Rear Suspension Questions

[Stallion]

Okay, I've been looking through my 1978 Service Manual and I have questions about functionality of the rear suspension (if there's on thing on cars that confuses me, it's suspension. There's just so much going on )...

I'm looking at a diagram of Strut Rod Mounting and it seems that the strut rods are attached to the strut rod bracket where they come together, but what are the outer ends of the struts attached to? It looks like they are attached to the spindles on each assembly. Is this right?

And, it looks like the differential is mounted right on the strut rod bracket. Is this so? Which route does the drive shaft take to get to the differential? Does it go rhgouth the crossmember?

And the differential looks like it is also mounted to the rear leaf spring. Is this so? Because then if you went over a bump, what would the differential be doing? Moving with the spring and strut rods?

I guess I don't really understand what the purpose of the strut rods are. What are they doing with the rear suspension? And the control arms seem to be holding the wheel bearings. Is this right? Does the control arm go bolt right to the rotor? Or maybe it is just attached to the bearing, in turn through the wheel.

What is the spindle doing? That also looks like it's in close with the rotor/bearing assembly. Correct? What exactly does the control arm do?

Thanks!!

TR

 

[yellow_2002_germany]

Some of the vette supplier catalogs have pretty good diagrams of how the suspension goes together. If I remember right Eckler's is one with good diagams.

Also, once you get your assembly manual it will have good pictures of how it all fits together.

 

[MaineShark]

To answer a few of your questions: the spindle, rotor, halfshafts, and wheels are all connected. They rotate. The wheel bearings attach the spindle to the trailing arm, keeping the spindle fixed in position, while allowing it to rotate. The strut rod helps to stabilized the camber (and, particularly, the camber change as the suspension moves up-and-down). If you look at your rear wheels, from behind, you'll notice that the top is a little farther in than the bottom. The strut rod is responsible for that angle.

In the C3 suspension, the halfshafts are also responsible for locating the left-to-right position of the rear wheel. In more updated suspension, a second rod, similar to the strut rod, is added at the top. With two rods to locate the wheel, the halfshaft no longer has to have sideways loads on it, which means it is stronger, and there is less wear on the differential.

The best way to figure it all out is to jack up one corner of your car, take off the wheel, and get under there with the diagram. That way, you can match pieces up with their counterparts in the diagram.

Joe

 

[JohnZ]

And, it looks like the differential is mounted right on the strut rod bracket. Is this so? Which route does the drive shaft take to get to the differential? Does it go rhgouth the crossmember?

And the differential looks like it is also mounted to the rear leaf spring. Is this so? Because then if you went over a bump, what would the differential be doing? Moving with the spring and strut rods?

What exactly does the control arm do?

Thanks!!

TR

The differential doesn't move - it's bolted solid at the top to the crossmember above it, which in turn is attached to the frame at each end through large rubber bushings. There's also a center mounting bracket from the front of the differential to the frame crossmember directly in front of it. Since it's solid and doesn't move, it also provides a convenient mounting point for the strut rod bracket and for the rear spring; all of those things are thus essentially mounted solid to the frame.

The aft end of the driveshaft goes above the frame crossmember the nose of the differential is attached to; since the differential is fixed and doesn't move, neither does the driveshaft (except for very slight up-and-down movement, since the nose of the differential is rubber-mounted to the frame (that mounting point, plus the two at the ends of the top crossmember, completely isolate the differential [and everything attached to it] from transmitting noise and vibration into the frame, and from there into the body).

If you're referring to the rear trailing arm when you say "control arm", its pivot at the front bushing (where the toe-in shims are in the frame pocket) allows the rear wheel to move up and down in the side view, and it also transmits acceleration and braking force from the rear wheel (through the spindle, wheel bearing and spindle support) to the frame so the car can accelerate and slow down. If you look at the suspension from the rear, the vertical position of the rear wheels (camber angle) is controlled at the bottom by adjusting the strut rod with the eccentric cam bolt at the inboard end; the outboard end, which is connected to the fork at the bottom of the spindle support, is just a pivot point. The fixed-length half-shafts provide the upper locating link for the trailing arm (in the rear view, it's a parallelogram, with pivots at each corner - the half-shaft is the upper horizontal line, the strut rod is the lower horizontal line, the differential is the vertical line at one end, and the spindle support is the vertical line at the other end).

 

[C3forME]

Check Zip Products, they have very extensive diagrams on there website and in their catalog.

 

[Stallion]

Thanks, John. I'll have to read over that numerous times to get it. If I don't understand something, I'll tell you. Thanks again!!

TR