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Old 04-16-2008, 11:35 AM   #1
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My own rear brace

I wasn't completely satisfied with everyone else's solution to the rear brace so I made my own.

I bought two M10 metric rod ends from Midwest Control Products. These have holes for an M10 bolt and M10 external threads. One right hand, and one left hand threaded and corresponding lock nuts. $34.

Then I had a 19mm solid aluminum 6061 bar end threaded to accept the rod ends. $18 for taps, the bar was free and it was machined on a lathe.

I bought two 50mm long M10x1.5 stainless bolts to mount it to the chassis. $5

The bar only weighs 1 lb 2oz.






Last edited by blue2000s; 04-16-2008 at 11:38 AM.
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Old 04-16-2008, 11:51 AM   #2
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Aren't people having an issue with the ends(where the bolts run threw) snapping under load?
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Old 04-16-2008, 11:52 AM   #3
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Cool, post pictures once its installed.
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Old 04-16-2008, 12:17 PM   #4
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Quote:
Originally Posted by blinkwatt
Aren't people having an issue with the ends(where the bolts run threw) snapping under load?
the rod ends in the pic are high end three piece and won't break. they're rated to around 16,000lb radial load. the bolts would shear first.

you might be thinking of the brace that doesn't use rod ends, just holes drilled in a bar. in this case, any chassis twist could cause a torsional fracture. better to use rod ends. blink's design looks right on the money.
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Old 04-16-2008, 02:17 PM   #5
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Quote:
Originally Posted by insite
you might be thinking of the brace that doesn't use rod ends, just holes drilled in a bar. in this case, any chassis twist could cause a torsional fracture. better to use rod ends. blink's design looks right on the money.
Have people had problems with the solid bars breaking? I don't normally check out Porsche Pete's board, but I did some searches over there and didn't find anything. I haven't seen anything on Renntech or Babblers either... Way to go Blinkwatt, starting awful rumors!

I think the setup that blue2000s came up with looks good. I would caution you on one thing though - use anti-seize on the threads of the heim joints. You're using a steel heim joint in an aluminum bar. Dissimilar metals don't get along well and will eventually fuse together. That's why I personally use steel heim joints with a steel bar and aluminum heim joints with an aluminum bar. Now this may not be a big concern in this application though if you just install the bar, set it, and then never touch it again. I'm just saying this is something to consider.
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Old 04-16-2008, 02:42 PM   #6
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Quote:
Originally Posted by Kirk
Have people had problems with the solid bars breaking? I don't normally check out Porsche Pete's board, but I did some searches over there and didn't find anything. I haven't seen anything on Renntech or Babblers either... Way to go Blinkwatt, starting awful rumors!

I think the setup that blue2000s came up with looks good. I would caution you on one thing though - use anti-seize on the threads of the heim joints. You're using a steel heim joint in an aluminum bar. Dissimilar metals don't get along well and will eventually fuse together. That's why I personally use steel heim joints with a steel bar and aluminum heim joints with an aluminum bar. Now this may not be a big concern in this application though if you just install the bar, set it, and then never touch it again. I'm just saying this is something to consider.
Kirk,

You've got that backwards. Mating threads of similar materials will tend to bind due to what's called galling. When two parts are screwed together, they rub against each other. It is important that one of these materials gives and not the other to avoid them both deforming and clogging up the thread. This is a well known and documented phenomena.
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Old 04-16-2008, 04:36 PM   #7
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Quote:
Originally Posted by blue2000s
You've got that backwards. Mating threads of similar materials will tend to bind due to what's called galling.

Sure, make me go and look it up... what I'm referring to is galvanic corrosion and it is a very real problem when using two dissimilar metals. I know because I've had trouble with it before completely fusing parts together in an automotive application. Stainless steel and aluminum are especially bad when exposed to a corrosive environment - such as from road salt!

Some people have replaced fasteners in their engine compartment with shinny stainless steel bits thinking they were doing good, only to find out that when used in aluminum they were corroding the aluminum and causing the fasteners to bind. Zinc will help to prevent this corrosion. Guess what's in anti-seize... yup, zinc.
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Old 04-16-2008, 04:38 PM   #8
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Quote:
Originally Posted by Kirk
Sure, make me go and look it up... what I'm referring to is galvanic corrosion and it is a very real problem when using two dissimilar metals. I know because I've had trouble with it before completely fusing parts together in an automotive application. Stainless steel and aluminum are especially bad when exposed to a corrosive environment - such as from road salt!

Some people have replaced fasteners in their engine compartment with shinny stainless steel bits thinking they were doing good, only to find out that when used in aluminum they were corroding the aluminum and causing the fasteners to bind. Zinc will help to prevent this corrosion. Guess what's in anti-seize... yup, zinc.
blue is right, and the worst culprit is aluminum on aluminum. this will seize more or less immediately. you are correct that ss and aluminum + salt more or less make a battery; anti-seize won't help much there....paint might.
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Last edited by insite; 04-16-2008 at 04:46 PM.
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Old 04-16-2008, 05:23 PM   #9
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Quote:
Originally Posted by Kirk
Sure, make me go and look it up... what I'm referring to is galvanic corrosion and it is a very real problem when using two dissimilar metals. I know because I've had trouble with it before completely fusing parts together in an automotive application. Stainless steel and aluminum are especially bad when exposed to a corrosive environment - such as from road salt!

Some people have replaced fasteners in their engine compartment with shinny stainless steel bits thinking they were doing good, only to find out that when used in aluminum they were corroding the aluminum and causing the fasteners to bind. Zinc will help to prevent this corrosion. Guess what's in anti-seize... yup, zinc.
Galvanic corrosion isn't what you were describing before. It is definitely an issue on the outside of a car. You can put different metals in contact with each other, but they have to be compatible by the anodic index. Here's a pretty good link:

http://www.corrosion-doctors.org/Definitions/galvanic-series.htm

The products that I design have to go through some fairly rigorous environmental testing.

Last edited by blue2000s; 04-16-2008 at 05:31 PM.
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Old 04-16-2008, 05:25 PM   #10
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Quote:
Originally Posted by insite
blue is right, and the worst culprit is aluminum on aluminum. this will seize more or less immediately. you are correct that ss and aluminum + salt more or less make a battery; anti-seize won't help much there....paint might.
You can use zinc-plated or nickel-plated steels against each other because the plating tends to act like a lubricant.
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Old 04-16-2008, 05:29 PM   #11
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Here is the bar attached to the car. I was surprised how close the 19mm bar comes to the shifter counter-weight. You can kind of see it in a couple of the pictures. I'd be a little nervous about using a bar any larger than 25mm.










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