Shock Travel / Shock Length

[JAKES1969]

I have a 69 Camaro sbc, 17 x 8'' rims on front running a 235/45/17 tire.
I'm using Global West control arms and the lower arm has a cup that lowers the front 1'' and i'm using Vikings dual adjustable shocks 400 lbs spring i'm not sure the length. So my question is when you are setting the ride height you want by adjusting the the spring position how much shaft should you want visible to make sure you getting enough travel ?
What shock length would work best with the 1'' drop ? Also is there a "best" shock ? for ride quality ? or a shock spring that is superior ?
I raced motocross for 40 years and i've always experimented with my shock(s) to get the bike dialed in.

I'd like the frontend to have more travel and not be so rough driving.



Thanks ... JT

[Jk918]

The shocks you are using are very good, moving to a coilover shock can have its benefits depending on how you want the car to ride/handle, try adjusting the shocks to get the desired results.

[dhutton]

Coilovers should be roughly centered in their travel at ride height. If you are not you might need to change coilover to something shorter.

Don

[marolf101x]

First start with the control arms.
We want to double check that the suspension geometry compared to ride height is acceptable.
Look at the vehicle from the front. Draw a mental line from the center of the ball joint on the lower control arm to the front lower control arm mounting bolt at the frame.
This line should be very close to parallel with the ground at your desired ride height.
If it is not you'll need to adjust ride height via lower ball joints or spindles.

Once this is set you can measure rod stick-out on the shock. . .though sometimes this is quite difficult as you cannot see up into the spring cup on the frame let alone get tools in there to measure.
So most of the time you have to calculate this number.

On most muscle cars the shock/spring is located half way between the lower control arm pivot point and ball joint, which gives a 2:1 motion ratio.
If the wheel moves 2 inches, the shock only moved 1 inch.

For best ride quality you want at least 5 inches of total wheel travel in the front. I typically set them up for 3" of compression and 2" of rebound.
You want more compression as the vehicle hits more holes, undulations, bridge expansion joints, etc than it ever does jumping (getting the wheels off the ground is the only way to reach full extension/rebound).


So, if the wheel needs to move 5", and the shock moves half as much as the wheel, your shock must have at least 2.5" of travel.
If we desire 3" of wheel travel for compression to soak up the bumps before it bottoms out the shock, you'd have 1.5" of shock shaft showing at ride height.

[marolf101x]

"Also is there a "best" shock ? for ride quality ? or a shock spring that is superior ?"

Ride quality is very subjective. Do you want "driving your couch" old Cadillac ride quality, or "sporty but not harsh" pro-touring ride quality?
Both are achievable, but require different parts to get there.

When it came to tuning ride quality I always shot for "BMW M3". . .tight and sporty, but not harsh.

What effects ride quality?

Suspension Travel:
The suspension has to move enough that it doesn't bottom out when compressed (hitting bumps).

Springs:
The spring has little to do with ride quality so long as it's:
-close to it's stated rate and that rate provides the desired wheel rate
-that it's stiff enough to not allow the suspension to bottom out when compressed
-and not so stiff if doesn't allow the suspension to move much
The above is directly speaking about linear rate springs. Progressive springs are a bit different, but we can discuss later if required.

Different control arm manufactures place the spring (coil over) in different spots which changes the motion ratio, and no two cars weigh exactly the same over the front wheels and/or have the same unsprung mass, but typically anything from 400-800 lbs/in rate will work.

Bushings:
The OE's use large rubber bushings. These allow the suspension components to "soak up" the forces imparted on the wheel/tire (bumps, etc) and not transfer that energy into the driver compartment.
Two downsides:
1-your alignment changes if the control arms move. Not great for performance.
2-as the rubber twists under normal driving it adds spring rate. More movement, more twist, more spring rate. The OE's calculate the rate of the bushings, the rate of the springs, everything to get what they want in the end.

The Aftermarket wants performance. . .we don't want the control arms moving, so we use poly or Delrin. These are great at not moving, but also pass more of the bump energy to the driver.
The best you can do is keep things "rattle free" but rotating as freely as possible.

Tires:
Tires have a huge effect on ride quality. However, most pro-touring cars need the look, so 17 and 18 inch tires with relatively short sidewalls are the norm.
Not much you can do about it.

Shocks:
Shocks have a huge influence on ride quality and performance. How much force they create, in which direction (compression or rebound), and when they make that force all play into ride quality.
Performance requires the shocks to react very quickly and at very low shaft speeds. The more force the shocks create when the car is barely moving (rolling like in a corner, diving like under braking, or raising like on the throttle), the more control you have on how long the tire stays on the ground. Unfortunately, very high force values can create terrible ride quality. . .if your shocks provide a crap ton of compression force as soon as the shock moves it feels like the car has 1500 lbs springs in it as the impact harshness is huge.

When talking about ride quality my philosophy was always keep the compression force as low as you could. Let the spring and suspension movement soak up the bump. Then use a lot of rebound force to slow the wheel/tire coming out of the wheel well.

[JAKES1969]

WOW, that's a lot of really good information. So would a standard size shock be the best to go with or a shorter one to keep the visual ride height and have more shaft exposed ? Thanks a lot ... JT

[marolf101x]

I'm not sure I understand. What do you mean by "standard" size shock vs shorter? Do you have examples of what you are looking at?
"standard" meaning OE size, and shorter being Viking or similar?

You state you have Viking DA's. Those are twin tube shocks, and for the price are decent.
There are better options out there, some bolt in, some don't. I've always liked Ohlins TTX's (for twin tube shocks), but they aren't cheap, and they don't just bolt-in.

Again, shock stroke does not matter so long as you have enough to get 5" of wheel travel.