Hey all. I plan to build my front and rear strut bars and have a question about construction. I plan to use 6009 series aluminum alloy. What form is best for construction? I thought I'd either build a twin I-beam shape or use rod and make a series of right angle triangles(welded together of course) like a bridge support. I understand that strut bars can be too stiff, do either of these forms sound like they would be too stiff?

 

why would it be too stiff ??

mmm
i want to build myself some bars too..and plan on doing it soon
i'll be basing my stuff on spoon bars ( my car is prelude 97)

but one thing i always wonder..why do some brands do bars with rotating part betwen the struts attachements and the bar itself ??

i will be using 7076 aluminum ( i'm not sure that's the correct number though ;p haha )
and steel plates for the rings

let me know how ur stuff goes

by the way..
have u ever looked at mugen bars ??
i think that they are the best design of basrs u can get..so maybe u could base urslef on them
hehe

 

If the bar is too stiff and enough pressure is applied, something has to give. Probably the bolts that would hold the brackets around the strut tower. I'm not an engineer though, so I'm not sure that's what would give.

I don't understand what you mean with rotating parts? Do you mean attaching the bar to the bracket with just one bolt?

What made you choose 7076? I picked 6009 from this list http://www.aluminum.org/default3.cfm...toaluminum.org
I'll also be using 3/8" steel for the brackets.
I've seen the Mugen bars. My mounts will probably look something like those to eliminate 'hinging' on the one bolt attachment. From the research I've done though, a tall bar would be stiffer than a wide bar, so mine will look different from the Mugen.
Have you ever welded aluminum before? I've done plenty of MIG and Arc welding on steel, but never aluminum. Any tips if you have?

 

what are you using as mounting brackets?? ive been tryin to think of what to use as mounting brackets for months now...would you please help me? my email is trandyan@yahoo.com ....if any of you could help me out in telling me what to use..thanks alot.

 

There is one thing you should know about welding 6000 Alum. Welding will anneal it ( make it soft ) to about the same strength as 1100 Alum, just a little stronger than Alum. foil. In order to get it back to the same strength you will need to heat treat it back to the 6000 temper.

 

I'll quote a passage from an excellent book I have on race car materials (Carrol Smith, Engineer To Win, isbn#0879381868):

"6061 is a weldable alloy that has good mechanical properties and is still reasonably formable... I use a lot of 6061-T6 for joining pieces and corners, and I make most of my fabricated brackets from it. I use it in sheet form for almost all track repairs simply because it is the strongest of all the aluminum alloys that I can successfully bend over a block and form with a hammer and sandbag.

7075 is the strongest and the stiffest of the commonly available aluminum alloys. It is also the most machinable. In rod and bar form, in the T6 condition, I use it for almost all of the bushings, spacers and the like that we make. I usually use it also for such machined suspension components as steering arms, antiroll bar links, and any straight suspension links that I maybe making. It machines very well indeed."

So for a strut-tower brace, I would say make you brackets from 6061 and the straight bar from 7075. Or the whole thing from welded 6061.

BTW, 7076 is mostly used for making forgings and is also not suitable for welding. And 7075 actually has higher tensile strenght, FWIW...

I'm no expert on metals (and don't want to be, hehe). So i'm just going by what the book says...

 

All good info jsi, Smiths books are a great resource, but when you weld 6061 Alum you remove the temper. ( thats what the T6 means ) The only way to get the temper back is to heat treat the alum. back to it's T6 condition. This takes several hours in a heat treat furnace, and then a quench in water. For grins...take a 1/16 or 1/8 sheet of 6061 Alum. and butt weld some 4x4 squares together. then bend them near the weld. they will bend like soft Alum.

 

Thanks guys, great info.
fatoldman7, what would I have to do to retemper? Just reheat it? (how hot?)
TranTegra, I planb to use 3/8" steel plate for my mounting brackets. I have access to a plasma cutter to cut out the round flat part and then I'll weld vertical plate on either side. Then drill 4 holes through the two verticals and mount with two bolts each side.

 

why don't u simply use steel something like 3/8 sheet for the rings on the struts ..and then use a bar of aluminum without welding it and only use a design as simple as the spoon one
it's a good design..that requires much less effort than tryin to weld all stuff together ..


for info ... could a strut bar be too strong ??

 

Retempering Alum. is done in a heat treat furance, in an inert atmosphere. The temputure is around 400 degrees. The time you hold the part at that temp. depends on it's mass. Then it's taken out and quenched in water. All this is best done by a pro who knows what they are doing. This is from memory...so...it might not be exact.

 

Thanks fatoldman7, I appreciate the help. I guess I'll have to pick a different alloy.
JinMTVT, the reason I don't want to use a solid bar or tube is strength+weight. An I-beam or bar constructed with right angle triangles would be a lot stiffer than a solid bar or round tube. For the forces exerted on a strut bar anyway. Generally, any bar/support, etc. that is supported on either end and spans a distance will be either I-beam shaped or use the triangles. Since with the strut bar, the forces trying to flex it would be pushing up and in at the mounts, the bar would want to flex in the middle. A solid bar would bend before an I-beam. I know my explanation could be clearer, maybe someone can clean it up
I plan to use the 3/8 steel plate for the brackets/mounts. I'd still have to weld the parts that the bolts would attach to.


[Modified by Steppin Razor, 3:40 PM 7/3/2001]

 

nah i perfeclty understand what u are explainning..and it makes great sense...

though i'm not sure that u would need that strong bar
cause u also have to consider the cost and time vs utility ...

i wonder if we can buy I shapped beams of aluminum somewhere ...

and mmm neone has links for buying good aluninum bars/beams at good price on the web ??



i'll be using about the same metal as u are for the ring plates..

though i want it to do all the upper part and then go down on the inside of the strut bump in the frame...
so it would actually support more than only the strut bolts..

i fear i'll miss some space on prelude on the passenger side though
eheh

so let me know where and what kind of beam will u be using for ur bar man

 

I'll let you know what I decide about materials for the bars (I am currently considering a supposedly very strong epoxy to put the bar together, but I have to test it out first.) Otherwise, I'll find another alloy to use.
As for the passenger side thing, I know what you mean. Check out http://www.ntpog.org under their strut bar install how-to. It seems the guy bent the metal 'clip' all those (cruise control?)wires attach to.

 

adjustable strut tower brace.

you'll probably spend more time on it than it's worth, lest you have access to a machine shop.

 

ok tough guy... go buy some god damn chromoly steel and do it like a man.
p.s.: i don't want to hear about "it's too heavy..." cry me a ******* river! the extra 5 or so pounds could be lost else where, like by removing the fat in your head!!!!

 

for reference that was posted by a friend Im usually not that hostile