Rear sway bar question
#41
#43
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.
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.
#44
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
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.
#45
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
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 01:46 PM. Reason: Put-er' ther Engineering
#47
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.
#49
#50
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?
__________________
Joe Padavano
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.
__________________
Joe Padavano
#51
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
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.
#52
I can suggest some mechanical engineering textbooks for you...
#53
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...
I can suggest some mechanical engineering textbooks for you...
#56
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.
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.
#57
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.
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.
Unless you plan on standing your rocket 350 on its end, powering it into Magnetawan then , you really should stuff a piece of 1/4" 0r 3/8 dia drill rod or threaded rod into the slop of the slot, fill it with silicone so it doesn't rattle and move when thrusting off the launch pad. 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, heavy weight oil , Colombian insulation with a thin cardboard filter... Then I'd grab my Jim Beam Zippo... fire em' up! 'n' lite my rocket. (Don't laugh,I still make rockets in my lazy boy! Its legal here now, you can fly around anytime ya' want now. ) Then. I'd lay on my back in the dark, out on the lawn, take off and hope to land on a young hot star!
One time, coming off a twin paper. I was flying over my wife, had a couple loose nuts fall out , how embarrassing, then me bolt came out 'n' yeah, fell rite into er'.
Put-'r' ther !
Last edited by 76olds; January 18th, 2019 at 11:48 PM. Reason: 45hrc is not that hard.
#58
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