Rear coilovers question

[Opie1964]

Hello guys,
ive got a question on rear suspension setup. I see a lot of older muscle cars that have converted the rear end to a coil over setup. The question is why do they have the coilovers setup at a 15-25 degree angle? What's the benefits to this? Currently building a 93 notch mustang that is mini tubbed. Planning on a coilovers since we lost the stock spring location from doing the tub. we would like to set it up to be good around corners. Thanks for any help.

[ford396]

From my perspective; I would run them as straight up as possible to obtain as much motion ratio as I can get. I believe many are mounted however it is convenient, and not necessarily how is best. Need to run stiffer springs as the shock angle increases. Shock shaft travel also decreases, reducing control.

Bob

[Ron Sutton]

As far as motion ratio and shock control are concerned, getting the lower axle housing shock mount as far (wide) as possible ... is more valuable than the angle.

If my upper mounts need to be 30" wide, and I make my lower mounts 30" wide, and my track width is 60", we have a .50 motion ratio for the shocks. (Springs too, if it is a coil over)

If I can move the shocks straight outward (equally top & bottom) on both sides ... we want to ... to increase the motion ratio & give the shock some more control. We just need to adjust our spring rate appropriately to end up with our target wheel rate.

But if I can't move the top shock mounts outward ... due to the frame or whatever ... and I can move the bottom shock mounts outward ... we will get a gain that way. Say we leave the top mounts at 30" & move the lower mounts out to 42" ... we now have the shocks at a 25° angle ... and the motion ratio is .634 ... a 26%+ gain in this example.

So it's not that we want to move the top shock mounts inward & run a big angle. That would be decreasing the motion ratio. (Opposite of our goal). But by moving the lower mounts out, and accepting the angle, we're increasing the motion ratio.

Hope that clarifies this somewhat.

[Josh@Ridetech]

As far as motion ratio and shock control are concerned, getting the lower axle housing shock mount as far (wide) as possible ... is more valuable than the angle.

If my upper mounts need to be 30" wide, and I make my lower mounts 30" wide, and my track width is 60", we have a .50 motion ratio for the shocks. (Springs too, if it is a coil over)

If I can move the shocks straight outward (equally top & bottom) on both sides ... we want to ... to increase the motion ratio & give the shock some more control. We just need to adjust our spring rate appropriately to end up with our target wheel rate.

But if I can't move the top shock mounts outward ... due to the frame or whatever ... and I can move the bottom shock mounts outward ... we will get a gain that way. Say we leave the top mounts at 30" & move the lower mounts out to 42" ... we now have the shocks at a 25° angle ... and the motion ratio is .634 ... a 26%+ gain in this example.

So it's not that we want to move the top shock mounts inward & run a big angle. That would be decreasing the motion ratio. (Opposite of our goal). But by moving the lower mounts out, and accepting the angle, we're increasing the motion ratio.

Hope that clarifies this somewhat.

Nailed it, as always!

[Rod]

Nailed it, as always!

nice to see you back on the forum Joshy

[dontlifttoshift]

A 4" stroke shock mounted at 25* gets you 5" of wheel travel. That plus what Ron said, plus they usually package better that way.

[ford396]

I guess I would prefer to have them as far out as possible and straight.

[MonzaRacer]

[QUOTE=ford396;1235598]I guess I would prefer to have them as far out as possible and straight. [/Q
But then your shocks are not working for anything but going in a straight line.
Back in the day I got to go through a driving school that took us through parts and what they did for the car. We wound up with a Chevelle and they had us moving shocks in or out and a straight up and down did not function well in corners.
I have been helping people build and tune cars for years and I dont put drag shocks straight up and down. I still set my shocks at around 10-12 deg in at top. That has worked well for us and if/when customer ever started driving they dont have to reset anything. And as I see it the axle never raises exactly straight up and down,there is always a certain amount of axle twist and the shock angles help deal with this. PLus what Ron said.

[ace_xp2]

Increasing shock angle does generally have a negative impact on its effectiveness, but in most cases the overall effectiveness still ends up higher if you can push out the bottom to gain motion ratio.

[CSG]

I did a fox with a sideways C notch and a mini tub. This put the coilover as close to the wheel as possible while accommodating the tubs.