Jclgodale3

* Update! Spreader bar and brackets now installed and functional. All in all...a cheap build vs buying a pre made one! Pics Below* Thanks for all the input folks!




Since viewing some others home built spreader bars I decided to tackle one on my own. I have the upper A arm brackets cut and drilled. My question is, if I have adequate clearance from the front to the rear of the brackets to clear pulleys, (with the bar) what is the best orientation for the bar to be mounted in the brackets, or does it matter? Center? Front? Rear?
Thanks for the input!

chevymans 77

just my opinion but I would say in the middle.

Meh

Yeah, I'd say as close to center as possible.

CGGorman

Two. One front and one rear....unless you can make an "X"

Damn. Wish I had that much room! Mine is mounted, quite literally, on top of the front mounting bolts. Another 1/2" back and I hit the PS pump.

b71vette

I would say in the middle.

Curious to know why you offset the holes ?

That may potentially weaken it, the hole closer to the edge would not be as rigid as if it were closer to the bend

JoeRags

I started sourcing parts for mine today as well.. so I'd like to hear what people have to say.


what thickness material did you use? I have a bunch of stainless 1" stock 3/16 thick.. wondering if it will be strong enough for the brackets. Thinking I might need wider pieces.

Jclgodale3

Mainly, just to level the "plane" of the brackets front to rear. Since the front bolts are higher than the rears. Think it's an issue being that the bar will not be right at the hole?

Jclgodale3

? Can you expand on your thoughts?

JoeRags

looks like he rotated the bracket a bit, it'll sit not parallel with the mounting points... I'm assuming its for clearence purposes, no?

litevette

I'd like to see that thing when you get done with it!

Jclgodale3

BerniesVette

I made my brackets out of the thickest 2" angle I could find. I located both holes toward the top of the angle iron because of clearance issues with a pulley and pulley guard located on the right side of the car. I kept the brackets in "plane" with the a arm too; I thought it would be stronger that way. I located the bar closer to the front of the brackets because that is where it clears the fan, pulleys and fan shaft to the engine. Of course, if you aren't running an engine fan, you will have the ability to mount the rod higher and closer to the front a arm stud.
Bernie

CGGorman

This stuff is difficult to explain w/o pictures!

I'm thinking that forces exerted on the upper a-arm mount happen more or less equally at the front and rear of the mount. If a spreader bar is installed in between the two mounting studs, the majority of the lateral forces (a-arm moving up-down or left-right) are transferred through the bar into the opposite mount. In that situation, the mounts are still allowed to twist (a-arm moving fore-aft) independantly of one another. If we add a second bar separated as far as possible from the first along the length of the a-arm mount we tie that bending moment to the opposite side of the car. Good, but not great. It still allows some movement that could affect caster and steering. If we can make those two bars into the shape of an X (front right mount ties to rear left mount, rear right mount ties to front left mount), we effectively eliminate all independent motion. The driver mount can still push toward the passenger mount, affecting camber, but we would have to build a third member tieing the X to the crossmember to eliminate that.

68 NJConv 454

Totally agree, X member would work best if tied to the frame/crossmemeber but for the purpose of a street car I doubt you would really notice the difference b/w a highly modified spreader bar and a simple one bar design. Unless your running auto-x.
If you planning on building that "L" bracket make sure you put gussets/triangles to fit in the "L and give it strenth. Also the spreader bar gains the best rigidity when pushing against the inside of the A-arm where there can't be any bend or forgiving of the metal instead of an "L" bracket mounted to the top of the a-arm. Do a search, someone posted a pick of what i'm talking about. When I spring for the dewitt dual spal fans and aluminum radiator I'll be fab'in up an "X" spreader bar that mounts to the inside of the A-arm bracket. Only issue here is adjustability. Haven't figured out a way to allow this "X" design to be adjustable. Good luck.
-B

norvalwilhelm

Twin Turbo added a gusset right below the upper a Arm mounting studs. I am pulling the motor this winter and will add this gusset also. I will fit it before pulling the motor and make it as big as possible to prevent flexing of the towers.
I totally overlooked a gusset here in the past when adding them everywhere else.
I did go solid mounts to use the block as a stiffening member.

Twin_Turbo

That gusset is not just a gusset, it's the inner structural part of the shock tower...I still need to finish the inside (after I remove the engine yet again) so it's a square section all the way tp the top. You can see the gusset is cut in 2 where the cross shaft goes through, this will be just a hole when done. To install the arms I have to disassemble them, stick the cross shaft through and bolt it down and then install the rest. That's the only way I can get the tower strong enough and not having to cut it in 2 to slide the cross shaft in.

I have gussets almost everywhere, even on the motor mounts & the rear kickup area.

68 NJConv 454

can you say trigger happy with a welder!

Voetsek

I don't even have my frame gusseted right now. but I do have a roll cage. I'll add gussets like Twin Turbos and gusset everything else as stated in the chevy power book. I'll try to weld as much seams as possible but, I don't plan on taking of the body so I'll miss the part under the bird cage. I also made the spreder bar out of 1/4 inch flat stock. I didn't bother with the angle iron becuase I don't think 1/4 steel would flex that much.

norvalwilhelm

Mark you still have poly motor mounts?? Why not go solid and use the motor as a stiffening member?
While I hesitated to go solid once I did I don't notice any different in the idle, no harseness in the car.

b71vette

Norval, I swapped out to solid mounts on my 71 383 stroker mainly to cut down on the engine torking so much. I never thought about it stiffening the frame though - thanks for pointing that out.