Shock/spring angle - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 14 Old 08-12-2011, 07:48 AM Thread Starter
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Shock/spring angle

I am thinking of moving my rear shocks inboard to make more wheel well room. I want to try and keep them as far out as possible and was thinking of tipping the tops in and running them on an angle. I think i can clear the mini tub by moving the bottom mount over a couple of inches then putting the top mount inside the frame rail. I remember rearing somewhere that by doing this it changes the spring rate. Can anyone point me to any data for this.


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post #2 of 14 Old 08-12-2011, 04:47 PM
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I assume you have coilovers, right?

Do some Google research on figuring out the motion ratio on a live axle and you will find what you need. I don't remember the details without researching it myself (and have all the points plugged into my program)

The more you angle them in at the top, the softer the same spring rate becomes at the wheels. So, if you have a 500# spring now with the shock straight up, you have pretty close to a 500# wheel rate. You lose some of that rate as you angle the spring in.

THere are some other considerations for wheel rate in bump versus roll and how those relate as you move the springs around, but for the most part on most cars, there isn't too much downside to leaning the spring in.

HTH,

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post #3 of 14 Old 08-12-2011, 10:15 PM Thread Starter
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Thanks for the reply. I had a link that i cant find that had some really technical info. I will do some searching for my answer.

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post #4 of 14 Old 08-13-2011, 08:57 AM
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The rate should change as a function of the hypotenuse between the shock's actual position and plumb. So if a 500 lb/in shock is mounted diagonally, with 6" laterally and 18" vertically between shock mounting points, the actual rate should be about 475 lb/in. Obviously, as the suspension articulates, the vertical parameter changes, so there will be some variability.
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post #5 of 14 Old 08-14-2011, 08:11 AM Thread Starter
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Thanks, I am trying to limit the angle to 3" laterally. From what you are saying it will change the rate minimally if i limit the angle.

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post #6 of 14 Old 08-15-2011, 07:29 AM
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Yeah, as long as your lower mount point is the same as stock. If you move it, you'll change the wheel rate.
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post #7 of 14 Old 08-15-2011, 07:56 AM Thread Starter
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So your are saying if i move the lower point inward that is bad. I am guessing it changes because of the distance to the end of the axle changes and that changes the ratio?

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post #8 of 14 Old 08-15-2011, 12:24 PM
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I c-notched the frame sideways. My shock retains the original angle. Top and bottom mounts were relocated but kept as far outward as possible. I also did an adjustable height upper mount so that ride height and shock length can be adjusted independantly.
I also kept the rear seat and the stock tank but can FULLY stuff 315's at all possible angles. I used a Koni "real" coilover shock.
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post #9 of 14 Old 08-16-2011, 07:23 AM
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Quote:
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So your are saying if i move the lower point inward that is bad. I am guessing it changes because of the distance to the end of the axle changes and that changes the ratio?
Yeah, because the moment arm of the spring force acting on the axle changes.
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post #10 of 14 Old 08-16-2011, 08:14 AM
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So your are saying if i move the lower point inward that is bad. I am guessing it changes because of the distance to the end of the axle changes and that changes the ratio?
Not "bad" it just needs to be accounted for. When you do the math on moving the mounts 1.5" or so you will see that the change is quite small.

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post #11 of 14 Old 10-28-2011, 11:07 PM
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Quote:
Originally Posted by CSG View Post
I c-notched the frame sideways. My shock retains the original angle. Top and bottom mounts were relocated but kept as far outward as possible. I also did an adjustable height upper mount so that ride height and shock length can be adjusted independantly.
I also kept the rear seat and the stock tank but can FULLY stuff 315's at all possible angles. I used a Koni "real" coilover shock.

Do you have any pictures of this setup? Do you have or have room for a panhard bar?

thanks

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post #12 of 14 Old 10-30-2011, 08:28 PM
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I have some somewhere but I can take some more. I run a watts link and a 3-link. A panhard bar would fit fine but you would have to fabricate the mounts as the notch in the frame is right where the normal mounts would be.
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post #13 of 14 Old 11-02-2011, 07:49 AM Thread Starter
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I would really like to see pictures of this. Please post them or PM me for an e mail address. I hope to start cutting in December as i now have cash for my axles and 1/2 of my rear brakes.

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post #14 of 14 Old 11-02-2011, 08:10 AM
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I will take pics this weekend and load them on my photobucket. I have an cad drawing as well that I will PDF and include.
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