SuperStock spring tips.

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Locomotion said:
Perhaps this will provide a better perspective:

* The bottom of the shackle (that is attached to the rear of the leaf spring eye) should be angled down, behind the vehicle. Basically, behind the upper eye mount.

...and a pic is worth a thousand words:
Click to expand...


Thanks for the pic! That is the way I had thought the rear shackles need to be set up. I'm glad
I'm set up correctly.
 
June 1965

'Black Arrow' {1965 Plymouth Belvedere 'Race Hemi'} S/SA

One of the 'best' launching cars ever.

Suspension set up by Tony Pizzi and Bill 'Grumpy' Jenkins.

* Spacer-shims between the front leaf spring hangers and frame.
* Unequal length rear shackles.
* 'Drag Shocks'

This was done to compensate for leaf spring wind-up.

While the other Super/Stock Hemi cars were rising at line, the 'Black Arrow' was launching
forward and usually jumped out to a full car-length lead.

Both the nose and rear of 'The Black Arrow' rose evenly. It was a 'Thing of Beauty' to watch.

[URL="http://www.doverdragstrip.com/phpBB3/download/file.php?id=1992"][URL="http://www.doverdragstrip.com/phpBB3/download/file.php?id=1992"]


Passenger Side front leaf spring hanger. ................ What looks different to you ?


file.php

[/URL]

[/URL]
 
You should read the Mopar Suspension book like I recommended.
 
The drawing shows it as he said it. The other way and there's little slack left and the body can't rise. Physics and geometry.

FWIW below is essentially a repost from another thread on snubbers and SS springs.
At my first job I worked with a technician who had been an old school racer - stock class racing. His own car was a red '67 GTX and became just a time trial and bracket car for fun. The snubber was just touching the floor - no gap - no delay - no slap. He had also removed the clamps from the rear halfs. Maybe you don't have to do that in your case. I'm not here to argue.

His son caught a B&W photo of the car at launch. You could see the back springs open, and the front wheels just off the ground maybe 6". The body looked almost parallel to the ground. Tires were 10" slicks IIRC, cetainly nothing wider.

He was one of my first mentors in this hobby and went with me to the track a bunch of times, along with one of my other coworkers. I saw the car, a '67 GTX with full interior etc. He had finally broken the axles and was going to have to either put a roll bar in or run slower to be allowed on a track again.

The GTX had torqueflite, mvb with reverse patten and column set up to slap. Funny I never noticed any advice not run a snubber on automatics in the Chassis book. I will say on my own car there were times that even for autocross I had to have the snubber touching to prevent spring windup. That was not the best solution but an expedient until I could change springs and hangers. For autocross and road racing I haven't used the SS springs but E-berg used a dearched set on the green brick.
 
I'm still confused by the part that states torsion bars have a front and back. I thought only the huge aftermarket ones were clocked, MP factory replacements were not and front or back did not matte.
 
actually shimming the front hanger does nothing for spring pre-load , the rear shackle is still a double pivot point so all shimming does is move the rear end back changing the rear angle shackle slightly and more importantly for launch -thrust angle , I just went through this with my car , the longitudinal wheel base was almost 1 inch shorter on the passenger side and the thrust angle was way out when we stringed the car , I added @7/16 to the passenger side bringing it within the 1/2 inch they speak about when using SS springs , remember the passenger spring at rest is taller so it pulls the rear end forward until torque loading evens the ride height which moves the rear end backwards in proportion to the compression on the spring .Ain't Geometry and Physics Cool ?
 
Well, I described it backwards....but I had it right in my mind and even was lookin at it in the book and still described it wrong. Oh well. lol
 
The rear shackles should be slanted slightly toward the front from the bottom attachment point.
sounds right to me
 
No I mean look at the diagram , the shackle is slanted forward from the bottom attachment point as he described in his post .This made sense to me the first time he posted it , your diagram while pretty has nothing to do with my contention that shimming the front perch with a couple of washers doesn't cause preload to the springs , what it does is slightly alter wheelbase , thrust angle and shackle angle all of which are also very important to launch and weight transfer hence the invention of altered wheelbase {Funny } cars . As long as the axle is suspended with one mounting point being movable you cannot create preload on the springs . Add a 4 link or pannard arm to fix the axle from moving in a longitudinal manner and you create 2 fixed point which you can use to create preload by shortening the span between them thus changing the radius of the spring arc but we're not talking about that sort of suspension are we .
 
Not sure if someone mentioned it, but FWIW, if the rear shackles are are straight down or pointed wrong, one can help the angle by fabricating a square/rectangular spacer to put between the shackle mount and the frame. This moves the mount (and upper shackle pivot point) towards the front of the car You just have to use longer bolts to compensate for the tickness of the spacer.

I think some people are still getting confused when others talk about angles from either the frame mounted bracket/pivot or spring eye pivot points. Just look at the pics.
 
Hey '69, No disrespect. But that diagram makes no sense. When analyzing launch and weight transfer, it should show the mass of the car being lifted by the torque arm created by the front half of the leaf. Getting weight onto the rear tires provides the force needed to generate the friction plus sticktion on the forward direction.

There's a few pages in the back of Fred Puhn's How to make your car handle that cover this well.
 
Mattax said:
Hey '69, No disrespect. But that diagram makes no sense. When analyzing launch and weight transfer, it should show the mass of the car being lifted by the torque arm created by the front half of the leaf. Getting weight onto the rear tires provides the force needed to generate the friction plus sticktion on the forward direction.

There's a few pages in the back of Fred Puhn's How to make your car handle that cover this well.
Click to expand...

The example,

Was from 'The Black Arrow' in 1965.

Explaining that 'lift' at the line cost you 'launch time'.

'The Black Arrow' never lifted, it just launched forward, like it was 'pre-loaded'.
 
I see what you're saying now. Thanks. The diagram doesn't show how that works but I can see how the arrows were conveying the general point you're making. The least lift needed to get the job done will certainly be the best. If none is actually needed, great.

To show how much (or little) lift will be generated, you need to find a diagram that shows torque, force and mass working through the link arm (or spring half), axle, etc. The result will then show the force down on the tire and this determines the amount of forward force a given tire can generate at the contact patch. If the torque arm created by the mass of the body and cg distance is greater than the torque from the tire (generated by the engine) resisisted by the axle and linkage/spring half then there will be no lift.
 
In 1965,

While the other 1965 Race Hemi B-Body cars were 'lifting-at-the-line'
before launching.

'The Black Arrow' was gone......

It barely lifted, as it left the line like a 'pre-loaded slingshot', and on 7" Slicks.

 
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