Rear sway bar question - Page 2 - ClassicOldsmobile.com

Rear sway bar question

Old January 9th, 2019, 03:23 PM
  #41  
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Showoff haha !
Wicked setup 69455, wilwoods to wooah er down, nice, that's going to be some kinda fun
Keep an eye on them bushings and links eh !
Those links aren't 7075 T73 are they ? haha.









Originally Posted by 69455 View Post


Go to a Detroit Speed set up.
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Old January 9th, 2019, 06:00 PM
  #42  
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That's a nice set up, I went with Hotchkis front and rear with adjustable QA1 shocks in the rear, Moser 9 inch with a Ford carrier...in the 64 F-85
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Old January 10th, 2019, 12:02 PM
  #43  
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Originally Posted by joe_padavano View Post
Sorry, but this is not correct. Do not confuse a material's stiffness with strength. The spring rate of the bar is a function of a property called modulus of elasticity (also called Young's Modulus), which is a measurement of the relative stiffness of a material. ALL steels have a modulus of about 3 x 10^7 PSI. This is NOT effected by any heat treat. High strength steels have the same modulus as mild steel. Heat treating (or lack thereof) affects STRENGTH, not STIFFNESS. Springs are typically heat treated not to increase stiffness (since it can't) but to increase strength so that the coils don't yield at full compression. The sway bar doesn't have enough deflection to yield even with mild steel, which is why I seriously doubt the factory bar is heat treated. I'll also add that if it IS heat treated, you aren't going to drill the holes out very easily.
OLDSter Ralph: I was referring to the OP's OPGI bar and 76Olds (4140 hRC 45) bar and torsional twist. These two bars don't seem to be factory bars. If you say the factory bar is just mild steel, then so be it.

Sorry, no. This is a classic case of "eyeball engineering". Lock washers will NOT hold this. Opening the holes means that the bar will shift on the LCA without twisting, which means that it is LESS effective as a sway bar. Eventually you will fatigue and fail the mounting bolts. This is a baaaad idea.
Bingo

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Old January 10th, 2019, 12:12 PM
  #44  
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I'm wondering if adding an extra set of shims on both sides might force the bar to bend slightly in the middle and give the tolerance? Yeah, I know - wishful thinking, but a thought none the less.
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Old January 10th, 2019, 01:25 PM
  #45  
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Originally Posted by OLDSter Ralph View Post
Bingo
Ahhh come on wait I only have 2 corners !!

I've been bending , twisting all types of steel for the past 35 years , From mild steel to spring steel to Dual phase steels.

Lets say ...
You have 2 OK 2 .... 1/2-13 bolts, fastening a lets say long bracket OK , with slotted holes in Spring steel it isn't going to move along the 12" at the rate of speed these cars go . Never !
Where do you guys think the twisting begins ?? Over the 12" you just fastened to which is boxed ? Even if you think it will , the twisting needs to get past the 90 bend radius. What do the rubber control arms take at that distance ?? The little twisting that cant get past the radius bend ??

Hold you arms straight out as far apart as you can , cut a piece of 4140 spring steel to that length, add material for bending 90deg up to 10" or 12" per side now. Now grab onto what you just fabricated," now bite down hard" OK... On 3-2-1..... now start twisting ....Keep biting down hard, harder .... Where is it twisting ? Ok.. Put er' in the vice , clamp at ahhh 10ft lbs to start were only using 10-32 bolts on our Maverick, well go up if need be.


OK... Wait a minute, were not done! Shut that ball machine off for a minute, I got 3 corners now going for the, Ohh 69 after this!
Thank-you!!
Now same deal, OK, no messin' around.
Let's use mild steel . Hey, lets go heavy, giver' up to 1.5 dia yeahhh. Ohhhh Hey, I jus' member'd.... Where going to need a few shots of "Jack D" first cuz it helps ya know.

It may take both of us, PfffffT, plus my wife complains if I leave him sitting up on our counter in the kitchen. Like he's watchin' er' or something i dunno. Anyway, So bring em' out to the engineering room with ya.

Ok, were set-up , vice on hand jus' in case, Now... Put jack on the back of the vice, he likes it their, plus it keeps his bum cool, of course.. on my imported plastic vice.

Now... OK... On 3-2-1..... now start twisting ....Keep biting down hard, harder .... Come on Harderrrr....
Ahh dam$t Jack something is biting me in the back of my arm, not ther, down closer to my elbow. Jack, get it off me!! Nevermind...Ok...
Jack get over here.... OK go.... Awww, OOOH no Where did it twist ??? How come it won't untwist and spring back ? How long will a distorted mild steel bar last on our Maverick Jack??

This is brought to you from,
JACK DANIELS @ Put-r-ther Engineering!

Eric

Last edited by 76olds; January 10th, 2019 at 02:46 PM. Reason: Put-er' ther Engineering
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Old January 10th, 2019, 02:14 PM
  #46  
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You have a very creative imagination....
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Old January 10th, 2019, 02:18 PM
  #47  
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Originally Posted by Allan R View Post
I'm wondering if adding an extra set of shims on both sides might force the bar to bend slightly in the middle and give the tolerance? Yeah, I know - wishful thinking, but a thought none the less.
The problem is that doing what you suggest puts a side load on the LCAs. They aren't designed to react point loads in that direction. That's why I said to bend the bar first, which shortens it, then add shims as needed.
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Old January 10th, 2019, 02:22 PM
  #48  
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Got it. Makes perfect sense. The shims are just to ensure proper fitment - period. I'll see if I can get my bar adjusted somewhere after winter leaves.
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Old January 10th, 2019, 02:30 PM
  #49  
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Originally Posted by 76olds View Post
Ahhh come on wait I only have 2 corners !!

