems to work fine, slow and easy is the recipe.

A pic of after the brace welded on and primed and another of the completed project.
Click to expand...

Very nice work!....but unfortunately, I'm an idiot. After cutting off the perches, grinding things smooth, and measuring this thing MULTIPLE times...I realized last night that the housing is bent...bad:banghead:...I really have no idea how I could have missed this earlier.....I suck :eek:ops:

Does anyone know if a MO875 with a back brace will clear a stock gas tank on a 67 Barracuda? I'm pretty sure this is the direction I'm going....no racing for me this weekend :violent1:
 
FYI LXguy has a nice A body 8 3/4 housing on here for sale.

How did you determine it is bent bad? No way to straighten it?
 
Use an alignment bar to check it.

Here's a good how to. I used a Moser back brace that I got from Summit. It fit real good, others I heard were not cut so good. Helps when gaps are small to start with.

http://www.moparts.org/Tech/Archive/race/20.html
 

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I added the brace , then had it shortened afterwards. ( 2 " a side ) and when he put the ends back on , he aligned it.
I was surprised how much it took , or how much it moved I guess.
But it is straight now.
 

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flyfish said:
Very nice work!....but unfortunately, I'm an idiot. After cutting off the perches, grinding things smooth, and measuring this thing MULTIPLE times...I realized last night that the housing is bent...bad:banghead:...I really have no idea how I could have missed this earlier.....I suck :eek:ops:

Does anyone know if a MO875 with a back brace will clear a stock gas tank on a 67 Barracuda? I'm pretty sure this is the direction I'm going....no racing for me this weekend :violent1:
Click to expand...
it cant be bent to bad if you were running it??????..Artie
 
Make sure that you stay in between the lines...

No, wait, that's coloring...

Back to the show...
 
Here is a pic of part of the problem.........and the solution to my problem :-D
 

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Moot point now, but was going to say chances are the housing is a bit tweaked to begin with. Fab guy I have used build jigs for damn near everything he does. For the little bit of extra $$$ it is just a piece of mind kind of thing.......
 
Seen a friend straighten a driveshaft, to within .010 with a torch and a wet rag, wonder if it'd work on something as heavy as an axle housing? I don't see why it wouldn't, but I don't have a housing to play with.
 
tubtar said:
I added the brace , then had it shortened afterwards. ( 2 " a side ) and when he put the ends back on , he aligned it.
I was surprised how much it took , or how much it moved I guess.
But it is straight now.
Click to expand...

maybe its an optical illusion, but those ends look off center.
 
motorhead446 said:
maybe its an optical illusion, but those ends look off center.
Click to expand...

They probably are indeed off center (tubtar can verify) but the axle isn't. If a housing is bent, you can either straighten the housing or relocate the housing end using a gage to locate center relative to the 3rd member. Either way the axle, 3rd member, and car don't know the difference.
 
The bottom of the tube is crushed in from the perch (not in the pic)...they had enough damage that I would not want to put it back under my 10 second car....especially if I decide to go deep in the 10's (or 9's) with my little blue friend:twisted:
 
The Moser is a good solution, that original looked like trouble waiting to happen. Sometimes it better to spend the cash, then domino the trouble to the tranny disaster that costs more. Good luck.
 
flyfish said:
Here is a pic of part of the problem.........and the solution to my problem :-D
Click to expand...

Your new housing looks great! Did you consider the other 8 3/4 offering from Moser? I think it is called the 8 3/4 Challenger housing and has the stock 8 3/4 appearance:

http://www.moserengineering.com/new...-8-¾-stamped-housing-for-challenger-drag-pak/

I noticed it can be ordered with backbrace installed.

Also, I'm just curious - Your picture above with straight edge seems to show the housing end is deformed rearward? Is that what I'm seeing? That would be most unusual since the forward tire force tries to deform it forward as was the case with mine.

Edit: I now think your picture shows it is deformed in the forward direction as would be expected. My bad. The clamp I see must be the emergency brake cable clamp on the passenger side.
 
I didn't consider the other, because the fabricated housing was stronger and cheaper. I got a heck of a deal on the housing. I had placed my order for a bare fabricated housing with back brace on Tuesday, Wednesday morning I got a call from Moser asking if I was interested in a housing that a customer ordered, and then cancelled the order (leaving them with a custom housing that no one wanted). It was back braced, powder coated, with perches in a weird location....anyway, we struck a deal, since I would have to do some cutting and welding to make it work (I got it cheaper than what I had ordered...with the powder coat upgrade:D). Got it cheep and FAST!! It showed up on my door step Thursday!! That's a 2 day turn around time :cheers:. I will definitely use Moser again in the future...GREAT customer service.
 
DC 340 said:
They probably are indeed off center (tubtar can verify) but the axle isn't. If a housing is bent, you can either straighten the housing or relocate the housing end using a gage to locate center relative to the 3rd member. Either way the axle, 3rd member, and car don't know the difference.
Click to expand...

Yep. I welded the back brace on and it definitely moved. Bob Fuller at C&F narrowed it and told me how I could have avoided this ( a fixture ) , but the axle ends are true to the carrier bores and it's all good.
I did weld in short sections , but that sucker was either bent when i started or really moved around.

flyfish said:
I didn't consider the other, because the fabricated housing was stronger and cheaper. I got a heck of a deal on the housing. I had placed my order for a bare fabricated housing with back brace on Tuesday, Wednesday morning I got a call from Moser asking if I was interested in a housing that a customer ordered, and then cancelled the order (leaving them with a custom housing that no one wanted). It was back braced, powder coated, with perches in a weird location....anyway, we struck a deal, since I would have to do some cutting and welding to make it work (I got it cheaper than what I had ordered...with the powder coat upgrade:D). Got it cheep and FAST!! It showed up on my door step Thursday!! That's a 2 day turn around time :cheers:. I will definitely use Moser again in the future...GREAT customer service.
Click to expand...

Ya gotta love it when a plan comes together. :D:D
 
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