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Re: Tips on making a rear end narrowing jig?
[Re: RobX4406]
#1701385
12/07/14 07:43 PM
12/07/14 07:43 PM
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Joined: Dec 2005
Posts: 11,645
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,645
Fulton County, PA
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Rather than trying to fix it after it's welded or welding the ends on off center, I've been doing it a little differently. I fixture the housing and pull the ends of the tubes forward (away from the brace), fit the brace to the housing at that point and hold the bow while welding it. It's going to pull. May as well have it pull back to where it needs to be.
I don't actually bend the housing and pull it so far that it springs back to where I want it, I just pull it to where I want it and hold it there. The 9" and 8.75" housings have some flex in them before they are braced up. Easier to do it before than after the brace is welded up.
Keep the jig bar in the housing and use it to measure how far off from axle centerline you are moving it.
The amount you pull it depends on the width of the housing and the brace. The longer the weld, the more it needs to be compensated for. Maybe 1/4 or so on a stock length housing, less as it gets narrow.
Spend the time to get a tight fit on the brace. Relying on filler to take care of gaps will make the pull worse.
If the results don't match the theory, change the theory.
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Re: Tips on making a rear end narrowing jig?
[Re: CMcAllister]
#1701386
01/19/15 09:53 PM
01/19/15 09:53 PM
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Joined: Jan 2003
Posts: 4,287
Morrow, OH
markz528
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,287
Morrow, OH
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Well you all scared me about how much it is gonna move so I ended making a jig. Its as good as I can make it, so if it moves I will use the jig to straighten it.
Back brace is pretty much ready to get welded.
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Tips on making a rear end narrowing jig?
[Re: markz528]
#1701387
01/19/15 09:56 PM
01/19/15 09:56 PM
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Joined: Jan 2003
Posts: 4,287
Morrow, OH
markz528
OP
master
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OP
master
Joined: Jan 2003
Posts: 4,287
Morrow, OH
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Having trouble with picture. Lets try this.......
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Tips on making a rear end narrowing jig?
[Re: markz528]
#1701388
01/19/15 10:11 PM
01/19/15 10:11 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Just weld short spots at a time and jump around.. do some on the left... jump to the right side and let it cool. if I can put my hand on it with my light gloves I'll burn there.. just jump around 
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Re: Tips on making a rear end narrowing jig?
[Re: markz528]
#1701389
01/19/15 10:33 PM
01/19/15 10:33 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Quote:
Well you all scared me about how much it is gonna move so I ended making a jig. Its as good as I can make it, so if it moves I will use the jig to straighten it.
Back brace is pretty much ready to get welded.
Your back brace is too short. It WILL bend out on the ends with the brace that short. You obviously have fab skills. I suggest you run the brace as close to the ends as possible and then "tube" the brace for the U bolts
Monte
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Re: Tips on making a rear end narrowing jig?
[Re: markz528]
#1701391
01/19/15 11:12 PM
01/19/15 11:12 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Quote:
Quote:
Quote:
Well you all scared me about how much it is gonna move so I ended making a jig. Its as good as I can make it, so if it moves I will use the jig to straighten it.
Back brace is pretty much ready to get welded.
Your back brace is too short. It WILL bend out on the ends with the brace that short. You obviously have fab skills. I suggest you run the brace as close to the ends as possible and then "tube" the brace for the U bolts
Monte
Monte - I was thinking of adding some end pieces that overlap the short brace by about 12 inches and bring it as you said, as close to the ends as possible. Do you think that would be effective?
Outside the perches is where it will bend...........needs something to support it
Monte
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