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Re: Shock Placement [Re: TUTS 59] #1333033 Fri Nov 08 2019 09:57 PM
Joined: Dec 2018
Posts: 421
A
Apache1 Offline
Shop Shark
Hey Tuts why not just forego the whole leaf spring and traction bar idea and incorporate a tri-angulated 4-link with coil-overs and be done with it. You are in the early stages of modifying this and that...new upper mount shock location, changing spring shackles etc. Just a thought although it would involve a little $$$$. But man it would be sweet. Best of both worlds in the end.


1959 Apache 3100 Fleetside SWB (Shop Truck) (modified)




Re: Shock Placement [Re: TUTS 59] #1333111 Sat Nov 09 2019 04:50 PM
Joined: Feb 2004
Posts: 19,129
H
Hotrod Lincoln Offline
Boltergeist
The guy who drew that diagram really needs to go back to school and study some geometry! He's all wet on his understanding of how and why a shock absorber works!
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Shock Placement [Re: TUTS 59] #1333177 Sun Nov 10 2019 01:51 AM
Joined: Mar 2007
Posts: 395
T
TUTS 59 Offline OP
Shop Shark
Jerry, I'm new to this class so school me on what's wrong and what's right with this shock geometry.


Craig

Come,Bleed or Blister somethings got to give!!!
Q:"What yah runnin"
A:"3/8 drive Black and Decker aquarium pump motor" (the movie HOTROD)

59' Apache 31, long term project (30 years and counting)
Re: Shock Placement [Re: TUTS 59] #1333181 Sun Nov 10 2019 02:28 AM
Joined: Feb 2004
Posts: 19,129
H
Hotrod Lincoln Offline
Boltergeist
The diagram shows the shock action at "100%" with the shock vertical. In fact, the shock will have its maximum stroke, and max fluid displacement at a 45 degree angle, since the hypotenuse of the right triangle formed by the shock and the suspension travel is greatest at 45 degrees. Shocks dampen by displacing fluid through restrictor valves in the shock tube, so the greater the angle from vertical, (up to 45 degrees) the more shock absorption will happen. 45 degrees usually isn't a practical choice due to space limitations, so around a 30 degree tilt is more common for rear shocks.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Shock Placement [Re: TUTS 59] #1333192 Sun Nov 10 2019 04:36 AM
Joined: May 2015
Posts: 1,515
K
klhansen Offline
Shop Shark
Sorry Jerry, the diagram is correct. The resistance a shock exerts is dependent upon the speed it compresses or extends. And the greatest speed occurs when the shock is vertical. At any other angle the shock is moving slower than the axle vs frame movement.


Kevin
First car '29 Ford Special Coupe
#2 - '29 Ford pickup restored from the ground up.
Newest Project - 51 Chevy 3100 work truck. Photos
Re: Shock Placement [Re: TUTS 59] #1333194 Sun Nov 10 2019 04:57 AM
Joined: Feb 2004
Posts: 19,129
H
Hotrod Lincoln Offline
Boltergeist
That's a physical impossibility- - - - - -traveling further in the same amount of time moves more fluid through the shock valving, unless you want to have some archaeologist dig up old Euclid and persuade him that he invented geometry the wrong way.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Shock Placement [Re: TUTS 59] #1333196 Sun Nov 10 2019 05:41 AM
Joined: May 2015
Posts: 1,515
K
klhansen Offline
Shop Shark
Ok you’re correct that the speed of compression is greater at 45 degrees off vertical, but the force of the shock is also acting at 45 degrees from vertical, with only about 70% of that force acting against the suspension travel.
What got me was you saying the hypotenuse was greatest at 45 degrees but that part isn’t right as a flatter shock mount would result in a larger hypotenuse, and taking that to the extreme would result in very little shock compression. Of course like you said, that would be impractical/impossible. Consider the absurdity of mounting the top of rear shocks over the front axle.
It’s too late at night to do math. frown


Kevin
First car '29 Ford Special Coupe
#2 - '29 Ford pickup restored from the ground up.
Newest Project - 51 Chevy 3100 work truck. Photos
Re: Shock Placement [Re: TUTS 59] #1333211 Sun Nov 10 2019 04:22 PM
Joined: Feb 2004
Posts: 19,129
H
Hotrod Lincoln Offline
Boltergeist
One more response, and let's move on. Force-feeding me alphabet soup (putting words into my mouth) doesn't work. I pointed out that the maximum shock travel happens at 45 degrees, and any angle beyond that results in a diminishing return.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Shock Placement [Re: TUTS 59] #1333212 Sun Nov 10 2019 04:30 PM
Joined: Mar 2007
Posts: 395
T
TUTS 59 Offline OP
Shop Shark
Gentlemen, thank you for the education. So taking all of this into effect the shock would perform best at 45 degrees, or as close as practical for mounting. With the rear spring mount being the position that changes under spring compression mounting the shocks behind the axel would make the most sense.... Apache1, you nailed the reason when you said $$$. That's just not in the budget. I m using an idea that my Father used on a 56' 210 he had. It's a ladder leaf design, it uses an additional leaf under the main spring with the leaf pack clamped together forward of the axel and the use of a ladder bar snubbed closely. It work very well on his 56', the ride was a little stiff but it hooked up great.


Craig

Come,Bleed or Blister somethings got to give!!!
Q:"What yah runnin"
A:"3/8 drive Black and Decker aquarium pump motor" (the movie HOTROD)

59' Apache 31, long term project (30 years and counting)
Re: Shock Placement [Re: TUTS 59] #1333612 Wed Nov 13 2019 03:30 PM
Joined: Feb 2000
Posts: 4,014
J
Joe H Offline
Shop Shark
The chart is correct, it has been around a long time, I pulled it from the HAMB web site, and a lot guys there know their stuff.

Vertical has the most resistances, just like you think they would, 45* has less due to the less travel the shock moves. It cannot compress as much the more it is leaned over, thus it has less effect on the axle. Here is a different chart, https://www.jalopyjournal.com/forum/attachments/afcoil-gif.2915921/

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