I've been bending , twisting all types of steel for the past 35 years , From mild steel to spring steel to Dual phase steels.
And I have been building and flying stuff like this for the last 40 years. That includes steel, aluminum, graphite, and titanium structures.






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Old January 10th, 2019, 02:32 PM
  #50  
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Originally Posted by Allan R View Post
You have a very creative imagination....


Allan,
Sway bars take some imagining ya know.

Anyway as for slotting the holes being "eyeballing engineering " Joe, has the eye ball doing? Read below , ANUF SAID.
--------------------------------------------------------------------------------------------------------------------------------------------------------------

The reality is that there was NEVER a 1" rear bar offered by the factory for the 64-72 A-body cars (yes, all 64-72 rear bars interchange). You either have an aftermarket bar or one for a different application. It's not surprising that an aftermarket bar would be made incorrectly. Is the problem that you can't bet the bolts in? Can you slot the holes in the bar slightly?
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Yes, it DOES have everything to do with the bolts. The arms are angled, not parallel. Sliding the bar rearward puts you in an area where the LCAs are further apart. Slotting the bolt holes lets you put the bolts in. Problem solved.
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Old January 10th, 2019, 02:38 PM
  #51  
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Yeah, I read the previous posts. I still can't understand why my OEM bar taken from a 1970 Olds A body doesn't fit properly on my 72. I had absolutely zero problems lining up the bolts or inserting the shims and tightening everything down.
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Old January 10th, 2019, 02:42 PM
  #52  
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Originally Posted by 76olds View Post

Yes, it DOES have everything to do with the bolts. The arms are angled, not parallel. Sliding the bar rearward puts you in an area where the LCAs are further apart. Slotting the bolt holes lets you put the bolts in. Problem solved.
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Slotting the bolt holes to slide the bar fore-aft has zero effect on transferring torsional load into the bar. Slotting the holes up and down, as would be required to increase clearance to the center section, DOES effect transferring torsion.

I can suggest some mechanical engineering textbooks for you...
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Old January 10th, 2019, 02:59 PM
  #53  
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Originally Posted by joe_padavano View Post
Slotting the bolt holes to slide the bar fore-aft has zero effect on transferring torsional load into the bar. Slotting the holes up and down, as would be required to increase clearance to the center section, DOES effect transferring torsion.

I can suggest some mechanical engineering textbooks for you...
Either way, the LCA's are on an angle.
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Old January 10th, 2019, 03:00 PM
  #54  
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Originally Posted by 76olds View Post
Either way, the LCA's are on an angle.
And???
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Old January 10th, 2019, 06:39 PM
  #55  
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Jus' floatin with the motion of the ocean .
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Old January 15th, 2019, 04:40 AM
  #56  
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So, when we look at the pictures off different cars with sway bars, it seems very common for me that the sway bar is close to the pumpkin..

i will see how it is when i have the body back on and maybe i will slot the holes. I dont think that, if the 4 bolts are tightened, the bar is able to move on the LCA's just because the holes are slotted. A bolt on connection doesnt has its stability from the "zero-play-situation" of the bolts in the holes, it has it because of the "press together force" that the tightened bolt puts on the 2 parts (bar and LCA in this case). Thats how i learned it as a machine fitter. So slotting the holes a bit should work IMO.
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Old Today, 02:49 PM
  #57  
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Originally Posted by 71OldscutlassS View Post
So, when we look at the pictures off different cars with sway bars, it seems very common for me that the sway bar is close to the pumpkin..

i will see how it is when i have the body back on and maybe i will slot the holes. I dont think that, if the 4 bolts are tightened, the bar is able to move on the LCA's just because the holes are slotted. A bolt on connection doesnt has its stability from the "zero-play-situation" of the bolts in the holes, it has it because of the "press together force" that the tightened bolt puts on the 2 parts (bar and LCA in this case). Thats how i learned it as a machine fitter. So slotting the holes a bit should work IMO.
Ahhh your all good ! 45hrc can be slotted easily with a carbide burr or file. Its not that hard at all.
Unless you plan on standing your rocket 350 on its end, powering it into Magnetawan then , stuff a piece of drill rod or threaded rod into the slop of the slot, fill it with silicone so it doesn't rattle. A bigger washer will hold everything in place and cover up the slot. How's that for eyeball engineering haha.
Hey, let me tell ya' I'm no "Rocket engineer " but,
When I was younger. I use to twist up rockets. Oh yeah, twin paper with a thin cardboard filter... Then I'd grab my Jim Beam Zippo... fire em' up! 'n' lite my rocket. (Don't laugh, Its legal here now, you can fly around anytime ya' want now ) Then. I'd lay on my back, out on the lawn and hope to land on a young hot star! Put-'r' ther !

Last edited by 76olds; Today at 02:54 PM. Reason: 45hrc is not that hard !
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